Milky Way Stuffed With an Estimated 50 Billion Alien Worlds

astroengine writes "Using data extrapolated from the early Kepler observations of 1,235 candidate exoplanets, mission scientists have placed an estimate on the number of alien worlds there are in our galaxy. There are thought to be 50 billion exoplanets, 500 million of which are probably orbiting within their stars' habitable zones."

Comments

Oblig.

[Anonymous Coward]

Might as well get it out of the way in the first post: http://xkcd.com/605/

Re:Oblig.

[Anonymous Coward]

a hobby worthy of hyperbole. indeed

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[Anonymous Coward]

"Past returns are no guarantee of future performance"

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[symbolset]

"Let's go look."

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[hairyfeet]

Not to mention this whole "habitable zone" thing is a load of crap IMHO. I mean what are the odds that some alien race is gonna come out just like us and therefor need the exact same conditions as us? We have already detected the possibility of liquid water on Europa IIRC, and that is pretty damned far from the "habitable zone" so who is to say there aren't plenty of creatures living on worlds farther out?

We have no idea what kind of gravity or other conditions may exist there so until/unless we find a way to actually get out there and look their guesses are about as useful as throwing a dart at a dartboard. hell on our own planet we have things living in conditions that would kill us instantly, things that live in unbelievable depths, things that live on methane, etc, so any guesses right now will probably be as worthless as primitive man trying to guess how the world worked.

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[VanGarrett]

Planets orbiting in regions which we identify as a star's "habitable" zone are potential locations to establish colonies.

Beyond that, if we go there and find intelligent life, then it'll be much easier to establish a relationship with a species that breathes our air, has an overlapping thermal range of comfort, and lives under gravity and pressure conditions comparable to our own. Once we've made successful first contact a few times, and gotten the hang of intergalactic diplomacy, then we can worry about making friends with the damn Tholians.

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[Anonymous Coward]

What they specify as "habitable zone" is still quite broad... But it refers to having liquid water available on the surface... and as far as i know life cannot exist without water...

Also, liquid water is also not the only requirement, but an energy-source is also needed. They have found microorganisms far below the surface of the earth that use certain chemicals for energy, but don't think that would be enough to evolve into larger multi-cell organisms.

So sure they are probably life all over the universe, but i suspect that most larger creatures would be limited to evolve in the habitable zone.

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[Anonymous Coward]

By the time we are able to traverse the stars (if we survive that long), we will have long gotten rid of our frail human bodies. If we discover life at that point, it had better be the same technological level or we will have no interest and vice versa.

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[kvezach]

Planets orbiting in regions which we identify as a star's "habitable" zone are potential locations to establish colonies.

I imagine it would be much easier to just build a Bernal sphere or O'Neill cylinder than to physically go to another world. For discovery purposes, nothing beats exoplanets, but for colonization, space stations are cheaper.

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[Third Position]

Beyond that, if we go there and find intelligent life, then it'll be much easier to establish a relationship with a species that breathes our air, has an overlapping thermal range of comfort, and lives under gravity and pressure conditions comparable to our own.

I don't know about that. We don't seem to be able to establish much of a relationship even with dolphins or whales, reasonably intelligent species on our own planet. Indeed, they apparently have no interest at all in establishing a relationship with us. In fact, besides humans, I can think of very few species which fraternize outside with other species, unless they've been bred for it by humans. We may be the exceptional case rather than the typical one.

Establishing relationships might turn out to be a tricky affair, even with life which has evolved under similar conditions.

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[julesh]

Not to mention this whole "habitable zone" thing is a load of crap IMHO. I mean what are the odds that some alien race is gonna come out just like us and therefor need the exact same conditions as us?

Habitable zone === possibility of liquid water on open surface. This is much broader than the exact same conditions we require, and as we've had theorists thinking for a long time about possible life chemistries that are different from our own, and most still think that water-based life is the most likely to occur, it seems a reasonable starting point.

We have already detected the possibility of liquid water on Europa IIRC, and that is pretty damned far from the "habitable zone" so who is to say there aren't plenty of creatures living on worlds farther out?

Europa is a pretty unusual situation. It also has a few serious disadvantages that may make it less likely that life would occur on it than a typical "habitable zone" rocky planet, some of which are likely to happen anywhere a similar feature occurs. The biggest is that it's quite small, which reduces the likelihood of a life-starting reaction occuring there. It's energy-starved in comparison to a planet with a warm surface, which also makes the likelihood of a life-starting reaction lower. Both of these issues are likely to apply to Europa-like moons in other star systems.

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[jbolden]

That may be a technological challenge. We still haven't really figured out how their language works yet. Once we know how to speak dolphin we can see how things turn out. As for fraternizing outside the species.... you see it a lot with herbivores.

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[__aatirs3925]

I saw on a BBC documentary how humans and dolphins would work together. The dolphins would push the fish inside the fisherman's giant nets and in the end, the dolphins get to eat a few fish for the day. But then again, that's just like training a dog, kind of... Another one was when the African tribal men would speak to birds to locate honey, and the bird would let them know. In the end, the bird does get a good cut. Some animals will work with each other to reach their goals too and I think that is the case with any animal that has the instinct of feeling more comfortable when there is partnership (like wolves, lions, elephants, etc).

Going back on topic, life doesn't always have to be carbon based and that has been proven last year by NASA, and there are definitively "life" in the most extreme parts of the world. It wouldn't be a surprise if there is life on Mars, in fact I'm 99.9% confident that there is, except it's not really an exciting kind of life form. The great thing about space travel now is that we don't have to be there to explore it. We've sent probes and robots to do the scouting for us, so if we need to scout planets with other human / non-human colonies which we will eventually, we're likely going to do it in the shadows.

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[nospam007]

"But it refers to having liquid water available on the surface... and as far as i know life cannot exist without water..."

The Inuit don't seem to have a problem with it.

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[NiteShaed]

The biggest is that it's quite small, which reduces the likelihood of a life-starting reaction occuring there

Well duh, that's what the monolith is for.

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[khallow]

life doesn't always have to be carbon based and that has been proven last year by NASA

No, that wasn't proven by NASA last year. They found an organism in briny water which they thought used arsenic in place of phosphorus on Earth. I understand that research has been shown to have serious problems. But even if true, the organisms in question still use typical amounts of carbon.

Instead, I'd say that modern computers show weakly that you probably can have life based on semiconductors such as silicon.

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[swalve]

But they are on a planet with surface water. A planet with no water on the surface most likely isn't going to spawn curious monkeys who learn to make tools.

The habitable zone is pretty vast: the area where planets have stuff in all three phases fairly available. If a planet is all gas, it is doubtful molecules will be in enough contact with other molecules to form anything close to life. And if it is all solid, nothing can move around. An all water (or some other universal-ish solvent) planet might evolve into an all fish-creature life form. The key to forming life is that the planet needs to be dynamic- stuff needs to slosh around just enough to have the potential for stuff to RANDOMLY combine into forms that lead to other forms that lead to life.

I also suspect temperature has something to do with it- too little energy in the system and there isn't enough time since the Big Bang for stuff to have randomly combined yet. To hot and any life that could form will have burnt out already, or the planet dried up before life could form. I suspect Mars is like this. I have no doubt that something life-like was there, but the planet didn't have enough "oomph" to maintain it. You can't tell me some of that stuff from the Mars Rovers doesn't look like ancient terra cotta. (Or would it be Mars Cotta?)

(Water is necessary for life because it is a universal-ish solvent. Enough different molecules can dissolve/mix with it that life can eventually form. I'm sure there are other solvents that are equally solvent that some other kind of life could eventually form.)

(moons are different- a moon around a gas giant might be able to support life, but that would be even more rare than a standard planet. The moon would have to be locked in some kind of orbit that allowed it to receive energy from a star (or the gas giant would have to be star like and emit/reflect enough energy) to create the dynamics necessary, and for long enough that they can adapt and reproduce before the moon swings around to the dark side. It is conceivable some form of life might form that can tolerate being frozen for half of its existence, but it is unlikely. On a universe scale, so rare as to be undiscoverable.)

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[TheRaven64]

Instead, I'd say that modern computers show weakly that you probably can have life based on semiconductors such as silicon.

Not really. They replace the neurones with silicon, but most of the 'body' of a machine is made of iron and so on. Often plastics, and then you're back to being carbon based. To have the same sort of reactions that carbon undergoes, you'd need a much hotter and denser environment - perhaps inside a gas giant you might see similar chemistry, but you'd need a gas giant with enough silicon for them to form self-organisng molecules.

That's the other problem with non-carbon-based life. The precursor chemicals for amino acid based life seem to be quite abundant and are produced at relatively low energy levels. Carbon forms four bonds at low energy levels, which means that it assembles into some very complex molecules. It is one of the lightest elements, so it's abundant in the universe - much more so than silicon. To form complex life, you need to first form simple life. To form simple life, you first need to form complex chemicals. This is much easier with carbon than with any other element. If there were an element that formed complex compounds at a lower energy level than carbon, then it would be a more probable base element for life, but there isn't.

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[GNUALMAFUERTE]

Maybe because we are looking for creatures that are sort of like us?

Sure, there are many extremophiles living on earth, but they are small, simple organisms. That's all that can thrive in those conditions. Sure, finding microorganisms outside of earth will be absolutely awesome, and we would learn a lot, but we would still feel like the only intelligent species on the planet. Our ultimate goal regarding the search for life in the universe, is to find other intelligent species, and we do know that more complex and intelligent organisms require certain conditions. The habitable zone is no guarantee, sure, but it's a start.
Also, even if the impossible were possible, and we discovered that there are mammal-like creatures with advanced brains living in Jupiter, we know for a fact that a manned mission to Jupiter would be impossible. We are looking for advanced creatures living in planets that we could eventually visit without dying.

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[khallow]

but most of the 'body' of a machine is made of iron and so on

Most of the body of the machine doesn't matter. We aren't a concrete-based or steel-based life form because we use considerable concrete and steel in our habitats and tools.

Your point about the prevalence of carbon is well placed, though it is worth noting that silicon is extremely prevalent in the inner Solar System and many places have far greater access to it than than carbon (the Moon and most asteroids, for example).

Also we use silicon rather than carbon in our computers because silicon is much easier to dope and yield the semiconductor properties we need for computers.

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[Anonymous Coward]

Modern computers are so far from showing anything like intelligence, much less life, that it is laughable to use them as evidence. They are very complicated but not very complex, whereas life is both, and the complexity increases the more we learn about life.

The difference between a hammer and a computer is massive. The difference between a computer and an ant, or even a cell, is to most people quite literally unimaginable, which is why the myth of computerized life is so prevalent. We're talking many orders of magnitude, like first comparing a house to a skyscraper and then a skyscraper to the earth.

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[khallow]

Modern computers are so far from showing anything like intelligence, much less life

You have "intelligence" and "life" switched. Also, computer viruses are a counterexample to the claim that modern computers are far from showing anything like life. They replicate like life, they consume resources like life, they even evolve like life (though that normally requires the intervention of programmers).

The difference between a hammer and a computer is massive. The difference between a computer and an ant, or even a cell, is to most people quite literally unimaginable, which is why the myth of computerized life is so prevalent. We're talking many orders of magnitude, like first comparing a house to a skyscraper and then a skyscraper to the earth.

Why would computerized life need that level of complexity merely to exist? The environment is simple and designed to run programs efficiently.

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[SteveFoerster]

Maybe if we do find a suitable planet, you and the rest of the racist "third position" can go live there in monochromatic solitude.

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[jbolden]

Your average computer today is vastly more complex than an ant. In the late 80's we could make comparisons between an ant's brain and a computer, today the computer has it by a mile.

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[jbolden]

Well you are actually disagreeing with the gp in that you think we have formed a relationship. I'd say I agree with him unless dolphins start bring over other dolphins. Then we are looking at the difference between training and trading.

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[ChromeBallz]

It's a statistics thing, though i agree the current sample size is too small to base too many theories around the concept of a habitable zone. The important factor here is liquid water, which is only found in the right conditions, ie, the habitable zone. At the moment we don't know whether it's possible for any other conditions to generate life, let alone how - But on the plus side, this can only mean that this is a worst case scenario and there are *at least* 500 million planets in the galaxy capable of supporting (human) life.

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[Peeteriz]

Today high-end computers have comparable horsepower to human brain - *if* we knew how to run human brain 'software' on silicon von Neumann machines, the raw computing power would be enough already.

Brute-forcing the problem will add many orders of magnitude, though - but if Moore's law holds for a couple more decades, then it will give us the computing power even for that.

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[jbolden]

Moore's law hasn't held up this whole decade. Look at what's happening with CPU speeds. But...

1) We are doing way better in optimizing libraries.
2) We are making improvements in parallelism.
3) We just had a major improvement in disk speeds (SSD).

So I think we get the speed increase. 1000 ~ 2^10. We can get 10 more doubles I think.

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[blue trane]

You don't go out in nature much, do you?

Off the coast of Baja, California, scientists find gray whales are uncharacteristically social with humans, even allowing their faces, mouths and tongues to be massaged as they bump up beside boats.

http://www.npr.org/templates/story/story.php?storyId=106541921

Each animal is an individual. Some want to enter into collaborative relationships, like birds singing with other species (including humans). I just watched a documentary on Tesla; he had a special relationship with a (wild) white pigeon that came to him when he called.

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[pckl300]

I don't know about that. We don't seem to be able to establish much of a relationship even with dolphins or whales, reasonably intelligent species on our own planet. Indeed, they apparently have no interest at all in establishing a relationship with us. In fact, besides humans, I can think of very few species which fraternize outside with other species, unless they've been bred for it by humans. We may be the exceptional case rather than the typical one.

Hell, forget dolphins and whales. We can't even get along with people from another country, much less another species.

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[Anonymous Coward]

Not to mention this whole "habitable zone" thing is a load of crap IMHO

You seem to be misunderstanding the point of the habitual zone.
No one is claiming it is the only place life can occur. No one is claiming life can't arise outside of that zone.

All that is being said is that within the habitable zone, we have one example of life happening (Us) where as outside of that zone we have zero.

If the odds of finding life in a zone are 1 over a huge number, that is still much larger than the odds of zero over the same huge number.

We are already grasping at straws, so might as well stick with the place with the proven higher odds of finding life.

If you wish to start up a scientific program and hunt for life in these far out areas, I doubt anyone will tell you to stop doing that. Though you might find it tricky to get funding with those odds.

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[Anonymous Coward]

If we discover life at that point, it had better be the same technological level or we will have no interest and vice versa.

Yes, because historically speaking that's what happens when an advanced race meets a group that's less developed.

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[Anonymous Coward]

Well, you obviously go out a lot, since all you can contribute to the topic is your speculation, based on a story you've read on the net. You should cut down on the TV, and get a pet instead maybe. Then you'll see how these things work, and how OP had a point.

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[Thing 1]

[...] so any guesses right now will probably be as worthless as primitive man trying to guess how the world worked.

Are you advocating exoplanet religions?

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[Thing 1]

Establishing relationships might turn out to be a tricky affair, even with life which has evolved under similar conditions.

Yep, the "you are crunchy and taste good with ketchup" foreign policy.

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[Artifakt]

If we make contact with something that needs 4 Gs +, and an atmosphere predominantly of methane, at 143 Kelvin, we have the advantage of knowing we won't covet each other's preferred real estate. A basic treaty, where they tell us where the light, Oxygen covered worlds are, and we tell them where the cold heavy ones are, and we start off with a common benefit to help smooth the path for other negotiations.

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[cavebison]

The "Goldilocks Zone" is only one of a number of conditions which need to be met for intelligent life.

There's the issue of the Solar Wind blowing your atmosphere away, so you need a magnetic field to shield you, which means a spinning planet with an iron core - at least I that's the only way I've heard about. The Drake Equation doesn't account for that.

Then there's biology. We can see on Earth that any civilisation, in order to progress technologically, requires enough food in their immediate environment to get beyond subsistence living. Evidence - Australian Aborigines, Torres Strait Islanders, PNG.. no advances because they had to spend all their time looking for food.

So the gap between "planet in the right zone" and "civilisation with radio dishes" seems a pretty big one, whether they're a humanoid or a frogoid.

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[Anonymous Coward]

You are thinking on such a minuscule scale. It's not going to be like Star Trek or some fantasy crap. There would be million or possibly billions of years worth of evolutionary difference. Currently, humans would be nothing more interesting than a slime pool of amino acids and proteins if a starfaring race were to even notice us.

How often do you or most people go out collecting samples from random slime pools to torture and subjugate?

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[daniorerio]

you clearly know nothing of biology...

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[Chalnoth]

Um, it's called symbiosis. Happens all the time. In fact, symbiosis is the norm, not the exception.

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[jbolden]

OK so what specifically is the biology thing I fail to know?

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[juhaz]

"But it refers to having liquid water available on the surface... and as far as i know life cannot exist without water..."

The Inuit don't seem to have a problem with it.

The inuits aren't 60% water like the rest of us? Wow, that IS huge. How come nobody noticed before?

5 x 10^19

[Anonymous Coward]

Taking the Milky Way as an average galaxy, and there are about 100 billion galaxies, that indicates that there are about 5 x 10^19 planets orbiting within their stars' habitable zones in the universe. Big place!

Re:5 x 10^19

[wierd_w]

however, the number of known civilizations (planet wise) is still 1, out of the 1,235. This makes a rather large dent in the computational threshold potential for Drake's famous equasion.

While there might be lots of dirtballs, and even more planets in need of a collossally sized gas-x pill, the number of potentially habitable is small, and of those the number that would be reasonably extrapolated to contain life would be even smaller, and the number with active civilizations even smaller still.

   

Re:5 x 10^19

[Rei]

I must have missed when they probed those 1,235 planets for evidence of civilization and declared that they were able to rule it out.

Re:5 x 10^19

[SnarfQuest]

When did they show that there was intelligent life here on Earth? I'll point to Reality TV as an opposing opinion.

Re:5 x 10^19

[wierd_w]

Natch! Good point!

Re:5 x 10^19

[outsider007]

You must be fun at parties.

Re:5 x 10^19

[swalve]

Someone had to be smart enough to figure out how stupid everyone else is.

Anyway, we are smart enough to make a radio tower work. That's something. Intelligence isn't canceled out by ignorance, it is enhanced by it. Rush Limbaugh is a grade-a moron, but he has legions of followers that make him *look* smart. Without them, he'd just be the smelly guy at the end of the bar annoying the patrons and looking for pills.

Overpopulated much?

[Anonymous Coward]

I guess L. Ron Hubbard was on to something after all

Re:Overpopulated much?

[Anonymous Coward]

Is that you, Miscavidge?

There's no intelligent life close by

[davidwr]

Any truly intelligent life would've detected us and fled to another galaxy long ago.

Re:There's no intelligent life close by

[Anonymous Coward]

No doubt. I'm fairly certain we've turned our arm of the galaxy into the cosmic equivalent of a Florida trailer park.

Re:There's no intelligent life close by

[Bruha]

There probably is, but apparently none of them have either invented FTL travel, or they have some prime directive crap going on. Then again ancient aliens is a pretty good show, makes you wonder if they really walked among us, why did they leave and never came back.

Re:There's no intelligent life close by

[Anonymous Coward]

>There's no intelligent life close by
Sure there is, there's you.

Re:There's no intelligent life close by

[AliasMarlowe]

I'm fairly certain we've turned our arm of the galaxy into the cosmic equivalent of a Florida trailer park.

Not yet, but we've only just started.

And that's the key point in the "OMG where are the intelligent aliens?" type of thinking. Earth has existed for about 4.5 billion years, and acquired some sort of life early in its existence. It's only in the last century that it has emitted anything which could be recognized from a distance as a sign of quasi-intelligent life (50/60Hz AC beacon, radio, TV, etc.). So there is a radius of about a hundred light years where our existence could be just barely detected; that's about one thousanth of the diameter of the Galaxy we live in. And maybe we just happen to be one of the fast developers; it may take another few billion years for comparable development on other suitable planets. And then, we have no data on the longevity of such developed societies. Maybe we're a slow developer, and the others are already mostly radioactive ashes.

BTW, don't bother citing the stupid Drake equation - it applies only to probabilities at steady-state, not to those in an evolving universe.

Re:There's no intelligent life close by

[alienzed]

Not necessarily but we so rudely never answer the subspace messages they keep sending! All for the better they are probably trying to sell us something.

Re:There's no intelligent life close by

[Anonymous Coward]

What's more apparent is that FTL travel is impossible. If it weren't, first race to invent it would've colonized everything long ago.

FTL is needed to escape nearby supernovas. Without it, all civilizations will inevitably die when their own or neighbour star explodes.

Re:There's no intelligent life close by

[Anonymous Coward]

Or they've been around 5 million years ago, before we evolved...

Re:There's no intelligent life close by

[MichaelSmith]

They could always build a ringworld.

Re:There's no intelligent life close by

[PingPongBoy]

Any truly intelligent life would've detected us and fled

The tragic truth may take on a couple of possible forms:

- Intelligent life forms typically evolve to be just like us. The conditions favoring life and evolution in all likelihood culminates in intelligent primates. Out of the chaos of the second law of thermodynamics, societies of intelligentsia will wind up with all our shortcomings. We can't trust them, and they can't trust us. Hell, we can't trust us.

- When we finally get face time with alien intelligence, it might not be intelligent life. Get off my lawn.

Re:There's no intelligent life close by

[DigiShaman]

Maybe that first race is very picky as to where and what to colonize. Just because the can doesn't have to mean they will.

Re:There's no intelligent life close by

[Black Gold Alchemist]

Three points.

Point 1 is that FTL is looking possible but hard. There are valid solutions to general relativity where Star-Trek like FTL happens.

Point 2 is that FTL is unnecessary for interstellar travel. Project Orion showed that interstellar travel might likely be possible without FTL. Even if biological beings can't live forever (which I think they can), robots can. If we advance, say 50-100 years from now, our economic productivity will be such that an individual, or small group of individuals, could launch a self-replicating interstellar probe that would send back information. If we've scoured the Earth and made surveys, but we haven't found any probes or remnants.

Point 3 is that neighbouring supernova events appear survivable even without travel. Life would suck, but we could predict if say Sirius was going nova and take precautions such as living under lead shields. Supernova of the current solar system would be survivable because of point 2.

In sum, I see two scenarios for why aliens aren't here yet:

1. They are, but they don't want, can't or otherwise do not interact with us. Why I don't know, but it could be true. If the aliens were human, some alien idiot would have broken the rules and contacted us for some reason.
2. They for some reason do not exist or are not developed yet. This I doubt. I believe that the Dinosaurs were on the way to sapience before the asteroid hit, and if it hadn't have happened, we would be Velociraptors. We would have achieved our technology level many years earlier.
Notice that there is no no-FTL scenario. This is because of self-replication.

Re:There's no intelligent life close by

[Black Gold Alchemist]

Even spam from the aliens might be very valuable. We might get a copy of Wikipedia Galaxy Edition included in the transmission to throw off spam filters.

Upon seeing your nickname, alienzed, I hope you can reveal this mystery to us.

Re:There's no intelligent life close by

[pakar]

Ehm... "again ancient aliens" and "good show" in the same sentence... Don't get me started on all the factual errors in that show.... But it's always fun to watch for a BIG laugh..

Re:There's no intelligent life close by

[Anonymous Coward]

Maybe the evolution of complex life is so rare that the chances of it happening twice in a single galaxy is practically zero.

Thing about maybes is that they are all equally "valid" and equally "wrong". There is no way at this point to say which way things go from the data.

Also note that the more habitable planets we find, the more of a paradox Fermi paradox becomes. Its the solutions that don't become clearer.

Re:There's no intelligent life close by

[Arlet]

If we advance, say 50-100 years from now, our economic productivity will be such that an individual, or small group of individuals, could launch a self-replicating interstellar probe

Unless our civilization crashes before that. Given the fact we're quickly running out of oil, that scenario seems more likely.

Re:There's no intelligent life close by

[julesh]

Point 1 is that FTL is looking possible but hard. There are valid solutions to general relativity where Star-Trek like FTL happens.

The validity of these solutions is somewhat disputable; they all require the use of some as-yet-unknown material that has negative mass. As no such material is even theorized to exist, to suggest these solutions are valid seems to be jumping the gun somewhat. All we can say is that general relativity by itself doesn't rule out FTL travel.

Re:There's no intelligent life close by

[Anonymous Coward]

hehe.
we are unique. there is no aliens.
yours, Sic Bo

Re:There's no intelligent life close by

[Zachary Kessin]

thats ok, its probably some green prince with $40,000,000 in a bank account he wants our help with. ;)

Re:There's no intelligent life close by

[TiberiusMonkey]

I've not seen Ancient Aliens in the UK, but we have a show called "Most Haunted" here where they visit so called, haunted places, and it pretty much sounds like the same thing, any noise, anything slightly strange that can't instantly be explained is labelled as a ghost.

Re:There's no intelligent life close by

[boristhespider]

actually it needs basically dark energy. if you believe that dark energy is responsible for the acceleration of the cosmos, you are lead to believe that alcubierre solutions are viable. an enormous caveat is that you also have to believe that quantum gravitational effects won't destroy the system. you also have to believe that it's a *physical* solution; like pretty much every solution in relativity it assumes that it is the *entire* spacetime, past, present, future and all the way to spatial infinity. that's never going to be the case. even in deep interstellar space you've got an absurdly complicated mess of "solutions" coming from the various combined star systems and their planets. the spacetime around you is only locally flat; the asymptotic infinities bear only an approximate resemblence to those of flat spacetime, and the overall causal structure is very different (you'll run into a black hole along a multitude of directions, if nothing else.)

and we have no clue if you can still make something like a "warp drive" solution viable, even assuming we can harness dark energy as a source, which even assumes it exists in the first place.

so it's a tricky issue - even trickier than you say, even though such a material *is* theorised to exist.

Re:There's no intelligent life close by

[boristhespider]

Precious few stars in our vicinity are going to go supernova anyway. Arcturus probably will but i don't think any of the others are anything like big enough. Sirius is the only other possibility within I think 30 light years or so, and for some reason I'm getting the dim memory of being told (at uni) it's too small. Supernovae are really not that common.

Re:There's no intelligent life close by

[Anonymous Coward]

- Intelligent life forms typically evolve to be just like us. The conditions favoring life and evolution in all likelihood culminates in intelligent primates. Out of the chaos of the second law of thermodynamics, societies of intelligentsia will wind up with all our shortcomings. We can't trust them, and they can't trust us. Hell, we can't trust us.

That is the most arrogant, self-important, big-headed piece of information I've heard all day. Look at the difference between humans (possibly an intelligent species) and a bonobo (not an intelligent species): we are mostly the same, with four limbs terminating in fingers, a head with two eyes, two ears, a nose and a mouth at the top of the body, very similar internal organs, and very similar size. Where am I going with this? What I'm saying is that most of our current characteristics were brought on by previous evolutionary stages which did not develop into intelligence, and only a recent change did. If within the Earth's climate we get such a large diversity, for example between a mosquito and a tree, then even a slight change would bring massive differences in what evolves in 3 billion years. At least all life on Earth is based off of DNA, which evolved here. Who is to say that alien life would also be based on DNA? It probably would be based on carbon, because it is very common and chemically versatile, but surely not on DNA.
Also, what is that on the second law of thermodynamics? We have many shortcomings because of our evolutionary past, not because of the fact that no process is possible whose sole result is the transfer of heat from a body of lower temperature to a body of higher temperature. Remember this only applies for closed systems, and we have a large input of energy: the Sun. And you seem to be contradicting yourself: why are we the pinnacle of evolution, the only form capable of possessing intelligence, and yet we have so much shortcomings? If their home planet is covered in more water than ours, why wouldn't they be water-based? Or if it was very far away from the star, but was geologically active and had an extremely large cave system, why would they have eyes?

Re:There's no intelligent life close by

[Anonymous Coward]

Wikipedia Galaxy Edition

Eh, most of it'll probably be petabytes of talk pages and administrative chatter, with the rest being deleted for non-notability. :P

Re:There's no intelligent life close by

[Intrepid imaginaut]

they all require the use of some as-yet-unknown material that has negative mass. As no such material is even theorized to exist

Einstein among others suggested that the Casimir effect might be indicative of the possibility of such a substance existing.

Re:There's no intelligent life close by

[Anonymous Coward]

Not to go offtopic, but I would like to point out that a show called "ancient aliens" on the "history channel" makes the history channel a bit more like the "speculation network" -- but wtf do I know. Our current history could just as much be broad speculation, and a bunch of especially slow people believe that it was only ~2,000 years ago when a miracle worker named Jesus walked the Earth -- yet ALL of these people think it is absurd that Xenu came to the planet and put hydrogen bombs around a bunch of volcanoes because he was a gigantic doucheasaurus rex.

tl;dr: its all hypocritical bullshit and we're probably wayyyyyyyyyyyyyyyy overthinking the past to explain what is lost to history and lack of written language

Re:There's no intelligent life close by

[TheRaven64]

The same can be said of non-FTL travel. The galaxy is about 100,000 light years across. If you can get to 10% of the speed of light - a bit beyond our capabilities in terms of engineering, but not in terms of science - then you can cross it in a mere one million years. Assume that you launch Von Neumann probes to all of your neighbouring stars. When they arrive, they start harvesting asteroids and launching copies of themselves for a few years. They could easily cover the entire galaxy in a few tens of millions of years. The galaxy has been around for a few billion years, but we've yet to see any evidence of a species doing this, which implies one of four things:

1. We're the first intelligent life form to evolve.
2. Something stops intelligent life becoming spacefaring (e.g. self destruction) in all cases before us, and potentially in our case.
3. There's a much simpler way of getting between planets (e.g. some form of wormhole) that science more advanced than ours discovers before launching galaxy-colonising probes becomes an attractive proposition.
4. There is something more interesting than space flight (e.g. sublimation / apotheosis) that civilisations do instead of colonising the galaxy.

Re:There's no intelligent life close by

[swalve]

Dark energy is crap. It was made up to explain why our math is wrong- we believe that stars are putting out X energy, but we are only seeing X-Y energy. Y must be dark matter! We can only see the energy that is zigging in our direction, we can't see the stuff that is zagging in all the others. Even though on the scale of the earth, EM waves/particles are functionally non conflicting, over the scale of the cosmos, a stream of photons coming from some galaxy toward us over the last billion years is going to encounter a LOT of other photons traveling every other direction and get nudged around.

Re:There's no intelligent life close by

[ArcCoyote]

Why? we're harmless.

Re:There's no intelligent life close by

[newcastlejon]

Why? we're harmless.

Well, mostly. See *Genocide.

Re:There's no intelligent life close by

[boristhespider]

Believe it or not but I'm a cosmologist by trade and while I agree with a part of what you're saying -- dark energy is a term in the equations that balances everything -- the evidence is a lot stronger than "stars are putting out X energy, but we are only seeing X-Y energy. Y must be dark matter!" (I imagine that was a slip of the fingers; dark matter and dark energy have contradictory effects. Dark matter is a non-luminous clustering form of matter which appears to be necessary to get galaxies to form how they do, while dark energy is a non-luminous *non-clustering* form of matter with some form of anti-gravitational effect. For reasons I won't get into at the minute, if you believe the Friedman model -- which is your call; I have firm suspicions but there are too many successes of the model to simply dismiss it -- including predictions that have been tested and found well within experimental error).

I may not actually *believe* it myself either because, like you, I feel it's pure phenomenology, the evidence is too strong to dismiss that readily. Also, the evidence is very difficult to replicate the features of dark energy by encounters of photons with a LOT of other photons and getting "nudged around". (I'm not totally sure how that happens, either. Light travelling over cosmological distances can and does interact with matter -- which has significant but very characteristic effects on the CMB radiation in particular -- but I'm not aware of any strong self-interaction between photons. QED would probably not be a renormalisable theory if photons were strongly self-interacting. But I'm not a quantum physicist so I could very well be wrong.) You can do it by putting us in a big void, but then you really struggle to fit the characteristic wavelength running through the large-scale distribution of galaxies (which isn't a myth; it's observed). Actually that wavelength is a killer unless you use dark energy :( *And* dark matter.

Re:There's no intelligent life close by

[rich_hudds]

The 'stupid' Drake equation takes into account the likely lifetime of a civilisation.

The best book I've read about the likelyhood of life being out there is The Eerie Silence witten by Paul Davies who is involved in the SETI project.

He actually thinks we may well be alone

Re:There's no intelligent life close by

[ArcCoyote]

Ok, MOSTLY Harmless.

Re:There's no intelligent life close by

[Anonymous Coward]

The basic assumption here is that there's intelligent life on Earth, but I think you've proven otherwise.

Re:There's no intelligent life close by

[rubycodez]

haha, people always talking about our incredibly weak radio signature. I'd like to submit for consideration the possibility that our nuclear tests of the mid 20th century have been detected, and a reply is already coming back in fusion powered craft at 3-7 percent lightspeed. In other words, in about 20 to 500 years this Earth will be sterilized of human life.

Re:There's no intelligent life close by

[Cold hard reality]

5. "a bit beyond" is a gross understatement, not just for us, but for all other life forms.

6. "mere one million years" is a fantastically long voyage for us. Beings with million-year life spans are unlikely to evolve very rapidly.

Re:There's no intelligent life close by

[rubycodez]

The oldest of the "metal-rich" Population I stars only have a fraction of the heavier elements that our Sun does. It's the later systems that have the elements to make life nutrients and rocky planets in abundance. Since after 5 billion years we only recently had humans, maybe the evolution of intelligent life will be common but we're kind of early so no friends yet.

Re:There's no intelligent life close by

[Black Gold Alchemist]

Given that civilization was supposed to crash by now for lack of food, and that fact that we are still alive, that is unlikely to be true. Those who look beyond the predictions based on linear extrapolations using current technology are already synthesizing oil from renewable energy sources, and are likely to create an unlimited amount of such oil in the future.

Re:There's no intelligent life close by

[Arlet]

Given that civilization was supposed to crash by now for lack of food, and that fact that we are still alive, that is unlikely to be true

That's not a very convincing argument. The fact that some of the predictions were premature doesn't mean they're inherently invalid.

Realistically, none of the proposed alternatives can scale up in time to replace falling oil production.

Re:There's no intelligent life close by

[Black Gold Alchemist]

In 30 years, wind will be the sole source of energy in the united states at current growth rates. This will scale up. Solar is falling in cost at 9% per year and still growing. Both together will scale up. EV's are shipping, and are going to be charged by the wind.

It happened with wood, it happened with whale oil, it happened with metals, and it happened with food. But we're still here. I know that those are past events, but they are events where similar lines of thinking occurred. In all cases, technologies that were denounced as fantasies that could not exist, be economical or scale up fast enough saved us. Today, those fantasy technologies are all around us, improving every day. We don't see much of the growth, but it's happening, and those who search for it can see it.

Notice how you said that none of the alternatives could scale up fast enough? A few years ago, you would have said that none of the alternatives were economical. Years before that, you would have said that the alternatives were technologically infeasible.

Re:There's no intelligent life close by

[Anonymous Coward]

No, FTL was patented, so they couldn't use it.

Re:There's no intelligent life close by

[blue trane]

I can't fully explain the orbit of Mercury, but saying that means the Sun is the center of the solar system is just silly.

Re:There's no intelligent life close by

[Anonymous Coward]

Some ppl are like horror movies, they get off on scaring others.

Re:There's no intelligent life close by

[dryeo]

Our vicinity will change over time. This brings up the point that the Sun is in a nice circular galactic orbit which keeps us in the galactic habitable zone. Many other stars have orbits that take them into the core region where presumably the radiation levels are too high for life and the odds of passing another star close enough to perturb any planets orbits goes way up.

Re:There's no intelligent life close by

[davidwr]

>There's no intelligent life close by
Sure there is, there's you.

I post on Slashdot without checking the "Post Anonymously" box. I'm pretty sure that disqualifies me right off the bat.

Re:There's no intelligent life close by

[lennier]

If any intelligent aliens out there have read E.E. "Doc" Smith's Lensman books, they'd leave the galaxy too.

And leave a firewall 10 galaxies wide, just to be safe.

Re:There's no intelligent life close by

[Anonymous Coward]

Yeah, they are all lurking in the Ida galaxy, those lurking little grey lurkers they!

Re:There's no intelligent life close by

[guybrush3pwood]

Is that you, Richard Dean Anderson?

Re:There's no intelligent life close by

[Anonymous Coward]

Or nuked us. Obviously, we have not yet been nuked by the nearest paranoid alien race who would send nukes the moment they detect life via radio waves. That means that either:
1. There are no such alien races.
2. Such alien races are further away than the distance required to detect the signals from 100 years ago, fire off the nukes (or any other world sterilizing technology), and for us to receive them.

Re:There's no intelligent life close by

[myoparo]

Yeah except that the radiation from our nuclear tests still travels at the speed of light, meaning it has not reached anything except whatever is within ~60 light years. It's not the any intelligent culture will know as soon as we set one off.

Re:There's no intelligent life close by

[rubycodez]

there are over a hundred stars within just 20 light-years. 1400 within 50 light years. Our nuclear tests could have been noticed ten years ago in that volume!

Re:There's no intelligent life close by

[kryliss]

.............. kill Zach ..........

Re:There's no intelligent life close by

[DrVxD]

On the one hand, it would be arrogant in the extreme to assume we are the only intelligent life in the galaxy.
On the other hand, somebody had to be first...

Only 50 billion?

[qmaqdk]

Since there are between 200 and 400 billion stars in the Milky Way that amounts to between 0.25 and 0.125 planets per star on average. Granted TFA states that there are at least this many, but I would have thought the number be much higher, considering the number of planets in our own solar system.

Re:Only 50 billion?

[Anonymous Coward]

Having planet formation at all is the statistically meaningful event. Getting one or nine as the terminal result is just a matter of the initial distribution of the cloud.

And 500 million in the habitable zone is only 5*10^8, which is a really small number to be plugging into a modified Drake equation unless the likelihood of life occurring and continuing to exist is overwhelmingly high and unless the probability of life developing intelligence is similarly high. If each term is 1% (by many estimates, an extremely large value) you are already down to 50,000 planets before you get into terms relating to how detectable civilizations are from what distance and whether they exist over a period such that we're able to detect them at this time and from this distance. Millions and billions of planets may sound like a lot, but it's pretty small from a SETI standpoint.

Re:Only 50 billion?

[jgoemat]

Kepler is only looking at Sun-like stars, which only account for 13% of the stars in our galaxy. Also the mission has only been going on for two years and they need at least two transits to say they might have found a planet, so this wouldn't count planets much further away from their star than Earth is from Sol.

Re:Only 50 billion?

[Anonymous Coward]

Also the orbit has to be more or less edge on to be detected.

Re:Only 50 billion?

[Anonymous Coward]

Bullshit. Kepler looks at every star in its field of view. Why wouldn't it? And indeed from Kepler Mission Scientific Objective:

1. Determine the abundance of terrestrial and larger planets in or near the habitable zone of a wide variety of stars;
3. Estimate how many planets there are in multiple-star systems;

Re:Only 50 billion?

[arcctgx]

"Kepler looks at every star in its field of view."

This is not entirely accurate. Kepler observes each star in its FoV, but doesn't send all the time-series data to Earth - just data concerning a selected subset of stars.

My experience

[Sarten-X]

Based on my time in high school, I expect those 500 million habitable planets are all inviting each other to parties, picking each other for teams, and definitely getting laid. Earth is getting left out, and nobody has the heart to tell us.

Re:My experience

[MichaelSmith]

Based on my time in high school, I expect those 500 million habitable planets are all inviting each other to parties, picking each other for teams, and definitely getting laid. Earth is getting left out, and nobody has the heart to tell us.

I think we should pass on getting laid for the time being thanks.

Re:My experience

[jcwayne]

I think we should pass on getting laid for the time being thanks.

And with that immortal phrase, Slashdot was born.

Re:My experience

[Anonymous Coward]

Paradoxic isn't it?

Re:My experience

[jcwayne]

Virgin Birth 2.0

Re:My experience

[lennier]

I think we should pass on getting laid for the time being thanks.

Not all aliens have tentacles. There are some very cute gelatinous pi-matter blobs just 50 lightyears away, and as long as you don't mention Andromeda or get them above 3 degrees Kelvin they're perfectly charming.

Re:My experience

[R3d M3rcury]

You owe me a new keyboard...

2001

[Anonymous Coward]

he thing's hollow—it goes on forever—and—oh my God—it's full of stars!

Re:2001

[MichaelSmith]

I watched 2001 again recently and noticed something new (for me). In the first scene which shows the space pod in the room at the end you see an internal display which alternates between "LIF" and something like "NONEXIST". We think we see this from Bowman's POV, but it seems the pod doesn't think Bowman is alive at all.

Re:2001

[Progman3K]

I watched 2001 again recently and noticed something new (for me). In the first scene which shows the space pod in the room at the end you see an internal display which alternates between "LIF" and something like "NONEXIST". We think we see this from Bowman's POV, but it seems the pod doesn't think Bowman is alive at all.

I remember (from reading the book) that Bowman literally had eons in that room to think.
A great deal of the time he thought about mortality, the nature of reality, existence...
I seem to remember him surmising form is illusion and (paradoxically) this leading to the evolution of the starchild.

78 million

[jgoemat]

Using the figures here I come up with 78 million in our galaxy: Kepler found 5 Earth sized planets in the habitable zone. They searched 156000 Sun-like stars. 13% of the stars in our galaxy are sun-like. There are 100 billion stars in our galaxy. Kepler would only find Earth if the axis of rotation of the system was within about 1/2 degree of the viewing angle. The relative angles are random. Sorry I only came up with 78 million, but if you take into account that there are 100 billion galaxies in the observable universe, that means there are about as many Earth-sized planets in the habitable zone around sun-like stars in the observable universe as there are grains of sand in ALL the beaches on Earth...

Re:78 million

[MichaelSmith]

So where are the aliens? With this many planets available we should be able to hear or see a few alien civilisations by now. Something is wrong with the assumption that aliens will "grow up like us". I don't think it will happen as often as we assume.

Re:78 million

[Anonymous Coward]

The aliens are somewhere along our path. The lucky ones are stuck in their respective solar systems by the lightspeed bareer and keep silent due to fears instilled by their respective Steven Hawkinses. The unlucky ones - on their rapidly warming planets, starved of useful resources and fighting each other for survival.

Re:78 million

[Arlet]

It's not that easy. Radio/TV transmissions leaking into space are very weak. There could be an alien civilization at 10 light years from us, and we could aim our arecibo dish straight at them, without picking up anything. Our only hope is that they'll point a very powerful transmitter straight in our direction, at exactly the same time as we point our most sensitive receiver in their direction. The chances of this happening are astronomically small.

And of course, most suitable alien planets are much further away, reducing the chances even more.

http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html

Re:78 million

[SnarfQuest]

Wouldn't it be funny if all the alien civilizations figured out some incredibly simple instant communications method, and have set up a giant network of communications bypasing the lousy radio waves, and we just missed it by that much.

Or, the Roman "Baths" were actually ancient communication booths, and their frequenting them was actually just getting the latest galactic sports scores. Then the goths lost a bet, and trashed all the "TVs". That's why no functional Roman bath exists today.

Re:78 million

[h4rm0ny]

Not only that, but there are two further qualifiers: One is that possibly radio-waves aren't the best way of communicating. Maybe there's some fancy quantum-entanglement doo-dad that we're right around the corner from discovering and which civilisations almost always progress to once they pass radio waves. Granted, it seems unlikely to us, but how would we know from where we are. Second idea is that sufficiently advanced civilisations tend not to waste power by needlessly broadcasting massive amounts of radio waves into space. We bounce ours off satellites. Maybe they do the same only even more efficiently. Maybe they all use focused lasers with really good aim. Maybe their planets become super-wired with fibre-grids and satellite relay becomes the less efficient option. Again, there ought to be some leakage, but it could cut down on the amount of transmission considerably. The phase during which a civilisation broadcasts Hitler opening the Olympic games (reference to the film Contact), could be a very, very narrow window in the grand scheme of things.

Re:78 million

[Penguinshit]

It could be that we are the first to reach the level of spaceflight. It could also be that we are the first to reach any level of civilization.

Re:78 million

[LordNacho]

Perhaps the thing to look for is some kind of spectral data? That might at least tell us if there's life (similar to ours). I'm not sure what the tell-tale lines for civilization are though.

Re:78 million

[LordNacho]

I hope we connect before intergalactic IPv6 runs out of addresses.

Re:78 million

[Anonymous Coward]

"So where are the aliens?"

They destroyed themselves shortly after achieving broadcast technology, after 5-100 years of transmitting into space?

Re:78 million

[rossdee]

Maybe many of those worls have simple forms of life, like this planet had handreds of million years ago, but haven't evolved into more complex forms yet. It took a long time for intelligent tool users to evolve here on earth, and we have only had radio transmissions for a bit more than a century. The aliens could have started to explore space, found it too expensive, and gave it up. Maybe they had a religious conversion, and gave up nearly all technology (except fireplaces)

Who knows

Re:78 million

[jbolden]

Why should be able to see and hear them? Are we sure we would even identify them if we did? Will it only be clear in retrospect? We just ran into a tribe living in the Amazon that hadn't been contacted. They saw airplanes, regularly and just associated them with the environment. They had sightings of cruise ships and military ships but since there was no such thing as a boat that big .... they didn't make anything of it.

Re:78 million

[Zachary Kessin]

It could be, but it would be weird if it were the case. Out of millions we are first? Ok someone has to be first but its still kind of improbable.

Of course our ability to spot the radio transmissions from other worlds is pretty thin still so we may well have missed some, infact it seems likely.

Re:78 million

[ee2go]

This can't be right: let's assume half of the 78 million are outside the center 1/3 of the galaxy where gamma bathes them. The volume we are talking about is 1000ly * pi * (100k^2-33k^2) = 28e12 cubic light years of volume? So we have about 700,000ly average distance between habitable worlds?

Re:78 million

[Jason Levine]

The two big problems are time and distance. For us to detect an alien civilization, they've had to have developed radio techology. They also need to have not progressed beyond radio. We're already moving to cabled systems instead of radio broadcasts. To an alien civilization trying to detect us, we'd be getting fainter and fainter. So there's a short window of time in which we could detect alien broadcasts.

In addition, space is big. (Insert Hitchhiker's Guide To The Galaxy quote here.) If an alien civilization is 10,000 light years away from us and developed radio technology 5,000 years ago, we wouldn't detect their broadcasts for another 5,000 years. The radio waves would have a huge amount of space to cover before reaching us.

Finally, considering time on our side, we've only been listening for a short period of time. If that hypothetical alien civilization 10,000 light years away developed radio technology 12,000 years ago and moved past the technology 11,000 years ago, the last alien broadcasts would have moved past the Earth in the early 1900's. They would have swept right past us without us knowing at all.

Re:78 million

[GeordieMac]

wait... some one counted all the grains of sand? The discrepancy is likely that you are filtering based on sun-like stars. A technological civilization may need a sun-like star, but algal lifeforms probably don't.

Re:78 million

[nospam007]

"...we could aim our arecibo dish straight at them"

Good luck with that, it's the one that's very hard to move.

Re:78 million

[Arlet]

Even though the main dish is fixed, the receiver still can be aimed within 20 degrees of zenith, resulting in a fairly decent amount of stars it can be aimed at.

Re:78 million

[Patch86]

That old chestnut assumes that every alien civilization screams into space on a decent spectrum of frequencies from the moment it's possible to the moment they go extinct. Thanks to more precise satellite-based transmissions and high-speed cabling, humanity's "radio age" seems to be coming to an end already, only a century after it really began.

And let's not even get started on whether we'd recognise an alien radio transmission as distinct from the the hissing void in the first place.

Assuming every civilization goes quite quiet after only a 100 year noisy period, and bearing in mind we've only really been listening out for it for a few decades, most of which time we had rubbish antiquated (from a modern perspective) equipment, it's not really that shocking that we've not heard from any neighbours yet.

And anyway, I'd still be thrilled to find space-mould, or better yet, space-simple-multi-cellular-organisms, if intelligent life isn't near by. That would still be earth-shatteringly fantastic.

Re:78 million

[swalve]

On the cosmic scale, our ability to be heard is infinitessmially small. Radio waves maybe 100 years. TV waves, what, 70? As it is, we are in the process of shutting down all our big broadcasting toward the universe sources. Digital broadcast TV is an order of magnitude quieter. We will likely move to all satellite broadcasting on the next change around, and we will be functionally silent to the outside. In other words, if they are dumb enough to broadcast Late Night with Luuuur the Unconquerable that wastefully such that we can hear it, they are not coming here any time soon.

Re:78 million

[rjhubs]

That amazon tribe was fake http://www.huffingtonpost.com/david-grann/the-truth-about-the-lost_b_172910.html

Re:78 million

[Anonymous Coward]

They're not yet advanced enough technologically.

Or they wiped themselves out before around 200 years ago.

I don't know if it is possible for a technologically advanced civilisation to exist and persist for a meaningful amount of time - a million years or so - so that they have the time to explore the galaxy, and also increase the chances of meeting another civilisation that has raised itself to a specific level of technology during that timeframe.

If we ever get into deep space, we will probably encounter less developed planets (with all their microbes, bacteria, spores, etc that would make it a bad idea to visit them in person until immunity was developed) and possibly some rather blasted planets, or planets/systems where there once were developed species, but shit happened and they're back to poking fires with sticks on the home planet. Mostly, we'll encounter barren sterile planets, and some of these would be ripe for terraforming if humanity ever gets the ability to look beyond five years in the future.

None of that will probably be happening in the next few hundred years. :-(

Re:78 million

[jbolden]

Wow didn't know that. OK example is disproven but main point about integration with technology and primitive people still holds.

Re:78 million

[Anonymous Coward]

So the only way to know for sure is to get out there and check. LET'S GET ON IT PEOPLE!! CHOP, CHOP!!

Re:78 million

[Anonymous Coward]

Finally, considering time on our side, we've only been listening for a short period of time. If that hypothetical alien civilization 10,000 light years away developed radio technology 12,000 years ago and moved past the technology 11,000 years ago, the last alien broadcasts would have moved past the Earth in the early 1900's. They would have swept right past us without us knowing at all.

Almost. The WOW signal was that civilization's final broadcast.

Re:78 million

[Anonymous Coward]

It is also possible, that if there were other intelligent life forms out there, they might not want to advertise their presence.

Re:78 million

[General_Fei]

If that hypothetical alien civilization 10,000 light years away developed radio technology 12,000 years ago and moved past the technology 11,000 years ago, the last alien broadcasts would have moved past the Earth in the early 1900's. They would have swept right past us without us knowing at all.

Good points, but check your arithmetic: you meant to say, they'd have "swept right past us" in the early 1000's, not the early 1900's. Move your decimal over one place.

Re:78 million

[lennier]

That amazon tribe was fake
http://www.huffingtonpost.com/david-grann/the-truth-about-the-lost_b_172910.html

Huh? Did you even read the article you just linked? It says the exact opposite of what you just said:

But that did not make the photographs "fakes" or a "hoax." The reason these tribes are classified as "uncontacted" is because they have retreated into the jungle and consciously avoided any interaction with settlers--an interaction that has frequently led to the extinction of Amazonian tribes.

Re:78 million

[Anonymous Coward]

There's another qualifier, or problem really. And it's huge. We don't know anything about alien life forms, but we do know something about the millions or billions of different species here on the Earth. While we have yet to explore every corner of this world, we have found life in many forms, and some of them could be considered different enough from human that they might be effectively alien. This is perhaps an example of what life out there might be life, at least in terms of how much like or different it might be.

Of all the species on Earth, we have found some that communicate in limited ways and some that communicate in detail, but of all of them. only ONE that we know of has invented radio communication. Only ONE has an intense need to communicate constantly with others of the same species. Only ONE has invented mass entertainment and used radio and other forms of eletromagnetic communication to distribute that entertainment.

We're the one. Nothing else here, that we know of, uses radio. Nothing else, that we know of, communicates at the level we do. Some animals do communicate at some level, but nothing like what humans do.

If life on the Earth is an example, however limited, it still tells us we should not automatically assume aliens anywhere will be using radio or TV or emitting signals we can detect at a distance. There could be intelligent life which never found the need for mass communication. There could be life that communicates some other way -signals unlike what we use for radio, or using methods that we don't use and never needed or discovered.

And then of course radio signals are actually a lot weaker at a distance that we assumed. Our own emissions from Earth may not get past our own helioshock zone, which means we may not even be observable more than a light year out. If this is true for other stars, radio signals may be harder to detect than we ever estimated.

So the whole concept of searching for radio signals is dicey. There has to be a civilization existing at the same time (this is not guaranteed), who needs to have mass communication, and emits it in a form we can detect, at a distance.

What this says to me is that radio is probably not the best approach. Or at least one you may not want to bet upon. I know the people at SETI work very hard for nothing, but they are truly chasing a needle in a haystack and it may come to nothing.

So what's better? I don't know. Some may say lasers or tryingt to invent quantum radio sets (which I think would be great myself) but we're still back to the problem that we can't assume aliens will feel any need to communicate like humans do, with broadcasts of any type or the entertainment signals that we emit. It's entirely possible that aliens may not need to talk all the time. Or there could be many planets like Earth but minus the species that invents radio. Take humans off the Earth and the Earth would still be a very much alive planet but very much radio-silent as well.

The silence doesn't mean life is not there.

Re:78 million

[Artifakt]

Really good encryption is very similar to random noise. Civilizations could go silent by using wire or laser communications to avoid wasting power, ala. your comment, or by using highly efficient encodings, or probably by a dozen various other ways that are likely to get invented within a few hundred years of radio, without it having anything to do with extinction. It's intregueing that we can think of several things besides technological civilizations being inherently short lived that could explain a lack of radio type alien signals, but extinction hypothesi are still very popular with a great many people.

Re:78 million

[Evil Pete]

The Kepler Mission can only detect planets whose orbits cross the disc of the star relative to the space probe. See here for a description of the methods. The result is that if Kepler was looking for the Earth from a suitable distance then it would only have a 0.465% chance of detecting it assuming a randomly oriented ecliptic plane. So even though it only found 5 Earth sized planets in the habitable zone that extrapolates to many more since only 1 in 215 stars would have the orbit oriented in a way that would be detectable.

Re:78 million

[Anonymous Coward]

If there are 500 million habitable planets, and say 1% of them develop intelligent life, then there are 5 million civilizations, each broadcasting for 1000 years before they move beyond (detectable broadcast high-power non-cellular) radio. If they all developed life at random times, then there's a time window of 10 to 13 billion years (age of the Milky Way), over which those 5 million 1000-year radio bursts are spread. If they were all spaced back to back that's only 5 billion years; random distributions aren't like that, but we'd sort of have a roughly 1 in 2 chance of having someone broadcast in the last 100 years. Okay, actually it's better than that because the distribution is likely to be non-uniform, and we're likely to be near the middle of the hump, so there should be a large cohort of detectable civilizations out there now. But maybe the monkeys only learn to hit each other with dinosaur bones on a tiny fraction of life-bearing planets, and most of those planets are probably too far away for us to pick up radio from them. Then there's the light-cone thing, and the fact that the 1000 year broadcast window is probably more like 200 years (high power broadcast seems like an inefficient way to use the radio spectrum once you have digital technology)...

But wait. There are probably always going to be niche applications for high power broadcast for navigation and such (look at wikipedia's US frequency allocation chart), and I wonder if you could get all that much additional data through the lower bands using digital cellular tech anyway. I mean yes, you can pump a lot more information through a 30 KHz signal with cellular directional QAM-256 than with broadcast AM, but if it's only a few Kbps, and your minimum cell size is 200 miles across, and you need a 1 meter antenna, then are we really going to reallocate that spectrum for cellular data (and build out a bunch of expensive base stations), or will we just keep using it for maritime comms where it's serving a useful purpose? Will broadcast ever really completely disappear as long as our civilization persists? I kind of doubt it. But I have no idea how well the remaining broadcasts will escape the ionosphere and cross 10,000 light years of space, either; it's hard to believe we could pick up chatter from an alien fishing boat's 12 volt battery powered radio, as opposed to, say, alien Glenn Beck on a high powered AM broadcast station. So maybe the detection window really is only a couple centuries. But I would think at least nav beacons and radar will be around forever.

Hard to say what SETI's odds are, we still just don't know enough of the constants in the Drake equation (though a real RF engineer and an astronomer could work up a better answer to the RF blackout question than a poseur like me). Seems like we'd have heard something by now, but who knows... just have to keep listening.

Re:78 million

[Maritz]

I read somewhere there's enough address space in IPv6 to give each cubic foot of the galaxy its own address. "A right few" as they say. They probably say that.

Re:78 million

[linoleo]

We're already moving to cabled systems instead of radio broadcasts.

Errrrr... for the past decade we've been moving back to wireless. Where have you been?

For all it even matters . . .

[Seumas]

My mother was barely a high school girl when we landed on the moon and since the last time we stepped foot on something other than the earth, she had children who grew to be old enough to have children who were as old as she was, then. We keep cutting budgets, because "we don't need all that there space sci-fi mumbo-jumbo when they can't even fix the potholes in front of mah damn house durr durr durr!". We talk about grand attempts to Mars, which we then never fund or push forward after having fancy press conferences about it. Then we do the same with plans to . . . go back to the moon.

I suppose an optimistic way to look at it is that while we may see no advances in exploration in the near future, we do continue to increase technology which will in turn make future exploration even more successful. Sort of the way you could set a computer to cracking an encryption today that could do it in a few hours, while if you had started cracking that encryption in 1980 and let that computer keep running, it still wouldn't have completed the calculations, today. Still, that doesn't put one at ease over the general lack of ambition. Not to mention the amount that the last major space effort contributed to the technological advances that we have today and are now counting on continuing to advance at a rate so as to re-jumpstart the space exploration.

I think it's safe to resign ourselves to little more happening in our lives. Our best hope is that while the likes of Carmack are building low orbit space planes and the likes of Richard Branson are building low orbit space hotels (which, let's recognize, are going to be nothing more than crammed little pods for decades to come), they somehow stumble into a viable commercial reason to explore some space out there. Otherwise, we're generations away from much more than sending RC cars to the surface of Mars, again.

Re:For all it even matters . . .

[Anonymous Coward]

The conservatives are just going to wait for the rapture.

Re:For all it even matters . . .

[worx101]

Just wait, the Chinese will be creating "bootleg" versions of the current IPad on Mars before the US can even get a good moon colony started... at least that is the way it is seeming now

Re:For all it even matters . . .

[Traiano]

You need not worry about our temporary stall in space exploration. Once Starbuck's, McDonald's, AT&T and Comcast figure out how to make money from it, we'll have manned stations on every rock between here and the edge of the universe.

Re:For all it even matters . . .

[LordNacho]

Not trying to be too ideological here, but what you might hope for is that these early space tourism efforts become profitable. What we saw with Apollo and the cold war was the government putting a whole load of money into sending Air Force pilots to the moon, and it worked, and it was a great achievement. But once the political goals were reached, the program somewhat stalled. If we had a profitable and lively space tourism economy, perhaps the private sector would get the snowball rolling, and we'd be talking to the Vulcans soon.

Re:For all it even matters . . .

[Tumbleweed]

The conservatives are just going to wait for the rapture.

Just think how disappointed they're going to be if the Rapture does actually come, and they find out Jesus actually _meant_ all that shit about peace and love thy neighbor, etc., and they don't qualify because they were so busy hating on everyone.

I'm not sure which I would wish for if the day comes - wanting to see them go so the rest of us can get on with things, or them NOT going, and then getting to see the looks on their faces.

A difficult choice...

Re:For all it even matters . . .

[Tumbleweed]

You need not worry about our temporary stall in space exploration. Once Starbuck's, McDonald's, AT&T and Comcast figure out how to make money from it, we'll have manned stations on every rock between here and the edge of the universe.

I think you're confusing Starbucks/McDonald's/AT&T/Comcast with the Hudson Bay Company. Very different business models. HBC, "Here Before Christ" :)

Re:For all it even matters . . .

[Anonymous Coward]

Disclaimer: I watched the moon landing as a kid. Read the picture books telling us about the future some of us would have working in space. I fully expected the futurism of Clarke & Kubrick's 2001 would not be that far off the mark by the millennium.

Not to mention the amount that the last major space effort contributed to the technological advances that we have today

This again. Honestly, and respectfully, I think this well-worn argument is bankrupt. Yes we got 'spin-offs' from the space push, but No we do not need a space push to have tech advances at the same or greater rate.

There is _so_ much to do and learn here, in biology geology climatology medicine physics (oh my god the list goes on and not to mention Douglas Englebart's incredibly important pet project that we're really just getting started with), that I just don't understand how anyone can think it's a let down, or a display of lack of ambition, that we're not on Mars yet.

I don't know, it just seems incredibly shallow, and frankly ignorant of the huge scientific adventure we're in right now. And I totally hate saying it that way because it puts you and me off on the wrong foot -- I really want you to see the depth and variety to be dealt with, and being dealt with, 'locally'.

Clearly, I'm not the spokesman who can pull that off. But do me the favour of being open to the idea and look around a little more yourself. There's all sorts of incredibly cool shit going on. Putting meatsacks on Mars is a friggin sideshow by comparison. Don't worry it.

Re:For all it even matters . . .

[jbolden]

From 1930 to the present has been a golden age for astronomy / cosmology. We've discovered a lot since the 1970s. It turns out that manned flight is not a particularly useful way to learn about space. We don't have the technology to do anything useful with men in space yet. Wishing doesn't make it so. One of the things we've learned is how hostile and dangerous space is, its a tougher environment to survive in than we ever imagined.

Now you want to do a good warmup, long term bases under the ocean which.... we've made substantial progress on. I have budget cuts too. But I think we can't argue that humanity is not learning at a pretty good clip right now. This is not a dark ages.

Re:For all it even matters . . .

[jbolden]

The whole idea of the rapture was invented by the fundamentalists. Other Christian sects had different end times philosophies.

Re:For all it even matters . . .

[TiberiusMonkey]

Yeah but even Jesus seemed to be a bit of a condescending, tree killing dickish person. Of course when the bible says something awesome happens Christians take it literally and claim it happened just as it's written, but when Jesus does something dickish, like killing a tree simply because he wanted fruit but the tree was out of season then it's "meant as a metaphor" so say people "who have r teh studied the bible for yearz and yearz", so what the fuck do I know.

Re:For all it even matters . . .

[Anonymous Coward]

We've already learned out to target any point on earth with an ICBM. What more is there to be learned from space?

Re:For all it even matters . . .

[maxume]

They have all the same issues with intense gravity that we do.

There's a joke about obesity in there, but even our mere millions provide plenty enough outliers to staff a few space toys.

Re:For all it even matters . . .

[Fnkmaster]

It would certainly help if there were some profitable enterprise that could come out of space exploration. If there were, it would be much easier to get it all funded. It's also hard to justify manned exploration when unmanned exploration is massively cheaper and easier to accomplish, unless there is something of economic value up there that needs factories, mines, or processing facilities with some human oversight.

Colonization for the sake of colonization is not going to happen anytime soon unless our species faces an existential threat so obvious and imminent that it kicks our ass into action.

Re:For all it even matters . . .

[Penguinisto]

I think the fear is that we will descend into a dark age (or even be obliterated entirely) before we can put that knowledge to use.

By way of explanation... with folks living in viable, self-contained colonies on the Moon, Mars, or in Bernal/O'Neill stations, we can at least have the ultimate backup for human knowledge (and humanity itself). This way, if things go to shit here on Earth, at least some people will still be pushing the boundaries of knowledge (or in some scenarios, still be alive in a not-as-hostile environment).

It's nice to have all the ever-increasing knowledge and all, but one 'oh shit!' event, and we'll lose it entirely, having to regain it over thousands of years. Even simple stuff like Concrete, first invented and used by *Romans*, was lost for well over a thousand years between their empire and the Industrial Revolution. Now imagine what it would take to regain something like a Transistor (let alone computer programming) if some massive or cyclical event plunged humanity into another Dark Age. It's not like we can simply write it all down and hope someone decodes it later - the concepts and techniques are too numerous, and far too complex. Unlike the fall of the Roman Empire, if we go down, it's going to get real ugly, real fast (mostly due to over-interdependence, resource distribution, knowledge distribution, and sheer population)... put short, we're balanced a bit more delicately in this particular cycle of civilization. This in turn will mean a longer recovery time. Asimov only scratched the surface of this in his Foundation Series (he should have dug deeper IMHO), but the idea still holds: The more complex a civilization/empire is, the longer the inevitable dark age that follows it.

Given things like historic/cyclic civilizational trends, NEO asteroids, hostile bacteriological evolution, overpopulation, nuclear weaponry, supervolcanoes, human industrial activity, 'idiocracy', zombies, whatever (in descending order of likelihood)? It just makes sense to me that we have a viable backup for all our stuff, our knowledge, and for our DNA (preferably breathing and reproducing).

Overall, It makes for a damned good idea to have some sort of place where humanity can carry on in spite of what happens down here. Besides, having folks actively working and living in space may even help solve some of the bigger problems we're already facing (even those I've listed... especially problems concerning population growth, asteroids, industry, etc). /P

Re:For all it even matters . . .

[cool_arrow]

all religions have, at their core, a death wish.

Re:For all it even matters . . .

[Anonymous Coward]

I think it's safe to resign ourselves to little more happening in our lives

... from the U.S.

Most of the western world still hasn't grasped the fact that they are not going to be in the driver seat much longer. In your lifetime, you will see China be the dominant country on the planet. The only thing the US can do now, is make sure it positions itself to prosper as best it can under that new dynamic. There is simply no way for the US to do the things you would like to see, even if they WANTED to.

As for the Chinese, You need not worry about ambition.

Re:For all it even matters . . .

[Tumbleweed]

The whole idea of the rapture was invented by the fundamentalists. Other Christian sects had different end times philosophies.

The whole idea of Christ being divine was decided by the First Council of Nicaea. When you start convening councils to decide on which details will make up your religion, it really reminds me of the fights between which version fo emacs or vi is the 'one true way'. And just as relevant. :)

Re:For all it even matters . . .

[jbolden]

Hmmm. Good points. I don't know if I would agree that the degree of a civilization determines the length of the dark age. Also its hard to imagine with anything like our current technology a Martian colony being "less hostile" than an earth with political problems for science.

I don't know how long it would take to get the transitor. Remember millions of millions of people know the basic progression: vacuum tube -> transistor -> silicon semi conductor. Knowing that it is possible and knowing the economic value it would be hard to repeat the steps for development quickly even if we don't know the details. The 2nd time around we wouldn't end up losing a few decades working on analogue computers before working on improving digital computers.

I'm not sure other countries can't back each other up still.

That being said, there is stuff to be worried about. I'd like more diversity I'm just no sure we are technologically there yet. My point to the grand parent though was that this century has seen a lot of technological advancement including in the last few decades. We aren't in a dark ages now.

Re:For all it even matters . . .

[Kjella]

On a human timescale that is certainly concerning, on a cosmological scale it doesn't really explain anything about life in the universe. We could wait 1000 years with further human exploration and it'd still be a blink of an eye in a universe billions of years old.

True, we don't get to do much colonization but I feel we live in a very exciting age when it comes to knowledge of the universe. I may have missed the moon landing but when I was born, exoplanets were just a theoretical concept. Now we have over 500 confirmed planets and 1000 candidates and we're mapping out uncharted territory right now. Within my lifetime I have good hope we'll find a earth-like planet in an earth-like orbit around a sun-like star, to me that is huge.

Like it or not, robots have become our eyes and ears and any human "exploration" we do probably really won't be exploration anymore. Long before any human has set his foot there we'll already know all about the landing site, ground conditions, atmosphere, temperature, weather conditions and so on. And apart from the few people actually going all we'll see are recordings anyway, except now with a man in a space suit.

Remote controlled and semi-autonomous robots do more and more advanced things, you have to ask if having a human on-site would be productivity enhancing or just productivity limiting in that he needs shelter, air, food, heat and such things. It's nice to know we can move a man to a bunker on Mars and eat canned supplies, but if that's all he can contribute with that's not really all that interesting. It would just be to prove we could do it, then we would stop just like with the manned moon missions.

I'm feeling we're no more than an Apollo decade away from landing on Mars, but what we really need are working plans for a Mars base. At least have them sit out one return cycle (happens every 2 years) and be there a few years, not two months. Try excavating some kind of structure that could be a starting point for later expeditions. Not just land and leave a flag and some boot prints.

Re:For all it even matters . . .

[jbolden]

The whole idea of the rapture was invented by the fundamentalists. Other Christian sects had different end times philosophies.

The whole idea of Christ being divine was decided by the First Council of Nicaea.,

When you start convening councils to decide on which details will make up your religion, it really reminds me of the fights between which version fo emacs or vi is the 'one true way'. And just as relevant. :)

But that doesn't change the fact that the fundamentalists (Dabney, et. al) invented the rapture idea. They also don't like councils.

Re:For all it even matters . . .

[Tumbleweed]

But that doesn't change the fact that the fundamentalists (Dabney, et. al) invented the rapture idea. They also don't like councils.

Still doesn't matter. It's like the Tea Party whackos - they can't even decide whether Obama is a Muslim, born in Kenya, or supported death panels in the health care reform bill. You can argue over which fantasy is 'truth' all day long, but it's just not relevant.

Re:For all it even matters . . .

[BJ_Covert_Action]

You might want to get your billionaires straight. Branson is the one building space planes. Carmack is building rockets. Robert Bigelow is building the space hotels. ;)

Re:For all it even matters . . .

[BJ_Covert_Action]

There is _so_ much to do and learn here, in biology geology climatology medicine physics (oh my god the list goes on and not to mention Douglas Englebart's incredibly important pet project that we're really just getting started with), that I just don't understand how anyone can think it's a let down, or a display of lack of ambition, that we're not on Mars yet.

Yes, there is amazing, cool, epic shit going on right now on this planet. There is no doubt about that. But the reason why it is a let down that we are not putting meatbags on Mars right now is because all the cool, amazing, epic science shit we are doing on this planet is not being done in space, on other worlds, on undiscovered frontiers, in places where no human has ever set foot before, in places and environments that we have only started to imagine.

If you don't understand why that's a let down in and of itself, then you probably never will. It all boils down to the spirit of exploration, in the most literal sense.

Re:For all it even matters . . .

[lennier]

with folks living in viable, self-contained colonies on the Moon, Mars, or in Bernal/O'Neill stations, we can at least have the ultimate backup for human knowledge (and humanity itself).

And we can get the same amount of backup much more cheaply by building a few hermetically sealed biodomes right here on Earth. There's nothing magic about space that would make it a better place to put a sanctuary, and many things that make it much worse.

things like historic/cyclic civilizational trends, NEO asteroids, hostile bacteriological evolution, overpopulation, nuclear weaponry, supervolcanoes, human industrial activity, 'idiocracy', zombies, whatever (in descending order of likelihood

For all of these scenarios, including asteroids and nuclear exchange, Earth is still the best location for a biodome. Nothing short of total vaporisation of the entire planet would render Earth appreciably less habitable than Mars. Take the very worst that humans could do to Earth: pollution, mass species extinction, warming, massive radiation, the oceans drying up: none of these would be fraction as bad as what's out there in space on the next planets over.

Seriously, no matter how bad it gets, things simply can't ever get bad enough for us to make leaving more attractive. The very worst case, we simply dig in here, build a few domes, and repopulate using the exact same techniques we'd use for terraforming space. Only we can start right now, building a few glasshouses, saving seeds, that kind of stuff.

The only way space could ever be 'better' than re-terraforming Earth would be if we got tomorrow a magical free energy hyperdrive that let us jump instantly to a fully Earthlike DNA-compatible Eden. Do you see that anywhere on the theoretical horizon? I don't.

So cheer up, emo spaceboy. We aren't leaving anytime soon, and we humans are harder to kill than the roaches. For all we know we are the space roaches.

Re:For all it even matters . . .

[Penguinisto]

Take the very worst that humans could do to Earth: pollution, mass species extinction, warming, massive radiation, the oceans drying up: none of these would be fraction as bad as what's out there in space on the next planets over.

Most scenarios, you're (mostly) right - a biodome of sorts would work out okay if you planned it right.

OTOH, some scenarios you just cannot escape by hanging around on Earth...

* A 50 to 100-mile-wide asteroid (there's plenty of 'em, some which get real close to Earth) would literally sterilize/melt/broil the Earth's entire surface to 4k degrees Fahrenheit, down to a couple of miles deep. Even if you could burrow deep enough to avoid being baked outright, you'd still have to hang around in that hole for about 3,000-5,000 years until things cooled off enough to come out, hope there's a breathable atmosphere and liquid water waiting up top by then, then drill your way out because the tunnel in will have most likely melted itself shut. May as well try having a colony on Venus for all the good it'll do you.

* Even with a smaller asteroid (say, 5-6 miles wide), you're going to have to be prophetic enough to park your biodome(s) somewhere that won't be cracked open by the resulting earthquakes, if not by the impact(s) itself.

* a virus or bacterium that is perfectly drug-resistant but fatal (but is not necessarily dependent on humans - maybe uses animals as a carrier but is non-fatal to them) would make life impossible on Earth for humans, in spite of perfectly normal climate... even if you could isolate yourself from the organism, you'd still be perpetually stuck in that biodome until that organism goes extinct. Nothing like having at least a quarter-million miles of hard vacuum (and one strong-assed gravity well) to keep the bugs at bay.

* If Yellowstone (or another supervolcano) goes off, you're going to be stuck in that biodome for a few hundred years... with no real source of energy (excepting perhaps geothermal), and zero solar power (think plants, not photovoltaic) until those ash clouds clear out.

Another problem with biodomes in general is the fact that you're holed-up, with not much room for expansion in most scenarios (especially those involving hostile biology), and you're going to have to add materials to it over time (if only for repair and maintenance). In some scenarios, you'd have a far easier/safer time finding those materials off of lunar regolith, or from other asteroids, or etc... than you will locally on Earth.

Finally, you may want to make that biodome defensible. You and your buddies may have a bed in there, but hordes of survivors will also want a piece of it. It's easier to welcome the relative few survivors who manage to get up to you with a spaceship, than it is to fight/kill off mobs of desperate people trying to get what you have - some of whom are almost guaranteed to have the weapons and means to take it from you anyway. Between the initial event, and a period of peace sufficient to consider rebuilding, there's gonna be a shit-ton of hungry, desperate people fighting each other for what's left - few of whom will care very much beyond their next meal or two... let alone about the future of human knowledge.

Seriously, no matter how bad it gets, things simply can't ever get bad enough for us to make leaving more attractive.

Engineer this one for a bit first... I think you'll find that there are a lot of factors that got left out in your assumption.

Now the fall of our current global empire (for lack of a better term) may make the whole biodome thing appealing. It would be similar to the role the Catholic Church played during the last Dark Ages (e.g. monks laboriously copying over the odd technical/literary script or two along with the usual scriptural copying.) OTOH, much like the pre-Medieval Church, a large amont of useful stuff will simply be cast aside due to political (and in their case religious) concerns, lack of manpower sufficient to copy

Re:For all it even matters . . .

[cavebison]

I think it's safe to resign ourselves to little more happening in our lives.

Thank god for that. Perhaps we can start to concentrate on fixing the problems on this (still unique) little world of ours. I'm all for scientific discovery, but can't help spotting the irony of searching for Earth-like worlds, while ours becomes a little less "Earth-like" every decade.

At least, once we've wiped out all life here, we can finally say our planet isn't unique any more.

Re:For all it even matters . . .

[Anonymous Coward]

The role the Catholic Church played in the last dark age of *preserving* knowledge? Who do you think *destroyed it*? Why do you think Enlightenment happened when a Catholic reformer (Martin Luther) was able to survive through the newly invented printing press making backup copies of his writing (unkillable and hard to destroy)? One large threat to a bio dome on Earth is exactly that -- other organized human parties perceiving it as a political threat (including a threat to dogmatic based power, as in the Catholic Church).

Re:For all it even matters . . .

[Penguinisto]

The role the Catholic Church played in the last dark age of *preserving* knowledge? Who do you think *destroyed it*?

Destruction occurred most often because of wars, civil order breaking down throughout what was left of the Roman Empire (hard to keep a school -- let alone the local local library -- going, when you can't even keep the local barbarian raiders from burning your town down at nearly every opportunity), and then locals getting a bit too zealous (The Library of Alexandria burned to the ground as a result of a local bishop+mob, who hated the chief librarian more than they ever did the scrolls - apparently she was too 'uppity' for their tastes).

Hell, the biggest factor was a general abandonment of the cities by the population at large, which in turn caused a complete lack of trade (for the longest time during this period, Rome itself was simply abandoned, and became a local quarry of sorts for building materials). Hard to constantly raid something that's an empty husk with no gold in it (and was unmaintainable anyway by then), or so the theory goes.

OTOH, your theory has one small problem: during most of the Dark Ages, the only knowledge being copied and passed around was through the few literate folks left... the monks who did all the manuscript copying.

The whole 'OAMG teh eevil churchez is out to bern my precious knowledgez!' trope is scattered and over-hyped at best.

One large threat to a bio dome on Earth is exactly that -- other organized human parties perceiving it as a political threat

Indeed... which is why one would be safer to park it out in orbit, where the local mobs can't quite reach it. OTOH, I think the biggest threat from other people will simply be that of the local starving/freezing mob wanting all the tasty bits and warm environment inside.

Like most mobs in the Dark Ages, you really don't care much about the dogma or politics - especially when your belly is empty and you're shivering from the cold.

Finding a planet is easy, finding life may be hard

[get_your_guns]

Long distance observations are becoming more and more precise but the chances of finding evidence of intelligent life is very slim. We have been listening for radio waves from outer space for about 60 years when AT&T was experimenting with microwave technology. That is a very small amount of time compared to the billions of years the Earth has been in the habitable zone of our solar system.

We are expecting another world to be transmitting at a power level for us on Earth to hear it. As our own human species matures on Earth our actual transmitted radio waves have been getting less powerful as we both perfect radio transmission and move away from radio transmission to fiber optic and other terrestrial types of communicating. Probably our highest powered transmissions into outer space was when we exploded Atomic bombs above ground and this was for maybe 30 or 40 years total. The chances that some other planet was listening during that time would be more astronomical than there being life on other planets outside of our solar system. And, there was no intelligence in the explosions for another planet to believe it was from intelligent life. The white noise of our universe that AT&T first heard 60 years ago is from billions and billions of hugely powerful star events that would easily wipe out all life on earth if we were just a few light years away from the smallest of these events.

So thinking that we will be able to hear evidence of life outside our solar system by listening to radio waves that make it to earth is a little far fetched though not impossible. I don't think we should stop for there might be some form of galactic space travelers that are purposely transmitting to earth a welcome message or such though if they have the technology to do so I don't think the human species will be able to understand it yet.

But, I think we as a species needs to accept the fact that space travel is the only way we will preserve our human race. This earth is doomed as our star has a limited life span. I know it may be millions or billions of years before the sun eliminates life on earth but it will happen. The sooner we accept this the sooner we will be ready to make the leap into outer space, that or die off as the sun dies off.

The measure of a fool

[symbolset]

If presented with evidence he denies it, he is an idiot. If he only says "idunno", then he is only a fool.

Re:The measure of a fool

[DigiShaman]

A fool is someone whom lacks intelligence. The word you're looking for is "ignorant". For example, I'm knowledgeable of my work in IT. However, I'm ignorant in biology. It's not that I can't learn it, just that I've never had a need nor cared to educate myself on the topic.

Please don't confuse the two. There is a difference between the ability to learn and the breadth of knowledge.

Re:The measure of a fool

[Anonymous Coward]

A fool is someone whom lacks intelligence.

A fool is someone who lacks wisdom. Someone lacking intelligence is stupid. Someone lacking knowledge is ignorant.

Please don't confuse the three.

Re:The measure of a fool

[Gilmoure]

And dumb? They cannot speak!

I hate when folks use dumb for stupid

Re:The measure of a fool

[Anonymous Coward]

Yeah, only dumbasses do that.

Re:The measure of a fool

[Gilmoure]

That's pronounced: du-moss

Re:The measure of a fool

[Ihmhi]

Personally, I think "I don't know" is one of the smartest things in the world to say. Better than "Nuh uh, I'm right no matter what you say!".

Aliens are statistically likely to exist

[Chaonici]

In a universe with as many stars and planets as ours, Earth couldn't possibly be the only planet whose orbit just happened to be in the right place to sustain life.

Re:Aliens are statistically likely to exist

[toejam13]

I've read in a few places that we may be one of the first around. Supposedly, heavy elements only came into abundant quantity around ten billion years ago. A much earlier universe couldn't have made our solar system. OTOH, it would be an utter mindfuck to confirm that there is other life out there. Even moreso if it was intelligent. But it would be equally amazing if it turns out that we're the only ones because we came first.

Re:Aliens are statistically likely to exist

[93 Escort Wagon]

In a universe with as many stars and planets as ours, Earth couldn't possibly be the only planet whose orbit just happened to be in the right place to sustain life.

Given that we only know of one planet that contains life, you can't possibly draw the conclusion (that aliens are statistically likely to exist). You're assuming the only requirement is that a planet be in a star's habitable zone - but you have nothing to base that assumption on.

You can't extrapolate a line from one point.

Re:Aliens are statistically likely to exist

[siimv]

Agreed, it's quite an arrogance from our side as always to presume, that alien lifeforms should flourish on the similar conditions that helped life to evolve on planet Earth. For all we know, there could be ultimate intelligence right here on our solar system living on Jupiter.

Re:Aliens are statistically likely to exist

[AGMW]

You can't extrapolate a line from one point.

Well, that's not true. And best of all you can chose which direction to extrapolate it! Obviously, this extrapolation then says more about the extrapolator than the data, but it can still be an interesting experiment.

Re:Aliens are statistically likely to exist

[M8e]

But if we find life on mars we got two points!

Re:Aliens are statistically likely to exist

[jcwayne]

In practical terms that's not really meaningful. Considering the timescale involved, you're probably dealing with a margin of error of +/- 1 billion years. Then consider that the speed of evolution, in all its forms (i.e. planetary, geological, biological, societal, and technological), is influenced by an incalculable number of interrelated factors. So, in reality, being "one of the first" could mean that we're several billion years behind some and ahead of others.

Re:Aliens are statistically likely to exist

[jgoemat]

Given that we only know of one planet that contains life, you can't possibly draw the conclusion (that aliens are statistically likely to exist). You're assuming the only requirement is that a planet be in a star's habitable zone - but you have nothing to base that assumption on.

You can't extrapolate a line from one point.

From what we know, liquid water is required to sustain life. For observational purposes we have a sample size of (1) planet which resides in the habitable zone for life to exist, and that one planet contains life. The sample size is small, but it is at least as good a bet that life exists on one of the millions of other planets in the same situation as ours that exist in our galaxy as it is to bet against it.

The oldest undisputed evidence for bacterial life on Earth is 3 billion years ago, but other evidence points to life existing 3.5 or 3.8 billion years ago, not long after the Earth cooled enough for liquid water to exist on the surface. We've found water on Mars, the moon, in the atmosphere of Venus and on other moons in our solar system as well as in comets that visit the inner solar system from the Oort cloud. Since water is made up of two of the three most abundant elements in the universe that is hardly surprising. I think it would be a very safe bet that some of the 80+ million Earth-sized planets in the right orbits for water to exist as a liquid would have it on their surface.

As far as life coming into being, we don't know. But again, we have a sample size of 1 and 1 positive result. We have 80 million candidates to choose from in our galaxy and 100 billion other galaxies to look at. To assume that life wouldn't exist anywhere else would be a much less tenable position than the reverse.

What we need to to is find a way to take the spectrum of those planets' atmospheres as they pass in front of their star. If we can do that, and we find that their atmospheres contain a lot of Oxygen, that would be almost certain proof of life.

Re:Aliens are statistically likely to exist

[Tumbleweed]

But if we find life on mars we got two points!

And if Mars is the Daily Double, we're golden!

Re:Aliens are statistically likely to exist

[Anonymous Coward]

Obviously, this extrapolation then says more about the extrapolator than the data, but it can still be an interesting experiment.

He extrapolates a line going up and to the right - he is an optimist. He extrapolates a line going back and to the left - he is a conspiracy theorist.

Re:Aliens are statistically likely to exist

[Anonymous Coward]

Given that we only know of one planet that contains life, you can't possibly draw the conclusion (that aliens are statistically likely to exist).

But we know of many planets that do not have intelligent life. This knowledge can be used in the extrapolation.

Re:Aliens are statistically likely to exist

[jbolden]

Not really. We don't know if there is life in the clouds of Venus. We have no idea about Europa. We never considered anything like Titan until recently with liquid methane playing the role that water does on Earth. Heck even on Earth we keep discovering new places that life exists, that our shocking.

The reality is we still don't know very much.

Re:Aliens are statistically likely to exist

[YooHoo2U2]

From what we know, liquid water is required to sustain life

From what I know, cable TV and Cheetos are required to sustain life.

Re:Aliens are statistically likely to exist

[ErikZ]

Why would we be first? We wouldn't even *be* here if the Dinosaurs weren't wiped out.

The firsts would have evolved around the time the Dinosaurs did.

Re:Aliens are statistically likely to exist

[justin12345]

The Earth has two other things going for it besides being in the right place around the right type of star and in the right part of the galaxy. It also has the moon spinning around it catching meteors, and a liquid iron core producing a strong magnetic field which keeps our atmosphere intact. Without those two things it might have been much more difficult for complex organisms to evolve.

Re:Aliens are statistically likely to exist

[Anonymous Coward]

Well, consider the odds of us coming first. Wouldn't those odds be astronomically remote?

Re:Aliens are statistically likely to exist

[Phleg]

I'm not so sure that's true. Obviously it's possible, but the paths evolution is allowed to take when starting from a blank slate may be very different from the ones available when most species are wiped out and the planet repopulates with a more advanced set of basic lifeforms.

Re:Aliens are statistically likely to exist

[ErikZ]

So, to get intelligent life, life has to be firmly established, then *almost* wiped out so the more advance forms have a shot of dominating an ecosystem?

I don't think we're going to find much in the way of intelligent life out there.

Re:Aliens are statistically likely to exist

[marcosdumay]

The magnetic field does not sound like something improbable. Ok, it does reduce the count of planets, but realy, by how much.

Unless you used it to state that life must evolve fast. On that I agree if technological life needs a magnetic field, it has less time to evolve.

Re:Aliens are statistically likely to exist

[marcosdumay]

Well, someone must come first. And it may be that nobody can come second...

Re:Aliens are statistically likely to exist

[Anonymous Coward]

The "we came first hypothesis" appears often in other domains by similar names such as "first post! Woot!", "you're in my seat", and "get off my lawn"...and is widely regarded by the scientific community as highly provable.

eh?.. This is like deja vous without the punchline

[Anonymous Coward]

An article that talks about how many planets are habitable in the milky way that doesn't mention the drake equation even once? 0.o

This line "So how many of these exoplanets have life? Unfortunately, there's no estimate for that question." strikes me as weird... There are thousands of estimates for that number.. what is he talking about?

Re:Finding a planet is easy, finding life may be h

[MichaelSmith]

Even if there was only one species like us reaching maturity every million years and there had been 1000 of them over one billion years, we should have seen some sign of them. We should see the odd bit of hardware on the moon, or specular reflections from old bits of gear as they float by. The lunar surface is so clean yet its been acting as a filter for passing meteorites for the last four billion years. I take your point about us being more careful about power emission, but at the same time we still broadcast TV, set off nukes. We should stand out like a sore thumb.

I don't think anybody is going to be out there.

Mmmm... Milky way...

[boazarad]

Wow, 50 billion?
That candy bar must have a lot of calories...

Re:eh?.. This is like deja vous without the punchl

[Palmsie]

It is my understanding that the drake equation wasn't meant to be a predictive tool for calculating the exact or even closely approximate amount of planets that harbor intelligent life. Rather, it was simply supposed to be a means to illuminate the incredibly likely event that intelligent life could possibly exist, given a big enough universe, under incredibly conservative and unstable estimates.

The thing to consider

[Anonymous Coward]

500 million in the habitable zone not 500 million habitable. Venus is in the zone and it's pretty extreme. Mars is on the ragged edge so it could go either way. Mars could be colonized but not Venus. There's also a myth that the Earth system is fairly normal. It's actually not very normal since it's a single star system. Most have two or more. If the talk of a brown dwarf nearby is true then we came close to being a binary system. Odds are most of the Earth like stars have companion brown dwarfs. The ultimate truth is the whole dynamic is far more complex than it's made out to be. Actual Earth like planets could be extremely rare given all the conditions needed. Not that it means life is rare. Mars and Venus type planets are probably fairly common and Mars could have life and Venus came close to being friendly it just went greenhouse and has a dense atmosphere. The bulk of life is chances are simple organism with complex ones occupying the more Earthlike planets. Complex life requires time to evolve and extreme planets will tend to have short windows for complex life to form. That's why there are no plants on Mars. At best it had a few hundred million pleasant years before it went cold. It could have single celled organisms but nothing much more complex. A wild guess would be that you need a billion to 3 billion years of non hostile climate for intelligent life. It's not all that long in the life of a solar system so there could still be a lot of intelligent life out there. The trick is making contact during it's technical period which could be brief. We've got maybe a hundred years under our belt when we could potentially receive signals. So far we've only really listened and not all that hard for a couple of decades. If our technical period lasts another hundred years then we're only looking at maybe a 150 year window when we were halfheartedly listening. At the rate we are burning resources we could collapse in the next hundred years so a 200 year tech window could be fairly normal. That means if in the last million years there were a thousand civilizations within a thousand light years each lasting 200 years, as in broadcasting years, we could easily see hundreds of years in dead air between each and that's a lot of civilizations. I'm confident there's intelligent life in our galaxy right now but the odds of receiving a signal from one is like winning the lottery.

hazard

[Anonymous Coward]

http://vega.org.uk/video/programme/156

Keep looking.

[dmomo]

We're gonna need more than that.. population growth. If when we die, we get our own planet, we're gonna run out!

Re:Keep looking.

[LordNacho]

This got me thinking that perhaps we should aim a few containers with microbial life at some nearby "Earth-candidates". That way we can at least ensure that something from here lives on, somewhere. (Hope there isn't already something there, that could mess up their ecosystem, hehe)

Re:Keep looking.

[amorsen]

We cannot really send containers anywhere useful except Mars, Venus, and Europa. Neither of those are particularly good hopes for sustaining intelligent life one day. Except Venus perhaps, but that is going to take more than some microbes.

Re:Keep looking.

[LordNacho]

I don't see why not? Surely we could develop a delivery method that can take its time to get to nearby star systems?

Re:Keep looking.

[michelcolman]

Yeah, just like that other nearby civilisation did before they were wiped out.

Re:Keep looking.

[amorsen]

In theory we can develop anything. In practice, we are far off from being able to send anything to even the nearest stars with a travel time shorter than thousands of years. It is unlikely that we can make anything which can last thousands of years and still be functional enough to find a planet and brake to a reasonable speed before landing.

Error: 50 billion, but not in Milky Way

[G3ckoG33k]

The articles headline doesn't make sense "Milky Way Stuffed with 50 Billion Alien Worlds" when the article says less, 500 million.

Do they 'borrow' Slashdot editors?

Re:Error: 50 billion, but not in Milky Way

[Adambomb]

It's not an error, it states 50 billion likely worlds in total based on current sample statistics. 500 million of those 50 billion are probable to be within what we currently consider to be potentially habitable orbits.

the numbers are referring to two different concepts. in other words, they're positing that 49.5 billion of those expected worlds aren't likely to be within a potentially habitable orbit and that just considers distance from their suns, who knows about all the other possible variables that may be required for life as we know it at least.

Re:Error: 50 billion, but not in Milky Way

[nzap]

Try reading that again. "There are thought to be 50 billion exoplanets, 500 million of which are probably orbiting within their stars' habitable zones."

Re:Error: 50 billion, but not in Milky Way

[VortexCortex]

who knows about all the other possible variables that may be required for life as we know it at least.

One of the silly things is that we keep having to redefine our ideas of what is required for life to exist.
See: Extremophiles

For instance: Take the ecosystem under the glacier that's responsible for the "Blood Falls".

Chemical and microbial analyses both indicate that a rare subglacial ecosystem of autotrophic bacteria developed that metabolizes sulfate and ferric ions. According to geomicrobiologist Jill Mikucki at Dartmouth College, water samples from Blood Falls contained at least 17 different types of microbes, and almost no oxygen. An explanation may be that the microbes use sulfate as a catalyst to respire with ferric ions and metabolize the trace levels of organic matter trapped with them. Such a metabolic process had never before been observed in nature.

A puzzling observation is the coexistence of Fe2+ and SO42– ions under anoxic conditions. No sulfide anions (HS–) are found in the system. This suggests an intricate and poorly-understood interaction between the sulfur and the iron biochemical cycles.

The other silly thing is that whole "life as we know it" thing. I'm not so sure that other intelligent life-forms must resemble "life as we know it". Finding exoplanets is neat, but we really don't even know where to begin when setting the parameters for the equation to compute existence of life...

Re:Error: 50 billion, but not in Milky Way

[Tumbleweed]

I started to read your comment, but then gave up when I realized you're really just meat that talks. Disgusting.

Re:Error: 50 billion, but not in Milky Way

[Rational]

Well, I can't moderate you up, but at least I can congratulate you on a well-chosen quote.

Re:Error: 50 billion, but not in Milky Way

[Brucelet]

As far as I know, all observed extremophiles still need some form of liquid water. As the habitable zone is simply an estimate of where liquid water can exist (modulo atmospheric conditions and the like), this seems to me like an adequate way narrow down what planets may have life on them.

Re:Error: 50 billion, but not in Milky Way

[Tumbleweed]

Well, I can't moderate you up, but at least I can congratulate you on a well-chosen quote.

We 4-digit userIDs gotta stick together! Kids these days, it's like they don't even know what a book IS. *sigh* :)

What is the human race?

[jgoemat]

The Sun won't extinguish life on Earth for billions of years. 6 million years ago we had a common ancestor with chimpanzees. If you think the dominant life form on Earth in 2 billion years will be "human", you are mistaken.

Re:What is the human race?

[Plekto]

Actually, the earth will simply get too hot to support life in about another 40 million years. Given the amount of water vapor that the evaporating oceans would create and the fact that the Earth won't have run down its internal magnetic field, as happened to Mars(magnetic field collapsed - atmosphere got blown away), we're looking at another Venus type scenario. In fact, Venus probably had life itself several billion years ago(since it's about the same size and composition originally as the Earth, there's no reason not to assume life didn't also start there at one time), but as the Sun got hotter as it aged, well, we can see what happened.

In fact, the Sun will make life nearly unbearable in as few as 5 million years. We might have to live underground or under the sea to escape the intense UV radiation and summer heat that could easily top 140-150 degrees.

As for life, well, I suspect that there's "life" on every planet with water on it. Every single one. But considering that it took our planet 3-4 billion years to develop even basic life forms, well, there's a lot of luck involved with finding anything at our level or close to it. We could find 1000 worlds with life on them and not find anything remotely capable of communicating with us. And anything much more advanced than we are would simply use communication methods that didn't use radio waves. Just the implications and speed of research into quantum entanglement(among many other technologies being developed or researched) makes it pretty clear that instant (or effectively FTL) point to point communications are less than a century away. We're really looking for a bunch of weak signals in a 100-200 year window. Out of billions of years.

Re:What is the human race?

[Tumbleweed]

The Sun won't extinguish life on Earth for billions of years. 6 million years ago we had a common ancestor with chimpanzees. If you think the dominant life form on Earth in 2 billion years will be "human", you are mistaken.

One unfortunately-timed solar eruption of a large enough magnitude could wipe out Earth any second. That's even aside from the threat of asteroid strikes, etc. There are no guarantees.

Re:What is the human race?

[Anonymous Coward]

Yet again: quantum entanglement doesn't give you FTL. Without a classical side channel, quantum entanglement is worthless, and that classical signal can go no faster than c.

Re:What is the human race?

[jbolden]

The sun is getting about 10% more luminous this billion years. Your timeline is off. Think of it this way. 2 billion years ago solar radiation was only 6% less than it is today.

Re:What is the human race?

[jgrahn]

Actually, the earth will simply get too hot to support life in about another 40 million years. ... In fact, the Sun will make life nearly unbearable in as few as 5 million years.

Says who?

40 million years is a very short period in the history of life, not to mention 5 million years. Popular science should be full of this stuff if it was an accepted fact, or even just a theory. Or are you saying there there is a Big Conspiracy to hide the Truth from the people?

Re:What is the human race?

[Plekto]

Luminosity has nothing to do with it. All we need is a few degrees more and life becomes impossibly harsh.

The Earth is slowly moving towards the Sun. Very very slowly, mind you. The habitable zone will have moved almost past Earth. The combination of forces means that in a bit over 60 million years, we'll be in a greenhouse cycle that will feed on itself, regardless of other forces. This might take another 100 million years to complete, but life as we know it won't be possible long before everything turns into a acidic hell. It's a pretty delicate balance that we have right now,and a few more percent energy from the Sun will be enough to start the cycle.

Earth will slowly start to turn into Venus. What happens in 3-6 billion years is a moot point.

The problem is that while the habitable zone is larger than we previously thought, the Earth is dangerously close to the inner edge of it. (~0.75AU ~2.0 AU) It only takes a small nudge of 2-3% at this point to create a greenhouse scenario, which means we simply lose and die out barring finding another place to live. I suppose we could make a orbital ring/shield to block 5-10% of the sun's energy, but that's just delaying the inevitable.

Most of this research is unfortunately not online and you have to read the originals or find it in books. It's not very popular to talk about it, though, as it gets confused and lost in the mountains of greenhouse gas pseudo-science. If you say "global warming" or "greenhouse" you typically don't think of or bring up results about solar aging.

Re:What is the human race?

[jbolden]

There is a discussion in the Journal Astrophysics and Space Science about the earth in a billion years and they still have the earth at 93m miles. So.... who is agreeing with your theory?

Re:What is the human race?

[Plekto]

It's a terribly small amount - a few mm a year due to friction and added mass due to debris being picked up by our atmosphere.

http://www.madsci.org/posts/archives/2006-07/1152815859.As.r.html
This is the relevant calculation/formulas. You also have to calculate in the Earth's albedo. Currently it is at ~0.367(that page is slightly off as human structures and pollution also contribute some), but with the ice caps melted, it will be ~0.13(that page is also slightly off because such high heat would also melt ice in glaciers and high altitudes as well). If we set a maximum to the upper limit of 328K instead of 373K (because we're talking about human life and 55C is pretty much the limit of what we can tolerate - 100C is a silly limit, it should be changed to 55C), the inner edge of the "habitable zone" relative to life on Earth for *Humans* is fairly close to our current orbit. We're really "this" close to a greenhouse scenario and most people don't get how something as large and as permanent in their minds, as the Earth is, can be turned into an unlivable mess in a very short time. Even if it's not immediate, it will mean that most of the equator regions will become deserts and too hot to support any sort of stable ecosystem. This means we could see the equatorial rain forests simply vanishing in a few million years(if we don't cut them down first, though that does increase albedo). Oxygen levels drop as well as UV radiation increasing due to our messing with ozone levels, resulting in us having to live underground or in domed cities. We simply are absorbing more energy that we are reflecting back into space at that point. This might not even take 1 million years with human activity added to the equation.

IMO, the only way that we can solve this is to build an artificial ring to block roughly 1-2% of the sun's energy. Everything else just isn't going to solve the issue of the sun getting hotter and the albedo changing. Nothing we do will matter if we can't make less energy hit the surface once the ice caps melt.

Re:What is the human race?

[rubycodez]

the mainstream estimates I've seen are another 300-500 million or so years due to sun expanding slowly http://image.gsfc.nasa.gov/poetry/ask/a10474.html

Re:What is the human race?

[Plekto]

True, but they don't factor in the fact that the Earth's albedo will drastically change once the ice caps melt. 5C higher temperatures in the summer alone would be enough to make birds and insects simply fall out of the sky in some areas, and 10C would be pretty much lead to a collapse of much of the Earth's ecosystem aside from insects and marine animals. Hotter temperatures also would create massive storms and fires, which while not being able to kill off life on the planet, would certainly cause severe problems for humans. 80% of human civilization lies in areas that rising oceans alone would put in danger.

My calculations come out to roughly a 2-3% increase in the sun's energy reaching the Earth's surface being enough to kill off most human life.(or force us underground). Even 1-2% more is a disaster at this point due to humans messing up our environment. Of course, an artificial ring would block about 1% of the energy and give us plenty of breathing room and also make global warming no longer an issue. We could make one in as little as 50 years with today's technology.

Re:What is the human race?

[rubycodez]

None of those changes will kill off Earth life, life will adapt. Over the long haul continents will move, so who cares what will be coastal or under or over water tens of millions of years from now?

Re:What is the human race?

[Plekto]

True, "life" will adapt, but large mammals including ourselves, will long be extinct.

Re:What is the human race?

[rubycodez]

baseless conjecture, plenty of large mammals can and do thrive in desert conditions. Maybe desert elephants will roam Europe.....

Re:What is the human race?

[Plekto]

150F, though, is simply too hot for most animals with a circulatory system to survive unless they spend most of the day underground.

Time to pack, then?

[macraig]

I'm dusting off my suitcases right now.

NOT.

I really didn't need to know this. It's way too big an always-out-of-reach carrot for a guy who's always thought the pasture he couldn't see must surely be greener.

Re:Time to pack, then?

[Tumbleweed]

I really didn't need to know this. It's way too big an always-out-of-reach carrot for a guy who's always thought the pasture he couldn't see must surely be greener.

Be careful - that pasture may BE greener, but that green might also be a toxic slime mold.

Re:Time to pack, then?

[a_n_d_e_r_s]

I think it just is Soylent Green.

And thats edible :)

Re:Time to pack, then?

[Tumbleweed]

I think it just is Soylent Green.

And thats edible :)

Soylent Green is recycling, people! (also: Soylent Green is recycling people)

The year of X

[Troll-Under-D'Bridge]

I think the era of humans living in space (exploring space is a mere idle pastime if all you're going to do is to snap blurred photos or vicariously poke some pebble in some distant landscape) will turn out pretty much like the fabled Year of Linux on the Desktop. There won't be a year of Linux on the desktop. We're just going to find out one day we are using Linux on the desktop. Or we won't (because by that time we'll all be using wallpaper or holographically projected computers).

Right now all we have is a token presence in space. Maybe in a decade, there will be another "international" space station where another half a dozen people will live for weeks at a time. Then maybe in another decade down the line, there will be hundreds of people living in half a dozen stations independent of any national space agency. By then maybe we'll have a moonbase or two (one for the international community and the other for some lone wolf space superpower). Like the first humans out of Africa, the trickle to space continues until one day we cross the threshold (a 1000 or 10 x 1000?) when we can say humanity is truly a space faring species.

Then again, maybe, like the explosion of the tablet computer (2010?) or Android phones (2011?), there will be one breakout Year that future historians will point back as the true start of the Space Age, when even mere millionaires can hop on a junket to low Earth orbit.

Re:The year of X

[ImprovOmega]

The 2030's see an energy revolution. Propulsion systems make generational leapfrogs annually as the applications become more and more apparent. In the late 30's and early 40's construction on the moon begins in earnest. Permanent bases are set up. Engineers and construction workers begin one of the most massive undertakings in mankind's existence. Regular flights for the rich and powerful become commonplace by the mid-40's. By the 50's, private spaceplanes are making regular trips back and forth as the rich make it the newest big vacation destination. Costs continue to tumble.

By the late 2060's purchasing a ticket to the moon is as common as purchasing a cross country airplane flight was in the late 1960's. Resorts and tourism drive nearly half of the lunar economy (the bulk had always been mining operations until then). As the 70's give way to the 80's all space exploration uses the moon as a launching point.

The future is a strange and wonderful place, with many worlds to explore. I look forward to it with great expectations.

Re:The year of X

[choongiri]

I enjoy your optimism, but...

The 2030's see an energy revolution.

...we need to be a little faster than that. Despite the current wars and recession, we live (historically) in a period of unprecedented wealth and global political stability. If we don't sort out our energy use before 2030, we aren't going to have the global stability necessary to mess around in space much longer.

Points taken

[G3ckoG33k]

Points taken.

My error in expecting 'worlds' to be 'inhabitable'.

Cratonism proof.

[orphiuchus]

Its a nice round number. See? God did that.

Re:Cratonism proof.

[Anonymous Coward]

All hail the mighty Craton !

Re:Cratonism proof.

[jouassou]

Why didn't he choose a number that is round in more bases?

50 000 (base 10) = C 350 (base 16) = 141 520 (base 8) = 1 023 252 (base 6).

Nah, Doug got it right

[Anonymous Coward]

"Mostly harmless."

So that's what that taste is

[Anonymous Coward]

stars

The word you're looking for...

[Anonymous Coward]

The word you're looking for is "ignorant".>

Is "skeptic".

At least when guesstimates such as "number of thingies in the galaxy" are concerned. Particularly, when such guesstimates are made from the above mentioned single known civilization.
Cause, that "Bs" in the end... it might actually be a divisor, and we may be using a wrong/bad equation to guesstimate.

Only a step on the evolutionary ladder

[petes_PoV]

I doubt that the entities we send to the stars would, today, even count as human - or have any sort of rights. However, those people/things will be able to prove a direct link to us - even if it's because we made them, rather than gave birth to them.

Humans are not designed for space travel. We don't live long enough. We're too fragile, need too much energy just to stay alive and can't eat electricity. Whether we overcome those design "mistakes" in biological or mechanical solutions will be an interesting turn of events. However in time, we will send stuff out there - though if history is a guide, it may be running away from us.

Re:Only a step on the evolutionary ladder

[Anonymous Coward]

"Humans are not designed for space travel. We don't live long enough. We're too fragile, need too much energy just to stay alive and can't eat electricity". Same can be said about travelling under the sea or high among the clouds...

Re: Creatonism proof.

[kanweg]

Yes, Yagolah must have done that. The article specifically said "exoplanets" so as not to include our sun's planets, which would have muddled the figure.

Bert

uh?

[Seraphim_72]

Yes, because as a Scientist I always trust an extrapolation that goes from 1000 to 500 million. On our Earth I believe these people normally peddle Homeopathy.

Re:uh?

[flyingkillerrobots]

Opinion polls do that fairly often with public opinion (around 1,500 samples, tops, extrapolating to 300 million), and usually end up off by no more than a few percent.

Re:uh?

[confused one]

And as an Engineer, I don't like extrapolation of that magnitude either; however, it's easy to see how this occurs: Picture a meeting with the project lead, NASA administration and NASA PAO. The project lead is told he needs to give them something, a fluff piece for the PAO, to keep the project visible in the public's too short attention span. The point is to maintain visibility so they're not caught up in any budget cuts. Wanting to keep his funding, the project lead does a quick back of the envelop calculation that he'd never dare put in a peer reviewed paper. The PAO takes it and runs with the story.

Re:uh?

[Brucelet]

One of the fundamental assumptions underpinning all of cosmology is that we're not in a uniquely special place in the universe, unless there is some a priori reason to think so. Yes, we need to live at a certain distance from a certain type of star, but on a larger scale there should be nothing special about the stellar environment we are in. As long as that assumption is true, it seems reasonable to me that we can take the stars around us as a representative sample of the stars in the galaxy and make this sort of extrapolation. In principle of course it should have some margin of error based on sample size and other statistical factors.

Re:uh?

[confused one]

Sure. But, there are problems with doing a straight forward extrapolation. There's some discussion suggesting that as you approach the galactic core and the star density increases, planet formation may become less likely. As you near the center of the core, there may be no "habitable zone" for a planet.

Where are the aliens? Simple

[SmallFurryCreature]

Lost in time. Lets say all those 500 million planets are earth like. That means they got a lifespan of a mere 10 billion years (earth is 4.5 billion old and got about 5 billion years left). On this planet (as far as we know) there has been one species influential enough to possibly be noticed in space or indeed notice space itself. For a grant total of just over a hundred years. In 10 billion. We have no way of knowing how long civilizations such as ours manage to survive. But even if you make it a thousand years, it still the shortest of blips on the time line of our planet.

Even if you account for that the fact that our planet wasn't always habitable during its life, it is still a VERY wide window in which to look. We could look at every single habitable planet and just never ever be looking at the right time to see life.

Every single planet could spawn life within its own lifespan and we still would never ever know about it. There are places in our own solar system that have possibly supported life and some still might, and we don't know for certain (yet) because we can't look for it yet.

I can not see a dinosaur, nor a dodo or an elephant bird or countless other forms of lifes which we know to have excisted, merely because time gets in the way. Space got far more time. We are not alone, just lost in a sea of time.

Re:Where are the aliens? Simple

[Anonymous Coward]

We have no way of knowing how long civilizations such as ours manage to survive. But even if you make it a thousand years, it still the shortest of blips on the time line of our planet.

Why only a thousand? You'd need to give me a pretty damn good argument to convince me that any intelligent species would cease to exist before their star runs out of hydrogen. Events that kill off most of the population? Sure. However, we're intelligent enough that if something happened tomorrow which wiped out all but small groups of 10 people here and there, we'd be back to running the planet in another 1000 years.

Re:Where are the aliens? Simple

[7Prime]

On the flip side, with the current level of human technology, we could probably survive (to a non-extinctional level) any of the conditions that made many former species extinct:

Meteor? Early warning defense system, missiles, cave habitation, and post-collision: air filters

Early earth? Lead radiation suits, air conditioning, shelters.

The list continues.

Of course, most of these things would still wipe out huge swaths of the world's population, most likely the poor, less educated, and less technologically sophisticated. But killing enough humans to cause permanent extinction would take something beyond what our world has seen in its lifetime. Of course, something of our own making could, but I highly doubt it would lead to mass extinction. Call me an optimist, but the human race is about as resilient as cockroaches, even though we require technology to be that way.

Re:Where are the aliens? Simple

[rrohbeck]

>But even if you make it a thousand years, it still the shortest of blips on the time line of our planet.
Depends on what you call civilization.
http://en.wikipedia.org/wiki/Olduvai_theory
That one may be pessimistic but the basic idea is correct IMO.

Re:Where are the aliens? Simple

[Anonymous Coward]

Lost in time.

And lost in space.

And meaning.

(meaning)

Re:Where are the aliens? Simple

[Anonymous Coward]

You might see a dinosaur when the aliens let you look at the videos that were made back then.

Maybe not exactly "stuffed"...

[Bohnanza]

500 million worlds within habitable zones sounds like a lot, but with ~300 billion stars in the galaxy those are spread fairly thin. And certainly not all of those planets are "habitable"...

Stuffed?

[outsider007]

Nice of God to "stuff" our galaxy with so many alien worlds. Did he "stuff" each of them with a Jesus?

Secret ingredients finally revealed!

[Anonymous Coward]

Gee, I always wondered what that nougat shit was anyway.

technology matters

[Gravis Zero]

* distance - the great thing about the moon is that it's not too far away, only a quarter million miles.
* already did it - we have gone to Mars multiple times, just not in person. the only good reason to send a person is for colonization and we dont even have the moon colonized.
* speed - Mars is reachable with the same technology but it would be crazy to actually take that trip to get to a planet so far away.
until we can achieve higher speeds, Mars is off the ballot. i'm not sure what the impediment is but it seems like
* FTL speed - without FTL travel going to another star is just crazy.
* motivation - we arent fighting a cold war of one-upping the russians, we cooperate now. china seems to like the cold war mantra but they never invent technology, just copy it.

Re:Finding a planet is easy, finding life may be h

[smallfries]

Why?

You seem to be confusing time and space. If there were 1000 of them over one billion years then the probability of their light cone intersecting ours is tiny. Unless you assume that on reaching maturity they somehow become a galactic civilisation with a presence in every star system. Even big noises like broadcast TV and nuke tests only propagate at the speed of light. If each civilisation manages to make a big noise for 1000 years after inventing radio then you still need to be in the right point in space, at the right point in time, in order to hear them.

Sad fact of the matter is that all of the grand space opera visions of the future rely on FTL that just doesn't look feasible. The alternative is life scrabbling around in its own backyard before it destroys itself. Unless our immediate neighbours go through the same process at the same time it will look like we are alone. Of course this isn't a testable/falsifiable difference to your opinion - they're both observationally equivalent.

Big whoop.

[mark-t]

Sorry... but this is not impressive to me.

Half a billion other planets that could potentially be habitable means approximately zilch to me because it would take so long to travel there that the spaceship that takes off would have to be capable of supporting multiple generations of humans, and there's a not altogether insignificant chance that the generations that arrive will not remember or care why they are even on that ship. What happens if a whole generation of people don't even want to be on that mission?

Re:Big whoop.

[Jason Levine]

I would think they wouldn't have much of a choice. They'd be beyond the point of returning to Earth. Their only other option would be to alter course such that they wouldn't have a firm destination at all.

Re:Big whoop.

[mark-t]

So the idea would thus be to create several generations of slaves, who would be required to carry out the objectives of the spaceship's designers, regardless of what they, as individuals, might want to do? This is wrong on so many philosophical levels it defies all sense of reason.

Re:Big whoop.

[lennier]

This is wrong on so many philosophical levels it defies all sense of reason.

That's never stopped science fiction before!

Re:Big whoop.

[marcosdumay]

As opsed to what? Do you really think you won't be interfering with the life of your offspring if you choosed to stay on Earth? Anything you do has consequences, some of them appear only on big timeframes. I'd say "get over of it", but no, you shouldn't, you should simply be aware of it.

Re:Big whoop.

[mark-t]

At least staying on earth they remain free to choose to do what they want, and go where they want. On a spaceship, they'd be stuck *on* the spaceship, which probably wouldn't have any dimensions larger than a few hundred meters at most, so they are confined to MUCH a smaller area than they would be on earth, and it would last their entire lives. Also, they are also forced to be space explorers, or else be directly involved in maintaining the functioning of the spaceship, and would not have the freedom to choose what they want to do as one does in a free society on earth.

Re:Big whoop.

[marcosdumay]

"At least staying on earth they remain free to choose to do what they want on Earth, and go where they want on Earth."

There, fixed it for you. And what if Earth ends up sucking big time? Also, why do you assume that a generational space ship has only a few hudred meters of diameter? Even Project Orion proposed something bigger.

translated to English: "give us money!"

[arcctgx]

This is a problem with science in general. Many scientists tend to make very bold claims, only to make sure the funding of their research will be continued.

It seems that the Kepler team is starting a campaign to ensure the Kepler mission will be extended.

Bad news for humanity

[Dr. Spork]

All those habitable worlds, and yet no sign of life. That's very bad news for us. There must be some kind of a great filter in the universe which prevents 99.99999999995% of all habitable planets from developing a visibly space-faring civilization like the one that we hope to soon become. ("Soon" in the cosmological sense.) This means that we should expect to fail before we ever get there, and never recover. That's bad news. If Earth-like planets had been rare, we could at least have had the hope that we have one big step of the great filter behind us, but apparently not - with means that it's probably in our future.

Re:Bad news for humanity

[eriqk]

The planets are in the habitable zone, it doesn't mean they're habitable or even Earth-like.

The filter you mention is distance. Space is too big to allow interstellar travel. We can fantasize about exotic methods of propulsion, but none of the ones we can come up with are feasible. We're stuck to our little planet, just like any other hypothetical civilization is stuck to theirs.

Reality isn't a sci-fi story.

Re:Bad news for humanity

[BJ_Covert_Action]

Wow, way to be a downer. Did you stop to consider the possibility that, in every 1/100 of these habitable planets, there could actually be thriving, intelligent space faring civilizations that are either

A) So advanced in technology that we simply do not possess the means to recognize them as being a civilization.
B) So far away that their communication signals have simply become too weak and/or distorted to be recognized by the time they reach us.
C) So far removed in time (evolved to spacefaring, lasted for thousands of years, and still died off before we stopped throwing rocks at each other) that we simply missed the evidence that they existed.
D) Or, finally, so far ahead of us in terms of cultural maturity that they have, thus far, decided to hide themselves from our view until a later time when we can accept them as a civilization?

There are 1,001 reasons that there could be advanced, sustaining, prolonged civilizations which exist in our galaxy, but which are still undetectable by our current means. When it comes right down to it, the only way we are really going to determine if there are advanced spacefaring species in our galaxy is by becoming one ourselves, and going out and looking with the level of technology required to become a spacefaring species. So don't give up hope and go slit your wrists just yet. There is absolutely no reason to assume that we will fail in our endeavors in space. Thus far, humanity has a great track record at achieving that which was once thought impossible, even if those journeys all had their minor setbacks.

Re:Bad news for humanity

[7Prime]

C) So far removed in time (evolved to spacefaring, lasted for thousands of years, and still died off before we stopped throwing rocks at each other) that we simply missed the evidence that they existed.

Your other arguments have merit, but this one I really don't believe is possible. The more a species spreads out, the greater its chance of survival is. For the most part, any civilization that has developed the ability to move off world in large numbers has freed itself from all known forms of extinction. Any other "what if" scenarios you throw at the equation are likely to be countered by advancements in technology, distance, or rapidly-growing numbers. As I like to say, "humans are just as resistant cockroaches, we just require our technology to do it." The same would be true for any alien species that developed past our level of technology.

Re:Bad news for humanity

[marcosdumay]

I disagree. They are not a lot. Put them in the Drake equation; yeah, it is bad, but will give you an idea on how many planets are we talking about.

Nope, estimate too low

[Progman3K]

Mark my words, in the future, we will discover that there are far many more planets than stars and that means our galaxy contains many hundreds of billions of planets.

Right now our equipment simply cannot detect the majority of them.

Re:Nope, estimate too low

[Redshift64]

I wouldn't be surprised if our galaxy harbored at least a trillion planets.

Key distinction

[Shadowmist]

500 million planets within the "habitable zone". With the zones as defined, three planets Venus, Mars, and Earth fall into that category here in the Sol System. Unfortunately two of them fall rather short in the market as prime real estate. As much as a 5 percent deviation in either way would send the Earth to either Runaway Hothouse or Runaway Glaciation. So that number needs to be taken with a great deal of salt.... especially given the major amount of factors of both low and unknown levels of probability that contribute to making this world and abode for life.... being at the right distance, and having a rather handy large satelite to stabllise the Earth's axis from wild precessions. So far the latest observations of exo systems have told us that pretty much the bulk of what we assumed of planetary system evolution has to be rolled up and pitched into the nearest waste bin. Given the present situation we have very little handle to establish the probability of an actual Earthlike world emerging from the set of stars that have long tierm viability for planets.

Re:Key distinction

[pz]

So, if the estimate of habitable is off by two orders of magnitude, that's still millions of planets.

Not one or two planets.

Millions of them.

Re:Key distinction

[Shadowmist]

It may be a lot more than two orders of magnitude. We still don't understand quite fully the significance of having a very large satelite like the Moon played in the development of life on this planet. With all the other things that could have gone wrong or ended life on this planet, with the wide scale evidence that almost every exo-system out there shows evidence of extreme violent planetary re-arrangement, we may very well be looking at well well beyond a mere "two" orders of magnitude. The probability for habitable worlds may be low enough that the average "Earth" may be located so far apart that we may never detect another within the lifetime of our species. It's quite conceivable that we are effectively alone in the universe, at least to the extent that any other intelligence is located so far away we'll never detect a sign of it, or it, us.

Its not just orbit that matters.

[WrongMonkey]

The Earth has a lot of special features besides a Goldilocks orbit. A couple obvious ones are that the Earth has a tilt that gives us seasons and it has a large moon that gives us regular tides and influences plate tectonics. Are these necessary for life or just necessary for life as we know it? There's no way to tell from a sample set of one.

Obligatory

[joeszilagyi]

http://www.youtube.com/watch?v=buqtdpuZxvk

Just remember that you're standing on a planet that's evolving
And revolving at nine hundred miles an hour,
That's orbiting at nineteen miles a second, so it's reckoned,
A sun that is the source of all our power.
The sun and you and me and all the stars that we can see
Are moving at a million miles a day
In an outer spiral arm, at forty thousand miles an hour,
Of the galaxy we call the 'Milky Way'.

The more there are...

[The Living Fractal]

The more pissed I get at the universe for playing a great cosmic joke on me. I should've been born during the era of human expansion into the galaxy... That's really the only thing that freaks me out about death: that I won't be able to observe things continue. I want to know how our story truly unfolds!!

Re:The more there are...

[lennier]

I want to know how our story truly unfolds!!

Hitlercat concedes defeat.
I can has moon?
I has a pollo!
Now wut?
I has a shuttle!
Nooo they be stealin mah shuttle!
I has a Hubble!
I can not has hiperdrive?
Tacgnol is charging his lazors! ===_
Itty bitty particle committee does not approve your dissertation.
I can has large hadron?
Invisible Higgs boson.
Srsly, I can not has hiperdrive?
Invisible fusion.
Invisible shuttle.
Invisible oilfield.
Invisible bees.
Srsly.
Monorail cat is offline due to critical future shortfall.
Unattainable hiperdrive is unattainable.

Re:The more there are...

[Anonymous Coward]

If I could at least just see some advancement in space travel before I die. Sigh.

Re:The more there are...

[marcosdumay]

How do you know you weren't born at the era of human expansion into the galaxy? Wouldn't you wish to be born at the expansion into the Local Cluster if you were born at the expansion into the galaxy? How do you know there will be human (or any species) expansion into the galaxy?

Oh my God.....

[Anonymous Coward]

It strikes me that if God exists, and if God is He of the Chosen People persuasion, that the possibility of life elsewhere in the universe is greatly diminished. But, if God doesn't exist, and life on this planet is merely a cosmic accident, then the likelihood of similar accidents throughout the universe is much enhanced.

Just Because....

[mlauzon]

Our planet is in this position and has life, doesn't mean that other planets have to be in the same position as ours to have life!

What's all this then about ancient aliens?

[Eggplant62]

The only ancient alien I've ever seen is an old Mexican dude that used to panhandle in Downtown Detroit, but not much anymore. Otherwise, ain't no getting over the relativistic arguments against FTL travel, so any argument over who or what might be living out on all these predicted exoplanets is an exercise in futility.

Re:What's all this then about ancient aliens?

[lennier]

Otherwise, ain't no getting over the relativistic arguments against FTL travel

That is of course assuming that the argument from relativity that matter can't travel faster than light is something more than a tautology.

It always bugs me that Einstein made a philosophical jump from an equation describing the observed relative motion of matter under the conditions within which we can observe it, to an equation describing the inherent properties of motion itself under every possible condition. That jump made calculation simple given early 20th century tools, but the one does not logically follow from the other. Is it possible that relativity was a case of premature mathematical optimisation?

For instance: if the Lorentz contraction were merely a second-order effect caused by the self-interaction of EM fields, it would be theoretically possible for the entities which generate those fields to themselves travel faster than light. But under the strict interpretation of relativity, it's forbidden to even frame that question because the definition of motion has now been redefined to assume its own proof.

The interesting thing is that Einstein's wider programme - geometric unification of all fields - failed to be consistent with observations from quantum mechanics, and even general relativity failed to be fully relativistic (doesn't implement Mach's principle completely), yet people still assume that his starting assumptions were completely correct. But if those assumptions couldn' be generalised to actually describe reality at the lowest level, is relativity-as-geometry really such a fundamental principle after all?

Re:What's all this then about ancient aliens?

[Anonymous Coward]

You are welcome to advance any reasonably complete and self-consistent theory of gravitation that is consistent with experiment and celestial observation.

This is not easy.

This is a very useful tool for gauging (pardon the pun) your theory's correspondence with measured physics: http://en.wikipedia.org/wiki/Parameterized_post-Newtonian_formalism#How_to_apply_PPN

There is more here: http://en.wikipedia.org/wiki/Alternatives_to_general_relativity#Testing_of_alternatives_to_general_relativity

(although someone should really double-underline the 'non-metric' in the first paragraph there)

Note that *nobody* in physical cosmology will refuse to examine a theory -- even a really weird one like Heim's, Cartan's or like several that Moffat has grinded out over the years -- that satisfies most of the items under the second link. Even ones that have one or wild PPN parameters (i.e., deviations in weak-field behaviour -- some of these are deliberate to explain DM or the metric expansion) have been examined; some have been studied extensively. Ones that simply have different strong field behaviours are even more attractive (pardon the pun). Also interesting are those which simply have dramatically different behaviours from GR at the longest length scales, or have some time dependency. It is, however, exceedingly difficult to construct a reasonably complete and self-consistent theory that reproduces or recovers classical mechanics locally in accelerating systems or in systems where gravitation is non-negligible (or both).

Incidentally, although AFAIK no theory of gravitation accords better with experiment and observation than GR, there is as yet no evidence of gravitational waves, and the "wait for LISA" answer to the non-detection by LIGO has been really really fertile ground for theorists looking to extend or replace GR, or to keep GR but to introduce things like slow-rolling fields that have negative pressure (in the FLRW sense). Why? Because gravitational waves seem like they should be much more easily and frequently detectable than they have been to date, notwithstanding headscratching about apparatus and method.

(It is actually kind-of fun to explore ways in which GR can be adjusted to remove gravitational waves, or the observation thereof, for example by adjusting the energy-momentum conservation relation \del_\muT^(\mu\nu) = 0 -- kind-of because this tends to lead to an almost-certainly-bad value for Omega_Lambda in trying to recover observations of large scale structures).

But under the strict interpretation of relativity, it's forbidden to even frame that question because the definition of motion has now been redefined to assume its own proof

I don't understand this sentence at all.

There is nothing in GR that forbids FTL motion as long as you are willing to abandon everyday interpretation of causality (and explain why we still have that locally). It is even easy to construct metrics in which an observer at a great distance observes cause-event inversion (e.g. Gödel's metric). Moreover, our particle horizon in the standard cosmology is an example of FTL recession (things at a great distance moving superluminally). Yes, in a metric theory, this is done by fiddling with coordinates (e.g. metric expansion of space), but since coordinates only have useful meaning with respect to physical oscillators (pace the de Sitter universe, which really does raise questions about the self-interaction of the DE field), this does not seem like a cheat, or especially circular.

That is of course assuming that the argument from relativity that matter can't travel faster than light is something more than a tautology.

It's a postulate of SR, not a tautology or a

Resign yourself

[aepervius]

Once you start to calculate the energy requirement to go to Mars or other planet, combined with potential time even with a technology much better than yours, you will come to the same conclusion as me : almost certainly we will never go out of our solar system, almost certainly we will never meet other civilisation/alien life, and almost certainly we will die out and be forgotten once the planet is being inhabitable for us (whatever reason, including increase of sun luminosity before turning red giant) and the chance of one of our extra solar sonde finding an aliena rchelogue is infinitesimal.

Re:Resign yourself

[marcosdumay]

My conclusion was that we are stuked at Earth untill we invent nano-assemblers*, and at the Sun untill we invent a way to make nuclear fission portable**. None of those seem impossible, and they are as near that we can not only conceive them, but already gave them names.

* Or any other kind of cheap manufacturing. The old idea of robotic explorers would do, but it seems that the one cheap manufacturing that can work (reliably and early) is nanotechnology.

** There are some ideas on how to make stars portable. Ok, that may be a bit too far, but "portable" doesn't mean "small" at space.

Crazy

[symbolset]

* FTL speed - without FTL travel going to another star is just crazy.

Ok, Gravis Zero is one more volunteer to wait here. Please make a note of it when sending out the mission invites.

Re:Crazy

[youn]

LOL put me down as a volunteer... even without FTL :)

narrowmindedness boggles my mind

[Anonymous Coward]

It really amazes me that no one mentions that we could be an ant colony that the whole civilized universe is observing. Perhaps they don't want us to know about them as it would foil their experiment with us? Maybe the guys who are a little more advanced than us are prohibited to contact us by civilizations that are so advanced that they don't even need vehicles to travel. Perhaps a civilization exists that is a billion years more advanced than us. At that point, would you even need or want to exist in any other form besides pure energy?

re: "There are no guarantees."

[symbolset]

Eventually the End will come. That much is guaranteed.

Nothing will be the sole source of energy

[davidwr]

If you'd said wind will be the only major source of transported-long-distance energy then I'd listen.

I'll pretend that's what you said and re-read the rest of your post.

--
"Locally used" energy will be whatever is locally available. The sun heats my neighbor's swimming pool and my running turns on the piezo-electric lights on my running shoes.

Even if wind does become the dominant power-plant energy source, there will be some non-wind energy sources on the power grid. There will also be some "it had the energy in it when it was mined" chemical fuels still in use even if most chemical energy sources are, from an energy-source perspective, much like today's rechargeable batteries and serve as nothing more than stores of energy that originated on a wind farm.

Oh, I'm not even counting food and other forms of energy derived from living things. Food and energy from living things are largely solar energy tapped through plants.

Hmm, I guess if you think about it, oil and some other fossil fuel energy is technically largely solar as well, but saying so makes it difficult to talk about renewable vs. non-renewable energy sources. Oil is technically renewable, it just takes a long long time to renew.

Negative mass exists and here's the proof

[davidwr]

People can have negative energy. At least that's what the psychic down the street from me says.

Energy is mass.

Therefore....

If we can't get there in less than 100 generations

[davidwr]

If we can't get there in less than 100 generations then I've got better things to spend my tax money on, thank you very much.

Alpha Centauri or Bust!

What? There's no intelligent life in that system? Good, no natives to fight! If I get there first I'm claiming it in the name of the Kingdom of davidwria!

OB OT sig reply

[davidwr]

davidwr@slashdot$ sudo mod TheRaven64 up
davidwr is not in the sudoers file. This incident will be reported.
davidwr@slashdot$

Sorry man, I tried.

I always knew ...

[porky_pig_jr]

we're gonna run out of IPv6 addresses sooner than we think.

Subspace messages misinterpreted

[davidwr]

Not necessarily but we so rudely never answer the subspace messages they keep sending! All for the better they are probably trying to sell us something.

Due to a slight miscalculation in the way the human brain works and the mistaken impression that human beings had conquered mental illness, messages of galactic peace from the Third Galactic Cooperative were dismissed as the ramblings of a crazy homeless man. It didn't help that the person they were communicating with actually was a crazy homeless man.

Air Water Earth and Fire

[presidenteloco]

For spontaneous emergence and evolution of life, here is an attempt at an environment requirements specification.

1. High prevalence of flexibly reactive / combining atoms of several types, to create a molecular structural alphabet and vocabulary.

2. Tendency for the reactive elements to be brought together more often than they are flung apart (a significant gravity well).

3. Presence of the prevalent potentially reactive atoms, simple compounds, and complex molecules in all of
Solid Phase, Liquid Phase, and Gas Phase. "Earth, Water, Air"

This is a crucial point. Life as we know it creates complex but repeatable processes and forms, by using an alphabet and vocabulary of structure but also an alphabet and vocabulary of transformation-process types. These energy-utilizing transformation processes of particular reliable forms are created using the interaction of liquids (carriers of energy and structural components), solids (containers and channellers of these liquids), and gases (carriers of more readily accessible/strippable energy-potentials).

4. The presence of a particular range of free energies. In other words, an "intermediate" thermodynamic regime in the local environment.

i.e. "Fire" (by weak but apt analogy). There must be common occurrences of free energies (energy disequilibria and coherent directional energy flows causing work to be done) which are just strong enough to re-arrange things periodically, and to allow controlled processes of transformation of energy and materials to occur. But there must be relatively few occurrences of enormous free energies which would blow structure apart completely or substantially, and there must not be a lack of free energy; an icy crystal dead zone in which no structural experimentation can occur, or a uniform high-entropy high energy zone like the interior of the sun, in which solid process-containment structure formation would not be possible.

So the ancient philosophers we denigrate were perhaps wiser than we or they knew.

I recognize that spontaneous life emergence in some kind of pure informational medium may also be possible. Perhaps simple information processing operations can achieve analogous combinatory and exploratory functions needed to discover working self-creating, self-sustaining, self-improving complex processes.
I haven't quite expanded my mind to imagine the details of that yet, and even so, I worry about the lack of generality of and problems with the sustainability of the information-medium and information processor, in such a case.

bad title, 500 million worlds in habitable zones

[Infoport]

Bad title for summary-- even the summary says 500 million of which are probably orbiting within their stars' habitable zones. Of course, the term "alien worlds" could refer to the uninhabitable exoplanets too, including uninhabitable planets in our solar system, but I doubt that this is what most people would imagine. Most people would probably think it means the possibly inhabitable ones-- i.e. the 500 million. While "alien worlds" could mean "foreign celestial bodies", look at the comments-- everyone immediately concentrates on the possibility of aliens or alien life.

Milky Way Stuffed With 50 Billion Alien Worlds...

[LowG1974]

...and ooey, gooey caramel.

MMMMMmmmmmm.......

Who cares?

[epine]

Affairs on planet earth would be so much improved to tune in the latest exoplanet night show discussing yesterday's current affairs: the great pyramids of Giza. You know it's a slow galactic news day when they spare a moment to humiliate planet earth.

I bet they're working up a great punch line about the Great Wall, coming to a screen near you on a slow news day sometime in 4'th m. AD

To quote the immortal Tammy Meztler, who cares?

But I'm sure there's someone out there rushing to sign up the Millennium Clock with a twitter account, just in case.

Nothing new.

[Anonymous Coward]

They've been saying this for years now, and still have yet to show us a single planet with so much as a microbe of life. It seems like any time the science world thinks it's getting a little dull out there, they play the "alien life" card, as if we've never heard it before.

The other equations...

[7Prime]

So, we have equations estimating the number of planets that exist in a habitable zone within our galaxy. And from that, we've extrapolated a relatively large number.

But the other equation is, from a perfectly habitable planet, what's the chances of life evolving? There require a lot things to come completely in alignment for life to occur. Who knows, a day later and the earth might have missed out on life entirely. My suspicion is that the chances for life occurring are extremely low. Maybe not as low as 500,000 to 1, but probably lower than the average person would seem to think. Then from that number, what's the chances of life evolving to such a level that they can even develop the means to envision space travel or communication? It's only happened once on earth, after all.

People think that just because there are a lot of planets that there should be lots of aliens. But I think that there are a lot of big equations left to work out. We have a very huge number which is probably countered by a number of very small numbers. I could easily imagine that we eventually find that the chances of life occurring on a "habitable" planet are less than 1 billion to 1, which would make the chances of life occurring elsewhere in our galaxy fairly remote.

Then again, I'm no expert. I'm just trying to bring up the other big questions we have yet to really tackle... at least as far as I'm familiar with.

Oblig.

[Anonymous Coward]

Might as well get it out of the way http://goatkcd.com/605/

Why we are not already in space

[DanielRavenNest]

There are two physical facts which are not changing: the mass of the Earth, and the chemical bonds in water. The first requires 30MJ/kg to get to orbit. The second gives you 15 MJ/kg in the best rocket fuel we have (H2 + O2 = H20). Since the best fuel only has half the energy to get *itself* to orbit, much less any payload, we are forced to use terribly inefficient contraptions to get into space. They burn a huge amount of fuel to get a smaller amount of fuel halfway to orbit, from which point that fuel can get an even smaller payload the rest of the way.

Efficient transportation systems like cars, trucks, and airplanes, have small fuel tanks and relatively large cargo/passenger areas. Rockets are the reverse, huge fuel tanks, teeny tiny payload area. So they are incredibly expensive to use. If you define insanity as doing the same thing over and over and expecting a different result, our space program has been insane for a long time. "Hey rockets are expensive, lets build another rocket!!, and it will be cheap this time!!"

The rational answer is to use another way to partially or completely replace rockets in getting to orbit. There are a number of options, and this comment space is too small to discuss them all, but the short version is "you are doing it wrong, try something else".

The term robophobe was coined to describe them.

[presidenteloco]

What are people who are terrified of and do not welcome our new artificial intelligence overlords?

Modern myths for 200 dollars...

Follow the money

[Msdose]

If there are 50 billion planets and no evidence of life other than us, then it must be because, in any universe, the first lifeforms destroy the universe. This is done by observing (creating) the Higg's particle. The Higg's field will immediately expand to the size of the universe, representing a force which will strip all the characteristics from the elementary particles, leaving a universe which is super symmetric, timeless and has zero entropy. It will then cool and collapse in a phase change which will give back the characteristics to the particles and the universe will be reborn. Pack a lunch.