Earth-Like Planets In Our Neighborhood

goran72 sends in a story out of the Chicago AAAS meeting contending that Earth-like planets with life-sustaining conditions may be spinning around stars in our galactic neighborhood — we just haven't found them yet. "'So I think there is a very good chance that we will find some Earth-like planets within 10, 20 or 30 light years of the Sun,' astrophysicist [Alan Boss]... told his AAAS colleagues meeting here since Thursday. ... The images from those new planets, he added, should identify 'light from their atmosphere and tell us if they have perhaps methane and oxygen. That will be pretty strong proof they are not only habitable but actually are inhabited. I am not talking about a planet with intelligence on it. I simply say if you have a habitable world. ... Sitting there, with the right temperature with water for a billion years, something is going to come out of it. At least we will have microbes,' said Boss."

Comments

Polluted by life?

[symbolset]

For the last 4 billion years the Earth has shed some 2 billion metric tons of genetic material per day. Solar winds have pressed some of this material more, and some less. Some of this material has been captured by extrasolar objects and carried away. Some of it has been captured by comets over which the sun no longer holds sway. Some of it has been so light and so thin that the solar winds have carried it far from home.

These solar systems polluted by life? How could they not be?

Re:Polluted by life?

[artor3]

Do you have a source for that? It seems hard to believe that Earth could have shed the equivalent of half its current mass in genetic material alone...

Re:Polluted by life?

[ean]

The human body contains about 100g of DNA. You're saying about 2E15 grams, or 20 trillion human body's worth, of DNA is not only released into the atmosphere but then escapes the earths gravitational pull and enters interplanetary space.
Sounds unlikely.

Re:Polluted by life?

[Arancaytar]

All right, What The Hell?

For a planet to "shed" anything except perhaps hydrogen or helium, that stuff has to overcome escape velocity, which (until rockets were invented in the 20th century), requires an (volcano or meteorite) that would incinerate any complex organic compounds and render DNA a fine ash.

Plus, Google will tell you that the following comes out to 44%, as an above poster already said:

(4 billion years) * (2 billion tons per day) / (5.9736Ã--10^24 kg) in percent

Less than 1% of Earth's mass is at a temperature that even permits life to exist. As for the part that actually consists of life, you can measure it in parts per million and still need scientific notation.

Re:Polluted by life?

[Anonymous Coward]

The chances of genetic material from the earth reaching other habitable planets is next to nil because:
1) You are forgetting how astronomically tiny Earth is compared to...what is not Earth. Really not much material here.
2) There aren't actually any known habitable worlds other than ours (doesn't mean they aren't there, just that they probably aren't prolific)
3) The genetic material would be traveling so slowly compared to the distance to any planets out there that they might as well not even be moving.

Re:Polluted by life?

[Anonymous Coward]

Mass of Earth is almost 6 sextillion metric tons.

Re:Polluted by life?

[dontmakemethink]

Man, imagine how rammed the courts are going to be when entire worlds get sued for pirating our copyrighted genomes...

Re:Polluted by life?

[Ihlosi]

There have been spores tested, and the verdict is that they can survive at less than 10cm to an atomic explosion.

Citation needed.

A couple thousand degrees temperature will break up pretty much any chemical bond.

One atomic bomb can kill, at best, about 50000 people, in a dense city block less than 1 square kilometer.

Eh, what? Both of the bombs used in anger so far killed more than that (both directly by the blast and delayed deaths by radiation). And, mind you, those were small 10-15 kT devices. In todays strategic arsenals, you'll warheads ranging from a couple hundred kilotons to 1.2 megatons. And then of course, there's this little baby:

http://en.wikipedia.org/wiki/Tsar_bomba

impossible dream?

[phantomfive]

Lately I've been really pessimistic about the whole thing, I mean, really, who cares? Even if there were intelligent life on planets that close, we would only be able to exchange communication once every 10 years, not enough to actually learn their language, and we would never be able to travel to visit them, right?

So realistically, there is not much point except for dreamers and space geeks. Might as well spend the effort here on earth. On the other hand, what if we could travel out there? Wouldn't it be COOL? I might actually meet a girl. Just kidding.

I want to believe that we will be able to travel long distances one day, hyper speed and all that, but it's pretty hard to see how it could happen.

Re:impossible dream?

[BungaDunga]

... exchange communication once every 10 years,...

We could give them, say, the entirety of Wikipedia, and they could give us their equivalent. Write up a "rosetta stone" with a bunch of pictorial/mathematical representations of words, and so on. Probably doable. Conversation back and forth will seem frustratingly slow, but there's no limit to the amount of info that can be streamed across.
Mind you the chances that we will be in the near vicinity of a civilization that communicates by radio waves that we can pick up is possibly quite slim- we've only been doing it for less than a hundred years. They could be in our equivalent of 1750 and we'd never hear a peep.

Re:impossible dream?

[MrPayne]

I would think that we wouldn't just send "Hi" and wait for a response. I think we would constantly be sending them information and let them learn what we are sending. We would hope they would do something similar.

Re:impossible dream?

[warrigal]

There have been several of these stories in the last month or so. Enough to make one suspect that someone has an agenda. It's all fantasy and dreaming until there's some hard evidence. For all the theories for there being intelligent life Out There, there are as many that run against it. The simple fact is we don't know and, apart from a desire to find something, we have no reason to suspect that there is life beyond this planet. So far we have one life-bearing planet in this solar system. The others we've inspected have drawn blanks. Again, there is no good reason to suspect that we are not alone. If we aren't, so much the better. But these breathless items about how many planets *might* support life serve no purpose. May as well say they'll cure cancer.

Re:impossible dream?

[Jane Q. Public]

Man, you ARE pessimistic. As well as wrong.

Once it became known that a civilization existed in a particular star system... and they knew about us... communication could be continuous both ways, not just back-and-forth like a walkie talkie every 10 years.

Starting with math: primary numbers, Fibonnacci sequence and other natural patterns, on to addition, subtraction, etc... then to logical propositions and conclusions... we could communicate an entire language and maybe even a couple of encyclopedias in the time it took for ONE 10-year round trip of communication.

And with ion drives, or Bussard ramjets (especially if they are Pellegrino-style vehicles that pull instead of push), maybe we could get there in, say, 50 years or so. And spend most of that time in something like cold sleep. There have been advances in that direction, too. Do we have the technology to do this? No. But we might in 10 years, or 20.

Of course, we would have to decide what and how much to send in our communications. There could be very real danger. I do not think most people understand just how deadly we (and by implication, they) could be, given enough time and effort, even to a civilization light-years away.

"Flying to Valhalla", by Charles Pellegrino, is a work of fiction. It is the book in which he introduced a totally new (but perfectly sound from an engineering standpoint) style of interstellar ship construction. As controversial as Pellegrino is as a person, there is no doubt that he is, as the saying goes, "wicked smart". There are some very plausible cautions in his book.

Re:impossible dream?

[Jane Q. Public]

People were doubting planes only a couple of years more than 100 years ago! Let's keep it in proper perspective!

Re:impossible dream?

[Seth Kriticos]

While technically it is no problem to send them large quantities of information, local law prohibits most of it and you will be sued by different interest groups if you try. So if we find someone out there, then we will probably start to spam them with viagra adds..

Re:impossible dream?

[gzipped_tar]

We could give them, say, the entirety of Wikipedia

REPORT ON THE INGREDIENTS OF THE EARTH'S CIVILIZATION AS SEEN FROM THE "WIKIPEDIA" SENT BY HUMANS * 20% ---- Elitist mod-trolls * 30% ---- Politics (a.k.a. sheeple herding) * 35% ---- Religion-like (i.e. spirituals, rituals, TV, Paris Hilton, Web 2.0, Slashdot, pr0n, etc) * 15% ---- Obsolete knowledge known as "science" and/or "technology" CONCLUSION Humans make good material for Soylent Green.

Re:impossible dream?

[gzipped_tar]

Sorry for self-replying, but the formatting was fried (I forgot about the line breaks)
REPORT ON THE INGREDIENTS OF THE EARTH'S CIVILIZATION AS SEEN FROM THE "WIKIPEDIA" SENT BY HUMANS
* 20% ---- Elitist mod-trolls
* 30% ---- Politics (a.k.a. sheeple herding)
* 35% ---- Religion-like (i.e. spirituals, rituals, TV, Paris Hilton, Web 2.0, Slashdot, pr0n, etc)
* 15% ---- Obsolete knowledge known as "science" and/or "technology"
CONCLUSION
Humans make good material for Soylent Green.

Re:impossible dream?

[shawb]

I honestly am not convinced that we'd need any brand new branch of physics to send someone to a star 10 lightyears away. When you start accelerating to high speeds, time dilation comes for free with the package. I remember someone showing me the math a while ago, but I don't remember who it was so they may have been full of it, but anyways... for traveling large distances under constant acceleration you can pretty much use classic Newtonian physics from the point of view of the traveler, as reaching relativistic speeds causes space to constrict rather than time if you are the traveler rather than the stationary observer.

What does this mean for traveling interstellar distances? If you can carry enough reaction mass or somehow collect it on the way, simply accelerate at a comfortable rate until you are halfway to the destination, then turn around and begin deceleration at the same rate for the second half. working the numbers shows that accelerating at 9.8 meters per second per second will get you halfway to a destination 10 light years away in 2.2 years. 4.4 year one way trip, 8.8 year round trip. All with 1G of acceleration so you would have no need for exotic technology to simulate gravity to maintain health. There would physiologically be no need for sleep/stasis for the travelers. Stasis may, however, prove to be more energy efficient and psychologically easier than being cooped up in a spaceship for about 9 years.

Granted, the relativistic effects would need to be taken into account for plotting the course, as the destination planet will have been traveling through space for much more than 10 years. And when you get home your descendants will probably have died of old age.

Re:impossible dream?

[ionix5891]

[citation needed]

Re:impossible dream?

[ion]

CONCLUSION: Mostly harmless

Re:impossible dream?

[shawb]

While it initially appears that you would be traveling faster than the speed of light, you indeed are not... when you reach relativistic speeds space itself compresses, so from your perspective the distance traveled between two points is less than the distance as measured from a resting observer. End result your measured velocity is less than C. To the resting observer, you travel the larger distance, but time is dilated such that your velocity is lower than C. Since the apparent distance between the origin and the destination is decreased, the amount of time it takes light to make the same journey would be less than the amount of time it takes you. In fact, from your perspective light is still traveling... at the speed of light.

Now, to take the concept to the ultimate (but unreachable) conclusion: to reach such a velocity that an outside observer would record you as moving equal to the speed of light: To the traveler it would seem as if there was actually no distance traveled, and the journey took no time at all. What the traveler would observe is space and time folded between the origin and the destination... for a 10 light year journey, you would instantly travel to the destination, but 10 years later. The return trip would also be instantaneous, but 20 years would have elapsed at home since you have left. Thus, the speed of light is not violated. However, to cut your travel time to zero in a Newtonian framework, you would need to reach infinite speed in zero time, which would require infinite acceleration, which would in turn require infinite energy. That is impossible, so an object with a resting mass cannot travel at the speed of light (or beyond.) But you still have to take into account the fact that at relativistic speeds, space constricts while time dilates, allowing for what on the surface appears to be traveling faster than the speed of light, but actually is not.

Re:impossible dream?

[John Meacham]

Or they were advanced enough at some point and have since bombed themselves back into the bronze age and are building themselves back up again. We really have no data about how stable a technological society is, if it turns out to be a hundred years of advanced technology for every 10,000 of savagry, it would be quite fortuitous to exactly line up with a suitable conversation partner.

Re:impossible dream?

[Robin47]

That sounds a lot like instant messenger.

Re:impossible dream?

[meringuoid]

Mind you the chances that we will be in the near vicinity of a civilization that communicates by radio waves that we can pick up is possibly quite slim- we've only been doing it for less than a hundred years.

And how much longer are we going to be doing it, with everything converging onto the Internet? If the earth lights up as a radio source in the early 20th century, but has gone dark again by the dawn of the 22nd because almost everything is now connected to fibre, what hope is there for SETI?

Re:impossible dream?

[GameboyRMH]

if it turns out to be a hundred years of advanced technology for every 10,000 of savagry

Who says the two are mutually exclusive?

Re:impossible dream?

[LateArthurDent]

we have no reason to suspect that there is life beyond this planet.

No reason to suspect? It goes like this. There is life on this planet. Therefore probability of life > 0. There are many, many, many stars in our galaxy, countless in the universe. No matter how small the chances are, given the size of the universe and since we have proven that the probability is greater than 0, it's inconceivable to imagine that we're the only ones.

In fact, the only reason to be arrogant enough to say that we're the only ones would be religious nonsense.

Re:impossible dream?

[djp928]

Actually, it's more like "one is one, two is many". Until we have some kind of proof of life beyond this planet, the reasonable assumption is that life is peculiar to this planet. Sure, from what we know of how life on this planet developed, it seems reasonable that we're not special. However, we don't even see it in other "reasonable" places in our own solar system. It's not evident on Mars, even though certain earth-like bacteria could probably thrive there. It's not evident on Venus, which despite having a crushing, corrosive atmosphere, appears to have pockets (floating in the high clouds, on high mountains or plateaus) where earth-like life could grab a foothold. The one thing we know about life is that it spreads to fill all niches. There's almost literally no place you can look on the surface or immediately under the surface of this planet where you won't find it.

I'm not saying we shouldn't look. We should. Finding non-terrestrial life would be the biggest discovery in the history of everything as far as we are concerned. I'm just saying our default position shouldn't be "We exist so others must!" That's not really a reasonable assumption, even though it would appear to be so to many people on the face of it. A zit on your nose doesn't imply a zit on your ass. Two or three or four zits on your face may well lead a person to believe you're just a zitty bastard, though.

Re:impossible dream?

[LateArthurDent]

Sure, from what we know of how life on this planet developed, it seems reasonable that we're not special. However, we don't even see it in other "reasonable" places in our own solar system.

It has nothing to do with what we know of how life on this planet developed. It just means that unless you assume development of life requires conscious divine intervention, it happened as a result of certain conditions. We could be very special in the sense of life being an extremely low probability, even given the right conditions. However, given the size and age of the universe, it doesn't matter how low the probability is: if it happened once, it's happened multiple times.

Don't misunderstand me. I'm not saying we'll ever meet E.T. If the universe is mostly uninhabited, there might be nobody close by. Even if there's any life "close by" they're not necessarily intelligent. Even if there's intelligent life "close by" they're civilization does not necessarily need to be alive simultaneously with ours. Even if they are, "close" in the scale we're speaking of is still impractically far for travel or even conversation.

A zit on your nose doesn't imply a zit on your ass. Two or three or four zits on your face may well lead a person to believe you're just a zitty bastard, though.

Your argument is actually sound, but it's not arguing what you think it is. A zit on my nose doesn't imply zits are common in the rest of my body. Similarly, life on Earth doesn't imply the universe is full of life everywhere. And that's not what I'm arguing.

What I am arguing is that a zit on my nose implies the existence of zits elsewhere in the human population. If you see a zit (or even something extremely rare that you've never seen before) on my face, it's illogical to assume I'm the only person in the world to ever have gotten that particularly thing, and that nobody else out of billions of people that have ever lived and will live will ever get it. And billions is a very small number when you're talking about stars in the universe.

Our Sun isn't that special of a star. There are many others that have been identified that are just like it. Countless others that we have never seen. It's completely unreasonable to assume that none of those have a planet in the sweet spot. Out of those that none of them have developed life. I'm not saying it's common, I'm not saying life is everywhere, I'm not saying we'll ever find it, but regardless of how common it is: you have no reason to assume it doesn't exist.

"may be"

[dov_0]

and there may be a treasure chest buried in my back yard... I just haven't found it.

Well, there goes the neighborhood.

[DigitalReverend]

I don't want an Earth-Like planet in my neighborhood because they bring down the property values.

Entia non sunt multiplicanda...

[Kupfernigk]

As I've posted before, this type of "Earth exceptionalism" is more related to the field of religion than science. There is no a priori reason to believe that the Earth is an unusual planet unless you buy in to the creation myths of some peoples who lived in the Near East circa 4000-2000 years ago. (Other societies, such as those of India, believed in a plurality of worlds and intelligent life forms.) Using Occam's Razor we would conclude that our planet revolves around a very ordinary star, everything else observed about our planet suggests it is unexceptional, therefore the emergence of life is likely to be unexceptional. Falsification of the default hypothesis would involve finding an earth-like or near earth-like planet which did not have life on it. Protestant Biblical literalism is not a scientific attitude. So far, the history of science has shown that every form in which exceptionalism has shown up has been found to be wrong, e.g.

• Earth is flat disc with crystal dome above
• Earth is sphere at centre of solar system
• Earth goes around Sun which is centre of Universe
• Sun is a star in the Galaxy which is the entire Universe

Re:Water alone wont cut it

[drinkypoo]

however a stagnant pool of water won't produce even microbes in any prompt fashion on a cosmic scale. The moon is as big a contributor to life on Earth as its water, because of how the tide has stirred the water like no other planet we've discovered yet.

Obviously you are unfamiliar with the concept of thermal turnover.

No tide is necessary to mix a body of water. All you need is rotation.

Nice try, though.

Re:Question

[Ihlosi]

So, out of curiosity, how big are these mushroom clouds anyway?

It's all mentioned in the article. The Tsar Bomba created a fireball about 8 km in diameter, and the resulting mushroom cloud was 64 km high.

If we were they, we wouldn't hear them

[Geoffrey.landis]

"They could be in our equivalent of 1750 and we'd never hear a peep."

In fact, they could be our equivalent of 2009 and we'd never hear a peep.

Except for one or two exceptions, no radio signals from Earth are strong enough to be detectable at interstellar distances using the receiving technologies that we use for SETI.

The "exception" is ballistic-missile warning radar, which might be detectable, if it were at the wavelength being searched, and they happened to be looking in the right direction when the Earth happened to be rotated so that the radar pointed the right way. But there's no signal in radar, and even the carrier would be gone when they looked again to follow up, so to a SETI search, it would be tagged "noise"-- most likely a side-lobe of a transient terrestial source, possibly a satellite. (Unless they knew the Earth's rotational period, so they could look again when the signal was aligned their direction.)

Re:Question

[EllisDees]

This will give you some idea how large a nuclear blast is:

Ground Zero simulator