Looking for Life in Light

Gearoid_Murphy writes "Earth-like planets around distant stars may be too far away to be reached by spacecraft but scientists could still investigate whether they harbour life. Telescope technologies are being developed that will probe the very faint light from these objects for tell-tale signs of biology. These are the same "life markers" known to be present in light reflected off the Earth - so-called "earthshine"."

Comments

Earthshine? Pah.

[ScentCone]

For some real signs of life, try a little moonshine.

Re:Earthshine? Pah.

[AoT]

Are you another one of those people who bought a low UID, or have you just been waiting for the right time?

Re:Earthshine? Pah.

[slashpot]

Wait a second.

I apologize. Sir.

I just realized that maybe you were interested in a excachange of cash for my "slashpot" userid.

Now oridinarilry, I'd turn you down Iraq style. But. Since I'm an unemployed tech worker who
has only been receiving head hunter calls from god damn indian fucks that don't event speak a
word of fucking english....

I'll be happy to sell you my stoner pun slashdot ID that goes all the way back to the beginning baby.

Let the bidding begin here.

Richest hacker gets her.
post your bids below
*chug*

Re:Earthshine? Pah.

[AoT]

Ooooh, you're one o' them high class, low UIDrunks. Glen Fiddich!

All I have is some tall boys of mickeys.

Re:Earthshine? Pah.

[slashpot]

yeah - right bitch - more like eh fuck it here goes my last paycheck

Re:Earthshine? Pah.

[AoT]

Yeah, I feel ya. But all I have left is my 5 dollars.

Well, $2 after the last two Mickeys.

Re:Earthshine? Pah.

[glens]

Who's got a low slashdot ID?

Re:Earthshine? Pah.

[shawb]

Hey... high class/Low UID drunk makes sense.

Low UID implies being a certain age. After a while you get tired of just getting pissed on cheap stuff. Once you develop a taste for liquor (or wine or good beer) you begin to realize that a $40 bottle of scotch can be more bang for the buck than cheap macro-brew if you are looking for overall enjoyment rather than just getting drunk.

I am somewhere in between: I thoroughly enjoy my 15yr bottles of The Glenlivet and The Macallan (not so much a fan of Glenfiddich) but I can still rock out the $1.29 40oz of Lucky Number High Gravity when the occasion demands. Then again, my UID's a bit higher than slashpot's. Probably by a year or two.

Re:Earthshine? Pah.

[tzanger]

Me.

Although Unitrode will probably come in and squash that theory. :-)

Comment removed

[account_deleted]

Comment removed based on user account deletion

By the sound of it, they will be using optics

[El Cubano]

Telescope technologies are being developed that will probe the very faint light from these objects for tell-tale signs of biology.

I am guessing that they are talking about optical observations, since it appears to be an extra-atmospheric telescope they are designing. However, at those distances, how can they discern the difference between the shine from a planet and the light given off by the star(s) near the planet? I would think that we observe the earthshine from small enough distances that we can see it in spite of the Sun. I am curious how this would work for distant bodies.

Re:By the sound of it, they will be using optics

[Poltras]

Probably will look at the shadow of the planet. What I am wondering though, is that if a planet is at, say, 700 light-years from here, and we're seeing a "civilization", or just plain life at least, then that life will be from 700 years before. Now with what we've been through in the last 100 years, put that a 10000 lightyears away and you have a heck of an evolution...

PS: funny part is, if they see our earthshine from the same distance, we humans wouldn't even exist. Talk about being stealthy :)

Re:By the sound of it, they will be using optics

[forkazoo]

I am guessing that they are talking about optical observations, since it appears to be an extra-atmospheric telescope they are designing. However, at those distances, how can they discern the difference between the shine from a planet and the light given off by the star(s) near the planet? I would think that we observe the earthshine from small enough distances that we can see it in spite of the Sun. I am curious how this would work for distant bodies.

I haven't studied the specifics, but when I hear about similar ideas, irt usually goes something along the lines of starting by just looking at the star. Based on the spectrum, the star has so much oxygen, so much hydrogen, etc. Then, calculate when the planet passes in front of the star. Then, see how the starlight changes. If there is a spike in the apparent amount of hydrogen indicated by the spectrum of the starlight whenever the planet passes in front, then the planet probably has a lot of hydrogen, and so forth.

Re:By the sound of it, they will be using optics

[kilodelta]

Light coming from a manned planet would be of a different frequency than natural light sources. Look at our incandescent, fluorescent and LED lights. All have certain spectra that show them to be the result of burning tungsten, ionized gas, or silicon junction spectra.

There has to be life out there somewhere. But the distances are just so vast that without FTL transport we'll never get to meet them.

Re:By the sound of it, they will be using optics

[DaedalusHKX]

Or we might see a death star heading our way in their "shine" and then blow up the day after :)

Seriously though, it seems to me that we always have this idiotic need to find ORGANIC life. Perhaps it might not be light emitting or light modifying. Perhaps they're not even "corporeal" or light necessitating. Perhaps they'd find Pluto's cold more hospitable than the wet juicy nature of our own ball of mud. Everyone always thinks in their own paradigm. Why not think outside the box that someone always demands we think within?

Re:By the sound of it, they will be using optics

[Rude Turnip]

"Perhaps they're not even "corporeal" or light necessitating."

Unless it's a hyperintelligent shade of blue, that is.

Re:By the sound of it, they will be using optics

[Thing 1]

I am guessing that they are talking about optical observations [...]

Yeah, and here I was hoping (from the ambiguous headline) that researchers were actually searching for intelligence patterns in photons.

Fairly recently (a couple months ago; no longer in my posting history), someone on here and I were discussing converting ourselves into energy. If we could determine a way to make interacting photons, then we could beam ourselves at a patch of empty sky and "live forever", since photons do not experience time. (One of Einstein's revelations of relativity.)

The other's response was that we should use tachyons, as they travel faster than light.

So, that's what was in my head when I read the headline, but it turns out we're just looking for terrestrial life. Oh well. ;-)

Re:By the sound of it, they will be using optics

[darthdavid]

Well certainly, there are alot of possibilities but the best geuss for life so far is carbon based, and any planet that'll support that has a good chance of showing up as having alot of the right stuff for life through a spectroscope. Anyway, look at it like this. We know carbon based life works, and we know it works reasonably well. That I'm typing this post proves that much. We know that alot of the reactions needed by an ecosystem we'd recognize need a certain temperature band to occcur. Now certainly, life could exist in other forms (different chemical chain, different temperature band, different anything you'd care to name), but we have no way of knowing how it'd be different so our only choice is to look for what we know, IE: signs of familiar life. I mean, if you take bob the silicon based beastie and make 5 billion of him and stick him on a rock rich in the things he needs to thrive and then take joe astronomer and have him look right at the ligt coming off that planet trough his spectroscope he'll see all the compounds that bob and his kin produce through living but won't be able to see that there's life there because his biologist friend who gave him a list of chemicals to look for as life indicators has never met bob and as such doesn't know what chemicals he gives off on a day to day basis. So the only life we _can_ find this way is gonna be similar to us at some level by default, because we wouldn't be able to tell that we were seing stuff from living creatures otherwise. Sorry about the uber-paragraph -_-;;.

Re:By the sound of it, they will be using optics

[Reality Master 101]

Seriously though, it seems to me that we always have this idiotic need to find ORGANIC life.

This is not just a case of assuming everything has to be like us. The reason we look for organic life is the same reason we're made out of carbon and the same reason carbon (organic) chemistry is an entire subject separate from inorganic (non-carbon) chemistry -- carbon is an amazingly versatile element, totally unlike anything else. Sure, it's possible there might be life made of something else, in the same sense that "anything is possible". But some things are a lot less likely than others.

To have life, you have to have a capability for very complex reactions. It's fun to speculate on "non-coporeal" life in a science fiction novel, but something has to be supporting the mechanisms of life.

Re:By the sound of it, they will be using optics

[MindHack]

I am actually working on this exact problem as an undergraduate astrophysics researcher. My mentor came up with the quite excellent idea of looking at the difference in luminosity of specific frequencies over the course of time.

Technically, we use polarization-encoding to split a light beam into two right-angle polarized beams, run them through different color filters, and then recombine them back into a single beam. We then use a fast polarization analyzer to look at each beam independently at speeds close to 100 frames per second.

The idea here is that as the orbiting planet goes through various phases, and shows us different surface area profiles as a function of time (think about the various surface areas of the moon that you can see as it goes through its phases), so we'd expect that the difference in signal for certain frequencies to vary with a period equal to the orbital period.

The difference in signal comes about by the fact that the planetary atmosphere and surface have a specific curve of frequency vs reflected percentage of light. This differs from the emissions of the host star, which follows a theoretical blackbody curve.

Re:By the sound of it, they will be using optics

[MindHack]

Ah, but some ARE looking for intelligence in photons. That is my future research interest, assuming that I graduate.

Essentially the same arguments as regular seti, but using optical frequencies as the target "waterhole". This new recent effort is labelled optical-seti, or oseti for short.

Instead of looking for narrowband radio broadcasts, we look for pulses of light that have an extremely short duration. With this kind of communication, you can use a typical earth technology laser in the megawatt output range, and blast data at fairly high bandwidths.

Re:By the sound of it, they will be using optics

[lawpoop]

I am no expert in this either, but I think it must be a little more nuanced to be accurate.

First off, if the planet is partially obscuring the star, most of what we are seeing is the dark side of the planet. So, all we should see is a reduction in the total amount of light from the star, but not much change in the apparent percentage of constituent molecules of the star. Some of the light we are seeing is the star beaming through the planet's atmosphere, which might change the apparent spectrum signature of the star, but I think that would be a small percentage compared to the total volume or star light.

However, there are also times when the planet is kind of on either side of the star. In that case, we are looking at all the light of the star, plus a partial reflection of the star's light off of the planet. So in that case, we would see the most amount of light, plus probably more of the chemical signatures of the planet in the spectrum. So at this time we are getting extra light with a complex spectrum

Finally there will be times when the star totally obscures the planet. In that case, we should see a more 'starry' spectrum, and a normal amount of light.

To wrap up, there are four 'phases' we should see:

1. When the planet is behind the star, we will see a more typical spectrum, and we will get the same amount of light from the star for a period of time.
2. When the planet starts peaking around the star's edge, we will be getting more total light, plus some extra elements in the spectrum -- probably some stuff we don't normally find in stars. The planet is most luminous when it first emerges from behind the planet and then later on when it goes back behind it.
3. When the planet works its way around to the front of the star, it's shadow will decrease the total amount of light we are getting from the star. We might see some of the planet's elements from the light that the star beams through the planet's atmosphere.
4. Finally, the planet will reach the other side of the star, where it will again add to the total luminosity and the signature of its chemical elements. This will look like phase two, until it finally recedes behind the planet and we are at stage one again.

Perhaps a real astronomer can correct my mistakes. ;)

Re:By the sound of it, they will be using optics

[lawpoop]

I just realized a mistake --

When the planet is in front of the star, the total luminosity will increase, but it the star's light that gets beamed through the atmosphere of the planet will show absorption lines of the planet's elements. So, conveniently, that kind of works as a check -- when we see both the planet and the star, we will see extra bands in the spectrum corresponding to the planet's makeup, and when the planet is in front of the star, we should see absorption in those bands. Finally, when the planet is behind the star, we should see a regular star-like spectrum.

Re:By the sound of it, they will be using optics

[advocate_one]

Perhaps they're not even "corporeal" or light necessitating.

what, like corporations? run for the hills... it's life Jim, but not as we know it...

Re:By the sound of it, they will be using optics

[m0nstr42]

I am guessing that they are talking about optical observations, since it appears to be an extra-atmospheric telescope they are designing. However, at those distances, how can they discern the difference between the shine from a planet and the light given off by the star(s) near the planet? I would think that we observe the earthshine from small enough distances that we can see it in spite of the Sun. I am curious how this would work for distant bodies.

The project is called Terrestrial Planet Finder (TPF). I don't know a ton about the details, but I know some guys who were working on it. One of the technologies being investigated (I'm not sure how well this relates to TFA, but it addresses your question directly) is an optical trick called a coronograph. The basic game is to design fancy Fourier optics that put more emphasis on small variations in off-center light. Like I said, not sure of the details, but it actually kind of works.

Re:By the sound of it, they will be using optics

[scharkalvin]

To separate the light from a planet and it's sun you need a telescope with sufficent resolution. It's just like the problem of 'splitting' multiple star systems into their separate stars, you need a large enough telescope. In this case though, we need a REALLY BIG telescope. We can't make one large enough, but we can combine the light from several telescopes separated by a long base line to get the same result. In fact such scopes are already being built and the first ones have already seen first light.
We might need to put such a multi-telescope system in space to get a long enough baseline, but it could be done.

Now imagine being able to actually see an exo-solar planet orbiting some distant star. We see it's night side and see some lights on the surface of the night side of the planet. The spectrum from that light is rich in Tungsten, Mercury, and Sodium.
I'd say THAT would be a sign of intelligent life (at least they had created electric
outdoor lighting).

Re:By the sound of it, they will be using optics

[Rix]

Why do we always look for organic life? Because we know for a fact that that sort of life is possible.

Re:By the sound of it, they will be using optics

[shawb]

I recall hearing that another clue as to whether there is a nearby planet is a periodic, albeit slight, reduction in luminosity as the planet goes BEHIND the star, as the reflected light is blocked by the star itself. It is feasible that using very sensitive equpment we could check the differences in spectral emissions between these points and determine an approximate total reflectivity of the planet.

If we would find earth-like reflection one could surmise that this planet would be a good place to look for life. Not that a terran environment is the only kind that could spawn life, but it is the only one I know of that has definitively spawned life, and in particular given rise to self-aware society forming organisms (which is what the search for ET life is really hoping for.)

Re:By the sound of it, they will be using optics

[LilGuy]

So we can finally tell the creationists to STFU once and for all.

Re:By the sound of it, they will be using optics

[susano_otter]

Right, because an all-powerful being that created life once couldn't possibly have created it more than once in the same universe.

And wouldn't it be hilarious if we did find alien life forms, and they treated us as idiots on account of our theories of evolution being totally at odds with their metaphysical religious convictions about the origins of life?

There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.

Re:By the sound of it, they will be using optics

[BrianTung]

My guess is that they will be looking for chemical signatures in the atmosphere of the planet, via absorption lines. That can tell you, indirectly, about the presence of life. For instance, one of the chemical indicators on the Earth is the presence of methane in an atmosphere containing significant amounts of oxygen. Ordinarily, methane "likes" to combine with oxygen to form water vapor and carbon dioxide. The reaction can go the other way, but it does so much slower. As a result, in a "dead" atmosphere, an equilibrium amount of methane exists, which is very tiny.

The Earth's atmosphere contains about 2 ppm of methane, by volume. Even that much methane, though, is out of equilibrium. It must therefore be continually replenished, ostensibly by life. We happen to know that it's largely biological in origin, from animals like cows. (I just wanted to mention "cows.") Now, that sort of thing doesn't have to be biological; it might, for instance, be volcanic, so that possibility has to be addressed: Biologically produced methane tends to be accompanied by ethane, while volcanic methane tends to hang around sulfur dioxide, and so on.

Eliminating volcanically produced methane doesn't mean that it must be life, because it might just be some non-life thing you haven't thought of. That's why it's useful to skim around the solar system, looking for the various non-life ways that methane might be produced, and how to tell the difference. At some point, if you're able to eliminate enough different alternatives, you begin to have confidence that you've detected life.

If that's the tack they're taking, it might explain why the detectors are looking in both the infra-red and the visible. Water vapor absorption lines are in the infra-red; methane absorption lines are in the visible. (They largely account for the color of Uranus and Neptune, for instance.) I look forward to seeing what they're able to see, even if they don't succeed in detecting signs of life.

Re:By the sound of it, they will be using optics

[What me a Coward]

Sure and while were looking through the telescope at them we see a telescope of their slide into view and discover their also looking at us!

  Only their's is higher resolution and we find out their looking at us in our homes in the tub or on the John!

    Intergalatic Perverts!

    What more reason do you need to build a fleet and wipe them out!!!@!

    Only problem is they'd see it and build one of their own to destroy it and then come here to subjugate us for their perverse pleasures.

    Theirfore we must build it in secret on the far side where they can't see it and then launch the fleet on a orbital trajectory that they can't see it till it's to late and Bamm!

    That'll teach though's pervs a leason or three.

    Ok a bit drastic but can you think of a better way to unite all the races and religens of earth than to stop intergalatic pervs? :D

Re:By the sound of it, they will be using optics

[LilGuy]

Its true. If it's not in the bible then wtf? Ohhhhh that's right.. they'll just say, oh well that part of the bible wasn't included.

Re:By the sound of it, they will be using optics

[susano_otter]

Heh.

Actually, you bring up an interesting point: Why should the Bible describe everything in the universe? What if it only describes things that are relevant to the main subject--the relationship between humanity and God?

Re:By the sound of it, they will be using optics

[LilGuy]

Well what if the Bible is just a bunch of made up stories that make people feel better about living and dying? In all honesty that's all I can see it as... not that there's anything wrong with that.

I just think people tend to go overboard when others don't "believe".

Re:By the sound of it, they will be using optics

[susano_otter]

I just think people tend to go overboard when others don't "believe".

Some people, sure.

But do you really think it's "going overboard" when the believers come up with a reasonable explanation for why the Bible doesn't include descriptions of aliens?

Also, why bring the issue up at all? It's not like anybody besides you was talking about the religious angle in the first place. So why the gratuitous jabs?

Re:By the sound of it, they will be using optics

[LilGuy]

Just beating them to the punch.

Re:By the sound of it, they will be using optics

[susano_otter]

Just beating them to the punch.

I don't get it.

Pardon me...

[GillBates0]

Pardon me while I illuminate my GIANT blinking "Welcome to Earth" sign.

If nothing else, it'll show up on the earth shine and indicate we're inhabited. On the other hand, they probably already know that...

Re:Pardon me...

[AoT]

Of course they know, that's why we haven't seen them yet.

Re:Pardon me...

[jpling]

Can they read morse code? ;] I question if the sun is really necessary for life on another planet. There is another world deep underneath the ocean where fish, crustations, and such live without light and can survive at extreme cold and hot temperatures. Pluto might even have some sort of life on there but it's a shame that we don't already know since it _is_ in our solar system.

Re:Pardon me...

[thc69]

I suspect that ultra-deep ocean life here still depends on light indirectly. For example, there's probably something light-dependent in their food chain. Maybe a deep dark octoplatyfungusapus eats deep dark selopodonkens, which feed on sunken plankton or which rise to feed on less deep fish who, in turn, feed on holy mackerel...

That's not to say that light-free life couldn't evolve independently, ultimately getting it's energy geothermally. Aren't there bacteria that have been found sustaining on geothermal energy? I vaguely recall something about them either being found in hot springs or ocean-bottom geothermal vents.

Earthshine

[Mr_Tulip]

We may call it 'earthshine', but advanced extraterrestrials probably call it 'signs of parasitic infestation', and warn tourists to stay away in case they catch something.

Re:Earthshine

[kyjl]

But I thought it was mostly harmless?

...but not life.

[JustinKSU]

From the article:

"'This gives you some information on habitability,' said Wesley Traub, chief scientist on the US space agency's (Nasa) Navigator Program..."

...but not life!

Seems primitive.

[jd]

If/when the kilometer array is built (it's an array of small radio telescopes, where the array has a diameter of a kilometer and a density of one dish every couple off metters or so), they will be able to resolve Earth-sized planets at a distance of 100 light years.

How will this help? Radio telescopes can look at the absorbtion spectrum of the planet for the tell-tale lines of water, methane, oxygen (both O2 and O3), and other markers of highly reactive chemicals - especially when they will react with each other. When you have an atmosphere that is chemically violently unstable (as is the case on Earth), it must be being maintained by some process.

That's the first clue, but only the first. The second clue is that "dead" planets will be in equilibrium with their surroundings, but "living" planets will always be in opposition. (Organisms will always create a dynamic equilibrium that suits them, so must always counter any and all natural phenomena that would push the system away from that preferred state. Simple negative feedback.)

Simple radio telescopes can do all this now, no new optical technology need be developed, and no assumptions about the type of life need be made. (All the above assumes is that life can never be inert and that any specific organism cannot function equally under all potential conditions. That's broad enough, although there will probably be exceptions even then.)

The Km array proposed (and the hectare array already built) are just a huge stack of ordinary satellite TV dishes. This could be done by anyone at any time. A mile array would give you 2.5x2.5 pixels ast 100 lightyears - enough to discern if weather patterns exist, though not enough for any long-range forecasts.

Re:Seems primitive.

[AoT]

Uh, hi, welcome to earth. We're primitive.

Nice to meet you.

Re:Seems primitive.

[jd]

"We" can't be a primitive, it's a composite type.

Re:Seems primitive.

[IceFoot]

"The Km array proposed (and the hectare array already built) are just a huge stack of ordinary satellite TV dishes. This could be done by anyone at any time."

Imagine a Beowulf cluster of satellite TV dishes....

Re:Seems primitive.

[thc69]

Just recently, I was considering that I could probably do something cool with discarded satellite dishes on three houses, internet-linked to one computer. My house, my parents' house, and my best friend's house form an almost equilateral triangle, roughly 20 miles on each of two sides and 24 miles on the third. I wonder what could be done with that idea...

By making some big assumptions

[EmbeddedJanitor]

Of course I have not RTFA because that is cheating.

If you do an spectral anaysis of IR etc reflecting off the earth, you'll get certain signatures for trees, grasslands, sea, coulds cities etc. So if observers see the similar patterns they will assume that the distant planets will have a similar biology, cities,...

Of course these are all just assumptions. The scientists hope to make discoveries which they can publish for fame and glory. Luckily for them, they'll probably be dead long before they can be verified by eyeball technology.

Re:By making some big assumptions

[Dastardly]

It is actually simpler. You are looking for the spectrum of the atmosphere. Then, based on that spectrum determine the composition. If the atmosphere is of a composition that is stable in the absence of life then it is unlikely there is life. Although there could be life that does not interac twiith the atmosphere.

If the atmosphere composition is unstable then there must be a mechanism maintaining that stability. One of those is life. The trick will be trying to exclude geological processes.

None of these is definitive proof of life or lack of life, but they should narrow the field and allow us to pick high probability targets for further study.

Why telescopes?

[talkingpaperclip]

I can't understand why these guys are searching so hard for life in light. There have to be at least a dozen half-dead bugs in the ceiling light about 7 feet away from me.

Re:Why telescopes?

[What me a Coward]

Because it's easier and better than searching for life in the dark!

      Dead or alive it is or was life, When was the last time you saw a corpse of a bug in the dark?

    Besides looking for a bug zapper is a better way of finding out theirs life out their than looking in the dark for life looking for light to zap itself on anyway.

    If you ask me it's killing two bugs with one light to go about it this way. :D

  Ok enough with the bug zapper enaligies i got more important things to do like goto that light over their..... So pretty and warmmmm........ZZZZtttt.

News?

[brian0918]

Where's the news? NASA's had the Terrestrial Planet Finder in the works for years now. Is it a slow news day at BBC?

Re:News?

[bware]

Because TPF has been cancelled so that the ISS can be finished so we can deorbit it into the ocean, thus honoring our commitments to our international partners (and screwing over our international partners on TPF). The scientists who are interested in trying to find life on other planets like Wes Traub are out there trying to drum up support for TPF so Congress might bring it back.

So maybe it's a slow news day, but maybe some scientists are engaging in public relations.

Re:News?

[brian0918]

IMHO, a Terrestrial Planet Finder is an inevitability, whatever form it finally takes.

Re:News?

[bware]

Only death and taxes are inevitable. NASA had two viable TPF candidates and had spent tens of millions of dollars building up teams and hardware and labs and knowledge. Most of that has disappeared, except for a few papers and a couple of labs. "Deferred" means "cancelled" means "start over from scratch" if it ever gets started up again. Wasted money, mostly.

What's the point?

[rm999]

We want to:

A. attempt to detect life on a planet that is too far away for us to determine if we are correct any time in our lives
B. using a method that has an unknown accuracy
C. despite the fact that we don't even have an idea of the *order of magnitude* of the chances of life out there

What's the point?

Re:What's the point?

[Daniel Dvorkin]

You're right, of course. We shouldn't be wasting our time with this head-in-the-clouds nonsense. Say, what's the latest news about Britney Spears' baby?

Re:What's the point?

[AWhiteFlame]

Because we can.

Re:What's the point?

[ChrisKellow]

Actually quite relevant to the topic. I saw this morning while standing in line at the supermarket that her baby is an alien. Now we don't have to search for proof of extraterrestrial life.

Re:What's the point?

[What me a Coward]

Haha LOL

    That's a two pointer!

Seeing the past

[TheDunadan]

That fact has always fascinated me. If we could travel faster than the speed of light with a huge telescope we could observe historic events. Thats pretty cool if you ask me.

Re:Seeing the past

[AoT]

Yeah, and if we could go back in time we could prove jesus never existed.

Oh, I come here for the witty conversation.

Re:Seeing the past

[Bastard of Subhumani]

But he did exist. You don't have to be a Christian, let alone a creationist or a fundamentalist one, to believe that.

As to his legendary (miraculous even) efficiency in catering arrangements and the question of whether he was a threat to the vinicultural industry, that's a different matter.

Re:Seeing the past

[bwintx]

As to his legendary (miraculous even) efficiency in catering arrangements and the question of whether he was a threat to the vinicultural industry, that's a different matter.

Not necessarily a threat. Actually, there was a marketing opportunity there, if the competition'd had enough sense to see it:

“Pick up some skins of Sea of Galilee® today. Our wine was never water!”

Re:Seeing the past

[AoT]

You may not have to be a christian to believ it, but that don't make it so.

Re:Queue xenophobic reactions

[rHBa]

Don't worry, Tom Cruise will be able to detect them with his eMeter ;-)

Greetings Earthlings

[Kozar_The_Malignant]

Is communication from Commander Znetab of Zygort Interstellar Death Fleet:

Radio frequency wavefront from your planet is passing through our fleet causing much physical distress. Auditory awfulness of "Wayne Newton" voice recordings we are considering weapon of mass destruction. Is reducing all fleet radio operators to disembodied protoplasmic goo. If not stopping immediately, destruction of your insignificant planet will be accomplished. You have been warned!

Is ending communication.

Isn't this called SETI?

[NittanyTuring]

Last time I checked, there exists a project already doing this. It's called SETI. They very thouroughly comb a large range of the EM spectrum for any data representing intelligent life. This proposal instead takes hazy samples from a very narrow band of data (the visible spectrum), to guess at the chemical composition of other planets. So we've replaced listening to white noise with looking at faint blue dots.

Re:Isn't this called SETI?

[MindHack]

SETI has a fine line difference with astrobiology.

SETI intends to find intelligent life, whereas astrobiologists, although happy to find ANY life, are mostly looking for unintelligent life.

Re:Isn't this called SETI?

[Urkki]

SETI has that pesky 'I' there, meaning intelligence. It's looking for signs of radio communications, based on assumption that only intelligent beings might communicate with radio. Though if a non-intelligent life communicating with radio was found, I don't think anybody would be majorly disappointed ;-).

TFA is talking about finding planets that have *any* life that can significantly change the atmosphere of a planet. Earth could have been discovered like this probably at least since we've had O2 (regular oxygen gas) and O3 (ozone) in our atmosphere, starting from about 2 billion years (*) ago. Contrast this time with the time we've used radio communications, less than 100 years.

(*) reference:
http://www.globalchange.umich.edu/globalchange1/cu rrent/lectures/first_billion_years/first_billion_y ears.html

Re:Isn't this called SETI?

[What me a Coward]

If that's the case they need only look around our own planet!

    Their's plenty of unintelligent life around here as it is without
  them trying to find more on other planets.

Re:Isn't this called SETI?

[MindHack]

Nope, the T means "Terrestrial", it's the I that means intelligent ;-p

Re:Isn't this called SETI?

[Dis*abstraction]

Your computer is misrendering I in single quotes as T. Let me guess--Linux/Windows user?

If someone were looking at Earth...

[swalker42]

and tried to find intelligent life by the light signature. All they'd see are the blue darters...

Too far?

[SEWilco]

...too far away to be reached by spacecraft...

It will just take a while to get there. Weapon systems are robust. Of course, we don't know when they detected us so we don't know how much time we have to set up defenses.

Carbon Life

[Mark_MF-WN]

There's a very cool article on alternative biologies on wikipedia. It's highly speculative, but a great read for anyone with an outsider interest in biochemistry.

As an aside, your signature brought to mind the high school I went to. Some silly idea about "self-directed" learning, which actually just meant that the school only had to pay its staff to mark papers and yell at kids who brought slurpees to the study hall, rather than actually teaching anything. The graduation rate was about 20%, most of whom graduated a few years late. What an abomination. Not quite the same thing as "unschooling", but a potent demonstration of WHY schools are the way they are. As sucky as that model is (and it is undeniably sucky), we just don't have anything better yet.

Re:Seems primitive. (Resolution v. Lightgathering)

[ookabooka]

Are you sure about the capabilities of such an array? There are two main properties to a radio telescope (or any telescope for that matter) and that is Resolution and Lightgathering. By increasing the diameter of the collecting dish you increase both the resolution and lightgathering capacity. By creating an array using interferometry you can increase resolution to create a "virtual" dish with a diameter equal to the distance from one end of the array to the other. This doesn't, however, increase lightgathering capacity the same way. Let me propose a crude analogy: think of dishes as buckets, you can put two buckets 50ft apart and infer how much rain fell between them by adding them and dividing by two, but if it was just a drizzle, your data wont be so hot. If however, you have a 50ft bucket, you're gonna collect a lot of water.

So an array of a bunch of teeny TV sattelite dishes wont have as much surface area as a dish a kilometer wide. So yes we could resolve a planet, but it would have to be bright enough to be seen.

Re:Queue xenophobic reactions

[bombledmonk]

Only if the planet has monitary based society. If there exists some money out there on another planet you can count on the Emeter to find it.

Re:This has profound implications

[Sensae]

Hey, who says they haven't detected us? Who says they care we're here, or as has been pointed out haven't discovered us yet? Or have you even thought of the chance they might not want to intervene in our development or self-destruction?

Re:Seems primitive. (Resolution v. Lightgathering)

[Jon_A_Mnemonic]

And with a really big single dish we could see planets that aren't bright enough to be seen? ;)

Re:This has profound implications

[Cobralisk]

How can this be when we are only the third most intelligent life form on this planet?

Re:Seems primitive. (Resolution v. Lightgathering)

[jd]

Yes, I'm certain.... but it is why you need the density of dishes. If you had one dish on each corner of a square, one kilometer on a side, then you would have the collecting area of those four dishes. Which, if they are TV dishes, is very little. If, however, you have that same square but one dish every five meters, you would have 200 x 200 dishes, for a total of 40,000. If each dish has a collecting area of one square meter, you then have a total collecting area of 40,000 square meters.

In practice, the Square Kilometer Array is intended to have a collecting area close to the physical area of one million square meters - requiring almost no gaps to exist between dishes.

My first calculation would be for dishes with a wider gap, which would give you much greater flexibility on pointing the damn thing, as you can't see through the other dishes. Personally, I consider this to be a much superior design, even though it would cost on the collecting area. Unfortunately, they are the ones being paid, even if I am the one who is right...

By way of comparison, Jodrell Bank Radio Telescope is a paltry 76 meters across, for a total collecting area of 4560 square meters, and that's one of the largest single steerable telescopes out there.

I'm going to guess that a collecting area about nine times that of Jodrell Bank, combined with a resolving ability that is, well, astronomical, you would get a very respectable image of Earth-like planets around other stars. If we accept the SKA group's claims, then you've a collecting area 250 times that of Jodrell Bank.

I first heard the 100LY=1 pixel resolution with SKA from Jill Tarter, head of the SETI Institute at a talk she gave at NASA Langley. From crunching the numbers, I can see nothing that could seriously contradict the claim. Even if you assume my model is the more reasonable implementation, the complete MERLIN network that has been detecting jovian planets for some time has only a fraction of that collecting area - probably something like a quarter or a fifth. (Aside from Jodrell Bank, the next-largest radio telescope in the UK is a paltry 32 meters across.)

If we go with SKA's claims, then we're talking about collecting possibly hundreds of times the total radiation, which would definitely be enough to spot even the tiniest of worlds - provided it had some characteristic reflected in the radio spectrum.

(It's also worth bearing in mind that networks such as MERLIN, which are hundreds of kilometers across, are set up for VLBI - very long baseline interferometry. That's fine, when you're talking about gas clouds or stars, but is probably none-too-hot for spotting very fast pulsars or rocky inner planets. On the other hand, a kilometer would let you use regular interferometry, which means these things would show up quite nicely.)

There are three drawbacks to all of this, and I'm surprised none of the posters has commented on them (so far). First, interferometry requires very exact timing of all the delays in the system, or it won't work. Let's go with the SKA estimate and say the dishes are 1 meter apart. Your clock must count an integral number of ticks for every meter the signal travels from the dishes, even after allowing for the natural variation in the data lines varying the speed of the signal. This is some astonishingly serious timekeeping.

The second problem is to keep the signal noise-free. Easy, for a giant single steerable dish - you plunk it in the middle of nowhere and surround it with a huge Faraday cage that only obscures the horizon. When you've a few tens of thousands - or millions - of very small dishes, the problem isn't so easy. The terrestrial radio sources will be far harder to screen out - not just

Re:Seems primitive. (Resolution v. Lightgathering)

[4D6963]

And with a really big single dish we could see planets that aren't bright enough to be seen?

Well then they would be bright enough to be seen, since there would be much more light gathered

Off topic, but

[DaedalusHKX]

"Parents who Unschool [wikipedia.org] should be charged with child abuse."

Strange, since it seems to me that its mostly an American thing... our children are lazier than hell. And public school teachers are coerced into standardizing a shitty education, instead of making it engaging, interesting, and possibly controversial (as in the case of history, politics, language, physics? I once had a physics professor who began class by explaining that explosions are really fast burns, and, in fact, that flour, as in the food ingredient actually does burn very fast and demonstrated blowing up flour. How's THAT for a controversial high school physics class?)

I came here with an eastern european education and found school easy, boring, and mostly a time sink for children, keeping me, personally from doing what I liked most... reading and researching for my own. (Keep in mind, most of eastern europe at the time had 6 day work weeks, and 6 day school weeks, but school was only about 4 hours a day and 2 or 3 days had also an after school gym class (mandatory, but VERY different than the lame duck gym we have here, most kids there were both limber, agile and rather thin.) // contrary to popular belief, I had plenty of food, it was just not MacFood, it was healthy food :)

You have no idea how mind numbing our schools here in the USA can be, especially to someone accustomed to learning a lot on the outside on the extensive free time the "communist" education system offered (4 hours of mandated science, language, geography, history (oddly, I find that they taught relatively accurate world history, other than aggrandizing their own power plays as "wonderful displays of humanity, etc" At least the commies weren't racist where I lived (the russians are another issue, I hear they didn't get along with the jews too well)). Anyways, everything they teach here is cut and dry, and they have VERY few classes that facilitate discussion, controversy, and therefore, growth. The promulgation of heroification in history and political science is also extremely disturbing.

Imagine, if you will, going into 5th grade math, having the lady give you the american used sign for long division, and setting up some random 6 digit number divided by 3. Now imagine the child in question, being thought "about 4th grade in math skill" because he takes the cube root (by hand) of said 6 digit number. I guess the word "radical" doesn't enter into mathematical speech until about 10th to 12th in our fine country of SOL testing buffoonery.

So I promote, less the unschooling, and more the MORE FREE TIME FOR KIDS AND MORE FREE TIME FOR PARENTS. We had school from 06:30 to 10:30 in the morning. No more, no less. Gym was 2 hours x 2 days. We only had Sunday off, but school was FUN because it actually taught challenging things, and homework wasn't just busy work, it was relative, and usually short, mostly a cementing factor (as opposed to homework in the US which is at best bland, and worst busywork). My parents came home from work around 0400, they left around 0700 (I always left first) and we actually had time together, there was less shit on TV, except one hour of anime at 18:30 (6:30 PM) and that was my TV watching. And imported movies, once or twice a week. Other than that, I spent my time becoming acquainted with the works of the masters, from Master DaVinci to Jules Verne to Aristotle and Shakespeare. Strangely I also had time to go outside, play soccer both for fun and in a club, AND play chess (freestyle and tournament). I can guarantee less kids have time for this before they're 11 in our country, because we're pushed to "spend more time in school". Efficiency is something that is advertised but STRONGLY discouraged in America. Freedom is another one of those things, strongly advertised and COMPLETELY antithetical to the way of life Americans endure.

We just want to guzzle more gas, more food, more TV, more everything while having others think for us, since thinking is far more painful for the majority of Americans than even the other most painful thing... losing weight.

Re:Off topic, but

[Reality Master 101]

So I promote, less the unschooling, and more the MORE FREE TIME FOR KIDS AND MORE FREE TIME FOR PARENTS.

That's not so much "more free time" as kicking kids' asses and making them work in the time they have. And that I totally agree with. The whole idea of "unschooling" is the ultimate expression of laziness. They don't want kids to be challenged, they just want them to do whatever the hell they want so the parents don't have to be parents and be involved.

Ok, I'll bite

[StonePiano]

Then which of geckos, termites or moss have you put below us?

Re:Ok, I'll bite

[baldass_newbie]

Go grab a copy of Hitchhiker's Guide, idiot.

Re:Queue xenophobic reactions

[rHBa]

Shouldn't this thread be called "Queue xenuphobic reactions"?

Re:leaving scientology aside...

[khakipuce]

I agree that the chances of detecting a signal are very, very small indeed. However I see a different problem, that being the length of time that high-power broadcast signals are being used by a civilisation.

It seems likely that in the next couple of decades a lot of our brodacast signals on the lower frequencies that can escape the ionosphere will have been turned off in favour of internet based tv/radio, microwave signals from satellites directed at earth and spread-spectrum technologies that are indistinguishable from background noise.

So that means we will have had about 120 years of broadcast that has escaped into space. So, assuming we are in anyway typical (BIG ASSUMPTION), we are trying to find a transmission from a planet that went through this 120 year phase at exactly the right time thousands of years ago so that the signal arrives at earth now while we are listening.

I think the universe is big enough for there to be life out there, it's just that we won't find it, and we definitely won't hear it's radio transmissions.

Re:We don't cherish life on EARTH...

[Rubinhood]

I'm not sure I understand. We, the "intelligent" inhabitants of our planet, are destroying our habitat, and killing each other in wars. If, for example, we don't respect HUMAN life in the 3rd world (just 1000s of miles away) enough to help them to a long-term resolution, then what would we do to NON-HUMAN life?!? I'm not only _expecting_ all SETI efforts to fail, I'm also _hoping_ they fail.

Very true.

Things that don't work on the small scale, will never work on a large scale. Can't make your family happy? Don't try to be a leader of your country (i.e. politician). Don't care about keeping your world in shape? Then stop dreaming about exploring other worlds.

Ob. Debbie Boone

[JonnyBnDC]

You light up my life
You give me hope
To carry on
You light up my days
and fill my nights with song

http://www.romantic-lyrics.com/ly6.shtml

I'm all for it!

[HRH King Lerxst]

I'm all for looking for more earthshine, after all, that was the best song of of Vapor Trails.

Re:Waste of Money

[MindHack]

SETI is no longer funded by NASA due to a congressional ruling, and hasn't been for some time.

At its current state, the institute is funded entirely from private donations by those who have hope that the discovery of ETI would bring wonderous advances to our society.

If you think its a worthwhile persuit, which I think it is, donate. http://www.seti.org/

If not, then don't donate. Unlike NASA programs, this one carries your democratic approval of support.

Re:leaving scientology aside...

[MindHack]

You bring up a very valid point, however recognize that civilizations could be sending communications actively or passively.

Passively in the mechanisms you described, by what I hear commonly referred to as "information leak" in SETI discussion circles.

Active communication however is the classification of those civilizations that will actively broadcast in the hopes of reaching people.

You may ask why would a civilization expend so much money and energy in such a persuit, and this is a valid point ss well. The common response is that there must be some advanced civilizations that are so far along that they can spare the change to send a few million photons our way. This gesture could be construed as a peace offering to us. A membership in a huge galactic family.

I'd like to offer a response however that I have not heard of before, in that a civilization could do so for its own benefit. By seeking communication, they are seeking further intelligence from other intelligent beings. Really, its a wonderful way to gain significant scientific understandings by asking others who have already done the dirty work for you.

Thus, from a knowlege standpoint, it is adventageous for a civilization to actively persue intelligent communications for the express purpose of learning, much like an inquisitive child asks too many questions.

Wrong. Only life makes oxygen atmospheres

[spun]

If we find oxygen in the atmosphere, we have found life. Oxygen is very reactive, without some process to constantly replenish it, any oxygen in an atmosphere would very quickly bind with other chemicals. The only process we know of that can do that is life. There could be others, but it is a very safe bet that where we find oxygen, there's life. Here's a link to the wikipedia article about earth's atmosphere, specifically the part about it's evolution.

P.S. Anyone else first learn about this stuff through SimEarth? Hehe. Fun game, very educational.

Re:Wrong. Only life makes oxygen atmospheres

[spun]

Like I said, their could very well be other processes that release oxygen, but I doubt there could be anything besides life of some sort that could do it continuously and rapidly enough to put a very large percentage of oxygen into an atmosphere. But that wouldn't fit in the subject line very well, so I had to make a more definite statement. Anyway, the chances are pretty good that oxygen == life. Or if not, something equally as weird and interesting!

Details about the optics of TPF

[m0nstr42]

One of my buddies is working on this project. He had this to say about how the optics work:

"The basic idea is that under Fourier optics, a wavefront with electric field E that hits a lens with focal length f will produce the Fourier transform of that field E at a distance f from the lens. This location is called the image plane. The location of the lens is called the pupil plane, and the idea is that if you block part of the light at the pupil plane (say with a piece of material in a particular shape, called a mask), it can change the shape of the Fourier transform at the image plane. If we consider the incoming light to be from a star and a planet, we can design the mask so that there is very little light from the star in certain regions of the image plane, and we can see the light from the planet in those regions.

For a more rigorous introduction, I might recommend this paper from our group, which covers the basics of shaped pupils and shows some of our more interesting mask designs. The real challenges in this area now are eliminating the effects of tiny errors in our optics--the best we can get physically is to reduce the error in flatness of the various mirrors in the telescope design to on the order of 0.01 wavelength. (TPF will work in visible light, so that's on the order of a nanometer.) We need 0.0001 wavelength, though, and so we're trying to use adaptive optics (mirrors that we can shape) to cancel these errors. Researchers in this area are very close to achieving the "10 billion times brighter" from the article, we just need to show we can deal with these errors. Very interesting stuff."

Re:Waste of Money

[ObjetDart]

This whole thing is a waste of money.

I could not disagree more.

I think this project is enormously more important than anything else NASA could possibly do in the next decade with that same amount of money. More important than scratching around on the moon, more important than figuring out how to get to Mars, *certainly* more important than futzing around on the ISS.

If this project could determine unequivicably once and for all that there is definitely life on other planets, that would be one of the most amazing, most profound, most astonishing discoveries in the history of humanity. It would be earth shattering, if you'll pardon the expression.

Who cares if we can't actually get to the planets themselves? The reward is the knowledge itself.

1903 Called

[wideBlueSkies]

1903 Called. It wants to know why the Wright Brothers had this idiotic need to fly across a field. After all, perhaps time travel would have been more useful, than say moving people from place to place......

Hmmm. (Thinking)

[jd]

Ok, you won't have much in the way of collecting power (too few dishes) but the resolving power would be amazing. Now, you don't need much in the way of collecting power to see "bright" radio sources - electrically active planets, for example, nearby stars, or globular clusters.

Your resolving power, however, should be pretty damn amazing at 20 miles diameter. Ok, so what's wanted here is something nice and noisy, where your ability to isolate a region of sky and/or track an object would be of value.

You could probably track the storms on Jupiter - you can detect those with even a trivial dipole and a receiver in the right range, so you've certainly got more collecting power than necessary. Not sure how accurate your measurements would be, but that would make a fascinating experiment.

GnuRadio will turn your computer into a suitable receiver (provided you either have a soundcard that works at the right frequency, OR you have a suitable analog-to-digital converter plugged in somewhere). You then need to process the streams into something interesting. I believe AIPS is what you'll want for this. It is "professional" Open Source software for interferometry (read: the interface is crappy, but the logic is superb).

The nearer satellites - such as those orbiting Mars - should be well within your ability to receive and track. I doubt there will be any encryption on the data being sent to Earth, so you might be able to get real-time(!) images from the probes. The only question there is whether the signal would be strong enough to correctly interpret. The same would be true of anything sent by the Cassini probe, although it is much further away and therefore would be far fainter, so you might be restricted to just knowing where it was. Which would be pretty damn good, even so.

I would certainly encourage you to give it a try and see what you can do, and also to diary what works. You may well be able to do far better than I expect - it depends on how big the dishes are and how well you are able to sort signal from noise.

You get your Real Ultimate Power badge if you can intercept a message from either Voyager probe, and an honorary lifetime membership of the Q Continuum if you can get any kind of signal at all from one of the Pioneer probes.

(Note to the humour-deprived: If NASA can barely achieve the former, and can't achieve the latter at all, on the Deep Space Network, there is no friggin' way an amateur is going to on three dishes... unless they ARE in the Q Continuum, in which case the prize is easy.)

Re:We don't cherish life on EARTH...

[Rubinhood]

altruism... the killer of dreams. Perhaps "they" are merely waiting for us to outgrow our clinging to this primitive tribalism

Hmmm. That makes no sense to me.

If I was an ET (if such a thing even exists in the first place), I would DEFINITELY wanna make sure that earthlings keep their house tidy, before eyeballing mine...

OK lets suppose there is a large tribe in the jungle. They are fighting among themselves, and destroying their country, even neighboring countries as the civil war progresses. At one point they realize they are VERY motivated to learn more about YOUR country.

Interested?

Thought so 8)

Re:We don't cherish life on EARTH...

[Rubinhood]

Oh yes, one more thing. Nobody kills your dream. It's just that it's a sequential thing: FIRST prove yourself on your home ground, and THEN venture another one. Nobody said dreams themselves were wrong, it's just that they are _conditional_ =)