Could An ExtraTerrestrial Find Earth with a Telescope? 179
Active Seti writes "If aliens were hunting life outside their own planet, could they peer through the vastness of space and lock onto Earth as a likely home for life? Researchers say with a roughly Hubble-sized array observers could measure Earth's 24-hour rotation period, possibly leading to observations of oceans and the chance of life. 'They would only be able to see Earth as a single pixel, rather than resolving it to take a picture,' said Astronomer Eric Ford. 'But that could be enough for them to identify our planet as one that likely contains clouds and oceans of liquid water.' The research will be useful to astronomers designing the next generation of space telescopes on our planet, because it provides an outline of the capabilities required for studying the surfaces of Earth-like worlds."
I've got an idea (Score:4, Funny)
Re:I've got an idea (Score:5, Funny)
Re:I've got an idea (Score:4, Funny)
Intergalactic quarantine symbol (Score:5, Funny)
Actually, that's a single moon (Score:2)
A pentagon-shaped smiley? (Score:3, Funny)
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Pentagons are a sound dig at the Pentagon of the USA.
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It's when they start using pentagrams that you need to worry.
Re:I've got an idea (Score:5, Interesting)
Impracticality? I mean, moving a star takes a tremendous amount of energy. Either that, or a massive gravitational mass that can be moved through more conventional means. (One of the drawbacks of stars is that you can't exactly setup thrusters on the surface of a flaming, gaseous body.) If they were even close to such technology, it would actually be easier to send out explorers than to muck around with the position of stars.
Assuming that such a civilization could even exist. Which is (unfortunately) somewhat doubtful. Everything we know so far suggests that life is exceedingly rare in the universe. Rare enough to make it difficult to find another civilization that used to exist, much less one that you can actually contact. (Don't even get me started on the incredible time scales by which the older civilization would be long dead before we could even see each other.)
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They might send some exo-sociologists and maybe beam up a few cows and hicks but that's it. We would be poison to them. They might even set up a few quarantine beacons outside the solar s
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Because maybe they just found food and water for their people? And space to expand?
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But while we're talking about impracticalities, you could have an easier time extinguishing the side facing the direction you want it to move.
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Well if such a civilization had reached a technological singularity event, most likely they've got a lot of time on their hands since they would have figured out how to avoid mortality by old age and would most likley use something like a gravity well to shift the stars slightly over billions of years.
Rather than push the start, they could move it in the direction of said gravity well over tim
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Impracticality? I mean, moving a star takes a tremendous amount of energy.
Correct, but maybe we're closer in moving stars than we may think (Yes, I'm speculating... but I always thought about this idea and I never saw it discussed, so please tell me where I'm wrong in the following: :-)
Maybe we could exploit the chaotical movement of stars (or other big masses) and, with a really powerful
simulator, could predict which small nudge could change the positions of the stars in a (short timescale) predictable way. This maybe would
enable us to produce large scale patterns in the univer
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Face it - that was a really dumb thing to say. We have no way to know how common or rare life is in the universe. Hell, we don't even know how common or rare life is in our own planetary system.
Stop stubbornly trying to prove you were right by using convoluted semi-logic.
Re:I've got an idea (Score:5, Interesting)
No, basic scientific principles told me this. While the Drake Equation [wikipedia.org] is not accepted by all scientists as a valid computation, the Fermi Paradox [wikipedia.org] is still a difficult problem to solve.
To throw an equally unfounded accusation back at you, you're a fan of Carl Sagan, right?
Let me put this in simple terms: The size of the universe is known to be at least 93 billion light years across, and is estimated to be ~13.7 billion years old. In a universe that big and that old, there is a strong chance that any other civilization(s) that may have formed are extremely far apart from one another. So far apart that there is a good chance that the civilization(s) will "miss" each other's existence.
Like it or not, if there was a civilization coexisting in our neck of our galaxy, we'd have some inkling of it already. Unnatural radio transmissions would stand out against the background radiation and give us a sense that another civilization is there. We have been scanning the skies with powerful equipment and so far have come up with little to no evidence of such transmissions.
The long and short of it is that from what we know today, there's an infinitesimal chance that we humans will ever meet another civilization. The best we can hope for is that we find planets that support more basic forms of life.
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If we extend it to 1000 LY in order to increase our chances, that means that any signal we get now is from a civilization 1000 years ago -- which is now 1000 years more advanced than when they sent that signal. Assuming they will receive
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Imagine a civ that is on a parallel development track as us but they are 2000 LY(light years) from us. We won't receive their transmissions for another 2000 years. They would have to be 2000 years ahead of for us to receive their transmissions. If the universe does support a variety of civ
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any further & they might as well not exist.
Some problems (Score:2)
1) As another poster pointed out, we have been sending and receiving EM transmissions for only a hundred years. The amount of star systems with a distance of less than 100 ly to the sun is not high.
2) It is very well possible that advanced civilizations this close to our own star system existed, but perished or moved long ago. Or, they are no longer using EM transmissions, but another way of communication we do not yet know or understand. For example, it is not unthinkable that a civilizatio
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You're wrong that the absence of EM evidence (or archaeological evidence) "prove[s] nothing". It certainly constrains the possible ways in which extraterrestrial intelligence could exist or operate. We have pretty much ruled out any nearby
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This is an ignorant argument http://en.wikipedia.org/wiki/Argument_from_ignorance [wikipedia.org]. Absence of evidence is not evidence of absence. Perhaps radio communication is not as ubiquitous as we believe it to be.
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This is an ignorant argument
Actually, not it isn't.
Absence of evidence is not evidence of absence.
Um, yeah it is. Particularly when you are looking for evidence. Said another way, your argument can be applied to argue that there might be invisible pink elephants flying overhead. Which is to say, it's useless and not an argument at all.
There are a couple of solutions to the lack of evidence problem, but the most probable one is that there simply is not technological life besides us within our visible light cone. Like another poster said, the Fermi paradox is basically insu
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Erm, hate to bust your bubble, but we've scanned part of the sky, and in a very narrow frequency range, for transmissions that must have been meant for crossing interstellar distances. If there was another Earth circling around Alpha Centauri, we'd have no idea it was there.
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That part is not true. Typical radio transmissions virtually disappear well short of a single light year. And by "virtually" I mean our own giant radio antennas wouldn't hear them.
We would really have a very hard time detecting ourselves just a light year away. Other transmissions that have a longer range
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Not true at all. Back in 1978, Science published an article on the topic [sciencemag.org]. Its title was "Eavesdropping: The Radio Signature of the Earth". If you're not a subscriber, you can find several copies of it online, as well as several other articles that cite it and do further analysis. The authors studied what could be learned about our planet by an astro
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http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html [faqs.org]
I haven't completely read what you linked yet, though I will at some point to give this a more proper reply. But was that article just drawing the bubble around the Earth in light years and commenting on the reach our radio signals? Or coming up with a cherry picked scenario to show how it could work? If you read what you quoted of me it says "typical radio transmissions virtually disappear well short of a single ligh
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Unnatural radio transmissions would stand out against the background radiation and give us a sense that another civilization is there.
The background radiation, really? You mean that [astrosociety.org]? Oh yeah do you see that little spot, right next the big blue blob? Might just be them..
Seriously, you seem to think that all our telescopes put together form some sort of super fish-eye that monitors the entirety of the sky permanently. If it was the case, then we would know a lot more than the small fraction of asteroids we
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In fact, there are few installations that could detect an "unnatural" signal against the background radiation unless it was generated very close by (in galactic measure), or was specifically directed at us with enough power. As I'm sure others will mention, any advanced civilization capable of SOME space travel would be using mainly directed transmissions which would severely limit our chances of detecting them u
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But if such civilizations were even reasonably common, we should have coincidentally observed at least a few such signals by now.
You're also equating life with "intelligent life capable of generating detectable transmissions". Life could be quite prevalent, but intelligent lif
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Nah; we've found that we can talk openly about the "anthropologists" visiting Earth to study its civilization. And you can talk about us all you like. Who's gonna believe you? Do you really want to be considered one of those nutcases that believe in visiting aliens?
It's sorta like that "Abrahamic God", y'know. Actually, he was one of the first wave of anthropologica
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BTW, the whole superluminal expansion thing, mentioned by another poster, is called "Inflationary [wikipedia.org] Big Bang Theory". It was proposed to explain why the cosmic microwave background is so uniform, because a slow (light speed or slower) Classic Big Bang would've produced a very lumpy universe. It stuck around because it explained a lot of other stuff, too.
Since the expansion of the universe is a property of space-time itself, not of the matter within space-time, this doesn't violate Einstein's Special or Ge
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The there is life on OUR planet (by itself) says absolutely nothing about an increased chance it would be on other planets. For the simple reason - in the hypothetical scenario where there was only one planet in the universe to harbor life, the inhabitants of that planet would be in a similar position to us - they know life exists on their planet, and nothing about the rest. But what about the billions of other pla
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I say we start looking for constellations that resemble our imaginations of aliens. After that we look for black hole clusters and then wipe
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A Space Ship to Visit the Space Alien (Score:3, Interesting)
If we really want to explore the stars, we must focus on high-risk projects that bust the fundamental notions of science. One such project is the hyperdrive [newscientist.com]. Burkhardt Heim developed a unique (almost incomprehensible) field of physics. If he is right, then we can build a space ship to visit the space alien peering at us.
Note that one dedu
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No civilization is crossing the vast emptiness of space for any reason other than settlement. The investment of resources required for such a journey would be too massive to be undertaken for any other reason.
Re:I've got an idea (Score:4, Insightful)
the universe is that none of it has tried to contact us.''
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I can't Mom. I've got to kill snow goons!
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Because they don't consider where someone lives to be especially important. You don't know or care where I live, right? The important thing is the ability to communicate, and they do that simply by having the ubiquitous robot probes install gateways to the galactic network wherever they come across a world that has advanced sufficie
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They just did, about 5 days ago. But we won't see the changes for several thousand years.
Too much work.... (Score:2)
Doesn't that mean.... (Score:1)
Single pixel? Not a problem... (Score:2)
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Too many assumptions? (Score:5, Insightful)
(1) Life on other planets has the same requirements for existence as us (Class M
planet, water, air like ours, gravity like ours, etc)
(2) Extra-terrestrials will be using technology similar to ours (as opposed to more advanced tech)
(3) (Basing off #1 being true as they did) there are planets suitable for life such as ours that
we haven't yet discovered that are looking in our direction.
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Well, I live in the Star Trek Universe quite often lately (check out http://www.startreknewvoyages.com/ [startreknewvoyages.com])...
But, that aside, this IS Slashdot... I'm pretty sure every geek... I mean Slashdotter here knows what a Class M planet is... and if not, you just provided them with the necessary explanation ;-)
Re:Too many assumptions? (Score:5, Informative)
Given this assumption, there aren't a lot of options for different types of life. The chemistry just doesn't work. Biology is chemistry, chemistry is physics, and physics is mathematics. It basically puts in some ground rules for life. There's a decent little wiki on this: http://en.wikipedia.org/wiki/Alternative_biochemistry [wikipedia.org]
As you can see in that wiki (there are pro's and con's for each of the alternates), based on our understanding life either does need most of the same things we do, or at least our biochemistry should be the most common in the universe. The math just makes it that way. There are some variables sure. And some alternatives. But for the most part, looking for stuff life us seems to most likely scenario.
Now, given this, #1 and #2 should fall somewhat in line with what they're thinking. Sure, the minutia of evolution could lead to exotic live from our perspective. Something other then DNA based life even. But they (the aliens) should still come up with e=mc And their biochemistry should, at least, be something comparable to ours.
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I'm no rocket surgeon, but this seems to me like an incredibly narcissistic set of assumptions.
It took us thousands of years to get some basic grasp of how life on this planet works, and that's with a big head start - we have it right here to experiment with.
Isn't it a bit
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Their energy source isn't the sun, and they're able to thrive in water that's very hot, in very high pressure, and with a lot of sulfur. But they're still carbon based life, they still take oxygen from the water. They're extreme, but still fall into line with "looking for us".
I, for one... (Score:1)
oxygen, man (Score:5, Informative)
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The Earth would look like a Quasar (Score:1)
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Nothing to see here. Move along.
Omygod (Score:2)
Might have water (Score:1)
This assumes..... (Score:2, Insightful)
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Now, how to go about building a giant concrete ear. Hmmm.....
OK, honestly. Me thinks that anything that would produce sound waves that made it through interstellar space and was able to be detected on Earth would most likely be easier to detect looking for photons. Whether that be radio waves, visible, gamma, etc...
Sound is just the movement of energy through matter in waves. While I have no doubt it's possible that in some alien world hearing would be more impo
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Unless the label change also implies that the "audible electromagnetic spectrum sensors" don't dominate their senses as ours, it hardly matters what label gets used.
Do we want to be found? (Score:4, Insightful)
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And then there is the possibility (Score:5, Interesting)
Lightspeed is slow (Score:4, Insightful)
Simple! (Score:2)
How about we launch some giant pixels so that they see more.
It worked with Google push-pins [blogspot.com].
They don't need to see us (Score:2)
only just starting to brainstorm in 2007? (Score:2)
mind boggling (Score:2, Insightful)
Nice day to you all!
Stephan
pixelization (Score:2)
Wow. That's one hell of an information packed pixel. Maybe he means one of those spooky, hyperadvanced alien pixels. I hear they're super effective.
If they are hostile aliens, we can only hope they do a lot of image processing. I hate to think the only thing sta
Re:pixelization (Score:5, Informative)
A single pixel can provide a hell of a lot of information: Do spectroscopy, and you can get the typical absorption lines (O2 for example should be easy to detect, and be a sure way for _anybody_ who detects it to tell something is odd about that planet).
Track the intensity over time, and you can get the rotation period.
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Thanks. I don't think anyone else did.
What a pointless question. (Score:2)
So, if the aliens have our level of technology or better, and are willing go through the effort, they could easily find Earth.
We've Already Been Discovered (Score:5, Funny)
The first time: they discussed us using irrelevant analogies, took a senseless poll, said things like "imagine a Beowulf cluster of these" and "itsatrap!", and one alien remarked "I, for one, welcome our new Earthling overlords."
The second time: they just shouted "DUPE!" and moved on.
How far? (Score:2)
I always wondered ... (Score:2)
Its a pointless discussion (Score:2)
Google Earth is your friend..DRMed, but still good (Score:3, Insightful)
When I see Earth with Google Earth (by the way, FSF [fsf.org], where I am a member, has called the creation of a free compatible client a high-priority project [fsf.org], and if you have free time please try to help, and if you need hosting for your project I can give you [algolibre.org]), I hardly can detect life, let alone humans, on Earth. Visually it's very difficult to detect it (and nothing suggests that an alien would expect a green planet to be filled up with plants, in fact a scientist would expect plant life to be red-coloured and in fact that's how it was in the past as red-colour has greater absorption efficiency... Earth plants became green only after changes in the atmosphere). I can see, of course, that the planetary atmosphere is a very dynamic system (clouds go and come every day), but all the rest is nothing but white places over the poles (ice), vast blueness (oceans), a few greenie plains (jungles, where remained by the human effects), and some light brownish-yellowish regions (deserts). That's all. I would need to analyse the Earth's spectrum or possibly other means to find out what chemistry this funnily coloured vastness has.
But wait, there's more: I can zoom in a little and see mountains etc. And if I zoom more I see that some oceans have little green islands in them, so perhaps I could start to understand that this bluish abyss could be some kind of liquid and the greenish spots could be areas of higher elevation. But still, it could very well be a dead planet with no life, let alone humans. So I have to zoom more. Oh, now I can see that there are some grayish spots near the greenery, as if someone had vomited on the Earth's plains. Yea, it certainly looks like vomit, but what is it? Zooming more... oh, it looks different from anything else, it has some kind of structure, lines etc. Still looking like vomit, though... structured vomit. Who the hell vomited on the planet we, the alien scientists, discovered? How can we write a paper on a vomited planet? Everyone will laugh, our academic reputation is at risk because of this vomit on this extra-Gliese planet.
But let's move away from this freaking vomit and look closer at the green plains and the brownish-yellow regions to see what there is there to be seen. Zoom a bit... oh what's this? Some kind of lines in the desert? Oh, it looks like other aliens visited this dead planet earlier and played some earth games on it, eh? Perhaps they were having some kind of planetary football games or something and this was their soccer field... But wait, some lines are quite intriguing. Nah... these aren't lines, these are complete drawings. Let's move away a bit and zoom closer... Hm, here these look like symbols. Ok, there may once have been some intelligence on this planet, but now it must be dead, probably, as it is too far away from its star (we the aliens like hot stuff so we live near our star, and this is what we consider the only habitable zone possible, for us if it feels hot it's good and we believe the whole universe is somehow made for us to explore and play in, so any planet outside our habitable zone must be dead because that's what the big scientists here say).
Where did this intelligence come from? Maybe it came from the vomit, so let's go back there and zoom more. Wow, what's that? It looks like the lines that divide the vomit in little rectangles have little ant-like things running over them. Oh, and by these lines there are big boxes. But what these boxes contain? Maybe there's more vomit in there! Ok, our scientists found the truth, these running things transfer the vomit from box to box! And maybe this vomit is intelligent! But not much, as it probably has not discovered telecommuting or work-from-home yet. And that's what we would expect from a planet outside the habitable zone, it must be so cold these (15-25C, which for us is too cold) that this vomit has its intelligence sabotaged by the tem
Re:Google Earth is your friend..DRMed, but still g (Score:2)
we are the aliens' pixels (Score:2)
Forgot to add that if you really want to see how our planet looks like from the vastness of space, just fire up google earth in skygazing mode. Every pixel now is a whole world full of action, with many of them having other smaller worlds in orbit around them, and perhaps on some of these there are creatures like us calling their little pixel their home, and arguing, making love and war, playing with their gadgets (oh yeah there are surely geeks out there!), trying to find new theories of everything (surel
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a) a slight headache
b) the feeling that there is somebody out there who's totally fucked up (and not me)
Just check the radio (Score:2)
No wonder we have not been visited yet!
Single pixel, eh? (Score:2)
let's hope they're not nearby (Score:2)
that is:Paraphrased from the book:
1. Any species will place its own survival before that of a different species.
2. Any species that has made it to the top on its planet of origin will be intelligent, alert, aggressive, and ruthless when necessary.
3. They will assume that the first two rules apply to us.
Add to this the facts of relativistic bombardment. A mi
I have the answer... (Score:2)
Soon you shall all die.
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Diffraction limit==One pixel earth.
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They're basing these ideas on a new telescope on the fact that other worlds hosting life would be hosting life that requires the same needs as our own to survive. I think these smart scientists are forgetting a very simple fact. We're creating these telescopes to find ALIEN life. They are called aliens because they are alien!!! And as anyone knows (or at least can imagine) when your looking for nothing but quartz, that diamond in the ruff doesn't shine so bright. ...
Nobody is forgetting that fact. It's just that we are playing the odds. So far, 100% of life we know has the same basic set of requirements (with some very good fundamental bio/chem/phys reasons for those requirements). 0% of life we know are your hypothetical rock creatures... It only makes sense to look for the former.
Furthermore, we are only focusing on what is possible. Since you cannot define a set of criteria measurable with our current technology for locating a "rock creature" or some other exo
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--Carl Sagan, Cosmic Connections, pg 150