What methods can detect life in distant galaxies beyond spectroscopy?

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Sunshine
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How can we study life in other galaxies?

By studying its spectra you can say what the galaxy is made of, how it's spinning, how far away it is, and how big it is etc, that can be helpful when attempting to find life, but is there other ways to study the chance of life in other galaxies?
 

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Sunshine said:
How can we study life in other galaxies?

Not anytime soon. I won't try to speculate too much on the advance of technology, but if that's even possible, we're a very long way away from achieving it. At the moment, we couldn't even detect life around the nearest star.
 
On the other hand with >1011 stars in a galaxy, if the chance of contemporary intelligent life is very low, say 10-11 per star, then maybe the best chance for 'Contact' is to receive a signal from a galaxy rather than a nearby star. The signal itself, of course, would have had to be very powerful for it to be detected against the galaxy's background noise, but that should not be an insuperable problem for an advanced civilization.

This was the theme of Fred Hoyle's 'A for Andromeda' 1960's TV SF series that would have been a classic if the BBC had not lost the original tapes!

Garth
 
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But how would we detect signals sent from outer space, by living creatures?
 
Radio signals. We've already sent hundreds, containing information about us. They say within the next 20 years that if there is extraterrestial life, we will detect them.

I think the radio is the only way. We can't detect habitable planets like our own in other solar systems yet, all we've seen are gas giants
 
yomamma said:
Radio signals. We've already sent hundreds, containing information about us. They say within the next 20 years that if there is extraterrestial life, we will detect them.

I think the radio is the only way. We can't detect habitable planets like our own in other solar systems yet, all we've seen are gas giants


But the signals from a planet in our own galaxy, never mind in another galaxy, would be SO weak. Never mind technology, would it be physically possible to isolate such a signal from background noise?
 
When we search for life in other galaxies we look for planets that have almost the same environment as earth, since it is believed to have the best opportunities for life to begin. Does anyone know some serious researches in this topic, or what techniques are used for this kind of researches, i.e. finding planets that have same environment and same possibilities for creating life. (I guess that we are counting with only carbon-based life if we are looking for planets similar to the earth.)
 
Hey Sunshine,

You've asked - several times - about 'other galaxies'; do you have a particular reason for wondering about things so far away? I mean, there are millions of stars in our own Milky Way galaxy that are an awful lot closer than even the closest (other) galaxy.

So, to your specific question - AFAIK, no one is looking for planets in other galaxies, let alone those that may have environments similar to those here in Earth (OK, there have been a few projects with tangential relevance ...).

As for Earth-like planets much closer to home (say, within 100 or 1,000 pc), then much work is planned (though NASA's recent budget troubles will likely postpone the only significant project that's on the drawing board, and it may never get off the ground).

Kind Regards,
Nereid
 
I've been reading about researches about life in our solar system, and the milky way, but I'm interested of knowing if these techniques can be used to study galaxies that are much farther away. So I'm mainly interested of the techniques used, and not towards what the results are heading ;)

Recently I read about NASA's Spitzer space telescope that discovered galaxies about 11 billion light years away, hidden behind dust... but can we analyze any spectra from there and/or get any information about the planets there, and from that make any conclusions if life could possibly have evolved there?
 
at the moment, no we can't. most planet detection methods rely on measuring spectra/luminosity of resolved star systems. These systems are not resolvable at 11 billion light years.

i am sure if you typed 'extra solar planets' in google, you will find a plethora of information!
 
I think if you are asking for a group of people involved in this job. SETI is the organisation you are looking for.Go to their homepage you will get all the information.
 
Hi Sunshine! We cannot even resolve stars in most galaxies outside our own, hence it is a bit premature to attempt to detect and translate any extra-galactic radio signatures.
 
Dr.Brain, SETI are studying only the milky way, aren't they?

Chronos, it doesn't need to be radio signatures specifically. As far as I know we can check the metallicity of a star outside the milky way, and hence tell if that star could have planets. If yes, could we then go further and base our "speculations" about the environment on these planets, on any more fact?
 
Sunshine said:
Chronos, it doesn't need to be radio signatures specifically. As far as I know we can check the metallicity of a star outside the milky way, and hence tell if that star could have planets. If yes, could we then go further and base our "speculations" about the environment on these planets, on any more fact?

If we were somehow able to detect life on other planets in the Milky Way, we could study the properties of the stars that hosted planets and then perhaps reasonably infer the existence of life around other stars in other galaxies. Even for this, however, we're a long way off. It's not enough to detect a planet, you have to find specific spectroscopic signatures of life.
 
Ok, so there are no current searches for life outside milky way but we CAN study spectra from outside milky way with our current technology, and by that either say that earthlike life can't exist there, or that there is a possibility it could have evolved as on earth?
 
Sunshine said:
Ok, so there are no current searches for life outside milky way but we CAN study spectra from outside milky way with our current technology, and by that either say that earthlike life can't exist there, or that there is a possibility it could have evolved as on earth?

We can't right now see spectra of planets in other galaxies (or our own, for that matter). Given what we know about other galaxies, though, there's no reason to think that life couldn't have evolved in them.
 
Sunshine said:
Ok, so there are no current searches for life outside milky way but we CAN study spectra from outside milky way with our current technology, and by that either say that earthlike life can't exist there, or that there is a possibility it could have evolved as on earth?
Getting a spectrum for one particular star in a distant galaxy is beyond our capabilities, unless that star is a supernova, and then we can absolutely rule out "life like us" in its immediate vicinity. :wink:

We can take spectra of distant extended objects like galaxies and of point-like objects like quasars, though. So far, those spectra have shown no evolution over time. In other words, light from these very distant objects (assumed under the Big Bang model to have been emitted from these objects over 13 Billion years ago) has been studied and the bodies emitting this light have been found to have metallicities (abundance of heavy elements) similar to or even higher than the metallicities of our own galactic neighborhood. This is a fair indication that conditions conducive to the appearance of life could have arisen around any number of stars in any number of galaxies for over 90% of the presently-assumed life of the Universe 13.7 Billion years. Under these circumstances, one would have to be an insanely pessimistic person to believe that we are the only intelligent life to have ever developed in the Universe.
 
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Hey Sunshine, how would you like to do some calculations for yourself?

Let's start by assuming that the folk working on the NASA TPF (Terrestrial Planet Finder) or ESA Darwin projects* have got their science more or less right, and that they would be able to observe the spectra of Earth-like planets orbiting in the Habitable Zone around F, G, or K main sequence stars within 25 pc sufficiently well to detect the abundance of enough molecules in these planets' atmospheres to allow chemists to say what the likelihood that Earth-like life has a large part to play in the composition of these atmospheres is (whew, what a long phrase!).

Now, what would the size of the (space-based) instruments need to be to do the same trick for stars in the SMC or LMC**? Might there be other techniques that could be used (instead of a coronograph and nulling interferometer)?

Finally, other than projects like Darwin or the TPF, how else could we constrain the possibility Earth-like life on Earth-like planets? For now, let's leave aside SETI-type searches (this involves a whole different set of questions, from the "I").

*OK nitpickers, this is a composite objective, not exactly aligned with those of Darwin, or TPF-C or TPF-I; I'm trying to make things a bit simpler.
**caveat #2: OK, neither is, in fact, the closest galaxy to the MW, but each is sufficiently large and close that individual stars can be easily seen, and complications of looking through the MW plane (if any) are sidestepped.
 
Hmm... I don't even know where to start, that's too advanced for me. I don't even recognize what system those 25 pc is from. If it's some american system then I don't know since I only use the metric system.

Anyhow... it would be interesting of to get the answer of your question "Might there be other techniques that could be used (instead of a coronograph and nulling interferometer)?" :)
 
"pc" = parsecs (approx 3.10^16 m), or the distance an object is, from the Earth, in order for it to subtend 1 second of arc in parallax (using the Earth's orbit as the baseline). It's a standard unit of distance in astronomy.

Why not go visit the TPF and Darwin websites, and read up on the mission specs?

I'd rather you get your mind around the 'baseline' methods before we start to explore possible alternatives ... and I feel that unless you have some appreciation of the underlying principles, we will have a rather uninteresting thread.

What say general readers?
 

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