Do you believe in possibility of life in other galaxies?

[jerry66]

With over a hundred billion galaxies in the universe. It is hard for me to believe that there is not at least one other solar system with life. Especially, when some scientists claim that they have already found some exoplanets that can be like Earth.

[bilateralrope]

Sure, the probabilities of life emerging aren't known yet as we don't have a large enough sample size. But with life emerging here on Earth, it's bound to have emerged somewhere else.

All we can say for sure is that we haven't detected it yet. But how far out into the universe can we look ?

I've got no idea what our range for analyzing exoplanet atmospheres is. Then there is the complication that if you've got an ice covered world with life in an ocean beneath the ice (eg, Europa) that's not going to show biosignatures in its atmosphere.

As for radio signals, the latest distance I've heard is that the Square Kilometre Array should be able to detect radio leakage from our airports at 100 light years. Which is important, as airport radar is the strongest radio signals we are putting out in all directions. But the SKA won't have first light until 2027.

[Eternal_Freedom]

Spotting and analysing exoplanet atmospheres is a tricky thing. For one, it relies on the transit method - the exoplanet has to pass across the face of it's parent star as seen from Earth, which lets us detect it in the first place and run spectroscopy on the incoming light. The furthest one I know of that has an exoplanet we've been able to study like that is only a few hundred light-years off, so there's likely a lot more in just our galaxy, never mind the rest.

The transit method though is inherently biased - we can only use it to detect Earth-sized exoplanets that have Earth, the planet and the star all line up neatly. If the exoplanet's orbital plane is off the line-of-sight by as little as twenty degrees or so we'll never see them. So odds on there are even more close by that we aren't able to detect yet via other methods (radial velocity changes, for instance, is a method biased towards big "super-Jupiter" like planets that are close to their star, so again not much use for Earth-size rocks).

Given the number of exoplanets we've found (nearly 4700 as of March 1st, most by the transit method, in ~3600 star systems) that are (relatively) close by, and the (probable) many other's we aren't seeing yet close by, the odds get to the point where us being the only habitable world in the universe are laughably remote - it'd be pretty damned arrogant to think we are all there is.

It's a question I get asked a lot when I'm doing outreach events for my astronomical society - my usual answer is "that's the wrong question, of course there's other life int he universe. The real question is: is there intelligent life close enough for us to meaningfully communicate with?"

[GuppyShark]

I believe there is life _in this solar system_. The rest of the universe? Likelihood approaching 100%. With the range of places on Earth that life is thriving in, there are some possible candidates (the ice moons likely have liquid water underneath closer to their cores).

[jerry66]

Sure, the probabilities of life emerging aren't known yet as we don't have a large enough sample size. But with life emerging here on Earth, it's bound to have emerged somewhere else.

All we can say for sure is that we haven't detected it yet. But how far out into the universe can we look ?

I've got no idea what our range for analyzing exoplanet atmospheres is. Then there is the complication that if you've got an ice covered world with life in an ocean beneath the ice (eg, Europa) that's not going to show biosignatures in its atmosphere.

As for radio signals, the latest distance I've heard is that the Square Kilometre Array should be able to detect radio leakage from our airports at 100 light years. Which is important, as airport radar is the strongest radio signals we are putting out in all directions. But the SKA won't have first light until 2027.

Yeah, you are right. Even if some forms of life really exist on some of the exoplanets, we cannot check it. These planets are too far and even if we could travel in space with the speed of light, it would take us a few years to get to a one of these exoplanets.

[jerry66]

Actually, I think that some forms of life can be found on Mars. You all may know there is water ( ice ) on Mars, so there is a possibility to find in that ice some forms of life or atleast some traces of life that existed on the red planet millions years ago

[His Divine Shadow]

Seems to me, life might be plentiful in the universe. But I think where it goes to heck is stability of environment. I think that's one of the great filters.

Consider the earth, it has managed to support life for 3 billion years at this point and under that time the suns luminosity has increased by 30% , but we're still in the habitable zone. That's a huge change in environment and would in most circumstances have ended life on a planet aeons ago. It's incredible that earth has had such a stable environment suitable for life and complex life for so long.

But we've been lucky, the planet has had the exact right composition to form the exactly right conditions for the planet to evolve both life and the proper feedback mechanisms to compensate, from plate tectonics (real important for maintaining life) to the stabilization of the magnetic field ~600 mya.

The evolution of life itself is a factor in earths habitability, life almost destroyed itself due to the great oxygenation event, but that event oxygenated the atmosphere and created the conditions for the ozone layer to be created. Which allowed life to move from the seas and onto land without being destroyed by the suns UV radiation.

There are a lot of factors, and a good deal of luck to get a planet that has been habitable as long as ours. I think ther emight be a lot of planets which are habitable, which evolve life. But they might not remain so. The initial conditions are such that the system is unstable, or unfavorable in other ways. Life might only get a few million years, or a few hundred million before the system is no longer compatible with life, complex life might not ever get the chance to evolve. And even if complex life is developed in such a short time, that's whole house of cards itself with special unlikeky conditions and luck required to happen.

I think most life evolves on planets like these, but never gets a chance to develop into more than bacteria.

[EnterpriseSovereign]

Never mind other galaxies, the chances of there being extrasolar life just within the Milky Way is practically a certainty, the real question is whether there's intelligent life out there and if there is, if it's possible to establish two-way communication.

Of course true two-way communication is for all intents and purposes impossible because even the nearest stars are light-years away and the Milky Way is >100,000 ly across and contains hundreds of billions of stars.

So until FTL communication and travel becomes a thing the question of extrasolar life is academic. Hell, even high sublight would at least make interplanetary travel practical, never mind interstellar.

[Batman]

Nevermind 'high' sublight. Even 'low' sublight (say 1% c) would mean you can get all the way out to Pluto in a single figure matter of 'weeks' instead of the years to decades we have now and Mars would be what, 2 days at worst?
Of course that would require power generation we can't so far dream of (not to mention acceleration compensation unless you want to take freaking forever to get up to those speeds) and given we've been stumped by viable fusion (which doesn't even begin to give the required power) for ages...

[Solauren]

Forget life just on other planets. I'm of the opinion that some UFO sightings are actually space-faring life forms entering our atmosphere to breath for a bit before 'submerging' back into the vaccuum of space. I'm not talking space ships or intelligent aliens. I'm talking animals like the 'Wake Angels' from After Earth, or the 'Space Whales' from Star Trek TNG. Something that could exist in Nebula, and migrate between them over centuries, going dormant between them, occasionally waking up in a gravity well to use a planet as a watering-hole of sorts.

Far fetched? Possibly.

[Soontir C'boath]

Ever since it came out that crustaceans like to evolve into crabs, I've wonder if Star Trek actually had the right idea and that our universe just have various types of humanoid civilizations. Having ambidextrous hands is pretty damn useful to do a lot of things than say a horse or a dolphin can possibly do with their mouths and hooves/flippers. Maybe there's a world out there with intelligent space faring raccoons.

Also, I would think it's very important for the planet to have the right composition. Imagine if Earth somehow didn't have the metals we commonly use to this day; copper, tin, zinc, iron, aluminum, etc. Would we take an extra ten thousand, one hundred thousand, etc years to build a rocket?

If we didn't have crude oil, would we be smart enough to create an alternative fuel or do we just continue to burn wood/coal until they run out?

It feels like there are so many things that can go wrong just on what planet you happen to be on nevertheless the possible irrational component of an intelligent being.

[His Divine Shadow]

If the earth had just a slightly different composition of radioactive materials we might have ended up like Venus without tectonic activity and no carbon cycle.

[His Divine Shadow]

Red dwarfs are interesting as a place for life I have to admit, not all of them have flare issues and might be good candidates for life. Though part of me wonders if there's something special about a larger star like ours that is required to develop complex life? I don't really know.

Another interesting thing about red dwarfs is that in the long future they will reach a certain stage of evolution where their brightness will increase and they will turn into blue dwarfs. The universe isn't old enough yet for those to have formed, but it's an interesting stage, they will increase the goldilocks zone of a dwarf star so it does not have to be so close and they will remain in that stage relatively stably for billions of years. A very short time compared to the red stage but long enough to for advanced life to appear.

So it might be that the universe has it's most life friendly phase ahead of it. We might be an extreme outlier to have developed so early on in a universe that is very hostile to life (at least hostile to life having enough time to develop).

[Solauren]

Of course, the idea of us being and outlier raises the possibility we're the only sentient life in our galaxy (or possibly even galactic cluster), while non-sentient life is common.


Rich, raises a question - If we are the only sentient life in our stellar/galactic neighborhood, but the area is otherwise teeming with life, do we steward it and stay off those planets that could develop sentient life, and effectively become the 'Ancients' to future sentient life, or do we just claim it all because we can?

[EnterpriseSovereign]

Of course, the idea of us being and outlier raises the possibility we're the only sentient life in our galaxy (or possibly even galactic cluster), while non-sentient life is common.


Rich, raises a question - If we are the only sentient life in our stellar/galactic neighborhood, but the area is otherwise teeming with life, do we steward it and stay off those planets that could develop sentient life, and effectively become the 'Ancients' to future sentient life, or do we just claim it all because we can?

You mean whether we should we colonise a class-M planet should we find one? All depends if the planet has any resources worth claiming. In the contest between the needs of the human race vs life that may or may not evolve on a planet it's a no-brainer.

Maybe there's a world out there with intelligent space faring raccoons.

You mean a whole race like this guy? That is both awesome and terrifying!

Also, I would think it's very important for the planet to have the right composition. Imagine if Earth somehow didn't have the metals we commonly use to this day; copper, tin, zinc, iron, aluminum, etc. Would we take an extra ten thousand, one hundred thousand, etc years to build a rocket?

If we didn't have crude oil, would we be smart enough to create an alternative fuel or do we just continue to burn wood/coal until they run out?

I can see how a planet having dilithium/infinity stones/naquadah might make space travel more accessible and those planets being more desirable for other space-faring races.

[Solauren]

Rich, raises a question - If we are the only sentient life in our stellar/galactic neighborhood, but the area is otherwise teeming with life, do we steward it and stay off those planets that could develop sentient life, and effectively become the 'Ancients' to future sentient life, or do we just claim it all because we can?

You mean whether we should we colonise a class-M planet should we find one? All depends if the planet has any resources worth claiming. In the contest between the needs of the human race vs life that may or may not evolve on a planet it's a no-brainer.

I was more thinking of, 'on most class-m planets, we find life, but nothing with obvious potiental, but on this one, we found the alien equal of high end great-apes that could become fully sentient if we them left alone'.

[Soontir C'boath]

Rich, raises a question - If we are the only sentient life in our stellar/galactic neighborhood, but the area is otherwise teeming with life, do we steward it and stay off those planets that could develop sentient life, and effectively become the 'Ancients' to future sentient life, or do we just claim it all because we can?

Given our history, I would presume the latter. Especially if it's the early stage of interstellar flight in a colony ship that may only have enough fuel and resources to reach its target planet.

[Tribble]

As others have stated, IMO it is practically a certainty given the scale of the universe that there is other life out there, including sentient life. I find the belief that human beings are “special” and are some imaginary sky god’s chosen children to be a colossal case of hubris- we assume we’re special when comparing ourselves to the life on Earth we have encountered so far (debatable), but in the grand scheme of things? When compared to the entire universe? Nah.

More pertinent questions are how often life forms, how often sentient life forms, and does it form often enough and close enough that we may one day make contact?

Plus just how accurate is our understanding of the universe thus far?

If our current models are in fact accurate and more or less complete… then odds are pretty low we’re ever going to have conclusive proof that other sentient life exists, let alone contact them, and let alone actually meet them in person! Space is just too big, and even the fastest thing in the universe is too slow (and we’re not likely to make spaceships that come remotely close to its speed anyways). Plus good luck actually managing to artificially create a useful and stable wormhole over interstellar distances.

Hell, even just reaching our closest neighbouring star in a form that’s useful for exploration/ colonization and in a timeframe that’s meaningful would be by far the single greatest feat we’ve ever accomplished.

I’m not really concerned about encountering other sentient life - again assuming that our current understanding of the universe or more or less accurate and complete. Just surviving against ourselves is enough of a challenge atm. Maybe if we are lucky we may get to start colonizing other planets in our solar system, but odds are not in my lifetime lol

[Solauren]

Spacial Compression Drives look promising (the Nasa 'Warp drive'), IF we can get them to work.

[EnterpriseSovereign]

Rich, raises a question - If we are the only sentient life in our stellar/galactic neighborhood, but the area is otherwise teeming with life, do we steward it and stay off those planets that could develop sentient life, and effectively become the 'Ancients' to future sentient life, or do we just claim it all because we can?

You mean whether we should we colonise a class-M planet should we find one? All depends if the planet has any resources worth claiming. In the contest between the needs of the human race vs life that may or may not evolve on a planet it's a no-brainer.

I was more thinking of, 'on most class-m planets, we find life, but nothing with obvious potiental, but on this one, we found the alien equal of high end great-apes that could become fully sentient if we them left alone'.

This reminds me of the Voyager episode Natural Law, where an energy barrier separated a primitive culture from an advanced one on the same planet. I would hope that humans would be able to coexist with such life on a planet, however humans have a long, long history of warring with natives of every country outside Europe which makes me doubtful.

Spacial Compression Drives look promising (the Nasa 'Warp drive'), IF we can get them to work.

Anything to drive up that all-important Delta-V!

[Solauren]

I was more thinking of something along the lines of the Prime Directive. "If we find something that high a high probability of developing sentience, leave that world alone. Otherwise, it's free real estate"

[Bedlam]

I was more thinking of something along the lines of the Prime Directive. "If we find something that high a high probability of developing sentience, leave that world alone. Otherwise, it's free real estate"

Which will of course keep many future lawyers well employed as to what high probability means probably while those planets are being bulldozed on the background.

Given that evolution doesn't have set goals (outside of survive) and sentience isn't necessarily a feature that's going to be selected again can you ever argue that something non sentient is going to become sentient in the future? Plus there might be a question of time frame, you could look at some slime mold and say that it's got a fair chance of being sentient in 3 billion years or so vs verses a random ape like creature which might reach the criteria in half a million years.

[Solauren]

Good questions

Hopefully the lawyers can figure it out!

[EnterpriseSovereign]

To be fair, the Prime directive applies to planets that already have sentient life. Unless you have time machine or a member of the Q continuum you have no way of knowing for sure whether it's going to arise on a planet.

Other questions along that vein are how widespread across the planet those creatures are found, if they're confined to one continent or spread more evenly. I can see study of such creatures would be fascinating to space primatologists. Same considerations of where on the planet natural resources are likely to be found, and where those areas overlap it gets awkward.

[JackWhite]

If we are going to speak about other forms of life like "Sci-Fi" movies, I would say that these forms of life are unrealistic to me whatsoever. Sure there are some proofs that on some planets there is a possibility of water, but in general, it's funny to hear/watch theories about aliens and everything related to this topic