Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Life on other planets would likely be brief and become extinct very quickly

astronomy.com

Post reply on HN
Print view View original

51–60 of 72 posts

Re: Life on other planets would likely be brief and become extinct very quickly

#51

Post by reasonattlm »

losteric wrote: post #48
reasonattlm wrote: post #18

No answer to the Fermi Paradox works if it requires all aliens to uniformly come to the same end state or satisfy some boundary condition without exception. All it takes is the one exception, one small group in one suitably advanced civilization, and you have self-replicating probes building an expanding wave of computronium, dismantling even the stars themselves as soon as the economics favor a better use for that m…

> simple economic analysis of our future tells us that we will tear them down in favor of more efficient arrangements of matter and energy? What tells us this is the case? How do we know there isn't an upper limit on the amount of computing resources a civilization desires, even if it's an absurdly high limit like "disassemble all the inner planets"? How do we know there is an incentive to build interstellar civiliza…

Again, you are looking for bounds on voluntary behavior that every civilization - and all its members - must satisfy. It only takes one to choose self-replicating probes to make the wilderness disappear in very obvious ways, visible in neighboring galaxies.

Re: Life on other planets would likely be brief and become extinct very quickly

#52

Post by givan »

leppr wrote: post #50
givan wrote: post #39

Earlier quoted context omitted.

> Witnesses claim to have observed a huge V-shaped (several football field sized), coherently-moving dark UFO (stars would disappear behind the object and reappear as it passed by), producing no sound, and containing five spherical lights or possibly light-emitting engines Do you really think the military has this kind of technology?

Do you think there used to be dragons roaming the earth?

Do you still think the earth is flat? This is how it sounds when you try to ridicule something that you don't know or probably don't want to know for various reasons, you should read more on the subject with an objective mind.

Re: Life on other planets would likely be brief and become extinct very quickly

#53

Post by baddox »

samstave wrote: post #31
breckinloggins wrote: post #9

Earlier quoted context omitted.

This gets my vote. My hunch is that intelligent life like the kind we would love to meet happens either on the order of once or twice per galaxy during the galaxy's entire lifetime, or it happens SO rarely that, if the universe is infinite in extent, then any intelligent observer looking out from the "center" of their observable universe will most likely be in the only intelligent civilization in that visible radius.…

Then why the fuck do we keep killing ourselves? Seriously, if we taught this level of intelligent-life appreciation to every born soul... the world would be a better place. Rather than starting with the teachings we do for youngsters; why not just teach them how freaking rare and lucky they are to be a consciousness present to hear that fact and then know that they can then expand the known universe... but do this in…

> Then why the fuck do we keep killing ourselves?

Because the knowledge that "us killing ourselves" collectively is bad for us collectively does not affect the decision for an individual to kill another individual.

Re: Life on other planets would likely be brief and become extinct very quickly

#54

Post by reasonattlm »

Florin_Andrei wrote: post #25
reasonattlm wrote: post #18

No answer to the Fermi Paradox works if it requires all aliens to uniformly come to the same end state or satisfy some boundary condition without exception. All it takes is the one exception, one small group in one suitably advanced civilization, and you have self-replicating probes building an expanding wave of computronium, dismantling even the stars themselves as soon as the economics favor a better use for that m…

> dismantling even the stars themselves It's unclear whether that's actually feasible from an energy balance perspective. You'll need a lot of energy to re-arrange things on that scale. Each star is already sitting at the bottom of its own local energy well. Maybe the far future will discover radically new ways to produce energy - but until then, this whole thing about the wave of computronium flooding the universe i…

Agreed, but stars are very fragile in some ways; surprisingly small disruptions in some of their transitional layers can cause novas. Stellar modeling is entertaining in that way.

So in place of "dismantle star" perhaps "provoke extreme mass loss" would be a more obviously net energy-positive goal for the engineers. Still, one should run the back of the envelope calculations on what you'd have to do with a stellar mass to produce greater energy than it emits in its current form, and whether the difference can be enough to make it a net positive to nova the star. My intuitive belief is that the difference in efficiency of use of materials can be huge, more than enough to justify large investments in stellar engineering at the stage when technologies means molecular nanotechnology plus nucleosynthesis: factories capable of taking in hydrogen and turning out anything.

Re: Life on other planets would likely be brief and become extinct very quickly

#55

Post by civilian »

AnimalMuppet wrote: post #44
monk_e_boy wrote: post #38

Earlier quoted context omitted.

Ha! But it does solve the 'this rare event happened here on Earth but it is very unlikely to happen anywhere' because those little single cells came here from somewhere else. That source infected millions of planets. It moves the problem of starting everywhere to starting in one place (more likely)

Getting it to occur once is more likely than getting it to occur many times. However, it does give you a new problem: making cells that can survive hard vacuum, radiation, and extreme cold, for millenia (at least), and still be viable when they reach a new planet. We're not talking speed-of-light propagation here. We're probably not even talking 0.01 c. So even to the nearest neighboring star is probably thousands or…

If panspermia does happen in the universe, I bet that it happens with the sheltering of asteroids and meteors. Life develops on low-gravity planets with turbulent atmosphere -> some cells get into space -> get caught by comets and other objects -> slowly propagate within comet -> comet has an unstable orbit that sends it to another system, where it has an encounter with a habitable planet.

An icey comet could provide radiation protection and it could accidentally go through a gravity assist to increase it's speed.

I suppose that the best evidence we could collect to prove or disprove panspermia is to see if it's happened between planets/moons/objects within our own solar system.

Re: Life on other planets would likely be brief and become extinct very quickly

#56

Post by kposehn »

theboywho wrote: post #35

The problem with this reasoning is that it considers this to be true: if intelligent life exists, we are gonna be able to understand its intelligence. What if there exist an intelligent life, so intelligent that their level of intelligence compared to ours is like comparing ours with...cats. We all know small genetic mutations can have huge impact. So huge they might just be technically/biologically out of reach. So…

> So maybe an intelligent life exists out there, but they are so ahead of us that we are not even capable of understanding how. Like a little cat watching a car thinking maybe it's an animal.

So true. We are really bad at looking at things outside the lens of our own experience. Why would life evolve in exactly the same fashion? Would it even have DNA as we know it? There is life that could form in ways we cannot even perceive - intelligence of a type that is so completely alien that neither could every notice or understand the other.

The universe may simply be filled with life, but because it evolves so differently it may simply be impossible to see most of it.

Re: Life on other planets would likely be brief and become extinct very quickly

#57

Post by yongjik »

nickbauman wrote: post #41

The book Rare Earth covers this topic throughly. The conclusion they come to is that complex, multicellular life is likely extremely rare in the universe. But simple, microbial life may be much more common than we think. http://www.amazon.com/Rare-Earth-Complex-Uncommon-Universe/d...

I didn't find the book very persuasive. The authors basically take everything that is (or might be) uncommon about the Solar System, and somehow turns them into an argument on why we are so lucky to have them.

E.g., we have big Jupiter. We don't know exactly what it does, but it might have helped the Earth survive its early days. Therefore, it might be the case that the rise of complex life needed Jupiter. Yadda yadda, multiply a dozen of these things, and suddenly life on Earth looks like an incredible stroke of luck.

The problem is, we don't know enough to make that verdict. What if the existence of Jupiter actually postponed the rise of life by sending big comets along our way?

I enjoyed "Life Everywhere" by Darling much more, though it is probably too dated to recommend in 2016. (Astrobiology is a rapidly changing field, I suppose.)

Re: Life on other planets would likely be brief and become extinct very quickly

#58

Post by kposehn »

orf wrote: post #10

People always talk about how vast space is, but rarely about how vast time is. We've been looking for life for the last what, 60 years or so? It seems like not only is space so vast which makes finding evidence of life hard, but this is made even harder by the small volume of time we are likely to be around to try and observe in the grand scheme of things. Alien life has to be relatively close in terms of distance as…

Excellent point.

I think that one advantage of interstellar distance is we can effectively look back in time a great distance, so in effect we don't have a visible radius, but a combination of time and distance.

We can see thousands of light years back in time, thousands of light years away. However, we don't have that picture of Tau Ceti at 11 light years away. Perhaps thousands of years ago there was a civilization there that flourished and died - and we'll never know because their signs of life are outside our distance/time perception.

A graph of Time/distance would be Time one axis, distance on the other and a diagonal line stretching up and to the right, showing what we could see at any given time.

Thoughts?

[edit: comment formatting ate my pretty ascii chart]

Re: Life on other planets would likely be brief and become extinct very quickly

#59

Post by vectorjohn »

samstave wrote: post #31
breckinloggins wrote: post #9

Earlier quoted context omitted.

This gets my vote. My hunch is that intelligent life like the kind we would love to meet happens either on the order of once or twice per galaxy during the galaxy's entire lifetime, or it happens SO rarely that, if the universe is infinite in extent, then any intelligent observer looking out from the "center" of their observable universe will most likely be in the only intelligent civilization in that visible radius.…

Then why the fuck do we keep killing ourselves? Seriously, if we taught this level of intelligent-life appreciation to every born soul... the world would be a better place. Rather than starting with the teachings we do for youngsters; why not just teach them how freaking rare and lucky they are to be a consciousness present to hear that fact and then know that they can then expand the known universe... but do this in…

We keep killing ourselves because so many people are so damned reassured that death isn't the end. That or they just pessimistically assume there's no way we'll make it to eons.

I think we could easily last for eons, but yeah. We have to get people on board with that possibility.

Re: Life on other planets would likely be brief and become extinct very quickly

#60

Post by leppr »

givan wrote: post #52
leppr wrote: post #50

Earlier quoted context omitted.

Do you think there used to be dragons roaming the earth?

Do you still think the earth is flat? This is how it sounds when you try to ridicule something that you don't know or probably don't want to know for various reasons, you should read more on the subject with an objective mind.

I think the comparison with dragons is appropriate. Religion and talk about hell and demons was in-vogue at the time so dragons fit in well with that. Why did aliens wait for us to develop advanced technology before manifesting themselves, and why did they stop now that smartphones and google-earth are common-place things?
Post reply on HN