Life on other planets would likely be brief and become extinct very quickly • Hacker News Board

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

#61

Post by breckinloggins » Sat, Jan 23, 2016, 12:56 AM UTC

baddox wrote: post #32

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.…

Where do you get the estimate of "once or twice per galaxy"? I can agree that it might be "rare," but I have no idea how you would pin down the rareness to that level of accuracy.

It's a total guesstimate. The interesting thing to me is that I have no idea how anyone else pins down THEIR estimates to any level of accuracy, but they are apparently confident enough in their estimates to posit things like the "Great Filter", when other (equally likely) estimates such as mine require no such thing.

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

#62

Post by nickbauman » Sat, Jan 23, 2016, 1:06 AM UTC

yongjik wrote: post #57

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 yadd…

That's interesting remember the book explaining Jupiter had a specific influence on earth's ability to develop complex life in that its size and position made it essentially prevent a lot of comets and dangerous asteroids from hitting earth by simply getting in their way.

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

#63

Post by vectorjohn » Sat, Jan 23, 2016, 1:08 AM UTC

putlake wrote: post #27

Liu Cixin's The Dark Forest, the second book in his 3-body problem trilogy, posits a similar philosophy: resources are limited so civilizations annihilate other civilizations. So if an alien civilization knew about earthlings, they will destroy earth ASAP if they are capable, lest the earthlings come after their resources. This is also why some people believe we should not try to make contact with intelligent alien l…

It just doesn't make any sense. Resources are limited, sure, but they're not scarce. In fact, they might not be limited even. If something can afford to come to Earth, they can afford to get unlimited resources from anywhere. Unless you're positing it's from one of our nearest stars and then just happen to be coming to Earth as a last ditch effort or something.

I mean, scenarios can be imagined where an alien would want to destroy life on Earth, but they seem far fetched.

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

#64

Post by SEJeff » Sat, Jan 23, 2016, 1:20 AM UTC

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…

Or worse, we do intercept the radio signals, from hundreds of thousands of light years away, from a an alien race long since extinct.

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

#65

Post by zardo » Sat, Jan 23, 2016, 1:26 AM UTC

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?

Not enough game theorists in charge.

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

#66

Post by johngalt » Sat, Jan 23, 2016, 1:33 AM UTC

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…

Exactly. 13 billion year old universe. 5 billion year old solar system. Life on earth was effectively pond scum for 3 billion years. Humans went from banging rocks together to transistors and space ships within 500k years. We have been a civilization for a laughably small time on astronomical terms.

Given the timeframes involved it's entirely likely that any 'aliens' are half a billion years ahead or behind us. Our first encounter with life will likely be one of three things.

1. Pond scum millions of years away from being anything else.

2. Aliens who have been extinct for millions of years.

3. Aliens so hopelessly advanced they are deities

Even just a million year gap would be insurmountable. Which is nothing on the universe's timeline.

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

#67

Post by pklausler » Sat, Jan 23, 2016, 1:35 AM UTC

I am convinced that we're the first/only space-capable species in our galaxy by the simple absence of killer self-replicating interstellar robots. I'm serious. Anything that's remotely possible becomes inevitable on these astronomical scales, and all it takes is one jerk making one self-replicating killer robot and that's it for life for the rest of time in the galaxy.

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

#68

Post by vectorjohn » Sat, Jan 23, 2016, 1:36 AM UTC

njharman wrote: post #26

Compared to age of Galaxy, Life on this planet has been brief. Also, aren't something like 99.99% of all species extinct?

Not really, life on Earth has existed for about 26% of the age of the universe (about 3.5 billion years). And we have good reason to expect that life cannot arise before a certain time because we have to go through a cycle or two of supernovas ejecting useful elements into their surroundings.

If you meant intelligent life, then nevermind :)

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

#69

Post by Florin_Andrei » Sat, Jan 23, 2016, 2:06 AM UTC

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?

We are slaves to our own genetic sequences to a much larger extent than we usually think.

It's pretty easy to show that the behaviors that lead to people killing each other are driven by mechanisms initially evolved to ensure that our own genetic sequences keep multiplying and spreading out, eliminating competition. And they're pretty dumb mechanisms, running on the lower levels of our brains, so don't expect them to be very selective, or run without failure. Sometimes they hit an internal bug and become runaway destruction loops, which sometimes even turn against the individual itself.

Many things that are typically considered "evil" can be traced back ultimately to these mechanisms that ensure that our own genetic sequences win the race. In a way, "evil" was actually useful, way back in time, in an evolutionary sense. It's just recently that we've acquired new desires and aspirations, which are in conflict with the old, narrow, dumb routines.

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

#70

Post by yongjik » Sat, Jan 23, 2016, 2:06 AM UTC

nickbauman wrote: post #62

yongjik wrote: post #57

Earlier quoted context omitted.

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 yadd…

That's interesting remember the book explaining Jupiter had a specific influence on earth's ability to develop complex life in that its size and position made it essentially prevent a lot of comets and dangerous asteroids from hitting earth by simply getting in their way.

I think I wrote my argument rather poorly. Let me try again:

I could buy that Jupiter in our particular Solar System had the effect of clearing asteroids in the Earth's orbit. However, that doesn't automatically mean that Jupiter was essential. What if, say, Jupiter's presence in the early days of the solar system prevented these asteroids from coalescing further, resulting in the presence of the asteroids in the first place? Or what if it didn't matter in the long run anyway?

Okay I just pulled that out of thin air, but what I'm saying is that there's too many unknowns to declare we needed Jupiter for life. The authors cherry-picks arguments that support their cause. Also bear in mind that this book was written in 2003, when we knew less than a dozen extrasolar planets and, IIRC, basically none looked like our Solar System (because the instruments weren't good enough to detect such systems). Even now, I don't think we know enough about planetary systems to confidently say whether Earth-like systems are common or rare.