The Fermi Paradox • Hacker News Board

Re: The Fermi Paradox

#41

Post by _greim_ » Thu, Dec 25, 2014, 10:21 PM UTC

gpsx wrote: post #32

_greim_ wrote: post #23

Earlier quoted context omitted.

We can't calculate the probability of life arising though because even if we did know how it arose here—which we don't exactly—we don't know all the possible different ways it can arise, which may or may not also be a number raised to a large power.

That is a good point. I agree with you. And people do have suggestions as to how life can be more probable than naively expected. But this answers the question why there is life at all as opposed to why we don't see more of it. My bias is that life is highly improbable and that we will not find any other life in our universe. But I also think it is no miracle that we exist, as I will describe. Given that I am trying…

The WAP accounts for high improbability by positing a multiverse, but (at least as I understand it) it doesn't predict high improbability, even if there is a multiverse.

Also, in a multiverse scenario, the improbable thing might not be the formation of life, but the fine-tuning of the laws of physics which allows the formation of life. In which case life might be relatively common.

Re: The Fermi Paradox

#42

Post by XorNot » Thu, Dec 25, 2014, 10:23 PM UTC

joe_the_user wrote: post #19

Xcelerate wrote: post #15

I am surprised a more common argument was not mentioned: other life exists but the laws of physics limit our interaction. Maybe there is undiscovered physics like wormholes or time travel, or maybe there isn't and the speed of light really is a fundamental limit that cannot be surpassed. In that case, no matter how advanced another civilization becomes, they still can't violate natural law and are thus unable to reac…

The laws of any potential biology and the messiness of the world could together effectively limit a civilization's energy usage to much lower than indicated by the easily deducible laws of physic (the explicit laws of physics might limit the output of an internal combustion engine to a certain but the effective maximum winds up less than that. Human biological systems experience serious damage by being weightless for…

The problem here is the assumption we need scientific progress to do this. We don't.

We have the technology today to launch satellites into solar-orbits which would be capable of beaming power back to Earth. It would be clean, efficient and non-disasterous to the biosphere.

With any amount of space-borne industry, the costs would also plummet and get cheaper with every additional satellite. Once you can harness the energy of an entire star, there's almost no reason not to achieve it.

Re: The Fermi Paradox

#43

Post by sgt101 » Thu, Dec 25, 2014, 10:25 PM UTC

gpsx wrote: post #32

_greim_ wrote: post #23

Earlier quoted context omitted.

We can't calculate the probability of life arising though because even if we did know how it arose here—which we don't exactly—we don't know all the possible different ways it can arise, which may or may not also be a number raised to a large power.

That is a good point. I agree with you. And people do have suggestions as to how life can be more probable than naively expected. But this answers the question why there is life at all as opposed to why we don't see more of it. My bias is that life is highly improbable and that we will not find any other life in our universe. But I also think it is no miracle that we exist, as I will describe. Given that I am trying…

This is one explanation, but for me fails two tests. The first (pointed out below) is that it is heliocentric - it's about us.

The second is that it avoids freedom of will and consciousness in the sense of self perception. It assumes that I am a zombie, and I deny that. I concede that others may be zombies, although I think that they aren't. My actions either navigate me from state to state or create new states. Physics does not account for this; physics is incomplete.

I'll leave occams razor on the shaving table, as it's a heuristic and I don't like it for logic - but infinite infinities fails occams too.

Re: The Fermi Paradox

#44

Post by XorNot » Thu, Dec 25, 2014, 10:26 PM UTC

Flow wrote: post #12

ZanyProgrammer wrote: post #7

Earlier quoted context omitted.

Or we just haven't observed them yet because we aren't technologically advanced enough? What if they don't use radio?

I hope there's something along the lines of sub-space transmissions. Once we discover it, we'll start listening and discover a plethora of civilisations out there. Would also be nice if they periodically transmitted decoding instructions :) But who knows, maybe it's far more rare with life that are similar to what we can recognise?

Pretty much the scientific experiment I've been waiting for: we set up some exotic state of matter, and then spot modulated and structured signals coming out of it.

Re: The Fermi Paradox

#45

Post by furyofantares » Thu, Dec 25, 2014, 10:31 PM UTC

jacquesm wrote: post #36

sampo wrote: post #21

Earlier quoted context omitted.

> until all of a sudden the most distant stars go dim Why the most distant?

Because if the events move at 0.9c the light still moves at 'c', so the furthest stars (of which there are more than nearby ones) will be the first to show you that something is up. The light from the older events will reach us before the events or the light from later events will reach us. Unless of course the whole thing originates in one of the stars nearby but the chances of that are smaller than that it will hap…

Wouldn't the most likely place for it to start be around halfway between us and the most distant observable stars in whatever direction it starts, then? And then we'd see the sphere of dimming stars increasing in size, while still seeing things behind, in front, or to the sides of the sphere?

Re: The Fermi Paradox

#46

Post by mangecoeur » Thu, Dec 25, 2014, 10:32 PM UTC

I don't see why a "Great Filter" is needed to justify there being no other highly evolved lifeforms - all it needs is for there to need to be a reasonably large number of key evolutionary steps and environmental conditions with a sufficiently low probability. Multiply those and you end up with some pretty tiny chances of observing life as we know it.

Re: The Fermi Paradox

#47

Post by gusgordon » Thu, Dec 25, 2014, 10:33 PM UTC

bdamm wrote: post #30

maaku wrote: post #10

The "we are the first" argument seemed less convincing than it could have been. A better argument from that perspective is the observation that Type III civilizations expand at an alarming rate. Whatever the motivation for expansion[1], basic simulations and back of the envelope calculations show that even with technology we could imagine building in the not so distant future, humans could expand into the cosmos at >…

This model assumes that interstellar travel is profitable. There is no evidence that this is the case, even if we had Star Trek technology. If it isn't profitable, then it turns into a drain on the home planet. That isn't sustainable.

It is certainly profitable for a type 1 civilization to move to a type 2 civilization as long as energy consumption and population continue to naturally grow as has happened so far here. Same thing for type 2 to 3. Also, I think that decisions about space travel are not purely for economic reasons and probably in almost any advanced species there is a large amount of the population willing to pay something to explore.

Re: The Fermi Paradox

#48

Post by darkmighty » Thu, Dec 25, 2014, 10:37 PM UTC

bdamm wrote: post #30

maaku wrote: post #10

The "we are the first" argument seemed less convincing than it could have been. A better argument from that perspective is the observation that Type III civilizations expand at an alarming rate. Whatever the motivation for expansion[1], basic simulations and back of the envelope calculations show that even with technology we could imagine building in the not so distant future, humans could expand into the cosmos at >…

This model assumes that interstellar travel is profitable. There is no evidence that this is the case, even if we had Star Trek technology. If it isn't profitable, then it turns into a drain on the home planet. That isn't sustainable.

I think it's a good assumption. If there are systems out there marginally different from our own, and the cost to send a "new civilization builder" doesn't completely exhaust Earth, how can it not be profitable?

Re: The Fermi Paradox

#49

Post by jacquesm » Thu, Dec 25, 2014, 10:38 PM UTC

furyofantares wrote: post #45

jacquesm wrote: post #36

Earlier quoted context omitted.

Because if the events move at 0.9c the light still moves at 'c', so the furthest stars (of which there are more than nearby ones) will be the first to show you that something is up. The light from the older events will reach us before the events or the light from later events will reach us. Unless of course the whole thing originates in one of the stars nearby but the chances of that are smaller than that it will hap…

Wouldn't the most likely place for it to start be around halfway between us and the most distant observable stars in whatever direction it starts, then? And then we'd see the sphere of dimming stars increasing in size, while still seeing things behind, in front, or to the sides of the sphere?

The part that we can see is so much smaller than what is out there that you'd have to resort to very leaky analogies to try to get the point across.

The upper limit to how much larger the universe is compared to the observable (and not the currently observed) universe is somewhere around the 10^20 to 10^25 times larger. Those are hard numbers to grasp but large enough that the chances of an event 'x' taking place outside of the observed universe are larger than inside it.

Re: The Fermi Paradox

#50

Post by keule » Thu, Dec 25, 2014, 10:39 PM UTC

mangecoeur wrote: post #46

I don't see why a "Great Filter" is needed to justify there being no other highly evolved lifeforms - all it needs is for there to need to be a reasonably large number of key evolutionary steps and environmental conditions with a sufficiently low probability. Multiply those and you end up with some pretty tiny chances of observing life as we know it.

I had the same thought and agree with what you wrote. But when you think about this set of evolutionary steps you still end up with the same scenarios: you are rare, you are first, you are fucked. So in that regard, you can subsume all of these steps into a filter.