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The Fermi Paradox

waitbutwhy.com

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Re: The Fermi Paradox

#61

Post by tomp »

sgt101 wrote: post #43
gpsx wrote: post #32

Earlier quoted context omitted.

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. Phys…

What does "freedom of will" mean to you? What you describe (actions move you from state to state) sounds like determinism to me.

Re: The Fermi Paradox

#62

Post by mda »

I think Authors is way way optimistic with these numbers:

"Let’s imagine that after billions of years in existence, 1% of Earth-like planets develop life" and "

"And imagine that on 1% of those planets, the life advances to an intelligent level like it did here on Earth"

Why 1% and not 10^-10%?

Re: The Fermi Paradox

#63

Post by has2k1 »

ScottBurson wrote: post #17

How about this possibility: the Great Filter is now! We entered it, perhaps, when we developed sufficient collective nuclear weapons capability to wipe out most or all human life; we won't be out of it until the major threats our civilization poses to the biosphere have been resolved.

I'll add another guess.

A resource crunch, i.e. we simply use up the required resources before we figure out how to explore our planetary neighbourhood. e.g When we figure out that a helium engine is possible, very efficient and very safe, we no longer have sufficient quantities left.

Re: The Fermi Paradox

#64

Post by dedward »

In that great expanse and time, there may also have been ample time for civilizations to rise, then fall. We might have just missed them on such grand scales. Nobody says we'll be hanging around for a billion years trying to communicate with others... if we even last that long.

Re: The Fermi Paradox

#65

Post by sounds »

coldtea wrote: post #60
darkmighty wrote: post #54

Earlier quoted context omitted.

But the Milky Way is only 50,000 light years in radius (~ average distance between stars?). That's not much at all on a evolutionary scale. So your argument explains why we're not currently observing an alien civilization (i.e. they would expand so close to light speed we would likely either be conquered or observing nothing -- so observing nothing is a consistent scenario). But it does not explain why no Type III ci…

> But it does not explain why no Type III civilizations (continuing with the assumption that civilizations all quickly go on to become Type III) has risen at all in the past hundreds of millions of years. I find the assumption about Type III at best. It's like expecting Moore's law to go on forever.

Did you omit a word? ("Type III __ at best")

I agree that a Type III Civilization is just an assumption of what direction a civilization would advance. The article does mention an alternative (they no longer care about meat space, or something similar).

If we do resolve the Fermi Paradox I suspect we'll be able to express the answer simply enough to not need to bring in Type III Civilizations, the anthropic principle, etc. Note that I find nothing wrong with them as useful tools for discussion, just that the answer likely isn't one we can construct by means of logic, it must be discovered -- as in, observational astronomy.

Which is what I intend to do: go out with a telescope and look at the stars. :)

Re: The Fermi Paradox

#66

Post by kbutler »

darkmighty wrote: post #48
bdamm wrote: post #30

Earlier quoted context omitted.

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?

Time delay. You're long dead before any profits return. How much current consumption are you willing to give for speculative distant future profit for others?

Re: The Fermi Paradox

#67

Post by danieltillett »

_greim_ wrote: post #23
gpsx wrote: post #6

This article does a good job of covering a lot of different ideas on this paradox. I have a problem with the idea of "big numbers" in it though, like where it implies 500 billion billion is nearly infinite, or that one-in-a-billion is a freak occurrence. There is a saying that if enough monkeys pound on a keyboard, one will type Hamlet. This would take a lot of monkeys. If we take the odds of hitting one character to…

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.

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.

We can't, but we can assume that any process that arises from a series of unlikely chained events (where the likelihood of each event are not correlated) will most likely occur near to the latest time possible. For example, if you run a trillion parallel 10-step chained experiments over a year starting at Jan 1 where each step is very unlikely to occur so that only 100 reach step 10, then the last steps are all likely to occur in December. The less likely each step is (or the more steps involved) then the more the experiments that reach the final step will cluster towards Dec 31. If you have a group of such events then you can actually calculate the likelihood of the chain series.

Intelligent life in a large universe is a similar to this imaginary experiment. While we only have one observed data point, we do know how close the appearance of intelligent life on earth is to the last possible time that it could occur. Outside of our geologically recent anthropogenic boost to the CO2 in the atmosphere, the long term trend of CO2 concentrations in the atmosphere is down (this is due to the sun becoming warmer over time requiring CO2 to be removal from the atmosphere to keep earth in the habitable temperature range). We are in geological terms close to the point where any further removal of CO2 will mean photosynthesis will no longer work (plants are already CO2 limited) - maybe a few 10 millions years. In geological time this is very close to our Dec 31.

What does this all mean? Basically it appears humans have evolved close to the latest time point possible. While we can't calculate the exact probability of intelligent life arising in the universe from our one example, we can say that the evolution of humans is consistent with the hypothesis that the evolution of any intelligent life in the universe is very unlikely.

Re: The Fermi Paradox

#68

Post by dennisgorelik »

How about the theory that we are the way super-civilization spreads?

If physical space travel is extremely expensive (as it should be, considering the distance), then may be it is better to send a signal that would trigger creation of life (in our case on Earth).

Then when Earth civilization is advanced enough, it would be able to receive complete boot sequence and then fully advanced alien civilization would be replicated on Earth.

Re: The Fermi Paradox

#69

Post by yzzxy »

danieltillett wrote: post #56
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 >…

I actually posted about this very topic a few days ago here. Once you have von Neumann machines spreading they will take over each new star system pretty much as soon as they reach it. Assuming the von Neumann machines are small and are being powered by an energy source (i.e lasers) from their origin star system they will spread through the galaxy at close to the speed of light. This spread method creates an interest…

Stephen Baxter's Manifold novels deal with this problem quite extensively. I would recommend them from anyone interested in the implications of the Fermi paradox expressed in science/speculative fiction.

Re: The Fermi Paradox

#70

Post by dennisgorelik »

danieltillett wrote: post #67
_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.

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. We can't, but we can assume that any process that arises from a series of unlikely chained events (where the likelihood of each event are not correlated) will most likely…

Why do you think that current CO2 concentration levels are important for intelligent life?

Slight adjustment in how body works can easily adapt organism to new CO2 levels.

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