The Fermi Paradox • Hacker News Board

Re: The Fermi Paradox

#31

Post by dmix » Thu, Dec 25, 2014, 9:25 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.

Curious: What would make interstellar travel not possible? Do you mean for humans or machines as well?

Re: The Fermi Paradox

#32

Post by gpsx » Thu, Dec 25, 2014, 9:30 PM UTC

_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.

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 to say this in one paragraph, it may not sound well justified, but it is how I view the problem. I'll start with Schrodinger's cat. A cat is in a box with some radioactive source that can decay and kill the cat. You can ask if the cat is alive or dead - and the answer is both. I will ignore the next part (Schrodinger's whole point) about what happens when the human observes it. There are different interpretations about why the human thinks the cat is definitely in one of the two states as opposed to both. This has to do with the human's observation and is not important for now. The point is that the cat is in both states. The universe can be in multiple states, some with life on earth and some without. Every possible state that can exist, does. So no matter how improbable we are, we will exist in some version of the universe. And there would be lots of other life too, just maybe not in our version of the universe. So the probability of life existing doesn't impact whether or not we should exist, but it does impact whether or not we see other life. I don't think we will. But as correctly pointed out, we don't know the answer to this right now.

Re: The Fermi Paradox

#33

Post by atom-morgan » Thu, Dec 25, 2014, 9:37 PM UTC

dmix wrote: post #31

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.

Curious: What would make interstellar travel not possible? Do you mean for humans or machines as well?

Profitable. Not possible.

Re: The Fermi Paradox

#34

Post by conesus » Thu, Dec 25, 2014, 9:46 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 universe may / be as great as they say / but it wouldn't be missed / if it didn't exist.

- Piet Hein

Re: The Fermi Paradox

#35

Post by jacquesm » Thu, Dec 25, 2014, 9:51 PM UTC

dmix wrote: post #31

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.

Curious: What would make interstellar travel not possible? Do you mean for humans or machines as well?

At scale it would not only have to be technologically possible but also economically feasible. If you can't afford it you can't do it even if you have the tech.

Re: The Fermi Paradox

#36

Post by jacquesm » Thu, Dec 25, 2014, 9:54 PM UTC

sampo wrote: post #21

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 >…

> 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 happen in a system further away.

Re: The Fermi Paradox

#37

Post by jacquesm » Thu, Dec 25, 2014, 9:58 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…

> My bias is that life is highly improbable and that we will not find any other life in our universe.

It's probable enough for you to be writing this. The only options are 0, one and many. We can rule out '0'. That leaves us to decide whether the chances of us being the only one are larger than the chances that we are one of many. Obviously the second one has more chance of being true the one where there is only one. But we like to consider ourselves to be special so most people will believe the 'one'. Just like the sun used to revolve around the earth, now we're essentially seeing the universe as revolving around us. The alternative, that we're not special is not compatible with a lot of our collective culture.

Re: The Fermi Paradox

#38

Post by sgt101 » Thu, Dec 25, 2014, 10:09 PM UTC

DavidSJ wrote: post #27

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 had this idea recently myself and to the best of my knowledge you're the only other person who's mentioned it. The closest I've found is the "galactic preemption" hypothesis published in the 80's, but that's more an explanation for why only one civilization would exist in a single galaxy, rather than for why a newborn civilization such as our own would look at the sky and see no signs of civilization in the whole u…

I've read a novel that featured this, I am wracking my brains to remember the title/author. It featured a generation ship that switched to a .com mode as it approached the star to be colonized and a race of bat people who were the putative colonization targets.

I am not making this up, but I may have dreamt it!

Re: The Fermi Paradox

#39

Post by XorNot » Thu, Dec 25, 2014, 10:19 PM UTC

nhaehnle wrote: post #29

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…

I often wonder this as well. The speed of light isn't really a physical limit to expansion - generation ships are theoretically possible. It may just be that the Great Filter takes the form of relatively benign[1] economic and/or sociological obstacles. At least, if you take a diff between typical beliefs at the time the Fermi Paradox was formulated vs. typical beliefs now, I would say the experience of the shutting…

If you consider the declining birth rates of modern nations as the standard of living goes up, then it stands to reason that once a civilization reaches the point where it might be able to engage in large scale space exploration, the population that can do so has become relatively stable.

So you simply never (or rarely) get exponential cosmic expansion. There might be a few billions of that race roaming the stars, but their numbers do not increase.

Re: The Fermi Paradox

#40

Post by ghaff » Thu, Dec 25, 2014, 10:20 PM UTC

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…

This is essentially the problem that I have with the Drake equation. It encourages--whether that's the intent or not--taking a reasonably known and very, very large number (number of stars) and multiplying it by probabilities/percentages, some of which (we think) we know with at least order of magnitude accuracy. But others we have absolutely no idea. And saying some of those events (such as the evolution of intelligence as we understand the term) has a 1 in a billion probability of occurring SOUNDS like a worst case for-the-purposes-of-argument plug-in. But it's really not.