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Dissolving the Fermi Paradox

arxiv.org

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Re: Dissolving the Fermi Paradox

#71

Post by Anderkent »

not_a_moth wrote: post #12

How can we be expected to take seriously a probability estimate of life being "out there"? Only 10 years ago we discovered how many Earth-like planets are likely in our galaxy (I didn't see this aspect mentioned in the paper...), and they are also calculating a probability of abiogenesis (emergence of life), which, while I'm not an expert, seems highly speculative.

Why can't you estimate probability of something speculative? Of course it must be speculative if you're talking probabilities; otherwise you'd just know if the life is out there or not.

If the assumptions are very speculative, you just end up with very wide probability distributions, which is exactly what the paper argues for.

Re: Dissolving the Fermi Paradox

#72

Post by Anderkent »

ISL wrote: post #37
mdpopescu wrote: post #28

Earlier quoted context omitted.

First, we know with absolute certainty that here is substantially different from anywhere else: we know there's life here, we haven't found life anywhere else. (And the null hypothesis is that we haven't found it because it doesn't exist.) Second, it's a waste of space only if 1) it was created on purpose and 2) the purpose wasn't "to allow us space to expand". If either of those is false, I don't see how it can be c…

First, we know with absolute certainty that here is substantially different from anywhere else: we know there's life here, we haven't found life anywhere else. I'll take the other side of that bet. What odds are on offer (10^15:1? 10^80:1?)?

Wait, are you saying you'll take a bet where you pay 10^15 to 1 if we do not find life out there? I'll take you up on that for $0.01 on my side.

Re: Dissolving the Fermi Paradox

#73

Post by onychomys »

PaulHoule wrote: post #69
squirrelicus wrote: post #66

Earlier quoted context omitted.

H2O isn't exactly rare in the universe, it's the third most common molecule after H2 and CO. Getting water into orbit is absurdly expensive compared to getting it from the other rocks with lower gravity and atmo, like Ceres. Weird premise for a movie

Exactly, H2O is rare on rocky planets. It makes more sense to mine it from Pluto.

Or to just go to the rings of Saturn, which are mostly water ice, and which give you the added advantage of having something pretty to look at while you refuel.

Re: Dissolving the Fermi Paradox

#74

Post by gnaritas »

mdpopescu wrote: post #28
ISL wrote: post #5

If the argument stated above is correct, there is an awful waste of space. (Thanks, Carl!) There is nothing in physical law to suggest that here is substantially different from anywhere else in the universe. To believe that here is manifestly different from every other place in the universe is a really surprising claim.

First, we know with absolute certainty that here is substantially different from anywhere else: we know there's life here, we haven't found life anywhere else. (And the null hypothesis is that we haven't found it because it doesn't exist.) Second, it's a waste of space only if 1) it was created on purpose and 2) the purpose wasn't "to allow us space to expand". If either of those is false, I don't see how it can be c…

> First, we know with absolute certainty that here is substantially different from anywhere else: we know there's life here, we haven't found life anywhere else

No we do not. We haven't looked anywhere else, we don't yet really have that ability. There's no reason at all to believe this place is special.

Re: Dissolving the Fermi Paradox

#75

Post by gmuslera »

The reasoning seem to be "as we don't have enough data, lets conclude whatever I want".

The Fermi paradox assumes that if there are aliens more advanced than us somewhere for a long time, they should be here by now. Maybe more advanced technology enables interstellar travel (maybe not, maybe is not practical at all), maybe they may not have all our motivations (expansion, technological advancement in our own focus, exponential growth, etc), maybe they don't want to expand or announce themselves because they went cyber or try to pass unnoticed in the dark forest, or things that we can't even imagine yet, as we are not advanced enough.

We just don't have enough data to give a meaningful answer. And maybe never will. The only way to decide if we are alone in the universe or not is actually finding someone else. But with so much outside our physical or practical line of sight we can't just say that there is no one else because we didn't see anything.

Re: Dissolving the Fermi Paradox

#76

Post by PaulHoule »

onychomys wrote: post #73
PaulHoule wrote: post #69

Earlier quoted context omitted.

Exactly, H2O is rare on rocky planets. It makes more sense to mine it from Pluto.

Or to just go to the rings of Saturn, which are mostly water ice, and which give you the added advantage of having something pretty to look at while you refuel.

Exactly, go outside the frostline and you are swimming in it. If you want to get away from it (or move it around) you can use some of it to make fuel or use it directly as reaction mass.

Beyond the frost line the scale is so much bigger. A population of 1 trillion beings in the Oort cloud is not going to be in a position of taking over the Earth and moving population there because it doesn't move the needle. They could create more "living space" by cutting up a Kuiper Belt Object and turning it into small ringworlds. I am not joking when I talk about Pluto as a better space colonization target than dry Mars.

Space technology from outside the frost line would have to be reconfigured to work inside the front line, why bother?

Re: Dissolving the Fermi Paradox

#77

Post by tgb »

Luc wrote: post #29
light_hue_1 wrote: post #8

It's "papers" like this by people that are either clueless or malicious that make everyone pine for the pre-arxiv days. Everyone considered this option. From the very first day the paradox was posed. We don't know the parameters well, it's within our margin of error that no one else is out there, so it's an option. This is such an absurd claim to take as your own that it's literally on the wikipedia page! It's also e…

But it's posted in the pop-physics category. It doesn't seem inappropriate as a popular science article.

Thanks for pointing this out, it changes my perception of this article entirely.

Re: Dissolving the Fermi Paradox

#78

Post by TeMPOraL »

squirrelicus wrote: post #66
TeMPOraL wrote: post #55

Earlier quoted context omitted.

> The most absurd thing about "Battle: Los Angeles" is not that aliens would come to Los Angeles (as opposed to Detroit) to steal water, Hey, they landed near all major coastal cities; the movie was just following one group of soldiers fighting off one part of the invasion force. > but that they would come to a planet which has a thin layer on the surface as opposed to being just a run-of-the-mill dwarf planet or ast…

H2O isn't exactly rare in the universe, it's the third most common molecule after H2 and CO. Getting water into orbit is absurdly expensive compared to getting it from the other rocks with lower gravity and atmo, like Ceres. Weird premise for a movie

It's a weird premise indeed, and I've seen it only in two places - as an in-movie speculation I mentioned, and as something the director alluded to[0]. Personally, I've discarded it in my headcanon - as it makes little sense, and one can imagine alternative explanations.

--

[0] - https://screenrant.com/battle-los-angeles-comiccon-2010/, C-f water.

Re: Dissolving the Fermi Paradox

#79

Post by Zimahl »

jandrese wrote: post #68
jcranmer wrote: post #63

Earlier quoted context omitted.

Only two variables of the Drake equation can be meaningfully estimated: rate of star formation and fraction of stars with planets. The number of life-supporting planets per star is surprisingly ill-defined (what number is that for Sol?). All of the other variables are basically knobs that let you control what you want the answer to be. > There was recent news from NASA about the discovery of organic molecules on Mars…

It doesn't help that we have a giant noise source in the middle of our solar system that shoots the noise floor through the roof when you're trying to detect laser comms over light years. Plus, even at lightspeed you're talking multi-year roundtrips to our nearest interstellar neighbors. Our entire history of radio emissions has only made it to around 500 solar systems currently. Even if someone was listening and res…

> multi-year roundtrips to our nearest interstellar neighbors.

At lightspeed it's an instantaneous trip to the traveler. It's only a multi-year trip to those who are still on Earth.

Re: Dissolving the Fermi Paradox

#80

Post by btilly »

I have trouble calling it a paradox, because there is nothing that needs explaining in my view. Just throw in the fact that known fudge factors are important, and throw in the fact that there are more fudge factors that we don't know.

For example the traditional Drake equation doesn't include as a major factor "large moon that stabilizes the axial tilt over evolutionary time". And yet that seems to be needed and at least somewhat rare.

The traditional Drake equation doesn't include as a major factor "life not wiped out by a supernova over evolutionary time". And yet per http://earthsky.org/astronomy-essentials/supernove-distance there are estimates that this might happen on average once per 15 million years. From the Cambrian explosion to the present is around 540 million years. The odds of that forbearance is on the order of 7 billion to 1 against. How much does THAT change the Drake equation?

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