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The Fermi Paradox

waitbutwhy.com

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Re: The Fermi Paradox

#11

Post by maaku »

equil wrote: post #9

I've always wondered at what distance it would be impossible for current technology to detect life on earth.

A very short distance. IIRC something like 20 or so light years, but I'm having trouble finding the citation. That's for radio waves (and the number is getting smaller as the technology is getting better -- EM radiation blasted into the universe is considered waste by hardware engineers).

For direct detection of life, that's still an open question. I remember a poster done by a grad student who looked at whether life would be detectable from the Moon, looking at the Earth. This was tested with data from one of the outer solar system probes which did a lunar flyby on its way out (Cassini?). The result, IIRC, was inconclusive -- you could see signs of life, but not anything that was absolutely definitive proof.

Indirect evidence might be provided by spectra of the atmosphere observed via solar transit. A biome is likely to have different spectra than would be predicted by inorganic atmospheric physics. Still, that's making some assumptions about what extraterrestrial life would be like, and only only visible along the elliptic plane.

Re: The Fermi Paradox

#12

Post by Flow »

ZanyProgrammer wrote: post #7
ccvannorman wrote: post #4

i love this puzzle. here are some theories: 1. simulation argument 2. civilizations have a high or inevitable chance to self destruct after 3. civilizations transcend our observable universe after 4. due to the single observer problem, humans fail to grok some very important feature of larger scale space that prevents detection/increases isolation [1] http://accelerating.org/articles/transcensionhypothesis.html

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?

Re: The Fermi Paradox

#13

Post by Houshalter »

ZanyProgrammer wrote: post #2

My solution to the Fermi Paradox: Who the hell knows, who the hell can know, when all we have is a sample size of 1 to extrapolate from. The solutions to the FP seem to be representative of the personal beliefs of whomever is discussing it.

Of course we can't know for sure. The article presents a large number of hypotheses and arguments for them, most of which are fairly reasonable.

Re: The Fermi Paradox

#14

Post by aswanson »

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 >…

Sounds like a hell of a book/movie plot.

Re: The Fermi Paradox

#15

Post by Xcelerate »

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 reach us.

Re: The Fermi Paradox

#16

Post by Pxtl »

ccvannorman wrote: post #4

i love this puzzle. here are some theories: 1. simulation argument 2. civilizations have a high or inevitable chance to self destruct after 3. civilizations transcend our observable universe after 4. due to the single observer problem, humans fail to grok some very important feature of larger scale space that prevents detection/increases isolation [1] http://accelerating.org/articles/transcensionhypothesis.html

4 seems likeliest. Interstellar colonization is simply impossible because of the vastness of the distance that must be covered. It requires more energy than can be summoned to get a useful amount of hardware across multiple lightyears.

Re: The Fermi Paradox

#17

Post by ScottBurson »

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.

Re: The Fermi Paradox

#18

Post by zw123456 »

I think they sort of cover this but here is my simple explanation. Think about how many slugs there are on Earth. How many of them have never seen a human? If we are slugs in comparison to advanced beings that have a billion years of evolution on us then it is no surprise we have not seen them.

Re: The Fermi Paradox

#19

Post by joe_the_user »

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 significant periods, etc).

I only recently realized that this "paradox" looking at the possibility not of "earth advanced" civilization but supposed advanced civilizations that would put out much more energy than humans put out.

The whole thing seems to rest on false-extrapolations of mid 20th century hard-science fiction authors. Our Western Civilization has experienced an exponential growth of some things, has expanded it's "frontiers" quickly in a variety of ways, conquering the rest of the globe and then labeling space "the final frontier".

But all this has been low-hanging fruit. We're reaching the end of population expansion, space is fundamentally hostile to human life in a way that would take tremendous progress to overcome and we're facing longer term consequences of the rapid expansions we have achieved (global warming is just one of the consequences). If humans survive this, we'll have to have somehow achieve a steady-state for energy consumption and related things. But once we do achieve that steady state, why would we want or need to suddenly start using the energy of an entire star (after the thousand years of scientific progress we'd need to under how to do that)?

Re: The Fermi Paradox

#20

Post by sampo »

maaku wrote: post #11
equil wrote: post #9

I've always wondered at what distance it would be impossible for current technology to detect life on earth.

A very short distance. IIRC something like 20 or so light years, but I'm having trouble finding the citation. That's for radio waves (and the number is getting smaller as the technology is getting better -- EM radiation blasted into the universe is considered waste by hardware engineers). For direct detection of life, that's still an open question. I remember a poster done by a grad student who looked at whether life…

The chemical composition of Earth's atmosphere (21% O2) is so far away from a long term chemical equilibrium, that any current astrobiologist would interpret it as a sign of planetary scale life. (And correctly so: the oxygen was produced by life.)

So life on Earth is pretty visible from the other planets in our solar system.

And spectroscopy to observe the composition of atmospheres of planets orbiting the nearest stars will probably happen in not-too-distant future.

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