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Fermi Paradox

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Re: Fermi Paradox

#31

Post by jiggawatts »

tcp_handshaker wrote: post #23
jiggawatts wrote: post #18

Earlier quoted context omitted.

Can you imagine trying to explain any of the current world leaders to little green men? “After they killed their first hundred thousand other people, why weren’t they arrested and jailed?” “Err…” “And why not arrest them after they stole billions from the public they were supposed to serve?” “Umm…” “I can understand voters making a mistake once… but repeatedly voting in the same autocrat?” “Well…”

Then when you explain the FIFA Peace Prize...I think we will be exterminated...

The same FIFA that made a documentary about how their leadership were battling corruption… a year before they were arrested on corruption charges? https://en.wikipedia.org/wiki/United_Passions

Show them this video and they’ll immediately commence a mass sterilisation program, like we do with invasive mosquitoes.

Re: Fermi Paradox

#32

Post by pavel_lishin »

jiggawatts wrote: post #18
root-parent wrote: post #16

Earlier quoted context omitted.

Most likely view ...We are so primitive we are like Sentinel Island. Nobody allowed to land here under severe penalties of the Galactic Council. They were going to upgrade us to a class B-1 civilization, but that was stopped after a second audit looked at the Politicians we have been electing....

Can you imagine trying to explain any of the current world leaders to little green men? “After they killed their first hundred thousand other people, why weren’t they arrested and jailed?” “Err…” “And why not arrest them after they stole billions from the public they were supposed to serve?” “Umm…” “I can understand voters making a mistake once… but repeatedly voting in the same autocrat?” “Well…”

Doesn't that assume a system of ethics and morals and social organization that's very close to ours? a feels more like a Star Trek episode than a realistic contract scenario.

Re: Fermi Paradox

#33

Post by hackeraccount »

Sample size of 1 but I tend to think something like Prokaryotes is common. I'd bet money that it either did or does exist on Mars. Eukaryotes will be much much less common for reasons that I do not understand and we'll never find intelligent life (or it won't find us) because the distances are too great and the probabilities too small.

Re: Fermi Paradox

#34

Post by tcp_handshaker »

goatlover wrote: post #24
jadbox wrote: post #9

Heretical view: intelligent alien life is everywhere swimming around us. We are just not capable of really understanding it. When a human walks past an ant, maybe the ant senses the shadow and the blockage of the sun.. but it isn't equipped to recognize the human. Likewise, I suspect we are in a similar situation where even our smartest minds and best scientifically advanced sensors are simply incapable of properly d…

Signal One is a free movie on Youtube that explores this idea along with the Dark Forest. I thought it was pretty interesting. One problem with the idea is that not all aliens will be that advanced, and some of them should be detectable if they're that common, unless the super advanced aliens precluded their existence by being first.

https://youtu.be/ZdwyBKZ0-Ow

Re: Fermi Paradox

#35

Post by GlibMonkeyDeath »

GlibMonkeyDeath wrote: post #22
WithinReason wrote: post #14

Earlier quoted context omitted.

Not so: They found that airport radar systems, which sweep the skies for airplanes, send out a combined radio signal of 2×1015 watts. That’s enough for telescopes comparable to the Green Bank Telescope in West Virginia to pick up as far as 200 light-years away. [0] 200 ly is about 100k stars [0]: https://earthsky.org/space/airport-radar-could-signal-earth-...

Huh - very interesting! Now I am going to have to calculate this for myself! Seems that (r_d/(theta_e z))^2 P t_p ~ 100 hv (~100 photons at 3 GHz; a single 3GHz photon is about 2e-24 J) I'll drop this to 1 photon below. Where r_d = detector radius, theta_e = diffraction angle of source, z is detection distance, P = 2e15 W (peak power of source, according to article) and t_p is pulse duration (say, ~5e-9 s). Now theta…

Replying to myself here, but three things:

1) the receiver arrays are about 50x 6m diameter (3m radius) antennas (https://www.seti.org/projects/ata/) So that helps about 7x.

2) The 2e15 W/10 MJ/pulse has to be all the radars summed together already, so that is all the power available.

Take these two points together, the single photon detection limit is indeed about 200 ly.

Third: if we assume a 1 Hz detection bandwidth, I get ~200 photons/s for the CMB @ 3 GHz. I can't find the original paper (just the abstract) so they must assume 100-200 s integration time or so to get to an SNR of 1. So 200 ly is on the very edge of possibility - the example curves were calculated for 10x closer (~30 ly), as I would expect. Still, a lot further than a fractional light year!

Re: Fermi Paradox

#36

Post by bediger4000 »

goatlover wrote: post #25
bediger4000 wrote: post #20

Earlier quoted context omitted.

Starting so rapidly after there was water on Earth's surface, and probably starting on Mars very rapidly as well, mitigates against this view.

Not necessarily. We only have a sample of one (Mars remains unknown). Life being a low probability event is still consistent with the data. Low probability events can happen at any time. It is a big enough universe.

The overabundance of long-chain carbon in Gale crater mudstone, and the iron phosphate and sulfide minerals discovered in Jezero crater mudstone is a lot of new evidence. Along with the ALH-84001 meteor magnetite, that "unknown" becomes whole lot closer to "probably".

Re: Fermi Paradox

#37

Post by pseudobry »

Diaspora by Greg Egan is a good book related to some of the themes I see in the comments, such as the whether an advanced civilization would even want to expand.

Re: Fermi Paradox

#38

Post by M95D »

pavel_lishin wrote: post #32
jiggawatts wrote: post #18

Earlier quoted context omitted.

Can you imagine trying to explain any of the current world leaders to little green men? “After they killed their first hundred thousand other people, why weren’t they arrested and jailed?” “Err…” “And why not arrest them after they stole billions from the public they were supposed to serve?” “Umm…” “I can understand voters making a mistake once… but repeatedly voting in the same autocrat?” “Well…”

Doesn't that assume a system of ethics and morals and social organization that's very close to ours? a feels more like a Star Trek episode than a realistic contract scenario.

But with our morals and social organization, will we ever be more than one-planet species? (Or even survive the next century without devolving into apes, like Einstein predicted?)

Re: Fermi Paradox

#39

Post by M95D »

GlibMonkeyDeath wrote: post #35
GlibMonkeyDeath wrote: post #22

Earlier quoted context omitted.

Huh - very interesting! Now I am going to have to calculate this for myself! Seems that (r_d/(theta_e z))^2 P t_p ~ 100 hv (~100 photons at 3 GHz; a single 3GHz photon is about 2e-24 J) I'll drop this to 1 photon below. Where r_d = detector radius, theta_e = diffraction angle of source, z is detection distance, P = 2e15 W (peak power of source, according to article) and t_p is pulse duration (say, ~5e-9 s). Now theta…

Replying to myself here, but three things: 1) the receiver arrays are about 50x 6m diameter (3m radius) antennas ( https://www.seti.org/projects/ata/ ) So that helps about 7x. 2) The 2e15 W/10 MJ/pulse has to be all the radars summed together already, so that is all the power available. Take these two points together, the single photon detection limit is indeed about 200 ly. Third: if we assume a 1 Hz detection bandw…

Consider military radars, Cernobyl woodpecker [1].

[1] https://en.wikipedia.org/wiki/Duga_radar

Re: Fermi Paradox

#40

Post by GlibMonkeyDeath »

M95D wrote: post #39
GlibMonkeyDeath wrote: post #35

Earlier quoted context omitted.

Replying to myself here, but three things: 1) the receiver arrays are about 50x 6m diameter (3m radius) antennas ( https://www.seti.org/projects/ata/ ) So that helps about 7x. 2) The 2e15 W/10 MJ/pulse has to be all the radars summed together already, so that is all the power available. Take these two points together, the single photon detection limit is indeed about 200 ly. Third: if we assume a 1 Hz detection bandw…

Consider military radars, Cernobyl woodpecker [1]. [1] https://en.wikipedia.org/wiki/Duga_radar

I am learning a lot about radar :) This radar is using 1 MJ, 3 millisecond pulses at ~3-30 MHz (not ~5 ns pulses at ~3 GHz), so peak power is a far cry from the 2e15 W in the article (~3e8 W.) That's why I think the 2e15 W in the article has to be peak power of all radars summed together.

The average power used by all human activity is something like 20 TW (20e12 W, https://ourworldindata.org/energy-production-consumption)

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