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The Absurdity of Detecting Gravitational Waves (2017) [video]

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Re: The Absurdity of Detecting Gravitational Waves (2017) [video]

#41

Post by perl4ever »

a1369209993 wrote: post #18
TomMckenny wrote: post #4

I wonder if gravity wave detection could be ever be precise enough for communication. I wonder this because it occurs to me that one possible answer to Fermi's paradox is that aliens don't use Radio or other EM to chat. And maybe they don't leak it because they move energy and information around more efficiently than we do.

Communication is a red herring; the actual Fermi paradox is why huge sections of the night sky aren't black[0] due to all the stars being enclosed by Dyson spheres. Or, for that matter, why the planet hasn't been eaten by von Neumann swarms yet. 0: technically a uniform dim infrared of waste heat

I thought that huge sections of the night sky are empty - we call them Cosmic Voids.

See: https://en.wikipedia.org/wiki/Void_(astronomy)

Re: The Absurdity of Detecting Gravitational Waves (2017) [video]

#42

Post by ajkjk »

andrewflnr wrote: post #31
sleavey wrote: post #23

Earlier quoted context omitted.

One reason would be that gravitational wave amplitude decays only as 1/distance instead of electromagnetic radiation which decays as 1/(distance squared). ...But man-made gravitational waves are, without some scientific advance eclipsing the discovery of electricity, completely beyond any human capability of being produced at the levels required for extra terrestrial communication.

> gravitational wave amplitude decays only as 1/distance Wait, what? How? The wavefront still spreads out over the quadratically increasing surface of a sphere, right, just like EM waves?

I thought about objecting to that also. But the case of spiraling black holes is possibly dispersing energy only on the plane of rotation, so it might actually be 1/r?

Re: The Absurdity of Detecting Gravitational Waves (2017) [video]

#43

Post by sillysaurus3 »

lovemenot wrote: post #34
tntn wrote: post #15

Earlier quoted context omitted.

I don't understand how this is any different from believing in God.

No doubt that was your parent poster's intention. There have been many ontological arguments throughout history. This was one such.

If it was, it was mostly accidental. The argument was derived from logic and reasoning, rather than e.g. family beliefs.

Re: The Absurdity of Detecting Gravitational Waves (2017) [video]

#44

Post by ianai »

sillysaurus3 wrote: post #13
TomMckenny wrote: post #4

I wonder if gravity wave detection could be ever be precise enough for communication. I wonder this because it occurs to me that one possible answer to Fermi's paradox is that aliens don't use Radio or other EM to chat. And maybe they don't leak it because they move energy and information around more efficiently than we do.

Another answer to the Fermi paradox is that a Kardashev Type 4 civilization is able to harness the power of an entire universe. We wouldn't be able to detect this by definition, since they exist outside of our perceived reality. At first glance, this seems to be a useless theory, since it's not refutable. But it lends itself to a belief system: by studying the universe, we gain an understanding of whatever created it…

I’ve heard mathematicians express similar reasons for studying math. It can be something of a universal language.

Personally, I think no matter how often matter-energy arrange themselves into life in the universe life remains vanishingly rare. For that reason, life should be as harmonious with itself as possible - diverse and varied but self supporting. The rest of the universe is rarely calm and stable enough for life to exist.

As for why we haven’t found life yet: we are very new to this game. We just in this last decade started being able to resolve properties of exoplanets. I don’t think we have the information to even posit a question like the Fermi paradox with any level of confidence.

Re: The Absurdity of Detecting Gravitational Waves (2017) [video]

#45

Post by perl4ever »

jobigoud wrote: post #20
sillysaurus3 wrote: post #13

Earlier quoted context omitted.

Another answer to the Fermi paradox is that a Kardashev Type 4 civilization is able to harness the power of an entire universe. We wouldn't be able to detect this by definition, since they exist outside of our perceived reality. At first glance, this seems to be a useless theory, since it's not refutable. But it lends itself to a belief system: by studying the universe, we gain an understanding of whatever created it…

This wouldn't really solve the paradox as it implies there are zero type 0, 1, 2 and 3 civilizations that we can detect in our Universe, which is still statistically odd.

There was a HN thread (probably several) not too long ago about someone who did a better analysis of the Drake equation with probability distributions rather than point estimates and found that given that improved methodology, it isn't odd that we see nobody - as it is quite likely we are either the first civilization in the universe or the only one within a galaxy or more. No new facts were used, only a sensible synthesis of the known information.

Re: The Absurdity of Detecting Gravitational Waves (2017) [video]

#46

Post by perl4ever »

ci5er wrote: post #16
sillysaurus3 wrote: post #13

Earlier quoted context omitted.

Another answer to the Fermi paradox is that a Kardashev Type 4 civilization is able to harness the power of an entire universe. We wouldn't be able to detect this by definition, since they exist outside of our perceived reality. At first glance, this seems to be a useless theory, since it's not refutable. But it lends itself to a belief system: by studying the universe, we gain an understanding of whatever created it…

> But why do humans find this idea so seductive? It's because of an underlying loneliness: we want to believe that we are connected with the universe in some fashion, that our existence has a point [...] No. It's simply that statistically, we can't believe we are the first, nor that we are unique. It would be (statistically) extremely odd if we were, and there is a bias against anthropo-centric theories. Heck, I'd be…

"we can't believe we are the first, nor that we are unique. It would be (statistically) extremely odd if we were"

Someone did a Bayesian analysis using probability distributions and found that, given what we observe (no aliens), there is a substantial probability we are the first civilization in the universe, or else the only one within galactic distances. They also inferred that whatever makes spacefaring life unlikely is probably in the past, not the future, which seems optimistic if you're worried about AGW or nuclear war.

"The Fermi question is not a paradox: it just looks like one if one is overconfident in how well we know the Drake equation parameters."

"The Fermi observation makes the most uncertain priors move strongly, reinforcing the rare life guess and an early great filter."

They end up with a 40% chance we are alone in the universe and about a 55% chance we are alone in our galaxy.

http://www.jodrellbank.manchester.ac.uk/media/eps/jodrell-ba...

Re: The Absurdity of Detecting Gravitational Waves (2017) [video]

#47

Post by mysterypie »

I figured that one tube is stretched by the gravitational waves and the perpendicular tube is unaffected, so you're measuring the difference between the two tubes. Simple and easy to understand. However, the video mentioned that both light and the detection apparatus are stretched by the same degree and the physicist says "the light does get stretched and that part doesn't do the measurement for us"[1] -- which makes me think that the simple and easy explanation is not quite right. There's some subtlety that I think I'm missing.

[1] https://m.youtube.com/watch?v=iphcyNWFD10&t=376s (6min 16sec into the video)

Re: The Absurdity of Detecting Gravitational Waves (2017) [video]

#48

Post by AnsisMalins »

mysterypie wrote: post #47

I figured that one tube is stretched by the gravitational waves and the perpendicular tube is unaffected, so you're measuring the difference between the two tubes. Simple and easy to understand. However, the video mentioned that both light and the detection apparatus are stretched by the same degree and the physicist says "the light does get stretched and that part doesn't do the measurement for us"[1] -- which makes…

Light takes different amounts of time to travel down the stretched vs squeezed tube.

Re: The Absurdity of Detecting Gravitational Waves (2017) [video]

#49

Post by a1369209993 »

nonbel wrote: post #36
a1369209993 wrote: post #18

Earlier quoted context omitted.

Communication is a red herring; the actual Fermi paradox is why huge sections of the night sky aren't black[0] due to all the stars being enclosed by Dyson spheres. Or, for that matter, why the planet hasn't been eaten by von Neumann swarms yet. 0: technically a uniform dim infrared of waste heat

This is called Olbers paradox, and is much older: https://en.wikipedia.org/wiki/Olbers%27_paradox

That's "Why are there any parts of the sky that aren't stars?". The Fermi paradox is "Why are there any parts of the night sky that are (unobstructed) stars?".

Re: The Absurdity of Detecting Gravitational Waves (2017) [video]

#50

Post by [deleted] »

AnsisMalins wrote: post #48
mysterypie wrote: post #47

I figured that one tube is stretched by the gravitational waves and the perpendicular tube is unaffected, so you're measuring the difference between the two tubes. Simple and easy to understand. However, the video mentioned that both light and the detection apparatus are stretched by the same degree and the physicist says "the light does get stretched and that part doesn't do the measurement for us"[1] -- which makes…

Light takes different amounts of time to travel down the stretched vs squeezed tube.

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