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Physicists Detect Gravitational Waves, Proving Einstein Right

nytimes.com

21–30 of 502 posts

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#21
post #15

Are gravitational waves supposed to be that weak or is it because of the distance between us and those black holes? Do they lose power as they travel through space?

Think of waves in a pond when you drop a rock in. The energy spreads out as it travels into the farthest reaches of the pond.

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#23
post #4

> And then the ringing stopped as the two holes coalesced into a single black hole, a trapdoor in space with the equivalent mass of 62 suns. All in a fifth of a second, Earth time. Am I reading this correctly, that shortly after the detector came online we just happened to observe the exact moment a billion years ago that two black holes collided? Was that extremely coincidental? Or do these events happen all the tim…

The predictions for the LIGO detection rate are very poor. They're based on a sample of just a handful of binary pulsars observed in our Galaxy, which would produce NS-NS mergers. The BH-BH merger rate is almost totally unconstrained, although it is generally thought to be less than the NS-NS merger rate. So the fact that a BH-BH merger was the first detection, and the fact that it was detected so soon after the sens…

If this events are so rare (that we don't even know how rare they are), how is it possible that they achieved the required certainty (5 sigma)?

I guess you could count one looong wave as a series of one-time events/measurements, but it could as well be a loooong interference.

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#24

Would it be possible to listen for information transmitted via gravitational waves? Would there be any benefit over radio?

The amount of energy needed to transmit via a gravitational wave is INSANE. It would involve very rapidly accelerating and decelerating a black hole / neutron star. While it might be possible to do this, it's not within the realm of something we could accomplish without several orders of magnitude technology improvements, and possibly may not be physically possible at all (moving object that heavy that quickly might require creating a black hole)--though I don't have the skill to prove or disprove that.

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#25
post #4

> And then the ringing stopped as the two holes coalesced into a single black hole, a trapdoor in space with the equivalent mass of 62 suns. All in a fifth of a second, Earth time. Am I reading this correctly, that shortly after the detector came online we just happened to observe the exact moment a billion years ago that two black holes collided? Was that extremely coincidental? Or do these events happen all the tim…

The predictions for the LIGO detection rate are very poor. They're based on a sample of just a handful of binary pulsars observed in our Galaxy, which would produce NS-NS mergers. The BH-BH merger rate is almost totally unconstrained, although it is generally thought to be less than the NS-NS merger rate. So the fact that a BH-BH merger was the first detection, and the fact that it was detected so soon after the sens…

[deleted]

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#26

For someone like me who knows next to nothing about this, that video was extremely well produced and it explained everything i was wondering about.

Jonathan Corum has had a fun career to watch; he's (I think?) a student of Tufte's. I discovered him with brunch.org; also, check out his style.org.

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#27

Would it be possible to listen for information transmitted via gravitational waves? Would there be any benefit over radio?

I think if you really wanted to think outside of box for this, quantum entangled particles is your best bet for instantaneous low energy communication

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#28
post #4

> And then the ringing stopped as the two holes coalesced into a single black hole, a trapdoor in space with the equivalent mass of 62 suns. All in a fifth of a second, Earth time. Am I reading this correctly, that shortly after the detector came online we just happened to observe the exact moment a billion years ago that two black holes collided? Was that extremely coincidental? Or do these events happen all the tim…

Typically one would assume that it was not coincidental and then adjust the bounds for how often we expect the event occurs based on observations, or lack thereof.

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#30
post #15

Are gravitational waves supposed to be that weak or is it because of the distance between us and those black holes? Do they lose power as they travel through space?

> Are gravitational waves supposed to be that weak or is it because of the distance between us and those black holes?

Distance. A billion light-years is a very long distance, and the inverse-square law applies.

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