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Physicists Detect Gravitational Waves, Proving Einstein Right

nytimes.com

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Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#161

Post by rdancer »

antognini wrote: post #10
losvedir wrote: 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…

What does that mean in plain English?

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#163

Post by daveguy »

snowwrestler wrote: post #70
pavpanchekha wrote: post #2

I remember learning about the LIGO experiment back when it was being built, a decade ago, and at the time it seemed so amazing: a giant tube of vacuum, sealed underground and so sensitive that it could detect animals walking nearby, listening to the moving and twisting of space itself… I guess we're finally seeing that with immense human ingenuity and the most careful of engineering, the universe will offer its secre…

Well we've accounted for about 5% of the universe--the stuff we know about. Dark matter (about 25%) seems to only interact gravitationally, which means that we've just, today, proven that we have an instrument that could possibly observe it directly. To date, all our evidence for dark matter is indirect--observing the otherwise unexplained behavior of normal matter. Today is the gravitational equivalent to Galileo po…

How do we know dark matter is some mysterious form of matter and not just small distributed particles (gas or solid) that are beyond our ability to detect? Do we have proof of a specific, exotic, non-atomic matter?

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#164

Post by swamp40 »

boardwaalk wrote: post #138

If they build a third observatory, can they triangulate where in the universe the events are occurring?

Yes.

There is a third one (VIRGO) near Pisa, Tuscany - a French/Italian collaboration.

Unfortunately it was not online for this event.

There is also one being built in Tokyo, and another being planned in India.

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#165

Post by drdeca »

hiphopyo wrote: post #139

Does this bring us any closer to warp drives?

Uh, I guess it might help with testing things that would?

Iirc the idea would be that inferometers would be used to test things like that.

I don't think we (humanity) will achieve warp drives, though, I do support the attempt.

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#166

Post by lutorm »

nappy-doo wrote: post #112

Does anyone know if G-Waves are effected by velocity, like EM-Waves are? In other words, if two bodies are moving relative to one another, one emits G-Waves, and one detects them. Are the waves at the detector doppler shifted in frequency by the relative velocities?

I don't see how they could not be. I think that shift arises from transformations between different coordinate frames, it doesn't matter what you're observing.

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#168

Post by astrosi »

ttflee wrote: post #95

How could this result be reproduced in an independent repetition, then?

In a very real way it was. There were two completely geographically separate instruments which recorded the same signal with a delay that is consistent with the light travel time between them.

In the future this will get better when VIRGO in Italy and KAGRA [2] in Japan come online. Then we will have 4 independent detectors which will be able to verify that same signal is observed at the same time.

Obviously of course given the transient nature of what is being observed once the merger has occurred it will very rapidly stop producing gravitational waves so we will not be able to measure the same event again.

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

[2]: https://en.wikipedia.org/wiki/KAGRA

Re: Physicists Detect Gravitational Waves, Proving Einstein Right

#169

Post by simcop2387 »

nappy-doo wrote: post #112

Does anyone know if G-Waves are effected by velocity, like EM-Waves are? In other words, if two bodies are moving relative to one another, one emits G-Waves, and one detects them. Are the waves at the detector doppler shifted in frequency by the relative velocities?

As they're supposed to be traveling at the speed of light I'd jump to the conclusion that you'd find them doppler shifted. In this case though we don't yet have anything like the spectral lines of hydrogen to be able to measure that shift so I don't think we can do anything with it yet.
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