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RE: Brace yourselves for gravitational waves
February 16, 2016 at 6:40 pm
(This post was last modified: February 16, 2016 at 6:42 pm by Alex K.)
(February 16, 2016 at 6:31 pm)Excited Penguin Wrote: Just one thing I couldn't wrap my head around at all. What are these deviations you keep referring to, exactly?
Imagine objects floating at rest in space arranged like the corners of a cube. The metric tensor might tell you that the distance going from one to the other is always x. Now, when the values of the metric tensor change a bit, for example because a grav. wave is coming through, the prescription how to calculate distances between the objects changes (without them having moved!), so the theory predicts that they might suddenly have somewhat larger or smaller distance. This is exactly what LIGO observed. Your eight objects can change relative distance or angles
The fool hath said in his heart, There is a God. They are corrupt, they have done abominable works, there is none that doeth good.
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RE: Brace yourselves for gravitational waves
February 16, 2016 at 6:45 pm
(February 16, 2016 at 6:40 pm)Alex K Wrote: (February 16, 2016 at 6:31 pm)Excited Penguin Wrote: Just one thing I couldn't wrap my head around at all. What are these deviations you keep referring to, exactly?
Imagine objects floating at rest in space arranged like the corners of a cube. The metric tensor might tell you that the distance going from one to the other is always x. Now, when the values of the metric tensor change a bit, for example because a grav. wave is coming through, the prescription how to calculate distances between the objects changes (without them having moved!), so the theory predicts that they might suddenly have somewhat larger or smaller distance. This is exactly what LIGO observed. Your eight objects can change relative distance or angles
Fascinating.
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RE: Brace yourselves for gravitational waves
February 16, 2016 at 6:55 pm
(This post was last modified: February 16, 2016 at 6:56 pm by Alex K.)
This by the way is also how the cosmic expansion of the universe is described mathematically. The numbers in the metric tensor simply grow by a time dependent factor called a(t). So "space" expands and distances between otherwise unbound objects increase. In this formulation, it is also clear that space doesn't have to expand into anything. It's just that the rulers change. This is all totally standard, not something I made up.
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RE: Brace yourselves for gravitational waves
February 16, 2016 at 7:49 pm
(This post was last modified: February 16, 2016 at 7:50 pm by Edwardo Piet.)
(February 16, 2016 at 6:31 pm)Excited Penguin Wrote: Just one thing I couldn't wrap my head around at all. What are these deviations you keep referring to, exactly?
Blackadder: It's very moving sir. Would you mind if I changed just one tiny aspect of it?
Prince George: Which one?
Blackadder: The words.
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RE: Brace yourselves for gravitational waves
February 16, 2016 at 7:52 pm
(This post was last modified: February 16, 2016 at 8:14 pm by Excited Penguin.)
(February 16, 2016 at 7:49 pm)Evie Wrote: (February 16, 2016 at 6:31 pm)Excited Penguin Wrote: Just one thing I couldn't wrap my head around at all. What are these deviations you keep referring to, exactly?
Blackadder: It's very moving sir. Would you mind if I changed just one tiny aspect of it?
Prince George: Which one?
Blackadder: The words.
What do you mean by that, exactly?
I don't want to have an off-topic argument here. So if you wish to respond, could we take it elsewhere? I am still interested in your response, I just don't want this thread to get derailed.
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RE: Brace yourselves for gravitational waves
February 16, 2016 at 10:31 pm
lol
I appreciate that but it amuses me because you'll happily derail all the other threads lol
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RE: Brace yourselves for gravitational waves
February 16, 2016 at 11:20 pm
Probably an observation that could 'never' be made, but using VLBI to observe distant point sources in the cosmos while an intervening system similar to the one just observed implodes might produce 'scintillation' or even stronger effects in the observed positions of those distant objects.
Might be fun to watch . . .
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RE: Brace yourselves for gravitational waves
February 17, 2016 at 4:37 am
(This post was last modified: February 17, 2016 at 4:38 am by Alex K.)
(February 16, 2016 at 11:20 pm)vorlon13 Wrote: Probably an observation that could 'never' be made, but using VLBI to observe distant point sources in the cosmos while an intervening system similar to the one just observed implodes might produce 'scintillation' or even stronger effects in the observed positions of those distant objects.
Might be fun to watch . . . In the Ligo press conference one of the speakers gave a quick overview over grav wave astronomy techniques for different frequencies, and I recall a picture of a radio array as an example for detecting very long wavelengths... We should check out what is behind that, maybe you're not so far off the mark...
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RE: Brace yourselves for gravitational waves
February 21, 2016 at 3:24 pm
(This post was last modified: February 21, 2016 at 3:32 pm by God of Mr. Hanky.)
Has this been discussed already?
Just saw a more recent video by Krauss on how LIGO works.
https://www.youtube.com/watch?v=3ctu24Hkg0k
After upgrading it's detection limits to 1/1000 the width of a proton, it can detect waves from a lot which is going on around it. In addition to black holes colliding, it's laser beams can pick up the distortions from a truck rolling 50 miles away, and of course there's also the distortion of Moon gravitation waves. The Moon gravitational behavior is predictable, therefore it should be easy to sort out from what the LIGO team is attempting to observe, but what of all the background noise that's coming in from every direction on Earth? You probably know me (even if you don't like me) that I wouldn't be saying nay, but I'd love to know how when I talk about it. Are they already able to apply Doppler to this emerging technology?
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RE: Brace yourselves for gravitational waves
February 21, 2016 at 4:22 pm
apply Doppler? What do you mean?
The fool hath said in his heart, There is a God. They are corrupt, they have done abominable works, there is none that doeth good.
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