Robittybob1 Posted April 2, 2016 Author Posted April 2, 2016 (edited) Citation needed. That does not seem to be what your equations say. That equation only tells you orbital frequency. It says nothing about gravitational waves. The equations you are using are approximations based on a point source. It assumes that the gravitational waves come from that point source but says nothing about how they arise (because at the distance these equations are valid, the nature of the source doesn't matter too much). That is a thought experiment of a wave tank. Two spherical masses linked and rotated. All of the GW animations show a similar pattern so why would you need it again? You need frequency for spheres as well. So how does your picture of spherical waves use that frequency to produce two waves per rotation? Now this is true: "The equations you are using are approximations based on a point source. It assumes that the gravitational waves come from that point source but says nothing about how they arise (because at the distance these equations are valid, the nature of the source doesn't matter too much)." So neither of us can use those equations to describe the nature of the source. Which is what I have been saying all along (last 2-3 pages at least). It's a sine wave. It goes up and then down, and then up and down, over and over again. The part where it's up is the wave front. You get successive wave fronts because the source keeps generating them. That is the purpose of the thread - to understand the generator of these waves. We must be using the same generator - a BBH? Should we limit our discussion down to just a 10,000 km radius? Edited April 2, 2016 by Robittybob1
swansont Posted April 2, 2016 Posted April 2, 2016 That is a thought experiment of a wave tank. Two mass linked and rotated. All of the GW animations show a similar pattern so why would you need it again? You need frequency for spheres as well. So how does your picture of spherical waves use that frequency to produce two waves per rotation? That's not what the analogy was used to explain. Stay focused and don't change the subject. The question at hand was successive wave fronts.
Robittybob1 Posted April 2, 2016 Author Posted April 2, 2016 That's not what the analogy was used to explain. Stay focused and don't change the subject. The question at hand was successive wave fronts. "Successive wave fronts" they are what you feel at a distance from the source. In my case whether I use the spinning garden sprinkler or two masses rotated in a water tank I get successive wavefronts at a distance. So I haven't changed the topic.
swansont Posted April 2, 2016 Posted April 2, 2016 So neither of us can use those equations to describe the nature of the source. Which is what I have been saying all along (last 2-3 pages at least). That is the purpose of the thread - to understand the generator of these waves. We must be using the same generator - a BBH? Should we limit our discussion down to just a 10,000 km radius? No, that is not the stated purpose of the thread. The title. The OP. "Does anyone have an idea of the description of a 3D gravitational wave at a distance from the binary?"
Robittybob1 Posted April 2, 2016 Author Posted April 2, 2016 No, that is not the stated purpose of the thread. The title. The OP. "Does anyone have an idea of the description of a 3D gravitational wave at a distance from the binary?" They go hand in hand. If you can describe the 3D nature you will understand how the GWs are generated.
swansont Posted April 2, 2016 Posted April 2, 2016 "Successive wave fronts" they are what you feel at a distance from the source. In my case whether I use the spinning garden sprinkler or two masses rotated in a water tank I get successive wavefronts at a distance. So I haven't changed the topic. You were asking how a sine wave gives you successive wave fronts, and all of the sudden you're asking how the analogy gives you a 2x frequency. That's new. You also suddenly insist that you want to know about the structure of the binary, but the OP asks about the wave. They go hand in hand. If you can describe the 3D nature you will understand how the GWs are generated. That does not follow.
Strange Posted April 2, 2016 Posted April 2, 2016 So neither of us can use those equations to describe the nature of the source. Which is what I have been saying all along (last 2-3 pages at least). And the paper I linked to earlier shows some more accurate approximations for what happens with two black holes getting quite close and also notes that, even before they merge, you need to simulate the full equations of GR. That is the only way you are going to understand the source completely.
Robittybob1 Posted April 2, 2016 Author Posted April 2, 2016 You were asking how a sine wave gives you successive wave fronts, and all of the sudden you're asking how the analogy gives you a 2x frequency. That's new. You also suddenly insist that you want to know about the structure of the binary, but the OP asks about the wave. That does not follow. Surely it must. If you can see a 3D structure you use that to deduce something about the source of that structure. The wave comes from the binary and has 2 wavefronts per orbit. We all know this from multiple discussions. I am sorry if you thought I "was asking how a sine wave gives you successive wave fronts". That to me has never been an issue. It is the question "Does anyone have an idea of the description of a 3D gravitational wave at a distance from the binary?" that is the purpose of the thread. two masses orbiting each other for a billion plus years has produced 2 waves that have traveled like 2 spirals if looked at on a plane extending from the orbital plane.Or a sinusoidal line if you look at the effect at a point. there are the 1D views and the 2D descriptions but we wanted the 3D picture. And the paper I linked to earlier shows some more accurate approximations for what happens with two black holes getting quite close and also notes that, even before they merge, you need to simulate the full equations of GR. That is the only way you are going to understand the source completely. Could you say what post number that was please?
swansont Posted April 2, 2016 Posted April 2, 2016 Surely it must. If you can see a 3D structure you use that to deduce something about the source of that structure. Baloney. I can detect a photon. That doesn't tell me how the photon was created. Further, as you have brought up several times, the GW equations are for the far-field waves - they assume a point source. It's not reasonable to conclude that they allow you to determine structure.
Phi for All Posted April 2, 2016 Posted April 2, 2016 ! Moderator Note Enough! The constant shifting of topic, the misunderstandings, ignoring the rules, WE'VE HAD ENOUGH! Robbitybob1, you've shown that you're inconsistent with the purpose of this site. We're here to learn, and that means when someone answers your question, you actually read the answer, or study the link provided. It's clear you rarely do that, yet insist on posting at every chance. You cause an inordinate amount of member focus on triviality due to your inability to keep two thoughts in your head at the same time. If you engage elsewhere in scientific discussion, you should try to adopt a more education-friendly style that helps you keep track of what you think you've learned. Thread closed.
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