Why can't we just measure the gravity waves from the Sun?
23 Jan 2006 15:44:09 UTC
Topic 190661
(moderation:
Since it's in orbit (around the galaxy center) shouldn't it be emitting gravity waves? And since it's so large and close, shouldn't these waves be the easiest to detect? But my understanding is that we're focussing our attention on smaller objects further away.
Why can't we just measure the gravity waves from the Sun?
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Guido:
Because the acceleration of the Sun about the galaxy center is extremely small the
GW the system emits are extremely weak. The strongest GW emitter in our neighborhood is Mercury which is still way too weak to be detected by any means foreseeable in the near term.
I figured that was the
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I figured that was the reason, but I couldn't imagine it would still be feasible to study objects hundreds (thousands?) of light years away instead of our own sun.
Unrelated question:
Is it safe to say NOTHING travels in a straight line and therefore EVERYTHING should emit gravity waves?
RE: couldn't imagine it
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The evidence suggests that there are relatively few things with the combination of acceleration and density to emit GW strongly enough to be detected at all.
Approximately yes. A proper discussion would involve discussing how mass concentrations interact in Einstein's GR equations.
RE: Approximately yes. A
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Yeah, in particular the accelerating mass(es) need to behave with a pattern that has a 'quadrupole moment' referring to the overall (a)symmetry of the movements.
I think the bad news is probably that if you're close enough to get a decent signal then it's not a healthy neighbourhood in the long term, and if you're out where it's safe then the signals are quiet. Spacetime is very 'rigid' in the sense that it takes alot of happenings to get it to wriggle much at all. The near space of binary systems tend to get hosed with buckets of electromagnetic flux at high energy, and so are unhealthy - and this may be at a distance where the tidal effects ( related to the gradient of the gravitational field strength ) of spacetime distortion might be otherwise tolerable for lives such as ours. While the objects being studied are small in dimensions ( of the order of tens of kilometers ) they are massive and hence dense of an order that is hard to fathom.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
The frequency would also be
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The frequency would also be much too low to measure any fluctuations in a feasible amount of time.
RE: Guido: Because the
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This is correct. Another reason is that the frequency of the waves is f = 2/year = 6 x 10^{-8} Hz. LIGO and other ground based detectors are sensitive to the frequency range from 50 Hz to 5000 Hz.
Director, Einstein@Home