What do GravWaves do?
15 Oct 2005 14:12:07 UTC
Topic 190012
(moderation:
what exactly does "ripple in the space time continuum" do? Is it like the "eddies" mentioned in The Hitchhiker's guide to the Galaxy triology? Like, if you happen to encounter one, you'll be able to time travel or something?
What do GravWaves do?
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Hi, DrSclarn – There's a pretty good overview on the nature of GWs and how they may be detected here
(At the bottom of that page on LIGO Livingston Observatory is a link “Next Poster”, and there are about 18 informative posters total for that site, so click through those, and when you get to the 5th and 6th posters, you'll see good illustrations highlighting the difference between gravitational wave radiation and electromagnetic radiation...)
What I want to know is the
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What I want to know is the time factor.
DrSdarn: The gravity waves
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DrSdarn:
The gravity waves being investigated in this study are very weak and just nudge things a little bit as they pass. Sorry, no exotic physics involved.
The waves themselves travel at the speed of light.
This animation, from the
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This animation, from the “Ripples in Space-Time” link on the LISA site, shows two massive black holes just about to merge:
Since the GWs are expected to propagate at the speed of light, are the masses in the animation shown moving at almost the speed of light, i.e., in the moments just before merging? Otherwise the wavelengths would be longer, right? (Makes sense if the GW waveform for this event is analogous to the sound of a “chirp”...)
RE: The gravity waves being
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Does that mean time also changes a bit?
Sorry if I'm quibbling. But why do you use the phrase "space time continuum?" It should be only space continuum.
DrSclarn: Without
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DrSclarn:
Without completely understanding your inquiry, on what exactly you desire, I can recommend the following informative links for reference:
Theory of Gravitational Waves & LIGO
Gravitational-wave pulsar signal take at an Earth-based detector
Laser Interferometer Gravitational Wave Observatory
Hope you will find the aforementioned links of use.
Regards,
Tom
Theory of Gravitational Waves & LIGO
Laser Interferometer Space Antenna - LISA
JPL-Caltech
RE: RE: The gravity waves
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There are probably lots better answers than this one, but I'll give it a shot:
In physics, asking about distance, without considering the time it takes light to travel that distance, is meaningless. And asking about time, without considering the distance that light travels in that time, is likewise meaningless. Hence, it must be “spacetime”...
RE: Since the GWs are
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There is no need for the to BHs to move as fast as that when their event horizons merge. The speed will depend on the masses of the two BHs.
In most situtations you would be likely to geta a small time effct too, but GWs mainly distort space.
In general relativity, which is the theory describing among other things graviation, tim and sapce are connected together in a very tight way and one cannot really deal with the separately. As an example, the gravitaional attarction from a large mass like a planet is composed of both a time-distortion effect and space-distortion effect.
RE: There is no need for
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Thanks, klasm – what about initial velocities, and circular vs. elliptical? How does the max velocity vary for systems with less mass, compared to more massive mergers, e.g., is it proportional to the total mass? Which system results in the greatest final velocity, and in terms of c, what is it expected to be?
The description of the
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The description of the gravitational orbits for two bodies can be taken as Newtonian unless the bodies approach each other close enough to make the critical radius (2G(M1+M2)/c^2) a significant fraction of the separation. Even then the effects of general relativity are initially small and can be described in part by removing mass and angular momentum from the system rather than changing Newtonian approximation. The shifting of an elliptical orbit’s major axis is not Newtonian and not related to gravity wave emissions but becomes less significant because the GR predicts that elliptical orbits will be circularized by the stronger gravity wave emissions while the bodies are closest and moving fastest.
Unless we are discussing binary black holes tidal disruption becomes the predominant feature before the full effects of GR are relevant. The BBH case is still under investigation.