Timeline for Black Hole Collision & Gravitational Waves
Current License: CC BY-SA 4.0
18 events
| when toggle format | what | by | license | comment | |
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| Oct 7, 2020 at 20:46 | comment | added | Steve Linton | @JanStuller The closer they orbit (and therefore the faster) the more intense the gravity waves they emit (by quite a lot) and also the higher frequency, which makes them easier to detect. If our detectors were more sensitive and to lower frequencies, we could detect them earlier. | |
| Oct 7, 2020 at 16:43 | comment | added | Jan Stuller | @SteveLinton: I suppose the black holes must have been orbiting each other for many months (if not years), whilst generating gravity waves. Why did LIGO then detect only a brief burst of waves? Would that be the big wave coming from the actual collision? | |
| Oct 7, 2020 at 15:26 | comment | added | Steve Linton | @JanStuller LIGO detected a brief burst fo waves. See ligo.caltech.edu/video/ligo20160211v2 for example. The intensity and frequency increase as the black holes spiral inwards, and then die down rapidly after they merge, | |
| Oct 7, 2020 at 14:30 | comment | added | Jan Stuller | Thank you for that remark, @KevinWells: may I then ask an additional question: if the orbiting black holes generated waves with frequency, then how come LIGO just registered one single perturbation? Perhaps the actual collision generated one large wave (ripple), whilst the orbiting generated waves with frequency, that however are not detectable by the time they reach Earth? | |
| Oct 6, 2020 at 15:53 | comment | added | Kevin | @JanStuller It's a reasonable intuitive assumption, but remember that there are actually many waves being generated and not just one. Each time the two black holes orbited each other it created another wave, so it is really a wave with a frequency (slowly increasing until the merge) rather than a single ripple | |
| Oct 6, 2020 at 15:27 | comment | added | Steve Linton | @JanStuller think instead of sound waves in water. The water is alternately compressed and stretched. A soft jellyfish floating in the water will be compressed or stretched proportionately to its size. Another consideration is that the wavelength is pretty large, at least comparable to the Earth. | |
| Oct 6, 2020 at 10:43 | comment | added | uhoh | Nice! For reference: How would a passing gravitational wave look or feel? and How close would you have to be to the merger of two black holes, for the effects of gravitational waves to be detected without instruments? and Transfer of energy from gravity back to other “more familiar” forms of energy? and (barely) Does shortening the path length of an excited etalon do work? What about LIGO? | |
| Oct 6, 2020 at 10:24 | comment | added | fraxinus | @JanStuller pretty original (and somehow reasonable) idea, but wrong in regard to gravitational waves. | |
| Oct 6, 2020 at 9:29 | comment | added | Jan Stuller | @SteveLinton: I somehow assumed that the distortion induced by gravity-waves is independent of the size of the object. Thinking of ocean waves, they will lift an oil-tanker the same way as a human body, when they pass underneath these "objects". I intuitively thought that gravity-waves passing through space time would "ripple" through objects the same way. | |
| Oct 6, 2020 at 8:48 | history | edited | Steve Linton | CC BY-SA 4.0 |
Replace strain by distortion
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| Oct 6, 2020 at 8:46 | comment | added | Steve Linton | @JanStulter The Earth is bigger than humans. The distortion of an object by a given strain is proportional to the size of the object. | |
| Oct 6, 2020 at 8:37 | comment | added | Jan Stuller | When you say "the strain drops off linearly with distance from the black hole", why would the black holes need to be closer to affect humans by 1mm than to affect the Earth by 1mm? Humans live on Earth: therefore humans and Earth are always the "same" distance away from the black holes: shouldn't they both be equally strained? | |
| Oct 6, 2020 at 8:28 | comment | added | fraxinus | The absorbed energy is probably the real hard part. The gravitational waves will have to couple somehow to acoustic waves. | |
| Oct 6, 2020 at 6:27 | vote | accept | Jan Stuller | ||
| S Oct 5, 2020 at 19:11 | history | edited | Steve Linton | CC BY-SA 4.0 |
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| S Oct 5, 2020 at 19:11 | history | suggested | Mithoron | CC BY-SA 4.0 |
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| Oct 5, 2020 at 18:21 | review | Suggested edits | |||
| S Oct 5, 2020 at 19:11 | |||||
| Oct 5, 2020 at 16:43 | history | answered | Steve Linton | CC BY-SA 4.0 |