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The Sun also wobbles because of the planets. Primordial black holes are (depending on theory of creation and path in later life) smaller than stellar black hole
by corty 5y ago
The Sun also wobbles because of the planets. Primordial black holes are (depending on theory of creation and path in later life) smaller than stellar black holes, maybe far smaller, in the order of lunar mass or even particle magnitude mass. So the wobble from a PBH will be overshadowed by that of Jupiter and the other planets. The sun doing a wobble of more than 30AU (what you would expect for a 1 solar mass PBH somewhere past neptune) with respect to the galaxy would have been detected ages ago, even the parallax measurements of yore are precise enough for that. From that fact, the magnitude of disturbance in other planets' and TNOs' orbits and the absence of gravitational lensing observations, our PBH should be in the order of planetary masses.
- ben_w 5y ago> particle magnitude mass IIRC, that small would evaporate almost instantly[0]. I think you’re thinking of particle radius, which would be mountain mass[1]. [0] this formula says less than a plank time and is therefore wrong: https://www.wolframalpha.com/input/?i=5120π%28G%29%5E2%28mass+proton%29%5E3%2F%28%28h-bar%29c%5E4%29 https://www.wolframalpha.com/input/?i=5120π%28G%29%5E2%28mas... [1] https://www.wolframalpha.com/input/?i=0.1nm*c%5E2%2F2G https://www.wolframalpha.com/input/?i=0.1nm*c%5E2%2F2G
- corty 5y agoYes, if it would have particle mass at the time of the big bang it would have evaporated long ago. But all small black holes do evaporate (the smaller, the faster), so if PBHs were e.g. car-mass at the big bang, they could just be the right size for particle-masses right now (and gone in a few years).
- ben_w 5y ago1.7e11 kg is a pretty big car: https://www.wolframalpha.com/input/?i=%28%28%28h-bar%29%28c%5E4%29%28age+of+universe%29%29%2F%285120π%28G%29%5E2%29%29%5E%281%2F3%29 https://www.wolframalpha.com/input/?i=%28%28%28h-bar%29%28c%... And again, the predicted lifespan of a proton-mass black hole is significantly less than a plank time, which in turn is therefore a sign that — one way another — the maths doesn’t actually apply to that situation in the first place.
- scatters 5y agoThe minimum mass for a black hole is the Planck mass, approximately 21 micrograms. Such a black hole is a Planck length in radius, has a Hawking temperature of the Planck temperature, and will decay in Planck time, releasing Planck energy of 1.9 GJ (about the same as a tank of gasoline).