3 ms·

The gravitational field would be enormous: 1,000–500,000 times Earth gravity, at one meter's distance, for the range of PBH masses this paper mentions. That's b

The gravitational field would be enormous: 1,000–500,000 times Earth gravity, at one meter's distance, for the range of PBH masses this paper mentions. That's balanced out by the relative speed being a brisk 200 km/s, so the interaction time would be short (microseconds). Still a pretty significant momentum impulse if one flew by.

H8crilA 2y ago
This is analyzed in the paper. There are two sources of problems: gunshot-wound-like, and the effect of transiently highly increased gravity on nearby tissues. The first one seems worse, and is the limiting factor. PS. The paper is very easy to read :)
bloopernova 2y ago
So gravity builds up over time? (Forgive the layman's attempt at understanding) If Bob is floating in space in a capsule, and a very heavy asteroid floats past, the amount that Bob's capsule is moved is dependent on the speed of the asteroid? Does that sort of thing have to be considered when planning the orbits of probes etc? Is Earth traveling fast enough, from the viewpoint of Alice floating near the sun, to have a gravity "tail" or "wake" trailing after it? (Alice near the sun thing is my attempt at a mostly static observer) And of course due to relativity, if Alice was orbiting retrograde to the big heavy object, she'd observe even more effect? I think I need about 6 more cups of tea before I can think about this!
- sapiogram 2y ago
  > If Bob is floating in space in a capsule, and a very heavy asteroid floats past, the amount that Bob's capsule is moved is dependent on the speed of the asteroid? Yes > Does that sort of thing have to be considered when planning the orbits of probes etc? Yes, it's a primary concern when sending probes to other planets > Is Earth traveling fast enough, from the viewpoint of Alice floating near the sun, to have a gravity "tail" or "wake" trailing after it? If I understand you correctly, then classically (i.e. ignoring relativity), no. Your gravitational acceleration towards the earth depends only your distance to it. If you consider general relativity? It's... complicated.
- ted_dunning 2y ago
  Force is the derivative of momentum. If you apply a gravitational force for a short time, the derivative is the same but the change of momentum is tiny. If you apply it for a longer time, the change is bigger.

H8crilA 2y ago

This is analyzed in the paper. There are two sources of problems: gunshot-wound-like, and the effect of transiently highly increased gravity on nearby tissues. The first one seems worse, and is the limiting factor. PS. The paper is very easy to read :)

bloopernova 2y ago

So gravity builds up over time? (Forgive the layman's attempt at understanding) If Bob is floating in space in a capsule, and a very heavy asteroid floats past, the amount that Bob's capsule is moved is dependent on the speed of the asteroid? Does that sort of thing have to be considered when planning the orbits of probes etc? Is Earth traveling fast enough, from the viewpoint of Alice floating near the sun, to have a gravity "tail" or "wake" trailing after it? (Alice near the sun thing is my attempt at a mostly static observer) And of course due to relativity, if Alice was orbiting retrograde to the big heavy object, she'd observe even more effect? I think I need about 6 more cups of tea before I can think about this!

sapiogram 2y ago
> If Bob is floating in space in a capsule, and a very heavy asteroid floats past, the amount that Bob's capsule is moved is dependent on the speed of the asteroid? Yes > Does that sort of thing have to be considered when planning the orbits of probes etc? Yes, it's a primary concern when sending probes to other planets > Is Earth traveling fast enough, from the viewpoint of Alice floating near the sun, to have a gravity "tail" or "wake" trailing after it? If I understand you correctly, then classically (i.e. ignoring relativity), no. Your gravitational acceleration towards the earth depends only your distance to it. If you consider general relativity? It's... complicated.
ted_dunning 2y ago
Force is the derivative of momentum. If you apply a gravitational force for a short time, the derivative is the same but the change of momentum is tiny. If you apply it for a longer time, the change is bigger.