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I don’t understand why there is a black hole information paradox. Nothing ever falls into a black hole in our frame of reference - it takes infinite time.
by mjfl 7y ago
I don’t understand why there is a black hole information paradox. Nothing ever falls into a black hole in our frame of reference - it takes infinite time.
- hnick 7y agoThat confuses me because it sounds a lot like Zeno's Paradox. If nothing ever falls inside how are we observing the effects of black holes which have mass? The mass must have fallen in at some point so it can't have taken forever. I know this stuff is confusing but an explanation would be great :)
- adrianN 7y agoCan we actually distinguish black holes with a singularity in the middle from more mundane extremely dense objects, e.g. quark degenerate matter?
- hnick 7y agoDo you mean empirically? I think so, based on gravitational lensing effects and not allowing light through directly. A lesser object won't have an event horizon. But I'm hardly an expert.
- l33tman 7y agoIf you mean two objects where the first has a singularity and the second "just" an equivalently heavy matter-object, strictly speaking in classical GR (as the only agreed-on current theory) the latter will invariably collapse into the former so the answer is no. But on the other hand, I don't think any modern particle physicist actually believes there is a singularity as its a purely classical construct. This is why there is so much research into black hole information processing in the first place.
- chrischen 7y agoAs time -> infinity, information destruction -> infinity.
- lostmsu 7y agoFrom my understanding, that is incorrect. As more stuff approaches "original" event horizon, the mass of the black hole + mass of stuff near the horizon grows, which extends the horizon outwards, effectively consuming stuff, that got close to it.
- lostmsu 7y agoHopefully better explanation: Imagine a black hole with mass M and radius R. Let's assume to have radius R+1m, a black hole has to be of mass M+1kg. Any falling matter trying to approach R will cross R+1m in finite time. At some moment 1kg of matter will cross R+1m. At this moment, that 1kg will effectively be inside the horizon.
- deleted 7y ago[deleted]
- millstone 7y ago"Effectively inside the horizon" isn't a good way to think about GR. Observers have reference frames, and can only observe according to their own clocks and rulers. If you (a distant observer) watched your blinking probe approach a black hole, you would see its blinks slow and red shift as the probe approaches the horizon. You cannot see it enter the horizon, as light cannot escape from inside the horizon. There would be a last blink, as the red shift approaches infinity. If the event horizon were to increase in radius, the effect would be to further slow and red shift the blinks.
- lostmsu 7y agoCan't you claim, that if probe reached R+0.5m (which you could potentially see), and then subsequently BH grew to R+1m, that probe's last blink happened in the area, that later became BH?
- perl4ever 7y agoOk, but what if you take the limit as +1 -> 0?