41–50 of 93 posts
Simple: the laws of most physics say you can look at something now and work it backwards. Once it falls into a black hole the previous state of what falls into it isn't able to be derived from working backwards because it just fell into a black hole. This isn't rocket science! (Maybe eventually though)
That doesn't really explain anything.
Earlier quoted context omitted.
It is not reversible because you’re ereasing information. If you want to have a reversible addition you are not allowed to destroy the information. The same happens if you apply the standard AND operator to two bits because the output is only one bit, therefore it is impossible to figure out the two input bits. To have a reversible AND operator you can define it like this: f(x1, x2, b) = (x1, x2, b XOR (x1 AND x2)).…
You’d have to do that for all results, not just one. This is basically what an event sourced system does: you store all the events and fold your state, so you can “play back” to any point in time. You could theoretically reverse from the end, but I haven’t seen it done.
Earlier quoted context omitted.
Which law of physics say information must be lost in a black hole? AFAIK if information is lost in a black hole it will also violate the second law of thermodynamics - so really you have many many laws saying it cannot be lost - and Hawking temporarily claimed it will be lost in black holes before recanting and saying it won't. So ... I don't quite follow. I mean this title is as concerning to me as something that cl…
I believe the 'No-hair theorem' is closest to a 'law' that says Black holes destroy information [1]. If it is true, then when you throw anything into a black hole, information about what you threw in (whether it is a chair, a star, a planet, etc.) is 'lost' as to the outside world they all yield the same observable parameters of the black hole. [1] https://en.wikipedia.org/wiki/No-hair_theorem
TLDW: They probably do have hair.
This is literally what the holographic principle addresses... https://youtu.be/B2ksDczJOAs Leonard Susskind has enough accessible vids and lectures to give a conceptual idea of how it works out.
which explains the paradox and several different competing theories at a high level.
> The important thing is that all evolution equations that we know of are time-reversible. I've heard this before, but it's so surprising to me, when one of the simplest mathematical operations - addition - is not reversible. e.g. if a+b=4 , you can't infer the values of a and b (beyond their linear relationship). This non-injectivity is a kind of summarising, with less information, where more than one state maps to…
Elsewhere the author says "all fundamental evolution equations in physics are time-reversible." By fundamental I'm assuming she means: Maxwell's equations, Einstein's field equations and the Schrodinger equation.
Simple: the laws of most physics say you can look at something now and work it backwards. Once it falls into a black hole the previous state of what falls into it isn't able to be derived from working backwards because it just fell into a black hole. This isn't rocket science! (Maybe eventually though)
Earlier quoted context omitted.
You’d have to do that for all results, not just one. This is basically what an event sourced system does: you store all the events and fold your state, so you can “play back” to any point in time. You could theoretically reverse from the end, but I haven’t seen it done.
A transactional database would tick that box, events are stored and can rollback to a point in time.
Earlier quoted context omitted.
It is not reversible because you’re ereasing information. If you want to have a reversible addition you are not allowed to destroy the information. The same happens if you apply the standard AND operator to two bits because the output is only one bit, therefore it is impossible to figure out the two input bits. To have a reversible AND operator you can define it like this: f(x1, x2, b) = (x1, x2, b XOR (x1 AND x2)).…
You’d have to do that for all results, not just one. This is basically what an event sourced system does: you store all the events and fold your state, so you can “play back” to any point in time. You could theoretically reverse from the end, but I haven’t seen it done.
man, watch the PBS YouTube channel SpaceTime. They're short, informative, and very well done. they dedicate a handful of episodes to getting you ready for Hawking radiation. https://youtu.be/qPKj0YnKANw