Relatively correct, given that, in the frame of reference of the object moving into a black hole, time obviously runs normal for them.
But yes, if there were two synchronised clocks, one on Earth and one on a ship, and the ship were to get into a black hole and then back to Earth, the clocks would show different times.
In the proper time it takes to fall in a black hole, to any external observer the time would be infinite. The falling observer would quite literally see millenia happen. Then die i guess.
Now, consider what an 'external observer' is. Is it something that receives information from (some region near) the black hole via, for example, travelling light which would have to reach them from there? In that case, what you get is that same situation that I described - two synchronised clocks, one comes back from the black hole. The details might look different, but that's superficial.
There is no such thing as an 'objective' moment of time in the sense that there can be no such thing as a global clock.
The phenomenom I'm pointing out is that an observer falling into a black hole experiences crossing the event horizon in finite time, a distant stationary observer sees time for the falling observer slow (and in fact calculates an infinite time to cross the event horizon), while the falling observer sees time pass fast for the stationary observer (with similar asymptotic behaviour). I didn't say anything about objective time, I said proper time, which is the time past on an observer's own clock in a not necessarily inertial reference frame. It's been a decade since my last proper general relativity course but I'm pretty confident in what I'm describing
I mean, I do understand this stuff, but the comment that you replied to was talking about the fact that there can be no global clock, motivated by the person I was first replying to saying '...or should I say relatively correct?'.
Also, not sure if physicists do that but 'finite time' kind of makes my ears bleed. Not that it can be rigorously defined, but 'bounded time' seems to be a much more apt expression.
Relatively correct, given that, in the frame of reference of the object moving into a black hole, time obviously runs normal for them.
But yes, if there were two synchronised clocks, one on Earth and one on a ship, and the ship were to get into a black hole and then back to Earth, the clocks would show different times.
In the proper time it takes to fall in a black hole, to any external observer the time would be infinite. The falling observer would quite literally see millenia happen. Then die i guess.
Now, consider what an 'external observer' is. Is it something that receives information from (some region near) the black hole via, for example, travelling light which would have to reach them from there? In that case, what you get is that same situation that I described - two synchronised clocks, one comes back from the black hole. The details might look different, but that's superficial.
There is no such thing as an 'objective' moment of time in the sense that there can be no such thing as a global clock.
The phenomenom I'm pointing out is that an observer falling into a black hole experiences crossing the event horizon in finite time, a distant stationary observer sees time for the falling observer slow (and in fact calculates an infinite time to cross the event horizon), while the falling observer sees time pass fast for the stationary observer (with similar asymptotic behaviour). I didn't say anything about objective time, I said proper time, which is the time past on an observer's own clock in a not necessarily inertial reference frame. It's been a decade since my last proper general relativity course but I'm pretty confident in what I'm describing
I mean, I do understand this stuff, but the comment that you replied to was talking about the fact that there can be no global clock, motivated by the person I was first replying to saying '...or should I say relatively correct?'.
Also, not sure if physicists do that but 'finite time' kind of makes my ears bleed. Not that it can be rigorously defined, but 'bounded time' seems to be a much more apt expression.