On Friday, November 8, 2019 at 5:05:31 PM UTC-7, Brent wrote:
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> On 11/7/2019 10:42 PM, Alan Grayson wrote:
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> On Thursday, November 7, 2019 at 10:54:33 PM UTC-7, Brent wrote:
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>> On 11/7/2019 8:43 PM, Alan Grayson wrote:
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>> On Thursday, November 7, 2019 at 5:20:13 PM UTC-7, Brent wrote:
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>>> On 11/7/2019 4:06 PM, Alan Grayson wrote:
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>>> On Thursday, November 7, 2019 at 11:41:11 AM UTC-7, Brent wrote:
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>>>> On 11/6/2019 10:31 PM, Alan Grayson wrote:
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>>>> On Wednesday, November 6, 2019 at 11:20:23 PM UTC-7, Brent wrote:
>>>>>
>>>>>
>>>>> On 11/6/2019 9:00 PM, Alan Grayson wrote:
>>>>>
>>>>>
>>>>> On Wednesday, November 6, 2019 at 7:17:21 PM UTC-7, Brent wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 11/6/2019 4:44 PM, Alan Grayson wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Wednesday, November 6, 2019 at 3:46:54 PM UTC-7, Brent wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 11/6/2019 12:05 AM, Alan Grayson wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Tuesday, November 5, 2019 at 10:23:58 PM UTC-7, Brent wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On 11/5/2019 9:09 PM, Alan Grayson wrote:
>>>>>>>>
>>>>>>>> Crossing the horizon is a nonevent for the most part. If you try to
>>>>>>>>> accelerate so you hover just above it the time dilation and that you
>>>>>>>>> are in
>>>>>>>>> an extreme Rindler wedge will mean you are subjected to a torrent of
>>>>>>>>> radiation. In principle a probe could accelerate to 10^{53}m/s^2 and
>>>>>>>>> hover
>>>>>>>>> a Planck unit distance above the horizon. You would be at the
>>>>>>>>> stretched
>>>>>>>>> horizon. This would be almost a sort of singular event. On the other
>>>>>>>>> hand
>>>>>>>>> if you fall on an inertial frame inwards there is nothing unusual at
>>>>>>>>> the
>>>>>>>>> horizon.
>>>>>>>>>
>>>>>>>>> LC
>>>>>>>>>
>>>>>>>>
>>>>>>>> Do you mean that clock rates continue to slow as an observer
>>>>>>>> approaches the event horizon; then the clock stops when crossing, or
>>>>>>>> on the
>>>>>>>> event horizon; and after crossing the clock resumes its forward rate?
>>>>>>>> AG
>>>>>>>>
>>>>>>>>
>>>>>>>> He means the infalling clock doesn't slow down at all. Whenever
>>>>>>>> you see the word "clock" in a discussion of relativity it refers to an
>>>>>>>> *ideal
>>>>>>>> clock*. It runs perfectly and never speeds up or slows down.
>>>>>>>> It's called *relativity* theory because observers *moving relative*
>>>>>>>> to the clock *measure it* to run slower or faster than their
>>>>>>>> (ideal) clock.
>>>>>>>>
>>>>>>>> Brent
>>>>>>>>
>>>>>>>
>>>>>>> I see. So if for the infalling observer, his clock seems to be
>>>>>>> running "normally", but for some stationary observer, say above the
>>>>>>> event
>>>>>>> horizon, the infalling clock appears to running progressively slower as
>>>>>>> it
>>>>>>> falls below the EH, even if it can't be observed or measured. According
>>>>>>> to
>>>>>>> GR, is there any depth below the event horizon where the infalling
>>>>>>> clock
>>>>>>> theoretically stops?
>>>>>>>
>>>>>>>
>>>>>>> I just explained that *clocks never slow* in relativity examples.
>>>>>>> So now you ask if there's a place they stop??
>>>>>>>
>>>>>>> Brent
>>>>>>>
>>>>>>
>>>>>> I know, but that's not what I asked. Again, the infalling clock is
>>>>>> measured as running slower than a stationary clock above the EH. As the
>>>>>> infalling clock goes deeper into the BH, won't its theoretical rate
>>>>>> continue to decrease as compared to the reference clock above the EH?
>>>>>> How
>>>>>> slow can it get? AG
>>>>>>
>>>>>>
>>>>>> It *appears* (if the observer at infinity could see the extreme red
>>>>>> shift) to *asymptotically approach stopped *as it approaches the
>>>>>> event horizon. This is because the photons take longer and longer to
>>>>>> climb
>>>>>> out because they have to traverse more and more spacetime.
>>>>>>
>>>>>> Brent
>>>>>>
>>>>>
>>>>> I'm referring to two clocks; one at finite distance above the EH, and
>>>>> other infalling. Doesn't the infalling clock seem to run progressively
>>>>> slower from the POV of the other clock, as it falls lower and lower? AG
>>>>>
>>>>> I appears to run slower as seen by the distant observer.
>>>>>
>>>>> Brent
>>>>>
>>>>
>>>> As it goes deeper and deeper into the BH, does the clock ever appear to
>>>> STOP? AG
>>>>
>>>>
>>>> It doesn't appear at all when it passes the event horizon. It appears
>>>> to stop as it approaches the event horizon.
>>>>
>>>> Brent
>>>>
>>>
>>> I know it can't be observed as it falls through the EH. That's why I
>>> referred to clock "readings" after falling through as "theoretical".
>>>
>>>
>>> Well it doesn't make much sense to call observations theoretical when
>>> it's the theory that says they can't be observed.
>>>
>>> On the other hand, LC says falling through the EH is a non-event, as if
>>> the infalling clock behaves as we expect based on a clock entering a region
>>> of strong gravitational field. But let's say the clock appears to stop as
>>> it approaches the EH, which is what I thought. How do you reconcile this
>>> prediction, which is certainly weird? AG
>>>
>>>
>>> Reconcile it with what? It's a consequence of the metric which is
>>> derived from Einstein's equations. It's not as if it's some unexplained
>>> observation. It's not an observation at all. It's a theoretical
>>> prediction.
>>>
>>> Brent
>>>
>>
>> You don't see a problem with a theory that predicts a clock which stops
>> as seen by an outside observer, when the observer using the clock, which
>> measures proper time, must see it moving forward? AG
>>
>>
>> No. Why should it be a problem? You're watching the clock approach the
>> event horizon and the photons from it come further and further apart until
>> you have to wait seconds between photons, and then hours, and then days,
>> and years...why because they have to travel thru more spacetime. If it's a
>> rotating black hole, as most of them will be, each photon will have to
>> orbit many times on it's way out.
>>
>> Brent
>>
>
> If clock which is fixed some distance from the EH, and the BH isn't
> rotating, why must the photons traveling to the fixed observer have to
> travel progressively longer times? AG
>
>
> It's because there is more time to traverse. It's a matter of the metric.
>
> Brent
>
Doesn't this mean that the gravitational field of the BH becomes *infinite*
at the EH? How else could the red shift become so large for photons leaving
a clock at the EH, that from the pov of the fixed observer above the EH the
clock approaching the EH seems to stop? AG
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