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 g00ru
lit pants tit licker
 
Registered: 08/09/07
Posts: 21,088
Loc: georgia, us
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 Pop Physics Questions 
#8648081 - 07/17/08 05:27 PM (15 years, 8 months ago) |
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I've been reading A Brief History of Time lately, I understand most of it but I do have a few questions, and if any of you physics geniuses feel like answering em that would be cool. I'm probably just missing something entirely, so in all probability the problem will be with my questions more than anything else, but wutevah...
1. When talking about black holes, Hawking talks about how all light rays at the event horizon must be parallel to each other by definition. From this we can see that the area must never decrease. But later, when he talks about Hawking radiation, he says that black holes will eventually "evaporate" due to the radiation of particles and the negative mass that enters the black hole. So my questions about this are:
a) I thought that the area of a black hole was directly related to it's mass, i.e. black holes of the same mass will always have the same area. But if black holes can lose mass but not area, doesn't this contradict?
b) If the black hole does eventually completely evaporate, then it has NO area, and either way that violates what Hawking says about light rays. So what's up with that?
2. When he talks about the modern inflationary model, where certain spin 0 fields in early regions of the universe cause it to inflate. One of these regions would be the observable universe. Is he just using Occam's Razor and disregarding the parts of the universe we can't observe, or is he still somehow inferring that inflation applies to the entire universe?
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 DieCommie
Registered: 12/11/03
Posts: 29,258
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Re: Pop Physics Questions [Re: g00ru]
#8650747 - 07/18/08 11:47 AM (15 years, 8 months ago) |
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Well, Im no expert in cosmology or black holes... but this seems funky to me...
Hawking talks about how all light rays at the event horizon must be parallel to each other by definition.
Really? hmmmm
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Stonehenge
Alt Center
Registered: 06/20/04
Posts: 14,850
Loc: S.E.
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Re: Pop Physics Questions [Re: DieCommie]
#8651823 - 07/18/08 04:10 PM (15 years, 8 months ago) |
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It's all just theory, don't take it too seriously. Black holes don't really have any area or volume, according to some thoeries. They are just points in space where matter has collapsed on itself.
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g00ru
lit pants tit licker
Registered: 08/09/07
Posts: 21,088
Loc: georgia, us
Last seen: 5 years, 4 months
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Re: Pop Physics Questions [Re: DieCommie]
#8652120 - 07/18/08 05:37 PM (15 years, 8 months ago) |
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Quote:
DieCommie said:
Well, Im no expert in cosmology or black holes... but this seems funky to me...
Hawking talks about how all light rays at the event horizon must be parallel to each other by definition.
Really? hmmmm
If they weren't parallel they would interfere with each other and fall into the black hole. The analogy used is that two people running away from the cops run into each other, and they are both caught. Idk if it's true or not but he never recants it.
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