Physicists observationally confirm Hawking’s black hole theorem for first time
1–10 of 73 posts
Re: Physicists observationally confirm Hawking’s black hole theorem for first time
#2So black holes can't evaporate? How does Hawking radiation works if the back hole are has to stay the same?
Re: Physicists observationally confirm Hawking’s black hole theorem for first time
#3Alright, I'm confused. How does this square with Hawking radiation? How can a black hole shrink without shrinking?
The article mentions both in the context that they are reconciled but not how they are reconciled.
Re: Physicists observationally confirm Hawking’s black hole theorem for first time
#4Alright, I'm confused. How does this square with Hawking radiation? How can a black hole shrink without shrinking? The article mentions both in the context that they are reconciled but not how they are reconciled.
They're not reconciled, it's just garbage reporting.
The 'area theorem' they are referring to was by Bekenstein and others, not Hawking. It's basically the equivalent of the second law of thermodynamics for black holes (dA/dt>=0 instead of dS/dt>=0). Hawking's insight was that this formula was wrong and the area could decrease due to radiation.
Re: Physicists observationally confirm Hawking’s black hole theorem for first time
#5Alright, I'm confused. How does this square with Hawking radiation? How can a black hole shrink without shrinking? The article mentions both in the context that they are reconciled but not how they are reconciled.
Exactly what I came here to ask. Is Hawking's theory that the area never decreases or that it does not decrease in a black hole merger as was tested here. "central law for black holes predicts that the area of their event horizons — the boundary beyond which nothing can ever escape — should never shrink" this seems to imply the former to me.
Does that mean with Hawking radiation the black hole effectively evaporates by loosing mass (?) from the inside without the boundary area never shrinking?
Re: Physicists observationally confirm Hawking’s black hole theorem for first time
#6Anyone can think of any practical effect this might have or is this something that at the moment seems to have only scientific relevance.
Re: Physicists observationally confirm Hawking’s black hole theorem for first time
#7So black holes can't evaporate? How does Hawking radiation works if the back hole are has to stay the same?
I think it's more a case of the press release people wanting to call it a unqualified "law", as far as we know black holes do evaporate slowly.
But there remains is a statement about how the final area relates to the area of the two merging black holes.
Re: Physicists observationally confirm Hawking’s black hole theorem for first time
#8so they're 95% sure.. how do they even come up with a figure like that? they didn't bother saying. might be equivalent to 'give or take a few trillion tonnes'
Re: Physicists observationally confirm Hawking’s black hole theorem for first time
#9Alright, I'm confused. How does this square with Hawking radiation? How can a black hole shrink without shrinking? The article mentions both in the context that they are reconciled but not how they are reconciled.
They're not reconciled, it's just garbage reporting. The 'area theorem' they are referring to was by Bekenstein and others, not Hawking. It's basically the equivalent of the second law of thermodynamics for black holes (dA/dt>=0 instead of dS/dt>=0). Hawking's insight was that this formula was wrong and the area could decrease due to radiation.
It is a pity about the reporting.
But it is a fascinating area of research. I never expected that we could measure gravitational waves in our life time.
Re: Physicists observationally confirm Hawking’s black hole theorem for first time
#10Alright, I'm confused. How does this square with Hawking radiation? How can a black hole shrink without shrinking? The article mentions both in the context that they are reconciled but not how they are reconciled.
Yes, black holes shrink because of Hawking radiation, but in reality this doesn't really happen because black holes are much colder than their surrounding space. Actually they are the coldest objects in nature. Stellar black holes have a temperature of a few Nanokelvins and the average temperature of space is 2.7 K so there's a net gain of energy/mass from absorbed photons from CMB radiation vs emitted photons via Hawking radiation.
In order to have a higher temperature than the CMB a black hole would have to be really small with a mass about half of that of the moon.