Hawking radiation

[Q-reeus]

Spine issues? No. I just couldn't be bothered because you hadn't appeared to have read the Wikipedia article I linked to.

Really? Let's check for this time around. Date stamp of my #77 - 8:42AM. Date stamp your response in #80 - 11:02AM. Massive improvement - less than 3 hrs reaction time. But that's still weird - because you have been logged in all that interval. No don't bother trying to explain it. A uniquely Daecon thing I guess.

Exactly how did I "give myself away" by asking a question?

Given how long you have been here at SF and how many scores of times you must have been exposed (and not just here at SF) to the notion of HR from BH's, it's strikes me as, well, strange exposure to alleged mass-temperature relation was not long ago a boring familiarity. Akin to an adult asking where the North Pole is. But hey, that's just my opinion.

 

[Daecon]

I post from my Playstation Vita. I usually just turn the screen off when I'm doing something else, so perhaps the forum software just keeps me logged in regardless of inactivity. I'll have to check that.

Anyway, OnlyMe asked for a reference for black holes radiating a thermal spectrum, I linked to the Wikipedia article on black-body radiation as that reference. Then you somehow got the idea that I was claiming that black bodies were the same thing as black holes.

Maybe I just forgot that the temperature was inversely proportional to the mass, or maybe it never occurred to me to check. I don't remember. Either way, brucep corrected me without being condescending about it.

 

[The God]

Would Hawking radiation have a temperature of about 2.7 Kelvin, the same as the cosmic microwave background?

Great question Daecon and admirably answered by bruce.

This is called take away from scratch, not give away... The fun part is that both Daecon and Paddoboy have the uncanny ability of finding out who is wrong and who is right, (Empahsis on 'Who' not on what) without knowing abc of anything....

 

[The God]

'Onlyme'

(Bruceps comment for you)
"For somebody who doesn't know much about this science you sure have a lot of irrelevant opinions."


I feel sad for you on this, you are trying your level best to come in the hatch of Brucep (Paddo, Daecon already are in), no need man, both Paddo and Daecon are kids in science and maths better off with their playstations, Brucep is abusive and uncivilised fool. You are much better off out of that hatch.

 

[Q-reeus]

I post from my Playstation Vita. I usually just turn the screen off when I'm doing something else, so perhaps the forum software just keeps me logged in regardless of inactivity. I'll have to check that.

I see. Fair enough then. AFAIK one remains logged in until choosing otherwise, though there may be an automatic boot-out time limit.

Maybe I just forgot that the temperature was inversely proportional to the mass, or maybe it never occurred to me to check. I don't remember. Either way, brucep corrected me without being condescending about it.

My reaction was tempered by noting your predominantly hostile, negative postings. 'Putting in the boot' seems to be a recreational activity for you. I dislike tearing down attitudes. Intelligent, constructive input, technically right or wrong, gets a far warmer response from myself.

 

[Daecon]

both Paddo and Daecon are kids

Are you Rajesh?

 

[hardalee]

I think I have solved my misunderstanding. The particle pair is created inside the BH. One tunnels out causing energy loss to the BH and the other remains inside. Both particles have positive energy, no negative energy is required.

Thanks for the suggestions.

 

[paddoboy]

'Onlyme'

(Bruceps comment for you)
"For somebody who doesn't know much about this science you sure have a lot of irrelevant opinions."


I feel sad for you on this, you are trying your level best to come in the hatch of Brucep (Paddo, Daecon already are in), no need man, both Paddo and Daecon are kids in science and maths better off with their playstations, Brucep is abusive and uncivilised fool. You are much better off out of that hatch.

You are obviously still fuming in being once again, shown to be wrong...me, bruce, now Deacon and OnlyMe...how about James, or anyone else that dares question the antics of two anti GR science cranks in this thread. You did though forget Professor Unhru and Professor Link, and Hamilton and quite a few others who have over a number of months shown you to be nothing more than a total fraudster.
Again my friend, your antics will in time be judged by your peers, just as mine will, and bruce's and OnlyMe.
Now don't forget to keep clinging to Qreeus's apron strings! You would both be lost without each other.

 

[paddoboy]

My reaction was tempered by noting your predominantly hostile, negative postings. 'Putting in the boot' seems to be a recreational activity for you. I dislike tearing down attitudes. Intelligent, constructive input, technically right or wrong, gets a far warmer response from myself.

You proceed under the mistaken idea that anyone really cares about what you think or believe.

 

[paddoboy]

Would Hawking radiation have a temperature of about 2.7 Kelvin, the same as the cosmic microwave background?

So they are really cold generally. With a little algebra you could predict the mass where the Hawking is around the 2.7 K.

Or WIKI may help!
With such an interesting question Deakon, and bruce's answer, I found this.....
https://en.wikipedia.org/wiki/Hawking_radiation
A black hole of one solar mass (M☉) has a temperature of only 60 nanokelvin (60billionths of a kelvin); in fact, such a black hole would absorb far more cosmic microwave background radiation than it emits. A black hole of 4.5 × 10*22 kg (about the mass of the Moon, or about 13 micrometers across) would be in equilibrium at 2.7 kelvin, absorbing as much radiation as it emits. Yet smaller primordial black holes would emit more than they absorb and thereby lose mass.

Professor Merrifield gives a reasonably simple assessment at post 78.

 

[paddoboy]

http://arxiv.org/abs/1401.6612

Besides the excellent reply from Professor Unruh himself, I think it is appropriate to post the Abstract of his paper that bruce gave,

Has Hawking radiation been measured?
It is argued that Hawking radiation has indeed been measured and shown to posses a thermal spectrum, as predicted. This contention is based on three separate legs. The first is that the essential physics of the Hawking process for black holes can be modelled in other physical systems. The second is the white hole horizons are the time inverse of black hole horizons, and thus the physics of both is the same. The third is that the quantum emission, which is the Hawking process, is completely determined by measurements of the classical parameters of a linear physical system. The experiment conducted in 2010 fulfils all of these requirements, and is thus a true measurement of Hawking radiation

 

[brucep]

Ah, I see. So supermassive black holes are supercold.

I post from my Playstation Vita. I usually just turn the screen off when I'm doing something else, so perhaps the forum software just keeps me logged in regardless of inactivity. I'll have to check that.

Anyway, OnlyMe asked for a reference for black holes radiating a thermal spectrum, I linked to the Wikipedia article on black-body radiation as that reference. Then you somehow got the idea that I was claiming that black bodies were the same thing as black holes.

Maybe I just forgot that the temperature was inversely proportional to the mass, or maybe it never occurred to me to check. I don't remember. Either way, brucep corrected me without being condescending about it.

I wasn't intending to correct you. I just wanted to answer your question because I know you're interested in this stuff. BTW it's very interesting to read about black hole thermodynamics. Jacob Bekenstein. Who passed away this December. When Hawking made his theoretical discovery for black holes radiating in the black body spectrum he was thinking he was going show some of the Bekenstein physics was theoretically incorrect. I could conceive of Hawking, Bekenstein, and Unruh sharing a Nobel for this physics.
https://en.m.wikipedia.org/wiki/Black_hole_thermodynamics

 

[brucep]

I think I have solved my misunderstanding. The particle pair is created inside the BH. One tunnels out causing energy loss to the BH and the other remains inside. Both particles have positive energy, no negative energy is required.

Thanks for the suggestions.

Read what Professor Unruh said. He explains why the Hawking flux falling back to the event horizon is negative. What was interesting to me was he discussed the dynamics of the entire flux rather than just a component of it.

 

[brucep]

Besides the excellent reply from Professor Unruh himself, I think it is appropriate to post the Abstract of his paper that bruce gave,

Has Hawking radiation been measured?
It is argued that Hawking radiation has indeed been measured and shown to posses a thermal spectrum, as predicted. This contention is based on three separate legs. The first is that the essential physics of the Hawking process for black holes can be modelled in other physical systems. The second is the white hole horizons are the time inverse of black hole horizons, and thus the physics of both is the same. The third is that the quantum emission, which is the Hawking process, is completely determined by measurements of the classical parameters of a linear physical system. The experiment conducted in 2010 fulfils all of these requirements, and is thus a true measurement of Hawking radiation

The three separate legs. One of the most informative abstracts I've read.

 

[brucep]

Are you Rajesh?

It's kinda unique for somebody to create a different identity just to get away from himself [everything Rajesh]. Usually it's a sock puppet trying to evade some kind of sanction. Either way they always forget to quit spouting their brand of crankism. If we were all in a room it would be stamped on the collective crank forehead.

 

[Daecon]

It was the "kid" line that made me suspicious.

 

[Daecon]

I wasn't intending to correct you.

I didn't mean it in any kind of negative way. I had forgotten a basic fact of black hole thermodynamics, and you didn't call me an idiot. Thanks for that.

No offence intended and no offence taken.

 

[Q-reeus]

I think I have solved my misunderstanding. The particle pair is created inside the BH. One tunnels out causing energy loss to the BH and the other remains inside. Both particles have positive energy, no negative energy is required.

Thanks for the suggestions.

Sure you haven't jumped the gun there? All believers in HR afaik consider only the case of pair-creation, or equivalent description, happening exterior to EH. So yours seems to be a hardalee-unique conjecture. And I'm not seeing consistency to it. If you acknowledge pairs are created with net +ve energy, where do you get an overall and *detailed* book-keeping energy balance? Seems to me your idea has the BH growing in mass while simultaneously ejecting +ve energy quanta.
While I think not, BH as perpetuum mobile is actually preferable to the implied Unruh picture of real -ve energy (negative gravitational mass!) quanta 'falling' into a BH.

 

[paddoboy]

The three separate legs. One of the most informative abstracts I've read.

Agreed. The Professor gave a comprehensive outline of Hawking radiation.

 

[KilljoyKlown]

The Universe it appears, is a weird and wonderful place.
I agree, it sounds far fetched on face value, but isn't this the case with most of quantum mechanics?
I suppose also a couple of centuries ago, the non absolute nature of space and time would have also seemed far fetched.
I've read two books on string theory and it's derivitives, and many scientists describe it as beautifully mathematically represented.
But talking of 6, 10 or more dimensions is still hard to fathom.
And despite a hell of a lot of anti string propaganda that's going round at the moment, the problem really is one of technology or lack thereof, and our inability to observe at such levels.
Thinking about this stuff makes my head ache...
Irrespective of my head ache but, we do have evidence that it certainly takes place...The Casimir effect.

The particle pair creation scenario is not violating any conservation law, because they are only virtual, existing for less than the Planck time.
Occurring at such levels, and within the limit of the uncertainty principal, means that no law of matter/energy of which we are more familiar is violated.
Far fetched? hard to understand? agreed.....but the Casimir effect supports it.

Sorry for the delay in responding. Let's assume that virtual particles are real. How would that help explain the current theory of the expanding universe?

I would say that constant interaction of virtual particles would create a slight positive pressure to our local universe. This positive pressure is so very slight that it is basically undetectable, But as you start putting millions of light years together the expanding effect of our space starts to become noticeable.