Hawking Radiation: Theory & Acceptance in Quantum Physics

In summary: The whole thing feels rushed and jumbled together.In summary, the article discusses Hawking radiation and its possible link to quantum gravity. It suggests that if loop gravity is correct, then black holes will emit thermal Hawking radiation, which will help to prove QG. The article is not well written and feels rushed.
  • #1
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In cosmology Hawking radiation, is often quoted as a way Black Holes evaporate.
AFAIK there is no way this can be tested other than getting up close to a BH,
so is HR accepted in the quantum phys world, as a good model?
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  • #2
What we need to do to observe HR is, as you say, to watch black holes evaporate. How can we do this? As the Wikipedia article says, large ones have a very low temperature, so have a negative net energy output.

We need small black holes.

Luckily enough there's going to be a new particle accelerator turned on in a couple of years - LHC (the Large Hadron Collider) at CERN. This will accelerate protons towards each other at 7TeV a piece - 14TeV centre of mass energy.

Unfortunately the modeling of black hole creation is pretty much a hand waving exercise as quantum gravity isn't at all well formed. However, there are simulations that can be run using latest theory that model black hole production at an accelerator. The main one used is Charibdis - http://www.ippp.dur.ac.uk/montecarlo/leshouches/generators/charybdis/

Whether or not a black hole is produced depends on the Planck Scale, something we don't know. The Planck Scale is in turn reliant on the number of hidden dimensions, which we don't know.

So, if there's a low Planck scale, many black holes will be produced at LHC, and they will (judging by a friend's study that has just been completed) light up the detector like a christmas tree.

However, if the Planck scale is large, there will be very few black holes produced (if it means anything to you, in some cases they were seeing production cross sections of order 10^-9pb - that's not very much... A Higgs Self coupling decay, by comparison, has cross section of order 20fb for higgs mass 120GeV, and that's a pretty rare decay), like one per two universe time scales or something silly like that.

So, we might see black holes at LHC, then again we might not. Depends on some fundamental knowledge we don't possess!

Edit: Original Question

Hawking Radion makes sense mathematically. If you look at particle pairs being created and annihilated from the vacuum, the maths works in terms of one pair from the particle being 'sucked in' to the black hole, where the massive gravitational forces involve essentially relativistically reverse the energy of the particle, so that energy is conserved. Otherwise you'd wouldn't have conservation of energy.

Hope this helps.
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  • #3
Thanks for that JAMES.

Luckily enough there's going to be a new particle accelerator turned on in a couple of years - LHC (the Large Hadron Collider) at CERN. This will accelerate protons towards each other at 7TeV a piece - 14TeV centre of mass energy.

So a proof of QG may come from CERN? Seems that HR is dependant on
many things so far unknown.

sorry i do not know the units at bottom of post.
  • #4
"picobarn".[itex] 1pb=10^{-40}m^{2}[/itex].

  • #5

A barn is a unit of area, abbreviated mostly as "bn", equal to 10−28 m2. Although not an official SI unit, it is widely used by nuclear physicists, since it is convenient for expressing the cross sectional area of nuclei and nuclear reactions. A barn is approximately equal to the area of a uranium nucleus. The etymology is clearly whimsical -- the unit is said to be "as big as a barn" compared to the typical cross sections for nuclear reactions.
  • #6
Yes, a barn can (very roughly) be taken as a representation of the probability of a certain decay process occurring. It's historically based in scattering and fixed target experiments.

I wouldn't say a proof of QG will come from LHC, just that we might see what looks like black holes evaporating, dependant on lots of things (backgrounds, relative intensities, cross sections etc etc). How this links to QG I'm not entierly sure, not being an expert on it... My work recently has been looking at techniques for more accurate event reconstruction in linear collider vertex detectors, but as I say I've picked up a fair bit of info on black holes at LHC from a friend who's been looking into them.
  • #7
James may i give you this,
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  • #8
You may. Interesting paper - would you like me to comment on it in some way?
  • #9
James Jackson said:
You may. Interesting paper - would you like me to comment on it in some way?
Please, i am interested in the possibility that HR will give a signature of
QG in future cern experiments. I only know what i have read an could
have the wrong end of the stick.
  • #10
What the paper seems to be saying is that if loop gravity is a correct theory (and I know nothing about it...) then macroscopic black holes will emit thermal Hawking Radiation, and not some horrifically over quantised spectrum that had been previously derived using a niaeve method.

As a sidenote, the curve you get from Hawking radiation resembles a black body curve very closely, except there are small pertubations due to things called grey body factors.

So... If we see black hole evaporation at the LHC, and we can separate it from backgrounds etc, we should be able to get a curve representing the Hawking Radiation, in which case, following that paper, it looks like a point for the predictions of quantum loop gravity.

That's my take on it anyway, it's not an overly complex paper at all, so I think I've got the right end of the stick.
  • #11
Thankyou JAMES

Some thing to look for in future papers i hope.
  • #12
Got to get the accelerator and detectors working first... They've started lowering the accelerator magnets now, which is nice.

Related to Hawking Radiation: Theory & Acceptance in Quantum Physics

1. What is Hawking radiation?

Hawking radiation is a theoretical phenomenon proposed by physicist Stephen Hawking in the 1970s. It suggests that black holes emit radiation due to quantum effects near the event horizon, the point of no return for matter and energy entering the black hole.

2. How does Hawking radiation work?

Hawking radiation is thought to occur when pairs of particles, one with positive energy and one with negative energy, are created near the event horizon of a black hole. The negative energy particle falls into the black hole, while the positive energy particle is able to escape and become real, detectable radiation.

3. Is Hawking radiation accepted in the field of quantum physics?

Yes, Hawking radiation is widely accepted in the field of quantum physics. It has been supported by mathematical calculations and has also been indirectly observed in the form of black hole evaporation.

4. Why is Hawking radiation important?

Hawking radiation has had a significant impact on our understanding of black holes and the nature of space and time. It also plays a crucial role in the study of quantum gravity and the unification of the theories of general relativity and quantum mechanics.

5. Can Hawking radiation be observed directly?

No, Hawking radiation has not yet been observed directly. It is a very weak form of radiation and is only expected to be measurable from very small black holes, which are not currently known to exist. However, indirect evidence for Hawking radiation has been observed and further research is being conducted to find ways to detect it directly.

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