The black hole information paradox is indeed a topic of much dispute. And one possible resolution is in fact that the information is somehow encoded in the Hawking radiation. But there has been no model proposed that describes how this could happen, or in what form the information would be encoded, or anything else of the sort. As of right now, it’s little more than a handwavy guess.
See this? This is why I think you’re conflating CMB with radioactive decay. The CMB are photons from the early years of the universe. That’s it.
The particles involved in Hawking radiation do not emit CMB photons. They are the radiation.
Background radiation is not a property of matter. This is your big hangup. It is a property of the universe. Neither the matter that entered the black hole, nor the matter that is evaporated have “background radiation”, though it may radiate on its own. It’s like you’re asking about the color of a song, and whether it has the same color before and after you sing it.
Or to put it another way, suppose you put a detector next to a lump of uranium. You detect radiation coming from the uranium. You can measure how much radiation the lump of uranium produces. You can do this for all sorts of things. Hot light bulbs. Radio transmitters. Lumps of ice. Rocks. All these things absorb and produce radiation.
It turns out that when you measure the radiation put out by all the things next to you…the rocks, light bulbs, lizards, radio stations, stars, lumps of uranium, and one by one eliminate them, you still find radiation. And this radiation is coming from every point in the universe in exactly the same amount. If you look at a star, the radiation gets more intense as you get closer. But not this leftover radiation.
Of course the background radiation can be blocked by all sorts of things, like the earth. So if you’re on Earth you can only detect the background radiation from the sky.
But the background radiation is just one of lots of other sources of radiation. So if you were near a black hole and could detect the Hawking radiation from it, you could also detect the background radiation. Just like if you were in a room with a hot light bulb and a radio transmitter you could detect both the light and the radio waves. The background radiation is just very very very very very very low energy radio waves. Or maybe they shouldn’t be called radio waves but something else. But they are are sort of like radio waves.
??? Certain of this? I would have said, yes, the CMB is an innate property of our cosmos’s space-time, and, if you could isolate a smallish chunk of the cosmos, it would be active with this radiation. Maybe not in a millimeter box, but in a light-year box.
(The CMB is brightest at around 2mm, so it would be darn tricky to observe it inside a 1mm box.)
(It’s still very different from the emission of particles near a black hole, so, to answer the OP, no, Hawking radiation will not resemble Cosmic Background Radiation. The former is usually individual particles, and the latter is a smooth, low-frequency EM radiation.)
Hawking radiation and the CMBR both have a black body spectra, but the CMBR is isotropic and homogeneous and Hawking radiation is not. This if you like is a product that the CMBR is radiation emitted at some stage in an isotropic and homogeneous spacetime, whereas Hawking radiation is a semiclassical property of a BH spacetime which at best will only have radial symmetry.
However the key ingredient needed for Hawking radiation is an event horizon (or I believe an apparent horizon will suffice) and our Universe, for each spatial location, has a cosmological event horizon. The difference is that a BH event horizon is the boundary of what can reach future null infinity, whereas a cosmological event horizon is the boundary of what can reach a certain spatial location. It is believed that there is radiation associated with our cosmological event horizon in a way that is analogous to the Hawking effect for a BH event horizon, but the difference between the two horizons (as stated in the previous sentence) makes the physicality of such radiation shakey.
Regardless though this “cosmic Hawking-Gibbons radiation” would have a wavelength much, much larger than the wavelength of the CMBR and so the two are not the same.
Not a one-millimeter box. A big box (however big you like), made of mesh with a one-millimeter spacing. And no, you wouldn’t observe any CMB radiation in that box: Where would it be coming from?
Unless the mesh temperature is below about 2.7K won’t it be emitting CMB ?
No, it would be emitting its own thermal radiation, which would bear no particular relationship to the CMB.
Just so I understand what you are saying : if I take your mesh box and have a very high resolution device inside that produces a spectrum - the spectrum will have only one peak corresponding to the temperature of the mesh and the spectrum peak corresponding to the CMBR will be missing ?
Are there any photons from the birth of the universe inside it?
Grey - I think you meant to ask Chronos that question. As far as I understand, you will always have photons from the birth of the universe everywhere.
Grey - thank you for bearing with me. So say a small region of the universe is made up of such escaped particles - can we call that part younger than the big bang ? If I did the spectral analysis in this region with an extremely sensitive instrument, will I see the peak (line) corresponding to the CMBR ?
If you build a nice big box instantaneously, it will contain CMBR for as long as it takes those photons to hit the walls of the box. Then there will be no more. The box will be empty of them. If you built your box from material at say 0.1K, there would be a background radiation with a spectrum corresponding to that temperature.
The CMBR is no different to the starlight we observe from very distant galaxies, it is just that it comes from a time in the universe’s history before even galaxies existed. So early that there was just pure very very hot matter. All we are seeing is the red-shifted image of that matter.
There is a gap in our ability to observe things between the CMBR and very old galaxies, but this is technological. The interest in infra red astronomy seeks to push our ability to see ancient galaxies back further. The Web Space Telescope is especially directed at this gap.
The point being that the CMBR is no more a signature of the Big Bang than anything else you see. It turns out that with some effort we can observe some interesting things about it, and those observations allow us to validate some theories and refute others about the nature of the universe’s origins. But there is nothing intrinsicly special here except that the CMBR is the oldest thing we can observe.
No it was to you.
Cool! (Jape intended…) I had thought the CMB was a property of space-time, and would be continued to be generated by empty space. I thought that it was due to the “temperature” of empty space. Empty space is about 3 degrees Kelvin, and thus radiates blackbody mw.
I’m being told no…but this is hard to swallow, as it contradicts what I’ve read so many places…
CMB photons are not emitted by space, they’re photons emitted just as the early universe became transparent. They raced off and have never bumped into anything since… Well except for whatever detects them.
Let’s take Chronos’s box and wait a few minutes to let any CMB photons in the box when it appeared to be absorbed or escape. So now you would never detect a CMB photon in the space but the place would be filled with virtual particle pairs appearing and disappearing. These are the particles that, when one is lost across an event horizon, make up Hawking radiation.
As I understand it (and this appears to be evolving!) yes, and yes. The particles emitted from a black hole (or near a massive atomic nucleus) would have a completely different spectrum than the cosmic background, but the cosmic background would still be observed in the same region as emitted Hawking radiation.
Sort of like… It’s daylight, and sunlight is everywhere – it’s on your roof, and your garden, and your car. Meanwhile, you have a microscopic black hole in your hand. It’s emitting radiation…but that radiation has no relationship to the sun’s heat-and-light radiation, which is all around you, including on your hand. Your hand has the unique benefit of both kinds of radiation.
ETA: I don’t like the phrasing “a region of the universe is made of such particles.” No: they’re within space-time. They do not “make up” new space-time. I think this may be a basic problem with how things are getting phrased here.
No. That portion of space-time is exactly as old as every other portion of space-time.
The individual particles are new, in the sense that particles often appear. The photons by which you are reading this are new and have just now appeared. Particles are not space-time. Radiation is not space-time. (Are particles=radiation? Unh-uh. Not touching that one. Go read a QM textbook.) You appear to want the two to be the same, but it’s not going to happen.
The confusion may come about from a simple mistake in tense. The CMBR does not come from everywhere. It came from everywhere. It stopped being created 14 billion years ago. But at that moment very part of the universe was emitting those photons. Right now you are made of particles that were once part of that super hot soup that created the CMBR. But a lot has happened in the universe since then.