As white hole should act with positive radiation pressure, shouldn't black hole act with negative?

[Jarek Duda]

T/CPT symmetric analog of black hole in Kruskal–Szekeres coordinates is white hole, which only allows photons to cross horizon outside, hence pushing objects around with EM - act with positive radiation pressure p=<ExH>/c vectors outside, absorption equation increasing the number of excited atoms (N2).
If so, shouldn't black hole symmetrically act with negative radiation pressure - pull objects around with EM by p=<ExH>/c radiation pressure vectors pointing inside, act with stimulated emission equation decreasing the number of excited atoms (N2)?

Such looking necessary effect of black hole could be slightly easier to observe than Hawking radiation, maybe even look below the horizon - would need e.g. telescope with excited sensor, monitoring its population - testing if it doesn't deexcite faster than usual by stimulated emission e.g. from black hole.

 

[DaveC426913]

If I understand correctly, you're looking at a hypothetical, never-seen, never-expected-to-be-seen mathematical object to guide us in modeling the real, physical, observed objects?

Shouldn't that modeling be the other way around?

 

[Jarek Duda]

I use white holes here only to better understand black holes - realizing that they should act with positive radiation pressure outside, symmetry says that black holes should act with with negative - like applying T symmetry to marine propeller situation:



Hydrodynamics is mathematically very close to EM, allowing such marine propeller analog:



White holes are allowed theoretically, and e.g. if there was Big Bounce I would expect symmetric: white holes before (?) ... so maybe could be also there before potential collapse of our Universe in far future (?) ... so, while sure highly unlikely, personally I wouldn't be surprised if observing them in some future ...

 

[Jarek Duda]

Including that while white holes should act with positive radiation pressure, black holes should act with negative radiation pressure, might resolve the black hole information paradox (?) - showing there was a lot of information exchange before reaching the end of evaporation.

https://en.wikipedia.org/wiki/Black_hole_information_paradox :

Hawking's calculation suggests that the final state of radiation would retain information only about the total mass, electric charge and angular momentum of the initial state. Since many different states can have the same mass, charge and angular momentum, this suggests that many initial physical states could evolve into the same final state.

 

[TheVat]

I couldn't relate the recent research on negative radiation pressure to BH theory.

The momentum and radiation pressure of light in negative-index metamaterials (NIMs) are commonly expected to reverse their direction from what is observed for normal materials. The negative refraction and inverse Doppler effect of light in NIMs have been experimentally observed, but the equally surprising phenomenon, the negative radiation pressure of light, still lacks experimental verification. We show by simulating the exact position- and time-dependent field-material dynamics in NIMs that the momentum and radiation pressure of light in NIMs can be either positive or negative depending on their subwavelength structure. In NIMs exhibiting negative radiation pressure, the negative total momentum of light is caused by the sum of the positive momentum of the electromagnetic field and the negative momentum of the material. The negative momentum of the material results from the optical force density, which drives atoms backward and reduces the local density of atoms at the site of the light field. In contrast to earlier works, light in NIMs exhibiting negative radiation pressure has both negative total momentum and energy. For the experimental discovery of the negative radiation pressure, one must carefully design the NIM structure and record the joint total pressure of the field and material momentum components.

Negative radiation pressure in metamaterials explained by light-driven atomic mass density rarefication waves - Scientific Reports

The momentum and radiation pressure of light in negative-index metamaterials (NIMs) are commonly expected to reverse their direction from what is observed for normal materials. The negative refraction and inverse Doppler effect of light in NIMs have been experimentally observed, but the equally...

www.nature.com

Metamaterials do not exist in nature.

 

[Jarek Duda]

https://en.wikipedia.org/wiki/Radiation_pressure is just p=<ExH>/c vector - positive if pointing toward given surface, negative if outward.
T symmetry switches white and black hole, reverses H magnetic field, hence also between positive and negative pressure - exactly like in hydrodynamical setting e.g. with marine propeller above, or similar EM: https://en.m.wikipedia.org/wiki/Barnett_effect
From atomic perspective, this T symmetry switches between absorption equation increasing the number of excited atoms, and stimulated emission equation decreasing the number of excited atoms (requires they were initially excited) using formulas above from https://en.wikipedia.org/wiki/Stimulated_emission#Mathematical_model
Here are more articles: https://scholar.google.pl/scholar?q=negative radiation pressure

 

[exchemist]

I use white holes here only to better understand black holes - realizing that they should act with positive radiation pressure outside, symmetry says that black holes should act with with negative - like applying T symmetry to marine propeller situation:

View attachment 7042

Hydrodynamics is mathematically very close to EM, allowing such marine propeller analog:

View attachment 7043

White holes are allowed theoretically, and e.g. if there was Big Bounce I would expect symmetric: white holes before (?) ... so maybe could be also there before potential collapse of our Universe in far future (?) ... so, while sure highly unlikely, personally I wouldn't be surprised if observing them in some future ...

Don’t understand the analogy. Marine propellors aren’t symmetrical. Running them astern is less efficient than running them ahead.

 

[Jarek Duda]

Sure practical marine propellers are probably optimized for forward propulsion, but could be made more symmetric, and boats have such reversed gear (e.g. https://www.yachtingmonthly.com/gear/how-it-works-marine-gearboxes-and-clutches-94640 ).

Anyway, this EM-hydro analogy is just for intuitions here: that as white hole should create positive radiation pressure, black hole being its T/CPT analog should symmetrically create negative ...
Also resolving https://en.wikipedia.org/wiki/Black_hole_information_paradox - while naively there is no interaction, such symmetric negative radiation pressure is a continuous information exchange.

Simplified diagram:

 

[exchemist]

Sure practical marine propellers are probably optimized for forward propulsion, but could be made more symmetric, and boats have such reversed gear (e.g. https://www.yachtingmonthly.com/gear/how-it-works-marine-gearboxes-and-clutches-94640 ).

Anyway, this EM-hydro analogy is just for intuitions here: that as white hole should create positive radiation pressure, black hole being its T/CPT analog should symmetrically create negative ...
Also resolving https://en.wikipedia.org/wiki/Black_hole_information_paradox - while naively there is no interaction, such symmetric negative radiation pressure is a continuous information exchange.

Simplified diagram:

View attachment 7044

I thought white holes had been dismissed as a mathematical fiction, haven’t they?

Or are you just interested in some of the crazy properties they would have if they were real?j

 

[Jarek Duda]

To consider symmetries, you don't need to have actual realizations all the possibilities - white hole is used only as a remainder that there should be interactions, currently neglected ... what leads to crucial issues like black hole information paradox.

Just appeared fresh Event Horizon Telescope news - showing surprising amounts of jets ... no longer surprising if thinking about this marine propeller analogy: white holes should form vortices going out, so symmetrically black holes should form vortices coming in.

New EHT Images Reveal Unexpected Polarization Flips at M87* | Event Horizon Telescope

eventhorizontelescope.org

"magnetized plasma swirling near the event horizon is far from static; it’s dynamic and complex, pushing our theoretical models to the limit.”

 

[Jarek Duda]

For better intuition, it is good to imagine vacuum cleaner with both suction and blow mode, switched by T/CPT symmetry - white hole has lightcones directed outside, hence would only blow also electromagnetically (positive radiation pressure outside - sucked from inside) ... and black hole as its T/CPT symmetry is not "doing nothing" but should have symmetric suction, also electromagnetic (negative radiation pressure outside - positive inside).

 

[Jarek Duda]

I have talked with experienced astrophysicist that such black hole negative radiation pressure should stimulate emission from surrounding matter toward it, increasing such directional emission, at cost of spontaneous which is isotropic ... and he confirmed - that all these BH images are "from behind" - not of isotropic radiation, but of bent traveling toward BH - exactly as expected from negative radiation pressure.

If so, we could also directly observe such negative radiation pressure (p=<ExH>/c) - if continuously exciting and monitoring population of sensor of telescope - technically challenging, but seems easier than observing Hawking radiation, e.g. to see lone BH now observable only by gravitational lensing (like recent https://www.quantamagazine.org/a-si...ewrites-the-history-of-the-universe-20250912/ ) ... and brings hope to finally look below the horizon.

 

[Jarek Duda]

A few more experimental arguments that as white holes should heat around, black hole should symmetrically cool around:
- https://arxiv.org/pdf/2509.10615 : "SMBHs are expected to be surrounded by progressively hotter gas the closer one approaches to the black hole (...) Surprisingly, our closest SMBH, Sagittarius A* (Sgr A∗) residing in the center of the Milky Way galaxy, seems to have no currently active jet or wind"
- faster growth as pulling not only gravitationally, but also EM with negative radiation pressure, e.g. https://www.nasa.gov/missions/chandra/nasas-chandra-finds-black-hole-with-tremendous-growth/
- nearly non-observation of https://en.wikipedia.org/wiki/Intermediate-mass_black_hole - such cooling could help with,

- and the best one: turns out in all these EHT black hole simulations they assume temperature of electrons there is much lower than of ions: their ratio T_i/T_e = R goes up to 160 - white hole heating/black hole cooling would be especially for electrons, exactly as they see, also regarding position:
E.g. from https://arxiv.org/pdf/2510.08848 : "midplane is brightest at Rhigh ≈ 10. The dominant emission region becomes slightly more diffuse and off-midplane for Rhigh = 40. Near Rhigh = 160, the emitting region shifts significantly toward higher latitudes and toward the jet-disk boundary".

 

[billvon]

A few more experimental arguments that as white holes should heat around, black hole should symmetrically cool around:

Nope. Due to Hawking radiation, black holes emit radiation that will heat local matter - and they have positive radiation pressure as well. (Gravity, of course, vastly overpowers that force.)

 

[Jarek Duda]

But imagine its symmetric version: white hole - it would act in many ways on surrounding (different than Hawking radiation), e.g. with heating/excitation - so why symmetrically black hole shouldn't cool/deexcite surrounding?
E.g. leading to much lower temperature of electrons than ions, as they require in EHT simulations (up to 160 times lower).

Another perspective regarding potential observation: imagine resonator in amplifier of radiotelescope is excited e.g. thermally - in theory it should allow to radiate such energy through antenna.
However, such radiated wave would be very difficult to absorb, usually could go literally to infinity - it means in CPT perspective there would be no mechanism for its creations - so could it radiate thermally?
But if there would be absorber in this direction (like black hole), it could emit such e.g. thermal photons - seen as "negative signal".

So the big question is if photon can be emitted if it will never be absorbed?
QFT, CPT symmetry suggest it cannot - what should allow to find absorbers like black holes as "negative signals".

 

[exchemist]

But imagine its symmetric version: white hole - it would act in many ways on surrounding (different than Hawking radiation), e.g. with heating/excitation - so why symmetrically black hole shouldn't cool/deexcite surrounding?
E.g. leading to much lower temperature of electrons than ions, as they require in EHT simulations (up to 160 times lower).

Another perspective regarding potential observation: imagine resonator in amplifier of radiotelescope is excited e.g. thermally - in theory it should allow to radiate such energy through antenna.
However, such radiated wave would be very difficult to absorb, usually could go literally to infinity - it means in CPT perspective there would be no mechanism for its creations - so could it radiate thermally?
But if there would be absorber in this direction (like black hole), it could emit such e.g. thermal photons - seen as "negative signal".

So the big question is if photon can be emitted if it will never be absorbed?
QFT, CPT symmetry suggest it cannot - what should allow to find absorbers like black holes as "negative signals".

View attachment 7127

This was answered, by me and others better qualified, on the .net forum. You are wrong. QFT does not require an absorber for every photon emitted. You are mixing up real, free photons with the virtual photons - which are not photons - that in QFT mediate the EM interaction between charged entities.

You are pushing CPT symmetry beyond what is legitimate, in order to sustain this notion of yours about white holes.

 

[billvon]

But imagine its symmetric version: white hole - it would act in many ways on surrounding (different than Hawking radiation), e.g. with heating/excitation - so why symmetrically black hole shouldn't cool/deexcite surrounding?

Nope. Most things in nature are not symmetric. The laws of thermodynamics, for example. Entropy increases over time, even for two "opposite" objects.

But it doesn't even matter if you understand that or not. We've observed black holes from far away. They have positive radiation pressure, and they heat objects in their vicinity. So your theory is falsified.

 

[Jarek Duda]

https://en.wikipedia.org/wiki/CPT_symmetry says that equations governing physics have to be CPT symmetric - of QFT, also general relativity.
So asymmetry needs to be only of concrete solution we live in - like lake surface symmetric in equations, to which we throw a rock - breaking symmetries in solutions.

To understand our asymmetries, it is good to think about Big Crunch hypothesis, recently made more likely due to DESI findings (e.g. https://news.cornell.edu/stories/20...-33-billon-years-universe-will-end-big-crunch ).
Its thermodynamical parameters like densities should be very similar to of Big Bang, so should be also entropy - what means it finally will start decreasing: 2nd law of thermodynamics will be reversed.

So Big Crunch would be basically time-revered Big Bang, hence e.g. as now there is tendency to form black holes, before Big Crunch there should be tendency to form our white holes ... which might survive to our time, as very lone shining points.

Another interesting asymmetry is that circulating electron now loses energy, but in CPT perspective it is still circulating charge ... this asymmetry again has to be in solution, like that there are more absorbers in our future, than emitters in our past.

But it doesn't even matter if you understand that or not. We've observed black holes from far away. They have positive radiation pressure, and they heat objects in their vicinity.

I think you are talking about the matter falling on them?
The black hole itself is only pulling - gravitationally, but should be also EM by negative radiation pressure - symmetrically to positive by white hole.

exchemist , regarding "QFT does not require an absorber for every photon emitted"
https://en.wikipedia.org/wiki/S-matrix#Interaction_picture says probability of scenario like photon exchange is <psi_f | U | psi_i> - requires both initial conditions psi_i like initial excitation of emitter, but also psi_f like absorber ... what is the probability of such scenario without the latter?

 

[exchemist]

https://en.wikipedia.org/wiki/CPT_symmetry says that equations governing physics have to be CPT symmetric - of QFT, also general relativity.
So asymmetry needs to be only of concrete solution we live in - like lake surface symmetric in equations, to which we throw a rock - breaking symmetries in solutions.

To understand our asymmetries, it is good to think about Big Crunch hypothesis, recently made more likely due to DESI findings (e.g. https://news.cornell.edu/stories/20...-33-billon-years-universe-will-end-big-crunch ).
Its thermodynamical parameters like densities should be very similar to of Big Bang, so should be also entropy - what means it finally will start decreasing: 2nd law of thermodynamics will be reversed.

So Big Crunch would be basically time-revered Big Bang, hence e.g. as now there is tendency to form black holes, before Big Crunch there should be tendency to form our white holes ... which might survive to our time, as very lone shining points.

Another interesting asymmetry is that circulating electron now loses energy, but in CPT perspective it is still circulating charge ... this asymmetry again has to be in solution, like that there are more absorbers in our future, than emitters in our past.

View attachment 7128


I think you are talking about the matter falling on them?
The black hole itself is only pulling - gravitationally, but should be also EM by negative radiation pressure - symmetrically to positive by white hole.

exchemist , regarding "QFT does not require an absorber for every photon emitted"
https://en.wikipedia.org/wiki/S-matrix#Interaction_picture says probability of scenario like photon exchange is <psi_f | U | psi_i> - requires both initial conditions psi_i like initial excitation of emitter, but also psi_f like absorber ... what is the probability of such scenario without the latter?

"Photon exchange" involves virtual photons, which are not photons. I suggest reading the link to Matt Strassler's explanation of the distinction that I provided on the .net forum. Here it is again: https://profmattstrassler.com/artic...ysics-basics/virtual-particles-what-are-they/

Read this please and then we can talk again, though I do not profess to be familiar with QFT.

Meanwhile, again as I pointed out on the .net forum, the notion that free, i.e. real, photons can only be emitted if an absorber is identified is self-evidently nuts. Just think of the CMBR. That is due to photons, emitted from the surface of last scattering, rattling round the universe for >13bn years without being absorbed. Get out of your mathematical rabbit hole for a moment and think about what you are saying.

 

[Jarek Duda]

You write "again", but I see this this link the first time ... and this is not about virtual photons, but the real ones: absorbed/emitted by atoms, radio telescopes ...

Please explain e.g. why circulating electron loses energy, while in CPT perspective it is also circulating charge, but gains energy instead?
Equations governing physics are CPT symmetric, so this asymmetry has to be in solution - I think it is because of more absorbers than emitters.
Do you have a different explanation for this asymmetry?