Readit News logoReadit News
machina_ex_deus commented on Dead Stars Don’t Radiate   johncarlosbaez.wordpress.... · Posted by u/thechao
jiggawatts · 3 months ago
> The conservation of baryon number is not consistent with the physics of black hole evaporation via Hawking radiation.

There are other black hole models that can conserve these quantum numbers!

Speaking of things that are so obviously true that you must be an idiot not to agree, there are statements so obviously false that you have to be an idiot to agree: People keep repeating the nonsense put out by Penrose, which require non-physical timelike infinities to work.

The current "pop science" (nearly science fiction) statement is that it is possible to fall into a black hole and there is "nothing special" about the event horizon.

Quite often, just one paragraph over, the statement is then made that an external observer will never observe the victim falling in.

The two observers can't disagree on such matters!

To say otherwise means that you'd have to believe that the Universe splits (when!?) such that there are two observers so that they can disagree. Or stop believing in logic, consistency, observers, and everything we hold dear as physicists.

This is all patent nonsense by the same person that keeps insisting that brains are "quantum" despite being 309K and organic.

If the external observer doesn't observe the victim falling in, then the victim never falls in, full stop. That's the objective reality.

Penrose diagrams say otherwise because they include the time at infinity, which is non-physical.

Even if the time at infinity was "reachable", which isn't even mathematically sound, let alone physically, Hawking radiation is a thing, so it doesn't matter anyway: Black holes have finite lifetimes!

There is only one logically consistent and physically sound interpretation of black holes: nothing can ever fall in. Inbound victims slow down relative to the outside, which means that from their perspective as they approach the black hole they see its flow of time "speed up". Hence, they also see its Hawking evaporation speed up. To maintain consistency with outside observers, this evaporation must occur fast enough that the victim can never reach any surface. Instead, the black hole recedes from them, evaporating faster and faster.

This model (and similar ones), can preserve all quantum numbers, because there is no firewall, no boundary, nothing to "reset" quantum fields. Everything is continuous, consistent, and quantum numbers are preserved. Outside observers see exactly what we currently expect, black holes look and work the same, they evaporate, etc...

machina_ex_deus · 3 months ago
First of all, kruskal coordinates show beyond doubt that the event horizon is just a regular null hypersurface that the observer wouldn't notice crossing locally. (Of course if you look around, at the moment of crossing into the event horizon you see everything else that was falling into it unfreeze and continue crossing).

If you want to take into account the evaporation of the black hole, then you should look at something like the vaidya metric. The mass function is a function of the ingoing Eddington coordinate v, which takes on a specific value when you cross the event horizon, and so you observe the black hole at a specific mass as you cross the event horizon. Contradicting your layman understanding of time dilation for the observer relative to the black hole.

Once you cross the horizon, the r coordinate becomes timelike, and so you are forced to move to decreasing r value just like a regular observer is forced to move to increasing t value. Your entire future, all your future light cone is within the black hole and it all terminates at the singularity. Minewhile, the t coordinate is space like which is what gives you space like separation from the mess that had happened in the original gravitational collapse. You wouldn't be blasted by a frozen supernova like you have said.

You can kind of say the universe splits at the event horizon, the time like coordinate changes from t to r and the future of the black hole branch of the universe is permanently cut off from the rest of the universe.

In rotating and charged black holes it is different, and you observe the evaporation of the black hole once you cross the Cauchy horizon. If the black hole is eternal (because someone kept feeding radiation to the black hole, maybe by reflecting the hawking radiation inwards), then you would in fact see timelike infinity as you reach the Cauchy horizon, so this time like infinity is quite physical. You would need to avoid being vaporized by blue shifted incoming radiation.

machina_ex_deus commented on The Google Willow Thing   scottaaronson.blog/?p=852... · Posted by u/Bootvis
machina_ex_deus · 9 months ago
Before invoking parallel universes, how about comparing the system to nature's mind-boggling number of particles in the macroscopic world? A single gram contains 10^23=2^76 particles. Google's random circuit sampling experiment used only 67 qubits, Which is still order of magnitude below 76. I wonder why, the chip had 105 qubits and the error correction experiment used 101 qubits.

Did Google's experiment encounter problems when trying to run RCS on the full 105 qubits device?

Before saying that the computation invoked parallel universes, first I'd like to see that the computation couldn't be explained by the state being encoded classically by the state of the particles in the system.

machina_ex_deus commented on Willow, Our Quantum Chip   blog.google/technology/re... · Posted by u/robflaherty
machina_ex_deus · 9 months ago
You learn a lot by what isn't mentioned. Willow had 101 qubits in the quantum error correction experiment, yet only mere 67 qubits in the random circuit sampling experiment. Why did they not test random circuit sampling with the full set of qubits? Maybe when turning on the full 101 set of qubits, qubits fidelity dropped.

Remember macroscopic objects have 10^23=2^76 particles, so until 76 qubits are reached and exceeded, I remain skeptical that the quantum system actually exploits an exponential Hilbert space, instead of the state being classically encoded by the particles somehow. I bet Google is struggling just at this threshold and they don't announce it.

machina_ex_deus commented on Researchers spot black hole feeding at 40x its theoretical limit   arstechnica.com/science/2... · Posted by u/nithinj
dustingetz · 9 months ago
machina_ex_deus · 9 months ago
The fact that radial coordinate is timelike inside the event horizon doesn't change when you change coordinate systems. The radial direction remains timelike in kruskal coordinates. Direction being space like or time like is independent of coordinate system.
machina_ex_deus commented on Researchers spot black hole feeding at 40x its theoretical limit   arstechnica.com/science/2... · Posted by u/nithinj
dustingetz · 9 months ago
No, this depends on your choice of coordinate system - has been debunked N times on physics reddit in virtually every thread that it comes up. The EH itself is not a singularity in the observers reference frame as they cross it nor do they particularly notice when they do.
machina_ex_deus · 9 months ago
I never said EH is a singularity. I said you could notice you're inside as your timelike coordinate becomes the radial coordinate. That's something you could easily notice if you look around, it would correspond to a shrinking universe, and our universe is expanding.

The "you won't notice crossing the event horizon" troupe is true only in a very local sense. If you move around and observe the geometry around you, you can definitely tell you're inside a black hole.

machina_ex_deus commented on Researchers spot black hole feeding at 40x its theoretical limit   arstechnica.com/science/2... · Posted by u/nithinj
aurareturn · 9 months ago
On the topic of black holes, there is a recent paper on black holes potentially converting mass into dark energy: https://iopscience.iop.org/article/10.1088/1475-7516/2024/10...

I'm not a physicist but it's interesting to think about the implications:

1. No singularity at the center of a black hole

2. Universe's expansion rate is not constant because it's blackholes powering it with matter

3. Eventually expansion slows, stops and reverses

And now my own crazy ideas:

1. Maybe the universe is a inside a black hole

2. Maybe the big bang was a result of the birth of another black hole somewhere else, and that the rapid expansion rate of the early universe was due to the a huge amount of matter converted into dark energy by this black hole

machina_ex_deus · 9 months ago
The universe is not inside a black hole. Inside black holes the radial coordinate is time like, which is definitely not true in our universe, where the time coordinate is timelike, and the radial coordinate is space like.

Inside of black holes looks nothing like ordinary spacetime. Inside black hole, everything in your future is with decreasing radial coordinate, which means space is shrinking until you hit the singularity where radial coordinate is zero and you have no future.

machina_ex_deus commented on Show HN: Exponentile – A match 3 game mixed with 2048   bellika.dk/exponentile... · Posted by u/MikeBellika
machina_ex_deus · a year ago
Love this game. I abused multiple tabs as a way to save the current game, as opening new tab copies the state of the game, and got to a high score of 150,000 (I could keep going, I didn't lose) and made a 4096 tile. Using multiple tabs to save the game when you get a good position makes it possible to play indefinitely. It's even more addictive when you can save the game because then it's not really over at game over.
machina_ex_deus commented on 'Lavender': The AI machine directing Israel's bombing in Gaza   972mag.com/lavender-ai-is... · Posted by u/contemporary343
hnav · a year ago
9/11 killed 3k people
machina_ex_deus · a year ago
3k out of 300 million, so 1 in 10000.

1k out of 8 million is 1 out of 8000.

Every person in Israel knows someone who knows a victim personally. Think how deep this trauma is to Israel.

Dead Comment

machina_ex_deus commented on If gravity isn't a force, then why does it "need" a boson?   old.reddit.com/r/Physics/... · Posted by u/thunderbong
johncarlosbaez · a year ago
It's too bad the top-rated answer on Reddit says "GR does not say Gravity is not a force (or if you do say it’s not a force, then none of the other forces are forces either)" rather than explaining what people mean when they say gravity is not a force (basically, it affects the geometry of spacetime in such a way that an unaccelerated particle can still move along a path that's not a straight line in the traditional sense) and why nonetheless we can treat gravity approximately (that is, perturbatively) as if it were a force, and why this perturbative description when quantized predicts a spin-2 boson, the graviton. Oh well.
machina_ex_deus · a year ago
Non gravity forces are quite linear and simple, the coupling with fermions is only through covariant derivative.

Gravity is extremely non linear, when you look at the expression for Ricci tensor, it is much more complicated than other forces.

u/machina_ex_deus

KarmaCake day1833August 9, 2022View Original