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A physicist who bets that gravity can’t be quantized

quantamagazine.org

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Re: A physicist who bets that gravity can’t be quantized

#361

Post by kgwgk »

consilient wrote: post #360
kgwgk wrote: post #304

Earlier quoted context omitted.

> Decoherence solves the preferred basis problem, not the hard problem of consciousness. Ok, I guess I misunderstood the scope of "There's also nothing special about observing." It's not clear to me if you (MWI) would say that rocks had defined positions when nobody was observing them - or whether the question of things having definite positions (and the very existence of those things) wouldn't even make sense in the…

> Ok, I guess I misunderstood the scope of "There's also nothing special about observing." There's nothing special about the physical processes constituting a scientific experiment. They're unitary evolution like everything else. Whether there's anything special about conscious experience (for my money: obviously yes) is outside the scope of physics. > or whether the question of things having definite positions (and…

If the MWI doesn’t contain the Earth, the seas or the molecules of water it may not be providing a very useful map until we add a lot of things to it.

Re: A physicist who bets that gravity can’t be quantized

#362

Post by guerrilla »

consilient wrote: post #357
guerrilla wrote: post #307

Earlier quoted context omitted.

Hmm so that would be a system being out of equilibrium but in a "negative" direction, which is nonsense since any amount of non-equilibrium is a positive amount of free energy. So, I don't understand any of the math in that paper but is there any easy/intuitive way to explain why a higher information density would require negative free energy? I guess I need to understand the relationship between information density…

> So, I don't understand any of the math in that paper but is there any easy/intuitive way to explain why a higher information density would require negative free energy? Not really, no. If you don't have the equivalent of a good undergraduate education in physics very little about QFT is going to be accessible to you.

I guess I'll have to wait for the PBS SpaceTime video then...

Re: A physicist who bets that gravity can’t be quantized

#363

Post by brianpan »

jacquesm wrote: post #179
brianpan wrote: post #172

Earlier quoted context omitted.

I think if it's point sized, you're allowed to imagine any shape of cat. :D

For a uniform gravity field it is essential that the cat is spherical.

All black holes I've run into are cat-shaped, yet they have uniform gravity fields around them.

Re: A physicist who bets that gravity can’t be quantized

#364

Post by mrguyorama »

Gordonjcp wrote: post #315
cornel_io wrote: post #243

Earlier quoted context omitted.

I think it didn't land because so many people are in the comments seriously arguing almost exactly what you were saying as a joke. Tough environment for parody to thrive in, alas...

I'm currently spending a lot of time in La-La-Laplacian Land, so maybe my sense of humour is currently a bit warped. A bit like my filter responses, really.

HN as a forum is no better than a pub or bar in a wealthy city. You cannot spout off an extremely common layman misconception and expect people to recognize that as a joke. Most of us are laymen in this area.

Re: A physicist who bets that gravity can’t be quantized

#365

Post by strogonoff »

mrguyorama wrote: post #355
strogonoff wrote: post #208

Earlier quoted context omitted.

A simulation produces philosophical zombies, yet you are not one.

You are asserting that there is something fundamentally "unsimulatable", un"real" about consciousness. If we are going to give up and turn to religion for our understanding of the universe then I pick "last tuesday-ism". It physically cannot be distinguished from any other compatible interpretation of the data.

> "unsimulatable"

Is so at least until it is known what it is. Opinions differ on whether that is knowable.

> un"real"

As the only thing you and I will ever have direct access to, consciousness is certainly real. Opinions differ on whether it is alone in that.

> turn to religion

I personally prefer philosophy, but you do you. To me religion seems about as capable of getting to truth as physics (that is to say, not very much when taken just by itself).

Re: A physicist who bets that gravity can’t be quantized

#366

Post by mrguyorama »

eigenket wrote: post #311
cryptonector wrote: post #268

Earlier quoted context omitted.

Between space quantization (Planck length) and the size of the visible universe, the minimum angle is fantastically small.

The Planck length does not mean anything like space quantization. It's just a length that pops out when you combine several physical constants. The values of those constants mean that the Planck scale is likely to be roughly where gravitational and quantum effects are both relevant but other than that it has no physical significance. I have no idea where this idea that space is fundamental discrete, and divided up in…

>I have no idea where this idea that space is fundamental discrete, and divided up into chunks of Planck length voxels or something comes from

Like everything else in quantum physics, this comes from various people who don't even know algebra listening to people who work all day in algebraic fields and number theory try to explain concepts that don't make sense without those mathematical foundations and actual experience in physics papers.

No, a quantum computer isn't "trying all combinations at once" No, the planck units aren't fundamental measurements of the universe No, quantum entanglement doesn't allow you to transmit information faster than light

etc.

I'm plenty guilty of this, I'm no physicist and I graduated after linear algebra, which I didn't do amazing in. The examples I reference are just the ones I was lucky enough to learn from people who managed to demonstrate and describe the underlying math enough to convey meaning. Plenty of educational and ostensibly knowledgeable physics and science youtube channels for example still run with those misconceptions.

Re: A physicist who bets that gravity can’t be quantized

#367

Post by mrguyorama »

TillE wrote: post #122
light_hue_1 wrote: post #41

Earlier quoted context omitted.

The word "probably" there is completely meaningless. There are many interpretations of QM and there is no compelling reason to choose one over the others. In particular the many worlds interpretation makes no testable predictions, it's just a story. There's absolutely nothing "elegant" about it. There's no math, no experiment, no explanation. A story like you read in some religious text or science fiction novel. It h…

The "popular science" takes on QM have generally been an enormous failure, focused on irrelevant fluff like this. I mean, I get it, it's a subject that you can't seriously understand without a degree in physics or chemistry. I had plenty of trouble with the math even at the undergrad level. But surely there's more interesting stories to tell of eg particle accelerator research, rather than fantasies.

More importantly, if you don't have 4 years worth of college math, quantum mechanics is EXTREMELY BORING from a layman's perspective. It's a bunch of extremely dense and specific math with very loaded concepts and terms and has no meaning to anyone who doesn't have a strong understanding of classical physics.

"If you make a blackbody radiator nearly absolute zero, it should emit insanely high energy radiation based on our current empirical equations for radiated energy. This can only be fixed if energy can only be radiated in discrete sized packets, including a minimum size of packet"

"Whats a black body radiator?"

People don't understand quantum physics, its ramifications, or why that's interesting to physicists because people can't even be assed to do simple mental math at a grocery store to get themselves good deals before they go back to their algebra teacher and complain that they will never use math in real life

Re: A physicist who bets that gravity can’t be quantized

#368

Post by dang »

Gordonjcp wrote: post #128
fsh wrote: post #109

Earlier quoted context omitted.

There is zero evidence that space is quantized, and this would contradict the Standard Model, as well as General Relativity. The Planck constant gives the relation between the energy of a photon (or more generally a harmonic oscillator) and its frequency. It has nothing to do with the structure of space.

[flagged]

Could you please stop posting unsubstantive comments and flamebait? You've unfortunately been doing it repeatedly. It's against what this site is for, so we have to ban accounts that keep doing it, and we've already had to ask you this more than once:

https://news.ycombinator.com/item?id=36449159 (June 2023)

https://news.ycombinator.com/item?id=34194236 (Dec 2022)

https://news.ycombinator.com/item?id=33501516 (Nov 2022)

Nothing Phone (1) - https://news.ycombinator.com/item?id=32086641 - July 2022 (97 comments)

If you wouldn't mind reviewing https://news.ycombinator.com/newsguidelines.html and taking the intended spirit of the site more to heart, we'd be grateful.

Re: A physicist who bets that gravity can’t be quantized

#369

Post by GoblinSlayer »

naasking wrote: post #358
GoblinSlayer wrote: post #329

Earlier quoted context omitted.

Problems 1-3 there are caused by point particles, not by space. They mention ultraviolet catastrophe was caused by continuous space, but it was caused by non-quantum radiation, so there's no classical electrodynamics with discreet space, instead there's quantum electrodynamics with continuous space.

I'm not sure what "problems 1-3" are referring to here, but all of these problems fundamentally trace their roots to issues with the foundational assumption of continuity.

Per numbered titles:

1 Newtonian gravity

2 Quantum mechanics of charged particles

3 Classical electrodynamics of point particles

They explicitly mention they use point particles. Problem in 1 Newtonian gravity is especially egregious example. They model planets(!) as material points and see how they come infinitely close to each other. The author does mention these problems are pure math unrelated to reality.

Re: A physicist who bets that gravity can’t be quantized

#370

Post by bowsamic »

Scarblac wrote: post #137
bowsamic wrote: post #17

Earlier quoted context omitted.

Because it’s very straightforward and has less assumptions and weird features than most other interpretations, and it has seen the most advancements in quantum fundamentals research

Complete layman here -- does that theory say that every time a quantum effect does or does not occur, in fact both possibilities happen but in different worlds? The entire universe instantly splits up in two for every quantum event anywhere in it? Edit: I read more comments and no, it's not literally that.

Yes, it does mean that
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