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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

#201

Post by urinotherapist »

omnicognate wrote: post #75
inciampati wrote: post #61

> So if gravity is quantized, that means space-time is also quantized. But that doesn’t work, But... How could space-time not be quantized? That would imply the existence of infinities in the structure of the universe. It is like the ultraviolet catastrophe but in space-time.

But as far as we know there is just such a singularity inside every black hole. (We don't know there really is, but unlike the ultraviolet catastrophe we have no evidence there isn't.)

So, it's like a bubble in a pressured bottle of water.

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

#202

Post by javajosh »

amelius wrote: post #189
javajosh wrote: post #81

Earlier quoted context omitted.

Ah, perhaps you are inclined to stop reading when you come across open parenthesis?

Ok, I confess that I didn't read the entire comment. But you have a second problem, as you should explain why the conventional explanation does not hold or is canceled by your theory.

I'm already convinced[0] the effect is small, if it exists at all. However I thought of another experiment that might be easier to perform, to see if there is any effect at all: take two crystals, as similar in depth as one can make them, with two different isotopes, and measure the difference in index-of-refraction. Silicon (28 and 30?) would probably be good for this, as would laser interferometry. (Maybe the Gravity Probe B people have some extra pure isotope wafers they'd be willing to lend?) If I'm right then the Si-30 sample will have a slightly larger index of refraction than the Si-28 sample. Someone needs to do the math though because if the effect is far less than like one layer of atoms, or a few impurities here and there, then the experiment isn't worth doiong.

0 - https://news.ycombinator.com/item?id=36671605

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

#203

Post by CuriouslyC »

eigenket wrote: post #141
CuriouslyC wrote: post #94

Earlier quoted context omitted.

Digital physics seems so obviously the correct approach from a philosophical perspective, it's a shame it blows up the math. Real numbers are the most ironically named thing ever, and infinity is a thought experiment - not a real thing. Any model of the universe based on such constructs should be heavily suspect outside the range of established observations, and taking predicted limit behavior seriously is just fooli…

Speaking as a physicist I think its very far from obvious that digital physics (or anything else) is the correct approach from a philosophical perspective. Real numbers are so ubiquitous in physics because space-time (and other quantities) look really continuous.

Rational numbers can produce "continuous" values to a precision way beyond what any equipment you could get your hands on could differentiate without physically ludicrous postulates.

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

#204

Post by FollowingTheDao »

kromem wrote: post #190
317070 wrote: post #140

Earlier quoted context omitted.

> our minds collapse the wave function While I know there are many sources available of people saying this exact thing, this is a common misunderstanding of the Copenhagen interpretation of quantum physics. There is nothing special about our minds.

I'm curious why you think the commenter is interpreting according to the Copenhagen interpretation? It sounds more like they are working within a view similar to the Von Neumann–Wigner interpretation.

Yes, and I feel that it will be proved to be right.

But I will disagree with them on one point, that I don’t think that consciousness is a thing that causes wave collapse, rather, the brain has a function that calculates the highest probability of a particle, and provides that to consciousness.

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

#205

Post by skinner_ »

nomel wrote: post #194
codethief wrote: post #105

> It’s become dogma. All the other fields in nature are quantized. There’s a sense that there’s nothing special about gravity — it’s just a field like any other — and therefore we should quantize it. I keep on citing Stephen Hawking here on HN, but it again seems very appropriate: > It would be rather boring if this were the case. Gravity would be just like any other field. But I believe it is distinctively different…

> it’s just a field like any other — and therefore we should quantize it. So, trade dogma for tradition!

I believe you are misparsing that sentence. The dogma and the tradition are the same thing.

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

#206

Post by krastanov »

miga wrote: post #199
codethief wrote: post #105

> It’s become dogma. All the other fields in nature are quantized. There’s a sense that there’s nothing special about gravity — it’s just a field like any other — and therefore we should quantize it. I keep on citing Stephen Hawking here on HN, but it again seems very appropriate: > It would be rather boring if this were the case. Gravity would be just like any other field. But I believe it is distinctively different…

Why would gravity behave different than Higgs field?

Any reason you are specifically picking the Higgs field in your question? I am asking, because this sounds a bit like you are riffing on a common misconception that the Higgs field has something to do with gravity, which is not the case. The interaction with the Higgs field is the reason some (only some) of the particles have a mass, but explaining gravity does not need to have anything to do with the Higgs field.

But yeah, it is fair to ask why gravity should behave any differently than any other quantum field -- in the context of Quantum Field Theory (one of the two incredibly successful theories of physics) that is a great question. One handwavy reason it seems different is that in General Relativity (the other incredibly success theory of physics), gravity has to do with the geometry of space and time, not with what other fields exist in that space and time (and as such is explicitly different than the other fields).

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

#207

Post by eigenket »

CuriouslyC wrote: post #203
eigenket wrote: post #141

Earlier quoted context omitted.

Speaking as a physicist I think its very far from obvious that digital physics (or anything else) is the correct approach from a philosophical perspective. Real numbers are so ubiquitous in physics because space-time (and other quantities) look really continuous.

Rational numbers can produce "continuous" values to a precision way beyond what any equipment you could get your hands on could differentiate without physically ludicrous postulates.

That is certainly true. In fact you don't even need rational numbers, it is entirely possible that there are a finite number of positions on the universe, for example.

Nevertheless physics seems to work very nicely when expressed in the language of calculus. Everything from Schrödinger's equation to the Einstein field equations, and from classical mechanics to the standard model of particle physics are expressed in the language of calculus. This all looks like a wild and strange coincidence if fundamentally we are living in a relm like the rationals, where calculus doesn't really make sense.

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

#208

Post by strogonoff »

kromem wrote: post #185

In the decades since the establishment of these theories, both the continuous (classical) spacetime of general relativity and discrete matter of quantum mechanics, the world has changed in rather significant ways. One of those has brought forth advances in technology which led to creating virtual world geometry with continuous function derivation which then gets converted into discrete voxels in order to track state…

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

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

#209

Post by lamontcg »

_a_a_a_ wrote: post #67
eterevsky wrote: post #48

Earlier quoted context omitted.

If they are close enough to each other and far enough from everything else, then why not. The smallest objects for which we measured their gravitational interaction weighed just 90 mg ( https://arstechnica.com/science/2021/03/researchers-measure-... ). The biggest object put in quantum superposition weighed around 1 mcg ( https://physics.aps.org/articles/v16/s45 ).

90 mg... that is beyond gobsmacking

I honestly can't tell if you're impressed we've measured the gravitational interaction of something that small, or staggered by our inability to measure a feature of things so large that you can easily hold them in your hand.

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

#210

Post by NoMoreNicksLeft »

H8crilA wrote: post #66
inciampati wrote: post #61

> So if gravity is quantized, that means space-time is also quantized. But that doesn’t work, But... How could space-time not be quantized? That would imply the existence of infinities in the structure of the universe. It is like the ultraviolet catastrophe but in space-time.

For the layman, what exactly is going to theoretically "explode" if spacetime is continuous?

Zeno would win. And though he is thousands of years dead at this point, I'll be damned if I'm going to let that happen.
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