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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

#11

Post by AnimalMuppet »

btilly wrote: post #2

If you believe in the Everett Interpretation, then he is wrong. The Everett Interpretation, aka Many Worlds, holds that both observer and observed are quantum mechanical systems. From this it follows that the act of observation does not produce a "collapse", but it does separate the observer into multiple observers that can't interact with each other again. So Schrödinger's cat is in a superposition of alive and dead…

> If you believe in the Everett Interpretation, then he is wrong.

If.

> And it is what quantum mechanics predicts.

It is an interpretation of what the equations predict. It is very much not the only possible interpretation, so it is not "what quantum mechanics predicts".

> But believers in other interpretations of quantum mechanics will disagree that this experiment tests anything at all.

Within other interpretations of quantum mechanics, this does test nothing at all.

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

#12

Post by edgyquant »

btilly wrote: post #2

If you believe in the Everett Interpretation, then he is wrong. The Everett Interpretation, aka Many Worlds, holds that both observer and observed are quantum mechanical systems. From this it follows that the act of observation does not produce a "collapse", but it does separate the observer into multiple observers that can't interact with each other again. So Schrödinger's cat is in a superposition of alive and dead…

Why would anyone believe such a thing?

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

#13

Post by weatherlight »

srejk wrote: post #7
sandworm101 wrote: post #3

>> Jonathan Oppenheim, who runs a program exploring post-quantum alternatives at University College London, suspects that’s because gravity simply can’t be squeezed into a quantum box. So... he is still part of the Orthodoxy. He is challenging ideas, but as an employee of University College London he is hardly any sort of outsider to the physics community.

You have to be trained in physics to theorize about it. Thinking otherwise is the realm of the crackpot. https://www.youtube.com/watch?v=11lPhMSulSU

I love Dr. Collier's videos. Her method of story telling/video essay is extremely unconventional but very effective.

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

#14

Post by bowsamic »

eterevsky wrote: post #8

(Not a quantum physicist. Please correct me if I am misunderstanding.) From what this article says, his assumption is that gravity is classical, but "fuzzy" or probabilistic: you can't precisely measure the gravitational field of a sufficiently small object. In the last years we've seen progressively bigger objects being put in quantum superposition. The theory from this article is incompatible with this process cont…

I’m a quantum physicist and yeah you’re totally right. It’s already obvious that a quantum theory of gravity is needed because we need a way to talk about superpositions of spacetime curvatures. Either QM is wrong in general or we need a way to treat spacetime that is in a quantum superposition

Also my old supervisor actually suggested an experiment to observe this gravity induced entanglement but it would require extremely low temperatures to not degrade due to thermal noise

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

#15

Post by lavelganzu »

x3n0ph3n3 wrote: post #5
btilly wrote: post #2

If you believe in the Everett Interpretation, then he is wrong. The Everett Interpretation, aka Many Worlds, holds that both observer and observed are quantum mechanical systems. From this it follows that the act of observation does not produce a "collapse", but it does separate the observer into multiple observers that can't interact with each other again. So Schrödinger's cat is in a superposition of alive and dead…

> This has been done, and we only see the gravity from the cannon ball that we placed, and not the alternate location it might have been placed at. Doesn't this presume that your brain deciding where to place the cannon ball was an uncertain quantum event? Doesn't it also presume quantum gravity does not exist?

No:

> Based on whether there is a click in a Geiger counter, choose which one to put a cannon ball next to.

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

#16

Post by bowsamic »

srejk wrote: post #7
sandworm101 wrote: post #3

>> Jonathan Oppenheim, who runs a program exploring post-quantum alternatives at University College London, suspects that’s because gravity simply can’t be squeezed into a quantum box. So... he is still part of the Orthodoxy. He is challenging ideas, but as an employee of University College London he is hardly any sort of outsider to the physics community.

You have to be trained in physics to theorize about it. Thinking otherwise is the realm of the crackpot. https://www.youtube.com/watch?v=11lPhMSulSU

I’m a quantum physicist and you wouldn’t believe how many people try and sell me on their theory that solves everything that is literally just an idea in their head and can’t even produce any quantitative predictions. The levels of self delusion that these people display is astounding and we need to mock it more openly imo

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

#17

Post by bowsamic »

edgyquant wrote: post #12
btilly wrote: post #2

If you believe in the Everett Interpretation, then he is wrong. The Everett Interpretation, aka Many Worlds, holds that both observer and observed are quantum mechanical systems. From this it follows that the act of observation does not produce a "collapse", but it does separate the observer into multiple observers that can't interact with each other again. So Schrödinger's cat is in a superposition of alive and dead…

Why would anyone believe such a thing?

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

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

#18

Post by rvcdbn »

btilly wrote: post #2

If you believe in the Everett Interpretation, then he is wrong. The Everett Interpretation, aka Many Worlds, holds that both observer and observed are quantum mechanical systems. From this it follows that the act of observation does not produce a "collapse", but it does separate the observer into multiple observers that can't interact with each other again. So Schrödinger's cat is in a superposition of alive and dead…

I’m a “believer” in the Everett Interpretation (on the grounds that it’s the simplest interpretation) but I can’t see how such an experiment could prove anything. This experiment seems to assume we can keep the whole apparatus including the Geiger counter and the mechanism to move the cannon ball from becoming entangled with the environment (decohering). This seems very far outside the realm of current technology.

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

#19

Post by tonycoco »

outlace wrote: post #6
sandworm101 wrote: post #3

>> Jonathan Oppenheim, who runs a program exploring post-quantum alternatives at University College London, suspects that’s because gravity simply can’t be squeezed into a quantum box. So... he is still part of the Orthodoxy. He is challenging ideas, but as an employee of University College London he is hardly any sort of outsider to the physics community.

Genuine question here, when was the last time a total outsider made a significant contribution to physics?

When was the last time an insider made one?
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