IANAP, but...
> if these hybrid theories are true, there must be some minimal amount of gravitational noise.
... this already sounds suspiciously Heisenbergian, reminiscent of quantum foam, the Casimir effect and all that jazz.
A physicist who bets that gravity can’t be quantized
151–160 of 378 posts
Re: A physicist who bets that gravity can’t be quantized
#152Earlier quoted context omitted.
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
These are just mathematical tools we use to make predictions. Assuming they represent objective reality and somehow prove an infinite number of universes doesn’t seem very scientific to me.
Re: A physicist who bets that gravity can’t be quantized
#153Earlier quoted context omitted.
I wish any of you with the down vtes would at least have a conversation with me...
There is absolutely no evidence that the Planck length is anything like the smallest possible length or wavelength. Its "just" a length scale that pops out when you combine several physical constants. That combination of constants means that at the Planck scale quantum effects and gravitational effects are likely to both be relevant, which is cool, but other than that it doesn't really have any fundamental meaning.
I’m giving you a hypothesis about the reason why the Planck length exists as a constant.
Below Planck length there is no length, time, mass, or temperature.
All of those things are given “reality” by our mental process.
Re: A physicist who bets that gravity can’t be quantized
#154Earlier quoted context omitted.
Because that's what quantum mechanics in it's purest form tells us. Avoiding the many worlds requires tagging on extra stuff not in the equations.
Quantum mechanics tells us that, in order to predict the outcome of a measurement, we have to compute a specific probability based on the amplitude of the wavefunction. We can explain this probability as some kind of collapse, or we can explain it as some measure of the number of observers making the measurement in parallel "worlds". Neither is inherently closer to the math.
Why should we not just take it as a probability based abstraction for something we don’t have a true understanding of and move on? Anything else seems like weird theology to me.
Re: A physicist who bets that gravity can’t be quantized
#155Earlier quoted context omitted.
> Assuming many worlds, and many here means: enormous amounts, far exceeding the number of particles in the universe, is everything but parsimonious. "Many worlds" is a misnomer. MWI is just wavefunction realism + unitary evolution. There's only one world, and really only one dynamical object: the wavefunction. It evolves according to some unitary operator, and that's the whole story. No splitting, no collapse, no ob…
Is it possible to observe anything at all in MWI? If yes, what does it mean to "observe something" in MWI? If not, is there any physical content in MWI?
Observations in MWI are just ordinary physical interactions. Specifically they're perturbative-regime interactions between the thing being observed and large thermalized systems (e.g. humans). From the perspective of the thermal bath, you get exponential suppression of everything but the eigenstates of the interaction Hamiltonian, which is why our observations "look classical".
Re: A physicist who bets that gravity can’t be quantized
#156> 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.
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Re: A physicist who bets that gravity can’t be quantized
#157Earlier 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
These are just mathematical tools we use to make predictions. Assuming they represent objective reality and somehow prove an infinite number of universes doesn’t seem very scientific to me.
I mean, that's obviously a huge matter of debate, but most of us physicists at least hope that our theories reflect objective reality in some way. Also, there are of course explicitly ontological aspects of quantum mechanics, such as PBR theorem and Bell's inequalities
Re: A physicist who bets that gravity can’t be quantized
#158Earlier quoted context omitted.
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
What do you intend to achieve by mocking these people?
To make them feel bad (I am salty)
Re: A physicist who bets that gravity can’t be quantized
#159Earlier quoted context omitted.
There is absolutely no evidence that the Planck length is anything like the smallest possible length or wavelength. Its "just" a length scale that pops out when you combine several physical constants. That combination of constants means that at the Planck scale quantum effects and gravitational effects are likely to both be relevant, which is cool, but other than that it doesn't really have any fundamental meaning.
I’m giving you a hypothesis about the reason why the Planck length exists as a constant. Below Planck length there is no length, time, mass, or temperature. All of those things are given “reality” by our mental process.
That is certainly a hypothesis, but there is no evidence for it.
Re: A physicist who bets that gravity can’t be quantized
#160> J. Oppenheim I wonder what influenced him to become a physicist.
I'm just waiting for a person with the surname Oppenheimest now.