Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

New theory claims to unite Einstein's gravity with quantum mechanics

phys.org

Post reply on HN
Print view View original

51–60 of 203 posts

Re: New theory claims to unite Einstein's gravity with quantum mechanics

#51

Post by tsimionescu »

lostdog wrote: post #5

Is there a decent explanation of what the conflict is about, that is understandable with a non-physics-major college level maths background?

User selecosi gave a beautiful explanation, but perhaps it's a bit too detailed.

Trying to give a slightly more high level idea, the conflict is simply that if you introduce the gravitational effects (spacetime bending) from general relativity into the equations of quantum mechanics you get infinities all over the place. This happens because in QM particles are not localized, they exist as a probability wave with certain values at any space and time, but the effects of their mass at all those spaces and times adds up to infinity if you just apply the calculations from relativity, in a way that we haven't been able to solve.

This is all very roughly speaking - the exact reasons are quite technical and I don't understand them myself. Electromagnetism and other interactions had similar issues, but we found mathematical solutions to fix them, and those solutions we know just don't work with the equations for gravitational interactions.

Re: New theory claims to unite Einstein's gravity with quantum mechanics

#52

Post by tsimionescu »

jeisc wrote: post #43

Our present day understanding of the universe is rudimentary at best and will be rocked with each new device invented to reveal its nature to us. When we explode a nuclear bomb here how far away in the universe would it be visible or detectable? If there were a highly developed civilization would they not be listening for this background noise to detect when a civilization had reached the nuclear point and used it fo…

Nuclear explosions on Earth, while very powerful, are not even a blip compared to the random noise in the amount of energy that the Sun gives out. You would have to very very carefully measure the Earth itself in particular to notice them in any way.

Re: New theory claims to unite Einstein's gravity with quantum mechanics

#53

Post by loosak »

sroussey wrote: post #26
selecsosi wrote: post #13

Earlier quoted context omitted.

Being _hyper_ reductionist, the standard model of physics, which describes, to an extremely high degree, the interaction (creation, elimination, and chance of one thing turning into another) of particles that constitute "stuff" (matter / energy) does not account for the interaction of matter via gravitation. Most things interact with each other, they create "particles" to exchange force / energy (actually in the case…

Coming from an engineering background, is there something about this that might prove useful? Like electron tunneling that made a good amplifier (transistor)? Could this “snapback” be utilized in interesting ways?

One day, Sir, you may tax it...

Re: New theory claims to unite Einstein's gravity with quantum mechanics

#54

Post by hoseja »

staunton wrote: post #41
hoseja wrote: post #40

What awful AI-generated illustrations. Anyway, is there any justification for treating spacetime as a smooth manifold, except for mathematical tractability?

Yes. GR does it and GR gives good descriptions for a lot of observed phenomena.

Except, you know, all the elementary particles. I have this intrusive thought those are just bits of non-smoothly kinked/knotted spacetime but have neither the physics background or sense where to even start to look further into that.

Re: New theory claims to unite Einstein's gravity with quantum mechanics

#55

Post by yetihehe »

dataflow wrote: post #10
mvdtnz wrote: post #6

Earlier quoted context omitted.

The fact that you, a random internet guy, knows this makes me believe that the world's top experts on measuring this exact thing probably thought of it, and if there is a mysterious divergence this probably doesn't account for it.

I figure as much, but that's kinda why I'm asking what made it mysterious. I actually hadn't heard of it being seen as mysterious until today - that comment is the first time I've seen that. Until today I thought it had been was unsurprising for scientists.

> I figure as much, but that's kinda why I'm asking what made it mysterious.

You expect simple explanations to VERY complex problems from random internet commenters. I think you expect too much.

Re: New theory claims to unite Einstein's gravity with quantum mechanics

#57

Post by bheadmaster »

bawolff wrote: post #50

> and this scale can be determined by another experiment where we test how long we can put a heavy atom in superposition of being in two different locations." Im a physics noob, but does this imply the theory helps explain why we usually only see quantum effects on the mucroscopic scale, since it says something about how heavy objects cant be put in superposition?

I'm a physics noob too, but from what I understand, the quantum effects don't happen on macroscopic scale because of high temperature and lack of "structure". Every interaction of particles seems to change the state ("collapse the wave function") of the particles, so such a chaotic environment makes things start behaving in a predictable way. Sort of how balls falling in a Galton board seem to converge to Gauss normal distribution: https://en.wikipedia.org/wiki/Galton_board

In low enough temperature and regular enough structure, even macroscopic objects can be entangled (or, I assume, show other quantum effects): https://www.scientificamerican.com/article/scientists-supers...

Re: New theory claims to unite Einstein's gravity with quantum mechanics

#58

Post by GoblinSlayer »

tsimionescu wrote: post #51
lostdog wrote: post #5

Is there a decent explanation of what the conflict is about, that is understandable with a non-physics-major college level maths background?

User selecosi gave a beautiful explanation, but perhaps it's a bit too detailed. Trying to give a slightly more high level idea, the conflict is simply that if you introduce the gravitational effects (spacetime bending) from general relativity into the equations of quantum mechanics you get infinities all over the place. This happens because in QM particles are not localized, they exist as a probability wave with cer…

Infinities appear if particles are assumed to be zero size: they become black holes with infinities at the event horizon.

Re: New theory claims to unite Einstein's gravity with quantum mechanics

#60

Post by [deleted] »

dataflow wrote: post #17
dotnet00 wrote: post #16

Earlier quoted context omitted.

If it were simply a matter of losing particles, I'd expect that one of the many very capable metrology labs around the world would've devised an appropriate experiment, e.g. storing two exact same masses at slightly different temperatures near absolute zero and characterizing the difference in mass (since presumably the higher temperature sample would lose slightly more mass if it were down to high energy particles).…

I mean I just gave one example of how it might lose mass. There are other obvious ways (like when they're picked up etc.). My point wasn't to present a hypothesis for people like myself here to rebut. I can do that just fine myself. I was trying to understand what about this has been confusing for scientists.

[deleted]
Post reply on HN