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

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

#71

Post by Y_Y »

pants2 wrote: post #27
irjustin wrote: post #23

Earlier quoted context omitted.

> Aren't there always some fraction of atoms or molecules with sufficiently high energy to escape the object? Can someone help me understand this? I thought that things were supposed to be stable given the elements used for le grand k. That they don't decay on their own and it would have to be another mechanism to explain the divergence? [0] https://en.wikipedia.org/wiki/International_Prototype_of_the...

In a system of particles, due to random Brownian motion and the nature of Gaussian energy distributions, a small number of particles occasionally gain significantly higher energy than average through statistical fluctuations. Maybe enough to escape the binding energy of le grand k. However I would think this is a very very small effect in platinum.

Perhaps you mean Boltzmann distributions?

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

#72

Post by quietbritishjim »

yetihehe wrote: post #55
dataflow wrote: post #10

Earlier quoted context omitted.

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.

I think the real question is: where is the evidence that scientists find it mysterious? That doesn't need any sort of explanation, just a reference for a claim made by a commenter. As with the other commenter, I've heard about the mass divergence before, but never that anyone found it surprising.

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

#73

Post by vanderZwan »

yetihehe wrote: post #55
dataflow wrote: post #10

Earlier quoted context omitted.

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.

I don't disagree with you, but on the other hand: if people claim something in a discussion thread we need to be able to ask them to back those claims up. Otherwise anyone can just assert anything.

Sure, the explanation might not fit in the margins here, but then a link to a source that does attempt to explain it would be fine too.

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

#74

Post by [deleted] »

quietbritishjim wrote: post #72
yetihehe wrote: post #55

Earlier quoted context omitted.

> 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.

I think the real question is: where is the evidence that scientists find it mysterious? That doesn't need any sort of explanation, just a reference for a claim made by a commenter. As with the other commenter, I've heard about the mass divergence before, but never that anyone found it surprising.

[deleted]

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

#75

Post by gumby »

quietbritishjim wrote: post #72
yetihehe wrote: post #55

Earlier quoted context omitted.

> 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.

I think the real question is: where is the evidence that scientists find it mysterious? That doesn't need any sort of explanation, just a reference for a claim made by a commenter. As with the other commenter, I've heard about the mass divergence before, but never that anyone found it surprising.

As has even been discussed on HN over the years (!), the cause is unknown.* This is one of the motivations to replace the official kilogram with a definition based on measurable natural quantities, as had been done with the second and the meter. It took until 2018 to do so: https://www.nist.gov/si-redefinition/kilogram-introduction

* it’s not like there aren’t good theories but you can’t experiment directly on “the” kg because you can’t risk changing it!

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

#76

Post by TheOtherHobbes »

fsckboy wrote: post #66
hoseja wrote: post #54

Earlier quoted context omitted.

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.

>> Yes. GR does it and GR gives good descriptions for a lot of observed phenomena. > Except, you know, all the elementary particles. except, you know, all the elementary particles don't do a good job of explaining what GR explains

Hardly an expert, but it seems more likely to me that GR is the smoothed-out limit of a lot of much smaller stuff happening, than QM is somehow low-level wrinkles in an otherwise perfectly smooth spacetime.

I don't think a smooth anything is physically tractable. You need infinite resolution for perfect smoothness - essentially an infinite amount of information at every point.

Except there are no points. So somehow you have equations that define curvature floating in some kind of metaphysical space which somehow gets mapped to observable phenomena.

And if it's a noisy smoothness - where does the noise come from?

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

#77

Post by pegasus »

rhelz wrote: post #3

The various standard kilograms held by the national bodies, and the prototype standard kilogram in paris, were measured very precisely over the past hundred years, and their weights did seem to diverge mysteriously.

I'm sure that if they suspected that variance in mass could support their theory, they would have investigated that possibility instead of proposing a new test.

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

#78

Post by Certhas »

defrost wrote: post #8

Jonathan Oppenheim: If you'd like to attend a public lecture (virtual or in London) about the postquantum theory of classical gravity, or contribute a donation to the group's research program, click "Donate" to add your email address to our list. https://www.ucl.ac.uk/oppenheim/ https://www.ucl.ac.uk/oppenheim/research.html See Also: Gravitationally induced decoherence vs space-time diffusion: testing the quantum nat…

This is all surprisingly substantative.

That said, there are many results that connect gravitational and thermodynamic phenomena. It would be good to understand how these look from the perspective of this theory.

Edit: just started reading, so if this is explained somewhere would love to get a pointer.

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

#79

Post by psc »

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?

ScienceClic on youtube has some really great videos, the first half of the string theory video [1] does a good job framing the conflict at a high level, string theory being one attempt to resolve the problem.

It doesn't go into math but mentions that in the standard model, interactions are local, which for example means something like photon emission is instantaneous. When applied to gravity/gravitons, you get infinities in the math. This sort of makes sense to me, but I have yet to find anything that does an understandable job explaining how/why exactly the math breaks down.

There's a series on the maths of general relativity [2] which I haven't completed but I'm hoping will provide a bit more background to understand the math.

Also, the article mentions that the new theory was motivated by solving the black hole information paradox [3], which there's a good video [4] about as well

[1] https://www.youtube.com/watch?v=n7cOlBxtKSo

[2] https://www.youtube.com/watch?v=xodtfM1r9FA&list=PLu7cY2CPiR...

[3] https://en.wikipedia.org/wiki/Black_hole_information_paradox

[4] https://www.youtube.com/watch?v=isezfMo8kWQ

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

#80

Post by guenthert »

hn_throwaway_99 wrote: post #2

> A second paper, published simultaneously in Nature Communications and led by Professor Oppenheim's former Ph.D. students, looks at some of the consequences of the theory, and proposes an experiment to test it: to measure a mass very precisely to see if its weight appears to fluctuate over time. Definitely don't know enough to comment about the overall proposal, but given how many grand physics theories over the pas…

> it's really nice to see the proponents proposing a test.

Is it feasible though? I wonder whether that test is not just outside of what can be technically realized today, but Heisenberg's uncertainty principle gets in the way.

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