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Particle mystery: physicists confirm the muon is more magnetic than predicted

sciencemag.org

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Re: Particle mystery: physicists confirm the muon is more magnetic than predicted

#101

Post by davrosthedalek »

thepangolino wrote: post #4
comboy wrote: post #3

Earlier quoted context omitted.

Neutrinos faster than light had 6 sigma. It just shows probabilistic significance. Confirmation by independent research teams helps eliminate calculation and execution errors.

This is the second separate experiment giving similar value.

"Separate" for slightly small values of separate. It's the same measurement approach, and using many components from the first experiment, so there could be correlated errors. But they made many fundamental improvements to the experiment, so it's great to see that the effect hasn't gone away.

Re: Particle mystery: physicists confirm the muon is more magnetic than predicted

#102

Post by m463 »

gautamcgoel wrote: post #41

Honestly feel sorry for particle physicists... Their entire gig is spending billions on fancy equipment, and hoping that observe something unexpected. If they see exactly what they expected to see, all that effort was basically wasted. Also, a lot of "discoveries" turn out to be equipment miscalibration - remember those particles which supposedly moved faster than light a few years back? Always struck me as an odd wa…

I think learning to observe anything at such small scales as a routine matter will increase understanding of all kinds of other things we look at. There are folks riding on their coattails, and folks riding on their coattails.

But yeah, it's the long game.

Re: Particle mystery: physicists confirm the muon is more magnetic than predicted

#103

Post by alephu5 »

davidivadavid wrote: post #37

Physics noob question: is there any physical framework that does away with the concept of "force"? I know a bit about how it is reconceptualized as space-time deformation in the context of general relativity, but that's about it. It just seems like one of those inherently anthropocentric concepts that (potentially) holds us back from exploring something different?

It's a good question.

One thing you find in modern physics is that ideas are often named according to some mathematical analogue to classical physics. You start thinking about forces by imagining a ball being kicked, and after boiling away the conceptual baggage you realise it's all about the exchange of energy.

It turns out that energy exchange is one of the most fundamental mechanisms that drives nature so it makes sense that this same mathematics appears in deeper theories. Unlike classical physics the symbols in quantum equations don't represent simple numbers, they're usually quite complicated and subtle actually but remarkably these equations share many properties with their classical counterparts. To be fair this could just be that phenomena that differ completely from classical physics are incomprehensible to us.

So an electron "spin", at least mathematically, is governed by equations that are remarkable similar to classical equations of angular momentum and so on. Force is in the same category and really just means "fundamental interaction".

Re: Particle mystery: physicists confirm the muon is more magnetic than predicted

#105

Post by mhh__ »

gizmo686 wrote: post #15
comboy wrote: post #3

Earlier quoted context omitted.

Neutrinos faster than light had 6 sigma. It just shows probabilistic significance. Confirmation by independent research teams helps eliminate calculation and execution errors.

As I recall, FTL neutrinos were the result of experimental error, not chance; and so are outside the scope of what sigma screen for.

It's probably worth saying that even "chance" is still a little misleading in the sense that the quantification of that chance is still done by the physicists and therefore can be biased

Re: Particle mystery: physicists confirm the muon is more magnetic than predicted

#107

Post by taylodl »

hinkley wrote: post #82
chriswarbo wrote: post #65

Earlier quoted context omitted.

Lagrangian mechanics is equivalent to Newtonian mechanics, but doesn't involve force https://en.wikipedia.org/wiki/Lagrangian_mechanics The idea of replacing a 'gravitational force' with spacetime curvature gave us General Relativity; extending this same idea to electromagnetism gives us Kaluza-Klein theory https://en.wikipedia.org/wiki/Kaluza%E2%80%93Klein_theory The current state of the art is Quantum Field Theory…

I still need someone to ELI5 to me how space curvature model explains the attraction between two bodies that have a delta-v of 0.

This is a good video explaining just that! https://www.youtube.com/watch?v=wrwgIjBUYVc

Re: Particle mystery: physicists confirm the muon is more magnetic than predicted

#108

Post by ArnoVW »

schmorptron wrote: post #96
BlueTemplar wrote: post #60

Earlier quoted context omitted.

Godel kind of proved that about Mathematics.

That sounds wild, do you have a link where I can read more about this, or is wikipedia fine to learn about it?

https://en.m.wikipedia.org/wiki/G%C3%B6del%27s_incompletenes...

TLDR: you can have a mathematics that always gives true answers (but that cannot answer everything). Or you can have a mathematics that can answer every possible question (but some answers are wrong, you do not know which). Choose.

This dispaired mathematicians of the early 20th century, who had hoped to create 'one mathematics to rule them all'. Of course you can have several disjunct mathematics, each one for the problem you like.

Re: Particle mystery: physicists confirm the muon is more magnetic than predicted

#109

Post by zcrackerz »

hinkley wrote: post #82
chriswarbo wrote: post #65

Earlier quoted context omitted.

Lagrangian mechanics is equivalent to Newtonian mechanics, but doesn't involve force https://en.wikipedia.org/wiki/Lagrangian_mechanics The idea of replacing a 'gravitational force' with spacetime curvature gave us General Relativity; extending this same idea to electromagnetism gives us Kaluza-Klein theory https://en.wikipedia.org/wiki/Kaluza%E2%80%93Klein_theory The current state of the art is Quantum Field Theory…

I still need someone to ELI5 to me how space curvature model explains the attraction between two bodies that have a delta-v of 0.

Think of your velocity vector as having a time component. The magnitude of this vector is c, so when you are at rest, you're moving full speed through time. When you accelerate, you shift some of this speed into the spatial dimensions. This is also why time passes more slowly for moving objects. Gravity also has this effect because not only is space curved, but space-time is curved. This means what would normally be a straight path through time is partially warped into the spatial dimensions when you encounter such a curvature.

Re: Particle mystery: physicists confirm the muon is more magnetic than predicted

#110

Post by atty »

treyh wrote: post #92
PeterisP wrote: post #36

Earlier quoted context omitted.

Sure they can fit any experimental result that way, they can probably fit any 19 experimental results that way, but in general if you would freely adjust a constant to fit one experiment then it would stop fitting other experiments.

My understanding is that with the lagrangian approach then the free parameters are not all interacting with each other because they are part of different terms. This means a change to a free parameter doesn't necessarily break experiments.

The point is that there are now 10s-100s of experiments that have been reported to very good precision (obviously not all to the extra-ordinary precision of this measurement). There are no longer any “free parameters” in the SM, in the sense that each one has been constrained by at least one experiment by now. Also, in complicated processes like this one, multiple parameters could make an effect on the observed value, such as the fermion masses. (Not saying the fermion masses actually affect g-2, it’s been a few years since I’ve done any QED, so my memory is a little cloudy :) )
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