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

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

sciencemag.org

Post reply on HN
Print view View original

11–20 of 301 posts

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

#11

Post by martincmartin »

misiti3780 wrote: post #7

What is everyones favorite book on quantum mechanics (I would love understand more of the 3 generations of matter)?

Quantum Mechanics and the three generations of matter are slightly different. Quantum Mechanics is like Newton's laws at small scales, in that if you know what things are like at time t, and you know all the potentials (forces), it tells you how they evolve. It also tells you what states are physically allowed (e.g. only certain energies for electrons orbiting an atom). You can study QM for years without any real look at the standard model, which is where the three generations come from.

If you want an undergraduate class in QM, edX has MIT's classes on line:

https://learning.edx.org/course/course-v1:MITx+8.04.1x+3T201...

If you want a textbook, Griffth's "Introduction to Quantum Mechanics" is the standard answer. It's very much a "shut up and calculate" book, you'll learn how to compute expected values of commutators without much intuition for what they mean.

Update: Others point out Griffth's "Introduction to Elementary Particles", read their recommendations, sounds like the way to go.

If don't want to spend 12 hours a week for 3 months and still not have learned much about the 3 generations, then ... I don't know, maybe QED: The Strange Theory of Light and Matter? I don't know if it has the 3 generations, but it only assumes high school math, yet gets into the quantum version of electricity and magnetism.

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

#13

Post by Robotbeat »

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.

That does help a lot!

Of course, this is still not good enough. But the nice thing about things that are real is they eventually stand up to increasing levels of self-doubt and 3rd party verification... it’s an extraordinary result (because, of course, the Standard Model seems to be sufficient for just about everything else... so any verified deviation is extraordinary), and so funding shouldn’t be a problem.

A decent heuristic: Real effects are those that get bigger the more careful your experiment is (and the more times it is replicated by careful outsiders), not smaller.

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

#14

Post by mhh__ »

misiti3780 wrote: post #7

What is everyones favorite book on quantum mechanics (I would love understand more of the 3 generations of matter)?

Bellentine's book is a good introduction to a lot of quantum physics (you will need mathematics), and to really understand particle physics you need even more mathematics

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

#15

Post by gizmo686 »

comboy wrote: post #3
gus_massa wrote: post #2

Only 4.2 sigmas. ;) That is really a lot. It's less than the official arbitrary threshold of 5 sigmas to proclaim a discovery, but it's a lot. In the past, experiments with 2 or 3 sigmas were later classified as flukes, but AFAIK no experiment with 4 sigmas has "disappeared" later.

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.

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

#16

Post by bodhiandphysics »

misiti3780 wrote: post #7

What is everyones favorite book on quantum mechanics (I would love understand more of the 3 generations of matter)?

How much physics do you know? How much math? Griffins introduction to elementary particles is the standard model at an undergrad level... and is great. To understand the three generations at a higher level you need a lot of math (you need to know what a Lie algebra is and Noether’s theorem)

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

#17

Post by misiti3780 »

bodhiandphysics wrote: post #16
misiti3780 wrote: post #7

What is everyones favorite book on quantum mechanics (I would love understand more of the 3 generations of matter)?

How much physics do you know? How much math? Griffins introduction to elementary particles is the standard model at an undergrad level... and is great. To understand the three generations at a higher level you need a lot of math (you need to know what a Lie algebra is and Noether’s theorem)

I do not use math or physics on a daily basis, but have an MS in Applied Math, and a lot of classes in EE.

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

#18

Post by misiti3780 »

martincmartin wrote: post #11
misiti3780 wrote: post #7

What is everyones favorite book on quantum mechanics (I would love understand more of the 3 generations of matter)?

Quantum Mechanics and the three generations of matter are slightly different. Quantum Mechanics is like Newton's laws at small scales, in that if you know what things are like at time t, and you know all the potentials (forces), it tells you how they evolve. It also tells you what states are physically allowed (e.g. only certain energies for electrons orbiting an atom). You can study QM for years without any real loo…

thx

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

#19

Post by beezle »

The Quanta write up is a bit more neutral on this announcement. There is a computational result that was not included in the theoretical value used to bench the test against. Once reviewed, this difference may yet go back to oblivion.

https://www.quantamagazine.org/muon-g-2-experiment-at-fermil...

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

#20

Post by bodhiandphysics »

misiti3780 wrote: post #17
bodhiandphysics wrote: post #16

Earlier quoted context omitted.

How much physics do you know? How much math? Griffins introduction to elementary particles is the standard model at an undergrad level... and is great. To understand the three generations at a higher level you need a lot of math (you need to know what a Lie algebra is and Noether’s theorem)

I do not use math or physics on a daily basis, but have an MS in Applied Math, and a lot of classes in EE.

Griffin is a good book then (as well as his intro to qm)
Post reply on HN