How can a particle be a combination of other particles?

[PeterDonis]

What I don't understand is why with less effort than that required to undo my poor efforts, he doesn't instead just do it right in the first place

You're missing the point. Somebody already did it right in the first place. Then you changed it to something wrong. If Orodruin, or anybody else, changes it back, what guarantee is there that some other non-expert won't come along tomorrow and change it to something wrong again? Answer: none.

In other words, if you're an expert, trying to keep a Wikipedia article's text correct ends up being an endless game of whack-a-mole. Experts have better things to do with their time. Yes, that means Wikipedia is often not a good source. That, quite frankly, is Wikipedia's problem.

 

[Orodruin]

If Orodruin, or anybody else, changes it back, what guarantee is there that some other non-expert won't come along tomorrow and change it to something wrong again? Answer: none.

Just to elaborate on this: I did not correct it because I want Wikipedia to be correct - as Peter says, that is a Herculean task and there is no guarantee it will not be changed to something wrong tomorrow. I reverted the change because these things could have a detrimental effect on the reputation of Physics Forums. Imagine someone sees your edit and realizes it is wrong - they go to the talk page, get your user name, search for it, and this thread will pop up. All of a sudden, Physics Forums is the place where you got your ideas from and vandalised the Wikipedia article.

 

[Buzz Bloom]

you misunderstood PeterDonis' post when he said you need higher energies to access the phenomena concerning particles having such masses, and you somehow conflated the two concepts.

Hi ddd:

Thanks for your post:

This is what I understood from Peter's and Orodruin' post.
(1) In particle physicsese, "mass" means "rest mass" as opposed to M = E/c² mass.
(2) GUT models predict the rest mass of particles.
(3) The particular predicted rest mass for a GUT predicted particle requires an extremely high amount of energy to produce such a a particle, either experimentally or naturally. This level of energy is called the GUT scale. This is the scale of energy that was naturally present during the stage of the universe before the strong force separated from the week-EM force.

What did I misunderstand?

Regards,
Buzz

 

[ddd123]

What did I misunderstand?

You probably should ask that yourself since you ended up editing the article with "energy" which can't be correct, since energy can vary a lot from the rest mass portion (e.g. ultrarelativistic regimes). Your "rest mass" objection is a different one from the first, which you came up with after you figured out you were wrong in the first place: that's a first misunderstanding. The second misunderstanding, different from the first, is the fact that the concept of rest mass really is useless on both fronts:

1) technically, it's just redundant: mass is already rest mass, because relativistic mass is just a flawed concept of old.
2) didactically, relativistic mass only confuses people more (as you are an example), since parallel or perpendicular forces have different results from such a mass: so it's not really what you think about concerning "mass" anyway - your "Babel" problem, in a reductio ad absurdum scenario, is still present and exacerbated if you just start editing all particle physics articles writing "rest mass" instead of "mass".

 

[Buzz Bloom]

I reverted the change because these things could have a detrimental effect on the reputation of Physics Forums.

Hi Orodruin:

Thank you for your post. I get and accept your point.

There is one more Wikipedia physics article I have edited. (There are many others for which I have only edited the Talk page.) It is

https://en.wikipedia.org/wiki/Solar_neutrino .​

I tell you this so if you want to you can take a look at it and let me know if you think I should undo it, and why.

Regards,
Buzz

 

[Buzz Bloom]

You probably should ask that yourself since you ended up editing the article with "energy" which can't be correct, since energy can vary a lot from the rest mass portion

Hi ddd:

Thanks for your post.

I misunderstood you post. I thought you were referring to Peter's latest post, when you were instead referring to Peter's post from September when he wrote

What this means is that, if we tried to detect such particles in our current universe, those are the masses we would have to be able to detect--which means we would have to be able to run experiments that involved particles with energies of that order of magnitude.

You are correct. I did not understand then that Peter's "mass" meant "rest mass" and excluded the alternative meaning of relativistic mass M=E/c².

Regards,
Buzz

 

[Buzz Bloom]

relativistic mass is just a flawed concept of old.

Hi ddd:

I do not understand what this quote means. In what way is this a flawed concept?

Regards,
Buzz

 

[Orodruin]

In what way is this a flawed concept?

What is relativistic mass and why it is not used much?

 

[ddd123]

Basically, writing "rest mass" is misleading since it seems to imply there are other kinds of masses (namely the relativistic mass, which as the article says is a contrived formalism which doesn't correspond to a mass in any concrete sense anyway). Besides, since the whole particle physics field uses the word "mass" a real lot, changing all instances would be insane.

 

[Buzz Bloom]

What is relativistic mass and why it is not used much?

Hi Orodruin:

Thanks for your post and the link. I now get why "rest mass" has become a unwanted usage. So the preferred vocabulary has become:

"mass" always means the inherent mass a particle has (ignoring its kinetic energy). "rest mass" is then redundant, and also by implication suggests an alternative, "relativistic energy" which is concept that has become out of favor.

"energy" means the "total" energy of a particle (including both it's mass equivalent energy and kinetic energy, and maybe also in some contexts its internal exited state energy as well), or with an adjective, a specific kind of energy.
​

When I was learning this stuff as an undergraduate, a very long time ago, usage was much different. Times change.

Regards,
Buzz

 

[Orodruin]

When I was learning this stuff as an undergraduate, a very long time ago, usage was much different. Times change.

Unfortunately, I believe this is still mentioned in some undergraduate modern physics courses, simply because the professors who are teaching them are not specialists in relativity and it is how didactic was when they were learning relativity. If you go to any higher level course or graduate course in relativity, you will most likely not encounter relativistic mass (apart from the professor briefly mentioning that you should not use it).