Kick ass physics!

[KrazyHorse]

How do we test the amount of mass in any given energy set

Blaupanzer, are you trying to ask how we measure the mass of a proton?

Because there are dozens of different ways of doing this

[KrazyHorse]

Originally posted by Krill
Yah, done group theory before (discrete groups, anyway), we have to understand in to explain molecular orbital theory. I's not that difficult, just not interesting.

Group theory is unbelievably interesting and difficult. What did you actually learn? My guess is that you only used a very few, simple concepts (this is not meant to be an insult).

[KrazyHorse]

Originally posted by Blaupanzer


KH, We can theoretically test the amount of energy in a unit of mass using a nuclear explosion to convert the mass to energy. Thus we can test the great equation: E = MC^2. However, can we somehow convert the energy to mass to test the opposite process: how much mass is represented by a given unit of energy? This was a curiousity question as was the dark matter/energy question. I know you keep up on these thins so I thought I would ask while you were looking.

a) I don't "keep up on these things". I am a high energy theoretical physicist.

b) I still don't understand what you are trying to get at here. The claim that this is a test of "E=mc^2" comes from (I'm guessing here) performing a lattice QCD calculation to determine the average energy density in a proton coming from interactions. This gives the E side. Then they compare to the previously determined m side (the mass of a proton). The answer agrees, somewhat (or so they claim).

c) The conversion of energy to mass is pretty easy to demonstrate. What do you think particle colliders do?

[Blaupanzer]

No more the potential mass represented by a photon say. If mass = energy in some relationship, said relationship proven by the A-bomb and the H-bomb, then energy must also equal mass in a roughly similar relationship. I was wondering how we would measure (and thereby test) the theory using energy as the basis, e.g., this much energy is equal to this much mass because we converted energy to mass using [WHAT?] procedure. May just be idle speculation. But if anyone on this forum knows, it would be you.

[KrazyHorse]

Dude, they measured the energy of interactions in a proton. They compared to the mass not due to the rest mass of the quark "composition". They got similar answers.

What is the objection?

[Krill]

Sorry, you're right, I should have phrased that better: the group theory that I learnt was that which was required to explain atomic/molecular orbital interactions. This explains the basics of what we learnt, we are expected to understand a fair bit more. For example, we we expected to use it in diffraction course explain Xray and neutron diffraction, in crystalline chemistry.

[KrazyHorse]

would measure (and thereby test) the theory using energy as the basis, e.g., this much energy is equal to this much mass because we converted energy to mass using [WHAT?] procedure

Smashing **** together at high energy. This is what modern physics is based on.

[KrazyHorse]

Originally posted by Krill
Sorry, you're right, I should have phrased that better: the group theory that I learnt was that which was required to explain atomic/molecular orbital interactions. This explains the basics of what we learnt, we are expected to understand a fair bit more. For example, we we expected to use it in diffraction course explain Xray and neutron diffraction, in crystalline chemistry.

Did you guys actually go into representation theory or did you simply use a given set of representations for any group? Which representations a given symmetry group allows and how these reps decompose is a major part of how you apply group theory in HE physics.

[Krill]

Originally posted by KrazyHorse
Did you guys actually go into representation theory or did you simply use a given set of representations for any group? Which representations a given symmetry group allows and how these reps decompose is a major part of how you apply group theory in HE physics.

No, we didn't use representation theory.

[KrazyHorse]

Okay. I'm always interested in what other people learn.

[Krill]

np

[Blaupanzer]

Originally posted by KrazyHorse

would measure (and thereby test) the theory using energy as the basis, e.g., this much energy is equal to this much mass because we converted energy to mass using [WHAT?] procedure

Smashing **** together at high energy. This is what modern physics is based on.

Smashing stuff together converts mass to energy in a spectacular manner. Can we convert energy to mass? Is that what fusion is? Do we end up with more mass than we started with despite the even more spectacular explosion?

Note I have no objection to the initial article except to agree with you that what was reported does not sound like a breakthrough. I just had a couple of questions on my mind and thought I would piggy back them onto this discussion.

[KrazyHorse]

Smashing stuff together converts mass to energy in a spectacular manner.

No. Smashing stuff together converts energy to mass. As only one example of many,

http://en.wikipedia.org/wiki/Top_quark

The top quark is the third-generation up-type quark with a charge of +(2/3)e.[1] It was discovered in 1995 by the CDF and D0 experiments at Fermilab,[2][3] and is the most massive of known elementary particles. (The Higgs boson, which may be as massive, has not yet been experimentally observed.) Its mass is measured at 172.6±1.4 GeV/c2, about the same weight as the nuclei of tantalum or tungsten atoms.[4]

That mass (172 GeV) comes from two protons (mass ~1GeV, and technically the tevatron is a proton-antiproton experiment) which each have a lot of kinetic energy (~980 GeV each). The remaining energy goes into kinetic energy of the top, along with making a bunch of other **** (some of which has mass).

[Jon Miller]

See, this is why you have more patience than I. I was considering possibly just posting that link but had decided not to.

JM

[KrazyHorse]

Every particle heavier than the proton was discovered by the conversion of energy to mass. We've been doing this for 80 years.