Two physics questions.

[Jasper]

No, not seamonkeys.

[Doktor Howl]

No, not seamonkeys.

Oh.  Sorry.  Never mind.

[Kai]

No, gluons are a verified part of the Standard Model. Which is where I'm taking all this from, and which is why I'm not mentioning gravity.

Fancy pictures are more fake evidence cf. "teacher's passwords" if they don't actually explain anything.

It's like answering "heat convection!" to the question "why is the plate hottest on the side closest to the fire?" You might as well say "Phlogiston!" for as much understanding it conveys.

[Golden Applesauce]

Well, mass and energy are pretty much the same thing.

And we still don't really know what mass is.  So far, it's been a really weird series of coincidences that everything has the same gravitational mass as inertial mass.

And that's not even counting potential energy.  If you take a rock and pick it up off the ground, it has more energy.  It isn't hotter, it doesn't spin faster, it isn't even heavier (in fact, it will be lighter since it's further away from Earth.)  We can't even say how much of this virtual energy it has - you could define that rock to be at zero potential, and then any other rock closer to the ground would have negative virtual energy, and both still hurt if you drop them on your foot.  There's no real reason to go around saying that some rocks have negative potential energy and some have positive potential energy, except that the math works out beautifully if you do.

[Kai]

Well, mass and energy are pretty much the same thing.

Thank you for reminding me of that.

And we still don't really know what mass is.  So far, it's been a really weird series of coincidences that everything has the same gravitational mass as inertial mass.

Please explain gravitational and inertial mass.

And that's not even counting potential energy.  If you take a rock and pick it up off the ground, it has more energy.  It isn't hotter, it doesn't spin faster, it isn't even heavier (in fact, it will be lighter since it's further away from Earth.)  We can't even say how much of this virtual energy it has - you could define that rock to be at zero potential, and then any other rock closer to the ground would have negative virtual energy, and both still hurt if you drop them on your foot.  There's no real reason to go around saying that some rocks have negative potential energy and some have positive potential energy, except that the math works out beautifully if you do.

I think that just confused the fuck out of my head. That makes absolutely no sense at all.

[Kai]

1. Quarks, for now, seem to be elemental.  They aren't made of anything, they simply are.  Kind of like how we thought atoms were elelmental, before we found out they had parts.  For now, they "are" the building blocks.

2. Short answer: dunno.  Still trying to work that one out.


Longer answers available upon request.

So, are quarks solid, or are they probability fields, like photons?

Solid.

I keep a jar of them on my desk.  But they're really hard to see if you spill them.

Am I taking this too seriously?

[Igor]

And that's not even counting potential energy.  If you take a rock and pick it up off the ground, it has more energy.  It isn't hotter, it doesn't spin faster, it isn't even heavier (in fact, it will be lighter since it's further away from Earth.)  We can't even say how much of this virtual energy it has - you could define that rock to be at zero potential, and then any other rock closer to the ground would have negative virtual energy, and both still hurt if you drop them on your foot.  There's no real reason to go around saying that some rocks have negative potential energy and some have positive potential energy, except that the math works out beautifully if you do.

I think that just confused the fuck out of my head. That makes absolutely no sense at all.

Gravitational potential energy can only be defined relatively. You can say what the difference between two potential energies is, but not what their absolute potential energy is. Well, you can, but you have to choose an arbitrary zero point. Which is why it still works if things go negative.

[Kai]

And that's not even counting potential energy.  If you take a rock and pick it up off the ground, it has more energy.  It isn't hotter, it doesn't spin faster, it isn't even heavier (in fact, it will be lighter since it's further away from Earth.)  We can't even say how much of this virtual energy it has - you could define that rock to be at zero potential, and then any other rock closer to the ground would have negative virtual energy, and both still hurt if you drop them on your foot.  There's no real reason to go around saying that some rocks have negative potential energy and some have positive potential energy, except that the math works out beautifully if you do.

I think that just confused the fuck out of my head. That makes absolutely no sense at all.

Gravitational potential energy can only be defined relatively. You can say what the difference between two potential energies is, but not what their absolute potential energy is. Well, you can, but you have to choose an arbitrary zero point. Which is why it still works if things go negative.

Explain that again, except Taboo "potential energy".

[Igor]

Yeah, I did use that phrase a lot...


It's pretty much the same as height. You can say how high something is off the ground, but this requires you to define what ground level is. So some stuff will inevitably be below that mark and have "negative height", so to speak. The only rigorous way of defining heights is saying "this is taller than that", rather than, as I said, choosing an arbitrary zero point (or ground level).

Does that make more sense?
I'm getting the feeling that I'm not great at explaining these concepts, which would suggest that I don't understand them fully myself. Oh well.

[Kai]

Yeah, I did use that phrase a lot...


It's pretty much the same as height. You can say how high something is off the ground, but this requires you to define what ground level is. So some stuff will inevitably be below that mark and have "negative height", so to speak. The only rigorous way of defining heights is saying "this is taller than that", rather than, as I said, choosing an arbitrary zero point (or ground level).

Does that make more sense?
I'm getting the feeling that I'm not great at explaining these concepts, which would suggest that I don't understand them fully myself. Oh well.

It would seem to me that every object everywhere has potential energy in relation to the absolute center of gravity for every other object in the universe, and that potential energy as it is used in basic physics exercises is useful in anticipating measures of velocity and acceleration, but is otherwise "floating" from the absolute zero point which is the center of the earth. Potential energy in this sense is predicted effect of gravitational attraction upon kinetic energy.

[Faust]

Gravity: In short we have nothing solid on this, because of the large range of influence and the low energy of the effect, we cant measure it precisely, so we can only work on theoretical stuff for it. Unfortunately Every theory for it so far falls apart because mathematically you keep getting infinity when you start plugging in values.

We have been able to work out an awful lot on small particles by replacing theoretical data with their mesured mass, giving remarkably accurate, repeatable equations for stuff down to the quark level.

Asking what any subatomic particle is at this level is inviting a migraine, we can tell you some of its characteristics and how it interacts with other things but anything more is currently closer to a philosophical question then anything else.

What is electromagnetism: Electromagnetism is the description given to the activity corresponding to the observed rules (maxwells mostly), that describe the interaction of the magnetic field and the electric field.
How does it interact with other stuff: Photons.

2. What is energy? I mean that, when we come right down to it, we have four basic forces, and all energy is derived from those forces, but what is energy /really/? This is not a "Does 2+2 really really equal 4" question. I believe (IOW, I anticipate) that gravitational energy is the warping of space time by mass, but what is electromagnetic energy, for example? And how is that contained as a quantum field we call a photon?

No one can answer that.
My personal and very vague idea is this: Every single physical law we have boils down to transformation, or interaction. A changing magnetic field gives an electric field. Energy or whatever you want to call it is probably the result of something changing somewhere else.

ETA: And if these are really stupid questions, please let me know. My qualifications are but a year of non majors physics in undergrad.

They aren't stupid but:

I'm not really interested in untestable hypotheticals. String "theory" being one of those.

At a certain level the only available answers are hypotheticals.

[Faust]

Potential energy in this sense is predicted effect of gravitational attraction upon kinetic energy.

Yes, that's potential energy in any sense not just gravitational, It is a resultant based on vectors of force, one of which happens to be the attraction between two bodies.

[Kai]

Potential energy in this sense is predicted effect of gravitational attraction upon kinetic energy.

Yes, that's potential energy in any sense not just gravitational, It is a resultant based on vectors of force, one of which happens to be the attraction between two bodies.

And it remains in potential while receiving an equal and opposite force. In the case of gravitation, that force is electromagnetic (repulsion of electrons). No net force leads to the object remaining at rest.

[Requia ☣]

1. Quarks, for now, seem to be elemental.  They aren't made of anything, they simply are.  Kind of like how we thought atoms were elelmental, before we found out they had parts.  For now, they "are" the building blocks.

2. Short answer: dunno.  Still trying to work that one out.


Longer answers available upon request.

So, are quarks solid, or are they probability fields, like photons?

Everything below a certain amount of kinetic energy does the weird probability field (except when its not) thing (at least according to my textbooks from when I did physics).  So in theory they're wave-particle hybrids most of the time and particles if you get them moving fast enough.  I don't know to what extent experimentation has borne this out.

[LMNO]

This is the most accurate and most vague answer, and because it's Quantum, it's most true: physics has, though it's history, quantified and calculated physical events. Those events have become so small that we can no longer observe the events, only the detectors of the events. From there, we can determine if those detectors matched our equations. Our current model/equations say that quarks are elemental, which means our equations can't break them apart. So, quarks "are" equations that line up with all the experimental data that we have acquired throughout the last century.