Two physics questions.

[Jasper]

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.

That is so fucking fascinating, because to me it sounds like a point where reality breaks down into energy and information.

But perhaps it only sounds that way because my metaphysical dualism is energy and information.

[LMNO]

Perhaps.

We have derived calculations that work. The observations of our detectors confirm our calculations.

[Faust]

Perhaps.

We have derived calculations that work. The observations of our detectors confirm our calculations.

Yep, all we have is the masses of some particles and how they interact with other ones. Asking for much more is stretching it a bit.

[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.

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.

No, gravity doesn't transmit its force in the same way that particles interact. Its definitely not the repulsion of electrons, they are waaaay to big to be the transmittable force for gravity. Even photons are too big. I mean it has to have some method of transfer, its just so tiny we cant figure out what it is.

[Jasper]

Perhaps.

We have derived calculations that work. The observations of our detectors confirm our calculations.

Yep, all we have is the masses of some particles and how they interact with other ones. Asking for much more is stretching it a bit.

So you're saying physics only describes reality so far?

[Cain]

Well, to describe it fully accurately, you'd need to replicate the Universe, so...

[Jasper]

I hate that some knowledge is simply off-limits, but I guess I'll live.

[Faust]

Perhaps.

We have derived calculations that work. The observations of our detectors confirm our calculations.

Yep, all we have is the masses of some particles and how they interact with other ones. Asking for much more is stretching it a bit.

So you're saying physics only describes reality so far?

We can take a good guess at all large scale (classical physics stuff). Quantum Mechanics is incomplete (for example no one can explain the gravitation force yet). Its nice, it means we still have new frontiers to explore.

[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.

No, gravity doesn't transmit its force in the same way that particles interact. Its definitely not the repulsion of electrons, they are waaaay to big to be the transmittable force for gravity. Even photons are too big. I mean it has to have some method of transfer, its just so tiny we cant figure out what it is.

I meant that the electromagnetic repulsion is the opposite and equal force to gravitational attraction when an object is at rest on the surface of the earth, or on the surface of any object suspended above the earth.

[Golden Applesauce]

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.

Think of gravitational mass as how much something weighs (kinda.)  The more gravitational mass something has, the more it feels the force of gravity, and the stronger its gravitational field is.  If you were to double the gravitational mass of the Earth, everything on it would weigh twice as much.  The Earth itself would also be pulled twice as hard towards the Sun, so what would probably happen is that the moon would crash into Earth and then both would fall into the Sun.  This is the m in g = G*m1*m2 / r^2 (Newton's Law of Universal Gravitation.)

Inertial mass is how hard you have to push something to speed it up or slow it down.  A car with lots of inertial mass will take more fuel to get up to speed than a lighter car, and has to have stronger brakes to slow it back down at the same speed (or just brakes more slowly.)  If you take a car and double its inertial mass, you also double its stopping distance - the brakes have to exert the stopping force for twice the distance.  This is the m in F = m * a (Newton's Second Law of Motion.)

The weird coincidence is that nobody's ever been able to find or create an object that has more or less gravitational mass than inertial mass - or come up with a good reason why such an object can't exist.  In science fiction they often have a super-metal with a strong gravitational mass but low inertial mass.  If such a thing existed, you could line the floors of your spaceship with it and get Earth-normal gravity inside (because it has a high gravitational mass, and creates a strong gravitational field) without having to spend a whole lot more fuel to push the spaceship around the cosmos (since it doesn't have correspondingly high inertial mass.)  Conversely, you could imagine a planet with normal inertial mass for a planet (if you try to push a planet, what happens is that you go backwards and the planet stays right where it is, thankyouverymuch) but with no gravitational mass - it wouldn't have a gravitational field, everything nearby would simply be weightless.

[Kai]

I think, after hearing your explanation, it's more confusing that some people would think an object could have unequal gravitational to inertial mass than the opposite and commonly accepted notion. If mass is energy via mass-energy equivalence, then to have unequal inertial to gravitational mass there would have to be some violation of the first law of thermodynamics.

[Faust]

I think, after hearing your explanation, it's more confusing that some people would think an object could have unequal gravitational to inertial mass than the opposite and commonly accepted notion. If mass is energy via mass-energy equivalence, then to have unequal inertial to gravitational mass there would have to be some violation of the first law of thermodynamics.

It doesn't violate the first law of thermodynamics we just don't know the actual values of the transmitant force of gravity.

I meant that the electromagnetic repulsion is the opposite and equal force to gravitational attraction when an object is at rest on the surface of the earth, or on the surface of any object suspended above the earth.

Not equal and opposite, different ratios, most of quantum mechanics and electromagnetism would be simple if they were one to one.
For instance a bigger electric field doesn't give a bigger magnetic field, its the rate of change of the E field that controls that. other stuff like resistance changes the values.
So as above gravity doesn't violate the first law because we don't know the the values of things interacting on different masses all we know is the gravitational force is small and has huge range.

[Jasper]

I'm spending a lot of time with this thread on my mind.

I'm reading the wiki on gravitational waves, it's got a lot to chew on.

[Faust]

I'm spending a lot of time with this thread on my mind.

I'm reading the wiki on gravitational waves, it's got a lot to chew on.

Its bizarre, isn't it. QM + EM was my favourite subject last year but its really tough and quite humbling really.

[Jasper]

I keep having to remember not to let my jaw go slack.