I Don't Understand The Physics

[DNK]

At first you need a firm understanding of electrodynamics. This isn't so bad, as it is all about classical waves. The math can get ugly, though.

Then quantum mechanics. The principles of it are fundamental to anything on that scale.

Then you also need statistical mechanics, especially quantum statistics and the Bose-Einstein statistics.

Understanding relativity is also useful.

Then you have to combine all these concepts into quantum field theory.

The problem with these concepts is, that they're very mathematical and it's very difficult and it takes quite some time to develop some intuitive understanding of it. And even then, those images a physicists has in his head are simplifications of the math, that are valid for some cases, but totally break down in other cases. The quantum world works totally different from what we expect from world surrounding us.

For example one can produce a state, where a photon and an atom form a strange mixed state, where there is no telling whether there is a photon or not. The photon exists and doesn't exist at the same time.

Thus the question: "What is a photon" isn't a question that can be easily answered.

Sources, books? I guess a forum isn't going to be able to answer all of this and my fundamentals are so dusty it won't be worthwhile then.

I've read The Elegant Universe and some Hawking, but neither seems to delve into specifics and the what is everything, just basic science ed stuff, I thought.

Why all the math? I know it's important and the language of nature and all, but why can't this stuff be explained solely via theory?

 

[GoodGame]

Why all the math? I know it's important and the language of nature and all, but why can't this stuff be explained solely via theory?

My own experience (Physics II) is that calculus (Calculus III for matrix calculus) is involved, because field functions are explained in 3 dimensions, often as the surfaces of 3-dimensional, non-orthogonal objects.

 

[uppi]

Sources, books? I guess a forum isn't going to be able to answer all of this and my fundamentals are so dusty it won't be worthwhile then.

I've read The Elegant Universe and some Hawking, but neither seems to delve into specifics and the what is everything, just basic science ed stuff, I thought.

Why all the math? I know it's important and the language of nature and all, but why can't this stuff be explained solely via theory?

In quantum mechanics, the math is sometimes the only thing we really know. The question what actually happens so that it behaves like the math predicts is sometime subject to interpretation. There are cases, where you have to stick to the formalism, because any intuitive approach is likely to be wrong.

It seems you would like some books who explain modern physics in words a non-physicist can understand. Unfortunately, the books I have read on these topics were all textbooks for my courses, which are pretty hard to digest. If you want that, I'd suggest you start with the Feynman lectures.

 

[raigainousa]

It confuses me ever so much. Please to explain these questions:

1. How do permanent magnets work actually?
2. Why/how does an electric current create a magnetic field?
3. When you say an electron is a wave, how big of a wave is it? Is it just like imagining a ripple if you shoot it at something, or is it like a cone? Is there any distinction between the wave an electron would make and one a photon would make?
4. Why/how does an oscillating magnetic field create electricity?

1 - I dont know

2 - becuse they are two side of a coin. Electromagnetic force is a fundamental force in the universe.

3.
De Broglie(did I got the spelling right?) says the wave goes around and round and round and round a circle. Remember wave-particle duality?(Or not?) And that's the wave of an electron.

A wave of a photon is called electromagnetic wave. It is two wave at perpendicular angle(please imagine!) Remember that photon is the carrier of electromagnetic force.(Or not?) And yes, they fly at speed of light because they don't have mass(In case you want to know)

4. That is the effect of the electromagnetic force.

At first you need a firm understanding of electrodynamics. This isn't so bad, as it is all about classical waves. The math can get ugly, though.

Then quantum mechanics. The principles of it are fundamental to anything on that scale.

Then you also need statistical mechanics, especially quantum statistics and the Bose-Einstein statistics.

Understanding relativity is also useful.

Then you have to combine all these concepts into quantum field theory.

...Then you can now start

Or .

Or

Or

Or even better:

I only understand relativity

 

[DNK]

I only understand relativity

So why does the universe impose a speed limit and how does it do this?

 

[uppi]

So why does the universe impose a speed limit and how does it do this?

One can show mathematically, that if the Gallilei transformation (i.e. just adding / substracting the velocities to get into another system) does not work (and the universe has certain symmetries), then there has to be a speed limit.

In other words: Because the relativity principle works for the universe, there is a speed limit. The fact that the relativity principle does work and what that limit is comes from experimental evidence.

I don't think there is an explanation, why the universe has these properties.

 

[Olleus]

Because the solution for maxwells equations in free space gives a wave that travels at a constant speed, no matter what the velocity of the source is.
From that, all else stems.

 

[DNK]

Because the solution for maxwells equations in free space gives a wave that travels at a constant speed, no matter what the velocity of the source is.
From that, all else stems.

So why is it that that is so?

 

[Olleus]

That is not a science question. Asking why nature choses to behave according to a certain set of laws is, at best, philosophy. Its like small children saying "yeah, but why is that?" to every answer that you give. Science is a description of nature which permits predictions to be made. Why a certain prediction is the way that nature acts is a non-sequitur, as any possible answer can be refuted by asking "But why does nature act that way?"

 

[raigainousa]

So why is it that that is so?

I dont understand whether its a question or a sarcasm.

Because the solution for maxwells equations in free space gives a wave that travels at a constant speed, no matter what the velocity of the source is.
From that, all else stems.

I see, it is also included in einstein's special relativity, referring to light in the vacuum.

 

[DNK]

That's not an explanation. Why would it be sarcasm to ask a question?

Yes, children's questions. Like why is the sky blue? "Because it is son, quit being silly."

Very unscientific mentalities ITT all of a sudden.

Thanks for the Lectures idea, I'll look into those.

 

[Olleus]

No, your question is more like this:

CHILD: Why is the sky blue?
PARENT: Because blue light diffracts more than the other colours so it appears to come from every direction
Child: But why is that?
PARENT: Because the refractive index of air depends on the wavelenght of the light rtaveling through it
CHILD: But why is that?

ad infinitum

 

[raigainousa]

That's not an explanation. Why would it be sarcasm to ask a question?

No, your question is more like this:

CHILD: Why is the sky blue?
PARENT: Because blue light diffracts more than the other colours so it appears to come from every direction
Child: But why is that?
PARENT: Because the refractive index of air depends on the wavelenght of the light rtaveling through it
CHILD: But why is that?
PARENT: Beacuse the explanation is really here

CHILD: *nosebleed*

even better...heehee...XD