Special relativity

I'm staying busy too, but I'm going to still make those episodes.

So what are those episodes going to be about? I'm going to be talking about special relativity, quantum mechanics, nuclear physics, atomic physics, particle physics maybe.

And yeah, I think the idea here that I have is to maybe try to organize some of the physics subjects or some of the introductory modern physics courses because I took modern physics last summer and it just feels like the organization of knowledge is just very bad because quantum mechanics deals with particle physics, maybe atomic physics, maybe even nuclear physics a bit and that overlap is weird.

you know um and thermodynamics thermodynamics is also part of modern physics and that that one that one feels very structured i think it's intuitive right but maybe it also has to do with quantum mechanics and stuff like that so so again my goal is to make these like roughly 10 episodes maybe on all these classes and well i'm going to be starting with special relativity now Special relativity is a theory that follows from two of Einstein's postulates, which is that what the speed of light is always constant and then all physical laws hold in non-accelerating reference frames these are i think kind of make sense but are also kind of kind of counterintuitive so let me just go through them again so if you have a laser and you shoot your laser and you're on the ground the speed of the laser the speed of light from that laser is this like constant speed of light okay similarly if you're in a car and you shine this laser again the speed of the speed of that laser is also just the speed of light this is different from what we're used to in classical mechanics if you were in classical mechanics you might say that if you're in the car that the speed of light is the speed of light plus the speed of the car that's moving right i think this is your first natural response but that's not true that's not true Now the accelerating thing part is that I'm not, I can't get into it too much because it's really confusing, but basically if you're accelerating weird things happen to the laws of physics or different things show up.

So for all our purposes, we're going to assume a constant speed.

We're going to assume no acceleration and therefore the physical laws hold.

All you need is the spacetime coordinates of this event, which you already have, and I think maybe the velocity of this other frame that's moving, I think, something like that.

And you literally just plug these equations, like two, a couple different things into this formula, and literally the spacetime coordinates come out in a different frame.

What right do I even have to talk about black holes, the number one characteristic of which is that you can't see them at all? So, that's where we're going to go in a minute.

And to do that, we have to talk about relativity, special relativity and general relativity, because those are the theories that underlie all of this.

So, before we go plunging into that, let me pause for questions at this point.

Yes? Yes, you should be.

Excellent.

All sorts of questions.

So now, let me at least start talking about special relativity.

There are two kinds of relativity.

That's why you rack.

We were talking about relativity, and where we ended up last time, we're talking about special relativity and all the weird things that happen to space and time.

And the question arose, what prompted Einstein to think these thoughts? And we talked a little bit about the fact that the speed of light is always the same, no matter what the velocity of the person observing it.

and how that then, if you take that literally, it tells you that space and time are weird, and are not constant and absolute the way you might think they are in a Newtonian sense, but vary according to the velocity of the observer.

Mathematicians like Poincaré, physicists like Minkowski, there were a whole bunch of people thinking about this.

And it was an urgent problem in physics, and so that had to be dealt with.

And if Einstein hadn't existed, it might have taken a little longer, but we would have gotten special relativity in the end.

That's not necessarily true of general relativity, as I'll explain in a second.

Part 1.

The Special Theory of Relativity.

Sections 1 through 3.

Section 1.

At this juncture, the theory of relativity entered the arena.

As a result of an analysis of the physical conceptions of time and space, it became evident that in reality there is not the least incompatibility between the principle of relativity and the law of propagation of light, and that by systematically holding fast to both these laws, a logically rigid theory could be arrived at.

This theory has been called the special theory of relativity, to distinguish it from the extended theory, with which we shall deal later.

In the following pages we shall present the fundamental ideas of the special theory of relativity.