The idea of holes and antiparticles strikes me as similar to temperature. Only allegorically, but I watched a documentary about the early understanding of cold, and how it was considered to be a separate, physical thing. It wasn't until a hundred years or so ago that we finally understood it to be the absence of something. I can't help but draw a parallel with the way our understanding of quantum particles might evolve.
That's a great way to see it. Drawing parallels has been extremely useful for me in learning physics. It's also a way to transfer knowledge from one field to discover something in another.
But now that I have free tuition from a physics graduate , behold my QUESTIONS!
It has been pointed out in Stewart's book that the orbit of the earth is not the effect of pulling from the sun, like the lead-ball-on-the-end-of-a-string-being-spun-round imagined in Newtonian physics. Rather, the planet is being deflected off the curvature in space caused by the sun, like the camber of a road. So, naturally, I got thinking about these things: https://i.ytimg.com/vi/X6e1y0WzzeE/maxresdefault.jpg
Why is it that the coin seems to exit the hole at the bottom with greater velocity than it began with? I can only assume it's an optical illusion, because no matter what exotic physics happens, the coin cannot gain kinetic energy unless that energy is provided to it from outside. As the coin makes a lot of noise, if anything it should be losing energy - the effect of gravity over the short vertical distance from the coin slot to the spiral can't add very much.
You're right, the short distance doesn't add much at all. But then, the coin doesn't weigh much at all either! Sound is actually super cheap in energy, and the coin does indeed gain energy from the gravitational field as its moves down the surface.
This is a good example of conservation of energy*. You can draw parallels between an orbit and a pendulum. A pendulum, like in a grandfather clock, swings back and forth. If you keep a close eye on it, you'll realize that its highest speed is at its lowest point. Meanwhile, at the ends of the swing it's not moving at all for a split second. What is going on in the pendulum is that the (small amount of) energy is perpetually being traded between potential energy (being high up in a gravitational field) and kinetic energy (moving fast). So following the parallel to the orbit of the coin, that fast speed it's got at the bottom is actually showing you the potential energy that was contained at the highest point of its path.
However, when I think about it some more, there might indeed be a little illusion at play as well. If it wasn't for the fact that the coin is constrained to a narrow tube, spinning like crazy, then its velocity might seem slower. When it is merely coasting on the top of the surface, we might see that as a slower speed than it really is, in comparison. However, the planets themselves do have higher velocities at the "lowest" points of their orbits. For objects like Sedna, or the hypothesized Planet Nine, this is quite a considerable difference. I would recommend trying out the mobile game Orbit for a relevant demonstration :D
The other question is, when we measure electromagnetic frequency, what is it the frequency OF? A sound wave, for example, is a measure of air pressure relative to a background equilibrium, represented as the x-axis at zero. So, is electromagnetic frequency an oscillation in the 'energy pressure/concentration' relative to some rest state?
In short, the field strength. I will assume first we're talking about the frequency of a loose piece of electromagnetic field, a photon. It will oscillate around the value of the background field, whatever that is!
A digression about the broader perspective: In some interpretations of quantum field theory, there is an electromagnetic field filling the universe. Its default value is zero, and we can know this for sure because any other value would affect particles. That is not to say that is ever is zero, because every single charge in the universe will add its own dimple. Electromagnetism can be seen just like gravity in this regard, as a huge sheet of dents caused by charges instead of masses/energies. The dents can of course go in two directions, because of the +/- nature of electromagnetism. The reach of electromagnetism is infinite, so this field technically has a non-zero value anywhere in space. By and large, though, this is so small you can ignore it. Even though the electromagnetic force is much stronger than gravity, the charges in the universe largely balance each other up (such as in neutral atoms), there just aren't enough free charges to have a cosmic effect.
Going back to the photon, this little electromagnetic lass will dance to her own tune, and if she dances up the stairs and onto a higher dancefloor, her dance will be a "higher" dance, but she won't care about that! Photons are not charged and they will not interact with electromagnetic fields. Only an outside observer will count the floor as well.
Wait, how can the (electric and magnetic) field strengths vary, but the photon have no charge? What confines these fields so they can't reach out and affect anything, and how can we measure the frequency if that's the case? I don't remember any good explanation of this! I will keep looking, though.
* Of course, it's due to a small energy loss that the coin falls down at all, but its behaviour is still very well approximated by conservation laws. Almost all of our laws are approximations when it comes to the behaviour of the real world, where a near infinity of minor effects take place constantly. We understand pretty much all of those minor effects too and we could always make a better fit, that's just a question of utility. Approximations are more powerful than they might sound. But I do want to make the point that physics can be overly simplified compared to the sheer complexity and beauty of reality!