What Is Space?

This is the part that I don't really understand - how does the electromagnetic force "know" the true distance?

Basically, there is an equation that determines the strength of the field that depends on the distance from the centre of the particle, or rather the "particle" creates a ripple in the field. The ripple still has a length though.

So, the question then becomes - somehow the fact that the field has a bigger differential between two spots in space, keeps from more "space" appearing between those two spots.

Yet where the field is zero (or whatever the lowest energy value is) more space can be created within the field. So, it seems that there is a "space field" and a number of other fields, that interact with each other and can influence the properties of each other.

This kind of makes sense, essentially if the "space field" can have values attached to it, that in effect would determine "distance" from our perspective, then the interactions with other fields can influence the change in distances.

IANAP, so if you are, would this be a correct line of thinking?

> Then, presto, bingo, one part of that wave function enters our telescope and hits our detector. Then all the dozens of pieces of that wave function, scattered across a billion light years, have to disappear, instantly, since with two telescopes we can never get two detections from the one photon.

> Well, that's tough to believe.

There are a dozen different possibilities for what the photon has done - a dozen different universes, if you like. As long as the photon never interacts with anything else, this bundle of a dozen universes can act much the same as a single universe. Certainly if you're just looking at a telescope, all dozen versions of that telescope are behaving the same, so they behave like a single unified instance.

When the photon hits the telescope in one universe, the perspective shifts: the telescope is now "inside" the 12-way split, either the photon went one way and the telescope recorded it or the photon went another way and the telescope didn't. And when we look into the telescope, we again shift from looking at the superposition from outside to being part of the superposition on the inside.

Our language isn't great for talking about this, because it's not a binary is/isn't thing - entanglement is a continuous phenomenon. If you imagine just two photons each in one of two states, then it's easy enough to imagine: photon A is in a superposition of states 0 and 1, photon B is in an independent superposition of states 0 and 1 - each photon has two possible "local universes", but because they're distant and noncommunicating, to each one the other looks like it's in a superposition. And it's easy enough to imagine: photon A is in a superposition of states 0 and 1, photon B is in a superposition of states 0 and 1, but they're entangled such that we know the sum is 1 - here there are two possible "global universes", and we see a superposition between them, but ecah particle knows the other is in the same universe - if A is an 0 then it knows B is a 1 and vice versa. The part that's hardest to imagine is that it's also possible to be somewhere in between these two states: A and B can be partially entangled such that e.g. there's a 75% chance that the sum is 1.

> So, maybe the universe is filled with tiny pieces of wave functions condemned to go on forever. Maybe that's the dark matter?

No. The evolution of quantum systems is unitary and conserves energy.

The speed of light is the same in any (inertial) reference frame. But you can't use it as a reference to compare other speeds against, because there are more degrees of freedom than you might think: a speed is calculated from both a distance and a time. So you and I could be looking at an asteroid and you say it's stationary and I say it's going half the speed of light, and we'd both be right, even though we both agreed what the speed of light was. Special relativity works like this.

> Also, doesn't time 'stop' when you are at C, so that the whole idea of space (speed * time) sort of collapses?

If you naively plug zeroes and infinities into the equations you won't get good answers, but if you're careful and work with limits then everything works right. What specifically were you asking about when going at C?