**Ask a monkey a physics question thread**

[MadMojoMonkey]

This is all a little simplistic for me.

It was an overly simplistic explanation, but I think I've gone into deeper detail at some point in this thread.

I just had an idea while rolling this spliff.

Strap in, boys, this gon' go good.

Space is expanding, right?

so the data shows

What does that actually mean?

It's based on Hubble's Law (empirical), which states that (simplisticly) the further away from us something is, the faster it's moving away from us*.

* on average. Objects in a rotating galaxy will have a bell-curve of recession velocities, centered around the average velocity of the whole galaxy. So, while they are for the most part all the same distance from us, they will not all be moving at the same speed relative to us. Those deviations are tiny compared to the average recession velocity, but my original statement can't be true if we don't take things like this into account.

Also, the Andromeda Galaxy is racing toward us, despite it's distance, but, again, this is not contradictory with Hubble's Law.

Can it be that if space is expanding, then not-space is not expanding?

Ummm... what, now?

Sure. I guess. IF something that we can't measure is doing something, then I cannot measure anything which refutes your assertion. It's just outside the purview of physics until it can be measured.

Let's call not-space something nicer... how about energy?

Not a great choice, since energy is already well-defined and complicating it with a new, altogether different definition will muddy up conversations. Especially when the already defined version of energy is a measurable scalar, and "not-space" is a dearth of anything known to mankind.

Where energy exists, expansion does not happen. Where energy does not exist, expansion happens. In this way, spacetime curvature is created. Gravity is lack of spacetime expansion caused by inertia.

There is plenty of energy in so-called "empty" space. Photons zipping hither and thither, plus the energy of the quantum ground-state of vacuum. Not to mention the non-0 gravitational curvature at all locations in space, as well as all the other fields which permeate and define space-time.

Maybe there are transient locations where the total energy in a finite volume can be 0 J, but I can't think of any way to produce that using any known methods. I could be well under-informed on the finer points of GR, though.

Holly can have my Nobel prize for inspiring me (strings attached).

As soon as I'm empowered to hand out Nobels, I'll let her know.