In his post in the thread "Mass Exodus From Big Bang Begins" (in the ATM section of BAUT - here), ngeo writes "does GR contain a mathematical description for ‘empty’ space, like a kind of ‘inert field’, or is it that space-like characteristics arise out of the mathematics, or do these characteristics exist only as spatial measurements? If the addition of matter/mass-energy to ‘empty’ space leads to expansion, what is it that expands?".

I've seen good questions about GR, and what sort of universe follows from applying the equations, several times.

While there are good resources on the internet, at many different levels, which explain these sorts of things (and more), I don't think there's a single place in BAUT where our members can go to ask questions about this, at the level they're comfortable with, and get helpful answers.

This, then, is the purpose of this thread.

In particular, let's take a look at Einstein's GR equation (G = T), and apply it to the universe.

Let's also consider what GR does NOT get into (e.g. hadrons and leptons; galaxies and superclusters) ... i.e. what extra 'bits' (from other parts of physics) you need to make a 'real universe' (the kind we can see around us, with our eyes).