Why are (some) physicists so bad at philosophy? (2011)

What do you mean when you say "mass"? Mass, matter, etc, at least to me, seem to be what you call certain processes when you look at them from an extremely "zoomed out" perspective. The further you zoom in, the less the concept of matter makes sense. Even concepts like fields, waves, etc may be just as much abstraction as the idea of "particles" is.

In regards to spacetime, is the 4d manifold we are situated in according to special relativity all that there is? Or if we zoom out, would we see a 4d manifold "wedged" inside higher dimensional spaces?

The proper definition of terms - same goes for the guidelines of discussion, even though those aren't as relevant to define in this instance - is indeed both an issue philosophy concerns itself with deeply as it is problematic in itself. Especially in the field of Ontology, 'to be' can and will have so many wildly varying definitions that discussion becomes tedious and at times impossible without learning the specific vocabulary of whatever subset of Ontology one is debating in or against.

Something and something and nothing and nothing are hardly the same ad hoc.

I'm by no means an expert in astronomy and astrophysics, as I only follow it with an amateur's interest. That said, as far as I'm aware, the quantum fluctuations that are presumed to have caused the big bang are fluctuations within a field of potential. While we may be inclined to call it 'nothing', as there was no matter yet, nothing tangible at any rate, the existence of said field and potential does not make it the absolute nothing philosophers would normally consider when they ask whether the universe came from something or nothing.

Gorgias of Leontinoi, contemporary of Socrates and eponym for the platonic dialogue Gorgias, argued that 'nothing', the absence of everything, allows this void to be filled with just about anything one pleases to fill it with. I can't recall the exact argument, but despite Gorgias being a troll of sorts - he famously perverted Parmenides' thesis on being - it was a rather sound foundation for his rhetorical efforts. Not much of his work on nothing remains, so it's hard to say for sure, but I'd argue that Gorgias is also talking about the nothing that still allows for potential. As silence, the absence of sounds and words, potentially allows for someone or something to make a sound. Take away anything that can make a sound, everything that could potentially ever make a sound, and everything that could potentially lead to something making a sound and we're getting closer to the silence that rivals the absolute nothing around which we cannot wrap our minds.

Absolute nothing would be the absence of anything, without any potential for something to ever come from it or exist in it, but that's not necessarily the same nothing people mean when they speak about nothing.