This was the point I was trying to make.As others have already said, in a world without mass- only energy- the rules of physics are likely different. The idea of time is different.
Speaking of which, you scoffed at the poster who claimed time doesn't exist, but if you are going to have an existential discussion about physics then it seems like perception is an important aspect. You acknowledged that there is at least one dimension we can't perceive, so who's to say that dimension is not as important as time? Perhaps it was the preeminent dimension in a universe that preceded matter? Perhaps it's the preeminent dimension in the universe that resulted from the creation of matter and we just don't have the ability to perceive it? Perhaps "time" is just a way for sentient beings to grasp a much more complicated concept? If that's the case, then a first cause isn't necessary. It would be as pointless as asking where the beginning of the earth is.
I said time didn't exist? And what poster did I "scoff" at for saying that it did. In my first post I specifically stated that the universe: time, space and matter had a beginning. A beginning that scientist estimate to be around 13.7 billion years ago.
And, again, perhaps a first cause isn't necessary, I can't prove otherwise and admitted so. Something came from nothing. Matter always existed.
But I don't know why that is any more rational and logical and requires a leap of faith than a first cause.
Also, for the sake of preciseness and clarity, I said that we can't
perceive dimensions higher than our own. Whether there are actually higher dimensions or not I don't know.