Are these Stephen Hawking's statements legitimate? I am reading 'Brief Answers to the Big Questions' by Stephen Hawking and it seems to me that some of his statements are just hypotheses, but they are written in such a way that they 'sound' like they are supposed to be scientific facts.
For example:


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*There was no time before the Big Bang.


I do not know much about cosmology so I tried to look it up and to me it looked like there isn't any consensus.


*Physical laws are unchangeable and universal.


While this assumption certainly makes life easier and no one has ever seen  anything that would disprove it, I am pretty sure that we just don't know that. We don't know whether laws of nature were and will be the same, just as we don't whether they aren't any different in distant galaxies. It's all just convenient assumptions, right? (Btw. yes I know the Occam's razor, but it just triggers me a little that he never uses phrases such as 'I assume' or 'hypothetically', when making this statement.)
 A: Light from distant galaxies emitted eons ago has the same spectral lines as from elements on Earth, excepted redshifted due to their journey through the expanding universe. That seems to me like good evidence that atoms then and there were obeying the same laws of physics as atoms here and now.
I can't offer similar evidence for “no time before Big Bang”. That was Hawking’s opinion. Some cosmologists think that our Big Bang may have actually been a Little Bang in a larger multiverse. In that case, there would have been time before our Little Bang.
A: I think these are more the philosophical type of facts than scientific facts. They stem from the axioms for our reasoning and definitions of the words, and thus cannot be "verified" because, well, they must be believed to be true.


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*The Big Bang is considered the beginning of everything. When we make this statement, it is implied that we believe Big Bang's existence as a priori; and "everything" means literally everything, including time. So yeah, the Big Bang is the beginning of time, the first event. And before the first event, by definition of the word "first", there cannot be time before the "first" event, otherwise the Big Bang would not be the first event, right?

*The physical laws, as a concept, do not change because they are defined as things that are unchangable. Careful that they are different from our perception of them, which is the useful thing that we use to make better of our lives. Sure, constants like pi can change, or maybe the sun starts rising from the West, but that cannot be because the laws suddenly change. It can only be because we are dumb, because our perception of the laws is flawed. The laws are still, as they always have been, by definition, the way they are. It's us who need to update our understanding of them.
Personal opinion: it's all just definition and tautology. Fun to read for a while, important to know, but at some point it becomes useless quarrelling.
