Liz, I think you are generally correct in what you write below. Current
writing by cosmologists etc on "getting a universe from nothing" assume
the prior existence of at least a background space-time. More usually,
this is assumed to be the vacuum of quantum field theory. So there is a
clear assumption that a framework, and a set of laws, are logically
prior to the coming into existence of the universe.
This makes sense, because if you want to give an orderly account of the
origin of the universe, you must give an account in terms of laws -- so
these are logically prior. Basic quantum mechanics, or quantum field
theory is usually assumed to govern this creation. In addition, if you
have some background space-time then you need laws that describe the
nature and behaviour of this substrate. General relativity is usually
assumed, at least a semi-classical version of GR.
My position is that the idea that you can explain the origin of "a
universe from nothing" is absurd. People who don't want to assume that
the universe just "pops" out of nowhere, complete with laws, generally
assume a previously existing universe of some sort that spawns daughter
universes in some manner. This, of course, does not answer ultimate
questions of origins, but if you want to work within current
understanding of the LOP, then you have little choice. The "popping"
scenario essentially leaves origins unexplainable.
Bruce
LizR wrote:
Now that we've sorted out the acronyms, I'd appreciate a response to the
points I made - see below.
Empty space _is _the same as nothing.
I would say far from it. Why should empty space exist? The questions
"why is there something rather than nothing?" "Why does the universe go
to the bother of existing?" "What breathes fire into the equations?" etc
are asking why /anything/ exists. That includes empty space.
I don’t understand your comment, “It presupposes the laws of
physics.” I don’t think empty space presupposes the laws of physics
and I don’t think “nothing” presupposes the laws of physics. In my
mind neither one presupposes anything.
Maybe if the empty space does nothing, forever, that might be true. (At
least we wouldn't exist to ask questions about whether it's true or
not.) But if anything arises from the empty space, then the LOP must
govern what appears. Why should tronnies appear rather than, say,
quarks? The answer, by definition, is the laws of physics.
Hence, if your description of the origin of the universe is correct, the
question "why is there something rather than nothing?" can be amended to
"why should empty space plus the laws of physics exist?"
This leaves open the question of why the LOP are the way they are,
rather than anything else they could logically have been.
Generally, attempts to answer this have taken two forms. One is to show
that the LOP are unique, and logically necessary - there is some
underlying reason they could only be the way we observe them to be.
The other is to admit that they could have been different, and perhaps
are in other universes - in this view the required explanation is not an
answer to "why do these particular laws of physics?" but "why do all
these different laws of physics exist?" This assumes that some more
general logical necessity needs to be invoked to explain all possible
LOP, and then anthropic selection can be invoked to explain why we find
them to be the way we do in our particular universe.
PS
TOE=Theory of Everything, IMO=In my opinion (be it ever so humble). I
often type in a hurry, so having generally accepted acronyms available
can come in handy.
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