Dear Professor Heinrich :

Thanks
for your comments . Let me start from down to up . First a question :
do you agree if universe fundamentally is a 4D Euclidean space so there
is no any notion of causality,change and time ? .

"And
this statement here is contradictory to the notion that one of the
dimensions changes from spacelike to timelike. No change means no
change."

Indeed
I don't think there is contradiction here . In many quantum gravity
theories spacetime ( both space and time or one of them ) are just
emergent
concept and at the most fundamental ontological level we encounter with a
non-spatial, non-temporal structure so we can say spacetime emerges
from something more primitive ( indeed notion of spacetime is
scale-dependent ). And in the case of emergence of temporal dimension
from purely 4D Euclidean space the situation is similar . in fact notion
of time emerges as consequence of initial symmetry breaking (
technically speaking ,by a wick rotation from Euclidean path integral to
Lorentzian one ). Also many recent results in Loop quantum cosmology
and some other theories strongly support such as view that at the planck
scale maybe we have just a 4D Euclidean space .

"The question is not "what hapened
before the 'big bang' singularity? If Hawking's explanation is
correct, then this question is rendered meaningless. It does not,
however, address Leibniz's question of WHY is there a universe...which
has absolute nothing to do with time.

Hawking's
no-boundary proposal is based on the mathematics of quantum physics,
general relativity, and M-theory. It may be the case that this
theory works out to describe out universe. So, if that's the case,
then WHY? Why is the universe explained by this theory, and not a
completely different theory?

Tegmark's MUH comes
close to answering this question because
Tegmark proposes that ALL axiomatic systems describe different equal and
independent universes. Thus if this is true, then the answer to
the question of "why" is simply that "because all universes are real."

The problem with Tegmark's MUH is that his proposition was simply assumed without any proof.

To summarize:

Axioms of M-theory --> Hawking's no boundary

MUH --> Axioms of M-theory

{} --> Physical relativism --> MUH

Physical
relativism does not rely on any axioms. It is a logical fact that
must be true to avoid contradictions. From physical relativism we
may _derive_ that Tegmark's MUH was correct. If the MUH is
correct, then M-theory is valid. If M-theory is valid, then
Hawking's no boundary condition is a viable explanation."

First
of all aim of no-boundary
condition is not just settle whether or not universe had a beginning.
Indeed according to this proposal universe had neither a beginning nor
is beginningless , instead it is inherently timeless ( both time with an
absolute beginning and with no beginning are incompatible with this
view ) .

Second : if we prepare to accept the actual
implications of no-boundary question , so all the ways down to a
inherently a " Mathematical Universe ", furthermore Hawking's model
doesn't rely on equations of GR and QM , rather than his model aims to
give a complete combination of both of them ( Euclidean Quantum Gravity,
briefly EQG ) . Indeed as I mentioned earlier this theory ( EQG) has
properties that none of GR and QM theories have them ( absence of any
notion of time ,causality and change and evolution ) .

I
myself so interested in Tegmark's thesis , but I think his concern is
more about different possible ways that universe
might have been not that is there any universe at all . Also anthropic
principle ( or better I say anthropic selection mechanism ) if any ,
just can help to explain why this universe not other ones and not the
question of what there is something rather than nothing at all ? (
Actually I don't even see any real difference between anthropic
principle and pure randomness ). this is a very subtle point . Indeed
the real point is ( I believe ) theories such as no-boundary proposal
strongly indicate a mathematical universe .

ALL THE BEST ,

KAVEH