Re: MU/MW (was Re: The neutrino has mass?!)

David Bowman (
Tue, 16 Jun 1998 7:51:15 EDT

Regarding Loren Haarsma's discussion of MW interpretations and MU

>The "many-worlds" interpretation of quantum measurement theory is not
>widely accepted by physicists, nor do I think it is likely to be.

I would *like* this to be true.

> I
>don't think it actually resolves the "problems" it claims to resolve,
>and it adds all sorts of new problems. I'm not aware of any observable
>predictions of many-worlds quantum mechanics different from "standard"

No argument from me here.

>Inflationary cosmology is a different matter.
>Inflation theory solves a few problems in non-inflationary cosmology.

Yes. That's why there is so much interest in inflation, and why it has
such a large following of fans.

><SNIP of nice discussion of the (1) relic monopole, (2) flatness, &
(3) horizon problems solved by inflationary senarios>

>A prediction of inflation theory is the "many different universes." As
>I understand it, it happens like this:

><SNIP discussion of decoupling eras and how inflation fits into them>

>The "inflationary epoch" is thought to happen after the TOE separates
>into gravity + GUT, but before the spontaneous symmetry breaking of GUT
>into strong force + electro-weak force.

This is why it is misleading to consider inflation as a real MU-type
cosmological theory. Since inflation happens *after* gravitation
"separates out" of the TOE and becomes effectively a *classical*, (i.e.
non-quantum on relevant scales GR-type) metric theory of spacetime, this
means that during and after any inflationary (post BB) episodes occur
when, for all practical purposes, we can treat spacetime as a single
classical topologically connected differentiable manifold. We usually
think of a universe in terms of a spacetime manifold such that each such
topologically connected manifold is associated with each universe. Even
though there may be many different regions of this spacetime manifold
which presently have become causally disconnected (because of a previous
rapid inflationary expansion of space) from our region each with its own
local conditions and values for some low energy Standard Model-type
constants, (e.g. particle masses, coupling constants, mixing angles,
etc.) coming from different freezing effects in separately seeded low
energy phase domains, this is not a sufficient reason to consider these
different domains as belonging to different universes than ours. They
all are just different parts of the *same* spacetime manifold. After
all, if we consider the events happening right now in the Andromeda
galaxy, these events also have no causal relationship with events
happening right now here on Earth, since it takes some 2 million years
for any causal influence (travelling at speed c) from those events to
reach our part of space. Even though I'll be dead well before 2 million
years have expired so that no influence from any current event happening
in the Andromeda galaxy can exert any causal influence on me, I do not
want to consider those events as belonging to a different universe than
the one I live in. IOW, the way I see it, if 2 events belong to the same
(topologically connected) spacetime manifold--even if they are spacelike
separated--even if they belong to different spatial regions that must
remain spacelike separated throughout the entire future history of the
universe--even then--they belong to the *same* universe. For another
example, consider a Schwarzschild black hole. All events occuring inside
the event horizon of the hole have no causal influence on any events
happening outside the horizon. But both the inside and outside belong to
the same topologically connected spacetime manifold and the same

The kind of MU cosmologies that I had in mind in my previous post were
those that considered the Big Bang as a quantum fluctuation in a theory
that had a fully quantum treatment of spacetime characterized by a
seething (high dimensional) ill-resolved spacetime "foam" of budding
separating, and re-absorbing micro-mini spacetimes where the fluctuations
occur on the Planck scale (10^(-35) m & 10^(-44) s). In such a theory
there are many universes which materialize as separate quantum
fluctuations, each which (may if they live long enough for a classical
spacetime manifold to form and unstably expand) has its own BB-like
initiation and its own separate topologically disconnected (or, at most,
possibly, pinched off with a pinched neck no larger then the Planck size)
spacetime manifold.

>What does this have to do with apologetics? If inflation theory is
>true, it may have some impact on the "fine tuning" argument. It is
>known that many of the "fundamental constants" of physics fall into very
>narrow ranges which make life possible. If inflation theory is true,
>then there could be a very great many different universes, each with its
>own set of fundamental constants.

I would only amend this to say that: "then there could be a very great
many different island regions of the universe, each with its own set of
fundamental constants". In any event, this nit-picky point does not
invalidate nor weaken this or the other points Loren makes.

> ... . Even supposing that
>inflation *would* produce a huge number of universes with a great
>variety of fundamental constants -- some of them "naturally" falling
>into ranges suitable for life -- it still begs two important questions:
>(1) How "finely-tuned" is the GUT and the TOE? and (2) Why should they
>exist at all? I wouldn't dare predict an answer to the first question.

Good points. (Neither would I want to dare to predict an answer.)

>Whether inflation theory is true or not, we can praise the Creator for
>an amazing creation. As for using "fine tuning" for apologetics, it
>would seem that wise use is cautious use.

Amen and Amen.

David Bowman