Before the Big Bang?

Trying again, my previous reply seems to have been
trashed somewhere.

"Phil" wrote in message
ink.net...

"George Dishman" wrote in message
...

"Phil" wrote in message
ink.net...

With respect to viable
options of thinking, we must subjectively choose between them.

No, it isn't choice . . .

Sure it is. Here is an analogy.

Given: My wife, Steph, has a frustrated look on her face.

George's explanation: Phil didn't take out the trash.

Phil's explanation: I'm spending too much time at sci.physics.relativity.

Steph's explanation: I just don't get the tax law. Who wrote this stuff.

George's speculations:

a) Phil didn't take out the trash.
b) Phil forgot their anniversary.
c) Phil forgot Steph's birthday.

George checks the anniversary and birthday dates and
finds they are both months away. George concludes
that the only currently available explanation not yet
falsified is that the trash was not taken out, however
before this can be raised to the status of a theory the
observation must be repeated. If an identical expression
appears on Steph's face next time the trash isn't taken
out and it never appears under any other circumstances
then it will be proposed as a theory.

If we then discover a new hypothesis:

d) Steph is struggling with tax law.

which also fits the observations, then we can design an
experiment:

1) Take the trash out while Steph is still struggling
with tax law.

2) Explain tax law to Steph.

3) Fail to take the trash out after Steph understands
tax law.

4) Compare expressions caused by 1) and 3) and determine
which is a match for the observed expression produced
by the unknown cause.

Now if the expressions are so similar that both are classed
as matching, then we have _two_ valid theories. They may be
different but _neither_ is wrong.

What many people fail to realise is that we are _not_ forced
to make a choice. The purpose of science is to predict so
since both speculations give the same prediction it doesn't
matter which one you use. On a day when Steph is either
struggling with law or Phil hasn't taken out the garbage,
her expression will be correctly predicted.

Now:

Given: Redshift indicates that galaxies are separating at an accelerated
pace.

No. Given:

a) Redshift is observed.

b) No relevant cause of redshift is known other than
Doppler and the "gravitational redshift" predicted
by GR.

c) Gravity should cause matter to clump together hence
what we see should not exist if it was 'steady state'.

d) Expansion provides dynamic stability

e) GR describes local gravitational effects exactly.

f) No other current theory can describe all the effects predicted
by GR which have been confirmed.

we can conclude that, pending a viable alternative, the
galaxies we observe at high redshift are moving away due
to expansion as described by GR.

Assuming that distant galaxies are at an extreme distance
which can be predicted by their redshift, SNe in them
should also be dimmer than nearby SNe of similar intrinsic
brightness.

GR includes a "cosmological constant" (CC) whose value is
not determined by the theory but must be found by
measurement.

It has also been suggested that there is something called
"quintessence" which drives accelerating expansion.

Given:

h) Sne at high redshift differ in brightness from the value
predicted by GR assuming CC=0 and no quintessence.

i) The brightness matches the value for some non-zero value
of CC.

j) The brightness matches the value for some non-zero value
of quintessence.

we would conclude that both are valid theories.

Further given:

k) The angular power spectrum measured by WMAP is a good
match to that predicted by GR with the same value of CC as
in i).

l) The angular power spectrum measured by WMAP is a poor
match to that predicted by GR with the same value of
quintessence as in j).

We now conclude that the combination of GR and the non-zero
cosmological constant is the current best tool for prediction.

George's explanation: Must be an accelerated expansion powered by dark
energy.

Phil's explanation: Who knows, maybe George is correct but maybe they are
acellerating in a gravity field.

Two objects moving apart and being acted upon by mutual
gravity should slow their relative motion as the kinetic
energy is used up increasing the potential energy. If the
speed is increasing then extra energy is being introduced
into the system of an unknown, mysterious or 'dark' nature.

The phrases "acelerating in a gravity field" and "dark
energy" are synonymous.

Steph's explanation: Angels are blowing them around for fun.

Its just impossible to not be presented with choices and we inevitably
choose among them. That's why science is, in some measure, subjective.

It is sometimes not possible to avoid being presented with
a choice but you are wrong when you say "we inevitably
choose". Science does not choose, it says clearly that all
the alternatives are valid until they are proven false. Thus
for example some people think we have to choose whether there
is an aether or not but for conditions where SR is adequate
we can equally assume a Lorentzian aether. The predictions
are identical hence both theories are valid and no choice
needs to be or can be made. In fact no choice _can_ be made
on the basis of limited data where SR is adequate and we
have to invoke Occam's Razor. It is only when GR is needed
that the Lorentzian model fails because it offers no model
for predicting the effects of gravity.

Cosmology isn't one of those cases. With some minor variations
which are essentially indistinguishable at present, we have
only one theory of gravity that is valid in all situations and
that is GR. In fact even that doesn't marry with QM so the real
situation is that we have to choose for a list of _zero_ valid
theories of quantum gravity.

George