NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/sci/physics/22524

Internet Message Format | 1993-01-11 | 17.1 KB

Path: sparky!uunet!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!caen!destroyer!news.itd.umich.edu!pablo.physics.lsa.umich.edu!metzler
From: [e-mail] (Chris Metzler)
Newsgroups: sci.physics
Subject: More of the Big Bang Argument
Date: 11 Jan 1993 21:57:29 GMT
Organization: University of Michigan Department of Physics
Lines: 315
Distribution: world
Message-ID: <[e-mail]>
NNTP-Posting-Host: pablo.physics.lsa.umich.edu


OK, Tom, here's the point-by-point I promised.

Tom Van Flandern ([e-mail]) writes:
(and all the quoted portions below are Tom's; the double-quoted passages
are from my earlier message, which Tom is quoting):

>     Not at all, Andrew.  Finding marginal but significant fluctuations in
> the microwave background radiation saved the big bang for the moment, but did
> no damage to alternatives.  Especially, it does not bear on Lerner's "proof"
> that the microwave radiation must be coming from relatively local sources,
> and can have nothing to do with a big bang fireball.  The essence of his
> argument is that galaxy luminosity differences between infrared and radio
> wavelengths show intergalactic absorption at such a level that the microwave
> radiation could not penetrate through more than about z = 1 or so, let alone
> the z = 10,000 or so required by the big bang.  [E.J. Lerner, Astrophys. J.
> 361, 63-68 (1990).]

First off, I'm sure that it's just a typo, but just in case, let me remind
you that the scale factor is approximately a factor of ten larger at
recombination than you wrote above -- that is, in the hot Big Bang model,
the redshift of recombination is z ~ 1100, not 10,000.

Now, regarding intergalactic absorption of the microwave background.
The presence of large amounts of free gas in rich clusters of galaxies
-- larger than the total mass of the galaxies in clusters -- implies
that the gas fell in from without, which in turn implies the existence
of an intergalactic medium.  However, quasar spectra show no Lyman
alpha absorption trough, which would exist if there were an absorbing
intergalactic medium filling the space between us and quasars.  The
standard interpretation of this is that the intergalactic medium
is ionized.  An intergalactic medium that has been ionized since at
least z=5, if not earlier, removes the absorption that Lerner would
appeal to.

This does not, of course, resolve the problem that Lerner is trying
to explain -- the difference in luminosities.  But I would argue that
there really isn't such a problem.  I should give this more attention
than I have, but . . .I skimmed the Lerner article you cite above.
For a galaxy with a given radio flux and 60 micron IR flux, one would
expect the flux of each to go down as you go out with distance, of
course.  He essentially claims that as you go out with distance, the
radio flux observed from his sample of galaxies drops faster than
the IR flux does.  Now, that can certainly be interpreted as
intergalactic absorption; it can also be interpreted as the result
of galactic evolution.  The galaxy sample he used ranged from a
distance of 700 kpc to 44.3 Mpc, or redshifts of 2.33 * 10^-4 to 0.0148.
If he wants to show an inconsistency with the Big Bang model, he has to
use the Big Bang model to analyze his data and thus arrive at an
inconsistency.  In the Big Bang model, the time between those two
redshifts corresponds to about two dynamical times (that is,
2 * 10^8 years).  That's a lot of time for the processes which result
in the 21cm continuum radio emission and the IR 60 micron emission (which
are, after all, different processes) to undergo very significant evolution.
Such evolution would indeed produce a correlation with distance, because a
correlation with distance is a correlation with age.

Lerner would like to dispose of this problem by claiming that Dickey
and Salpeter showed a strong correlation between IRAS 60 micron flux
and 21 cm flux of 80:1 (or was it 1:80?  I can't remember.).  But
Dickey and Salpeter got this result by examining only spirals in the
Hercules cluster (A2151, z=0.0371).  In other words, they established
that a group of spirals that are essentially all at the same location
(thus having about the same age, in the Big Bang universe) show a
strong correlation between the amount of radio and IR emission.
To then assume that that correlation should not only exist but have
the same form from then on, and apply that correlation to a sample
of galaxies at various distances/redshifts/ages, is cheating.  And
since his sample doesn't extend out as far as the Hercules cluster
-- in fact, three dynamical times or so have passed between z=0.0371
and 0.0148 -- he cannot claim that the 80:1 correlation should still hold.

In short, on first pass, I don't think this paper shows anything.

> and [e-mail] (Chris Metzler) writes:
>
> > The book, to put it bluntly, is a crock.  Having failed to convince the
> > scientific establishment of the validity of his version of Alfven's
> > model, Lerner has gone to the public to plead his case -- as if scientific
> > fact was something that you vote on, rather than, well, fact.
>
>     Lerner used carefully reasoned arguments against the big bang, in
> contrast to this ad hominem criticism.  Lerner's arguments in favor of Plasma
> Cosmology are, by his own admission, somewhat more speculative.  He could be
> persuaded of another alternative.

What Lerner (and, I guess, you) feel are carefully reasoned arguments,
most of the scientific community familiar with the book does not.  And,
from having read the book, it is clear to me that most of Lerner's
arguments against the Big Bang are not scientific but instead sociological
in nature.  That is, Lerner seems to consider his most persuasive
arguments those in which he assails the scientific community and the
manner in which he thinks scientific investigation is done.  This is not
science.  In fact, I would claim it to be "ad hominem criticism."  A
scientific theory is killed by evidence against it, and not by claims
about the psychology that generate or perpetuate the theory, regardless
of whether those claims are true or not.

> > Whether or not the hot Big Bang model is right or wrong, it has
> > successfully explained a very wide variety of observations and experiments;
> > no other competing cosmological model has been able to do this.
>
>     All theories "explain" a wide variety of things.  The same is equally
> true of all alternative cosmologies.  This tells us nothing to distinguish
> them.

This is not true.

As an extreme example of why this is not true, how would you react if I
advanced a theory in which I claimed that the origin of the microwave
background is a cloud of little gremlins orbiting the Earth which create
the CMBR with synchronized waving of magic wands?  You would pay my
theory little attention, and rightfully so.  It is not enough that a
theory offer an explanation for some phenomenon; the explanation should
have its basis in what we believe to be correct scientifically.  We may
be wrong in our beliefs, but rational and well-supported arguments are
rightfully necessary to change those beliefs.

The Big Bang model does not carry any new science as baggage; its
fundamental basis is Einstein's Theory of General Relativity.  If you
wish to argue that GR is invalid, that's fine.  Have at it.  I'll
probably try and pass the argument onto someone else at that point,
because I have but a VERY rudimentary understanding of GR.  But the
point is that the hot Big Bang model is well grounded in pre-existing
physics; it does not require assumptions that have no physical
explanation at present (e.g. plasma cosmology's "filaments"), and it
does not require the abandonment of much successful modern physics
(e.g., if I remember correctly, your own Meta model).

> > Whether or not the hot Big Bang model is right or wrong, it has
> > successfully PREDICTED (God, I'm capitalizing!  Help me!) a wide variety
> > of observations and experiments (yes, even experiments); no other competing
> > cosmological model has been able to do this.
>
>     The use of capitals was chosen as a crank indicator because it indicates
> emotional involvement.  You are not crankish in any sense, and neither is
> Lerner.  But your use of capitals does suggest to us, your audience, a bit of
> emotional involvement in this issue.  Please recall that all scientists are
> supposed to continually strive to criticize and find fault with all
> scientific theories.  That is how we make progress.  I think Lerner did this
> well in his book.

I agree with your statement about criticism; otherwise, I wouldn't be
having this conversation at all.  I simply disagree that Lerner did
this well.  See my comments about arguing sociology vs. arguing
science above.

>     In fact, critics such as Lerner have argued that the big bang has yet to
> make a single successful prediction.  For example, Lerner discusses the
> history of the supposed prediction of a microwave background radiation.  The
> various predictions were well off the mark in temperature.  By contrast,
> Eddington in 1926 (in Internal Constitution of the Stars) predicted that all
> interstellar material with time to cool to equilibrium would reach a
> temperature of 3 degrees Kelvin, since that is the radiation temperature of
> starlight.

Within the hot Big Bang model, to predict the current temperature of the
microwave background requires knowledge of the redshift of recombination,
or another equivalent parameter.  At the time of the prediction of the
microwave background, no data existed to nail down the temperature.  That's
unimportant.  The fact that the blackbody radiation was predicted
AT ALL is the fairly amazing thing.

As for the Eddington quote above, could you be more specific about where
in the book you mean?  I'm not familiar with the book.  At any rate,
surely you know that a sum of black body sources all at the same
temperature, in an expanding world model, would not look like a perfect
thermal black body to us.

Finally, to give another example of a successful prediction of the Big
Bang, I offer the existence of three light neutrino species.  Let me
make this clear -- in advance of the experiments of LEP and SLAC, Big
Bang nucleosynthesis theory predicted that three and only three light
neutrino species exist.  If L3 at LEP had published results indicating
that the Z0-invisible width included four neutrino channels, Big Bang
nucleosynthesis would have been in serious trouble, if not dead; and by
extension the Big Bang as well.  That sounds like a prediction that could
be falsified by a simple experiment to me!  But instead, experiment
confirmed this prediction.  In the meantime, I don't know of a single
prediction put forth by alternative cosmologies which can be tested by
a repeatable experiment (I don't mean "astronomical observation" here; I
mean "experiment").

>     At present, every one of the big bang's element abundance predictions is
> off the mark by several sigma, and has had to be "restored" with ad hoc
> helper hypotheses.  For example, the beryllium abundance was found to be 1000
> times too high, so cosmic ray spallation was invoked.  None of the original
> predictions stand without such help.

Well, I know very little about the theory of Big Bang nucleosynthesis,
and I'm not going to read up to try and discuss this right now because
I promised I'd put this up on Monday.  But Schramm was here two months
ago, and from that talk (and conversations with others around here), it's
my understanding that the predictions of the Big Three -- the hydrogen,
helium, and lithium isotope predictions -- haven't really changed since
the theory's inception.  More on this when I learn more.

I might also add that to the best of my knowledge, NO other cosmological
model even takes on the issue of light element abundances.  The plasma
cosmology, for example, makes no effort to explain light element
abundances.  Even a theory which does but a "passible" job of explaining
the data is better than one which offers no explanation at all.

> > There is not one single observation -- not one -- that falsifies the hot
> > Big Bang model.
>
>      "Proof" is in the eye of the beholder.

Absolutely true -- which is why I didn't use the word "proof."  Scientific
theories are not "proven"; they are supported by evidence.  But even if
scientific theories are not proven, they can be falsified.

>  But Tifft's observations of the
> quantization of redshift (recently confirmed by Guthrie and Napier), and the
> time variability of redshifts, are potentially just such a falsification.

Actually, I'm not sure we're in that great of a disagreement here.  Let me
say that I think (and, I think, most people think) that the question of
whether this effect is real is very far from settled.  However, if the
effect turns out to be real, it would indicate that the simplest model of
the expanding universe is wrong.  Thus, in turn, either the Big Bang model
is wrong, or there's physics going on (in addition to the Big Bang model)
that we're missing.  But modifying the fundamental model in such a way
would certainly take away a lot of the theoretical appeal for the Big
Bang.  Either way (whether the Big Bang is right or wrong), true
confirmation of this result means new physics; so it's certainly a very
important line of research.

>  I
> would add the following list:
>   -  Lerner's observations indicating intergalactic absorption at a level far
>      too high for the big bang;

I don't agree.  See my statements above.

>   -  The "pencil-beam" surveys that show "great Wall"-like structures at
>      regular intervals out to seven billion lightyears on either side of us
>      [e.g., Science News 137, 287 (1990)];

No.

I presume you are referring to the paper by Tom Broadhurst,
Richard Ellis, David Koo, and Alex Szalay, "Large-scale distribution
of galaxies at the Galactic poles," Nature v343, 22 Feb 1990.
Of the four authors of the paper in question, the only one that I
haven't discussed this result with is David Koo; and this is my field,
so I do feel like I know a little about it.

Anyway, this result says absolutely nothing for OR against the Big
Bang.  You have fallen into the trap I referred to in my previous
message; you confuse the Big Bang model with something else. The
result could have much to say about various competing theories for
the formation of large-scale structure, such as the biased cold dark
matter model.  But it would only make problems for the Big Bang
if the theories of structure formation that it does make problems
for were the only ones permissible in the Big Bang model.  This
is patently false.

There is more that I can say about this result in the context of
CDM, but it's not relevant to this conversation.  More if anybody
cares (probably not).

>   -  Bulk streaming of local galaxies in one direction out to at least 500
>      million lightyears, and on the opposite side of the sky too [D. Lindley,
>      Nature 356, 657 (1992)].  This would disappear if the microwave
>      radiation were not used as a standard of rest.

Please explain why you feel that this observation is a problem for the
Big Bang.  I can't think of a reason.  I have a suspicion that you are
again confusing the Big Bang model in general with specific models of
large-scale structure.

> > If you are seriously interested in studying this in more depth, I would
> > suggest reading P.J.E. Peebles, D.N. Schramm, E.L. Turner, and R.G. Kron,
> > "The case for the relativistic hot Big Bang cosmology," Nature v352,
> > pp 769-776.
>
>     See also the point-by-point rebuttal to that paper in:  H.C. Arp and T.
> Van Flandern, "The case against the big bang," Phys.Lett. A 164, 263-273
> (1992).  This was also discussed extensively here on the net last fall -- a
> discussion in which Turner participated.  -|Tom|-

I have read both of these articles, as well as the reply (from Arp \etal)
and the reply-reply (from Peebles \etal) (these are both in Nature v357
28 May 1992 pp 287-288).  I would note that it will be difficult to
impossible to convince scientists that the Big Bang is wrong when
the proponents of alternative cosmologies, such as Halton Arp, seem
to argue in favor of abandoning much of the Standard Model of Particle
Physics.  Physicists have a difficult time abandoning theories that
allow them to correctly predict the results of experiments to many
decimal places.

        -- Chris

P.S.  If you wish to continue this discussion, I'm sort-of willing
(boy, am I stupid when I have this much work to do).  I agree with your
comments about criticism of scientific theories, and regardless of the
outcome, I think it'd be educational for me.  But I won't be able to
respond on more than about a weekly basis or so, or my advisor is going to
think twice about continuing to pay me.

P.P.S.  On that note, how should I refer to you?  I prefer to write
messages like this in a conversational tone.  Some people get grumpy
when I use their first names (too familiar), while others feel
"Mr. or Ms. (last name here)" is too stuffy and annoying.  I go by
Chris.

--
SNAILMAIL:                                       AT&TMAIL:
Chris Metzler                                    313-764-4607 (office)
Department of Physics, University of Michigan    313-996-9249 (home)
Randall Lab, 500 E. University
Ann Arbor, MI  48109-1120 USA

E-MAIL:  [e-mail]