Big Bang Cosmology
Rav Dessler zt"l
The Slifkin Affair
May 8th, 2005
Thank you for forwarding the comments below by a prominent physicist to my
paper (currently under revision) on big bang
cosmology (BBC) and the age of the universe. I don't know who the physicist is
but my response follows.
> The big bang is no longer controversial, and with the recent (last 5
> years or so) discoveries of accelerated expansion, and the convergence
> of a wide spectrum of amazingly accurate and revealing cosmological
> measurements, many more details seem now to be settled. For example,
> it now seems clear that only about 5% of the matter/energy in the
> universe is the ordinary sort of matter that we see around us or that
> is in stars, 25% is cold dark matter of which nobody knows what it is
> (a known unknown) and the remaining 70% is something called dark
> energy, of which nobody has a clue what it is (an unknown
> unknown). But these numbers seem pretty solid.
I realize that as a layman it appears ludicrous for me to argue with experts in
the field. However, I have seen comments such as the above by other physicists
in response to the paper and they no longer puzzle me as they did at first, and
I would like to explain why they do not address the issues raised in the paper.
Responding to the six assumptions underlying
big bang cosmology
The first thing to note is that there is no
admission that the issues I raised are cause for concern. For example I quoted
Steven Weinberg who stated that the fundamental BBC assumption of the
cosmological principal hangs like a "dark cloud" over the standard model because
it is an untested yet fundamental assumption. So I would expect a tacit
admission of the concerns raised followed by a "but .... I can explain why these
concerns can be answered". Or I would expect an analysis of why the concerns are
not even concerns. Perhaps it can be shown that I got the facts wrong (entirely
possible for a layman).
So is Steven Weinberg's admission still correct today or not? If it is correct,
why not admit to the concern?
The same applies to the other issues raised in the paper (six of them in total).
How do deeply held theories get debunked?
Einstein and scientists of his time (prior to GR)
deeply believed in an eternal static university. Yet BBC overthrew all of this
with the age of the universe suddenly decreased from minus infinity to 13.7
billion years (to Einstein's shock and that of most other physicists of his time
such as Eddington who thought the very idea of a beginning was repulsive).
We are trying to explain that fact -- how could these great scientists make such
a major mistake? Again, perhaps the same mistake is repeated with BBC?
Speculative vs. Empirical Science
The thesis of my paper (which I owe to others
including Maimonides in the second section of the Guide) is that we must
not confuse necessary conditions with sufficient conditions! When
you have checked out some necessary (but not yet sufficient) conditions your
theory is still speculative especially where it is plagued by other concerns
such as stubborn anomalies (see below). My contribution was to apply this to BBC
in an attempt to tease apart the scientific claims from the evidence
for the claims.
For example, since the cosmological principle has not been verified in the lab.,
this means that it is a sheer assumption. Thus, it is vulnerable to being
falsified. If so it would undermine BBC despite other points of evidence such as
the discovery of the cosmic background radiation (CBR). The cosmological
principle is a necessary condition and the CBR is a necessary condition for BBC,
but even when taken together they are not sufficient to guarantee the truth of
BBC as then other concerns I raised would have to be addressed. Since
experimental evidence is the sina qua non of science I suggest we can
distinguish when a theory is speculative vs. empirically proven using the
following indicators (see p7 of my paper):
- (a) To what extent have the foundational
assumptions checked out directly in the lab?
- (b) What interpolations and extrapolations
have been made and to what extent the extrapolation is made (large backward
extrapolations being most suspect). A large extrapolation may be an educated
guess but it is nevertheless a guess!
- (c) What stubborn anomalies plague the
- (d) What untested hypothetical entities are
postulated that have not been directly confirmed in the lab? (deep theory).
Since BBC suffers from all of the above I
consider it to be speculative and so it is (unless the facts that I present in
my paper are wrong). The indicators (a) to (d) can thus be used to distinguish
between speculative science and empirical science. (Technology
such as the space age
marvels such as getting to the moon and mapping the human genome are all based
on empirically verified operational science, not the speculations made in
cosmology and evolutionary biology).
The comments by the physicist agree that nobody
has a clue about the postulated dark energy (or the missing dark matter) a force
totally different in kind from any other force ever observed apart from the fact
that nobody has ever directly observed it in the lab. It is a
entity that is invented to explain observations that contradict the standard
theory in the same way that the hypothetical planet Vulcan was (incorrectly)
invented to explain the Mercury anomaly.
The pre-BBC static eternal universe suffered from same vulnerabilities to
experimental evidence as BBC and that is why I label both as speculative, and
this explains why Einstein, Eddington and the rest were proven wrong. I have yet
to see an alternative explanation for the failure of the deeply held eternal
The reason I am unsurprised that physicists appear unable to admit to this
simple point (assuming I got my facts straight) is because their training is not
in logic and epistemology. Scientists are (correctly) interested in an inference
to the best explanation. Given two theories say T1 and T2 that
both (approximately) explain the known facts, then if T2 makes a
prediction (say P) that T1 cannot match then we accept T2
as the new theory provided we later observe P. Now I realize that I am
being over-simplistic here for the sake of brevity, but this does explain in
part what I believe is a much used mode of reasoning (e.g. see Brian Greene's
book "The elegant universe" p.210-211 on the difference between a prediction
and a postdiction).
Now all this is fine for science to make progress but it does not make BBC an
empirically tested theory. I have no objection to this mode of reasoning
provided speculations are clearly labelled as such and the proper distinction is
made between a claim and the evidence for the claim. It should not be left to
layman like myself to tease apart the claims and the evidence for
the claims -- this should be done by scientists themselves who are in the best
position to understand the complexities and subtleties of the issues. Again we
should not confuse the confirmation of a necessary condition (such as P
above) with that of the sufficient conditions needed to confirm the theory.
Since I provided what I believe are 6 untested assumptions of BBC I would expect
a proper rejoinder to address each of these issues (and there are more problems
with BBC that I have not yet incorporated into the paper).
This is why I say I am not puzzled but rather disappointed at the lack of
response to the substantive issues raised
Is big bang cosmology more compatible with
> One thing that seems ironic about the piece
is this: The big bang is
> often presented as the discovery of science most compatible with
> religion. In fact I recently heard that the resistance to the big
> bang, at first by Einstein and later by others, like Fred Hoyle, was
> due to their dislike for religion. However, I don't believe that.
This is a good point -- BBC is superficially more compatible with creation when
compared to a static universe.
However, I hesitate to build anything substantial on speculations. Indeed many
physicists now feel that they can explain the big bang without the need to
appeal to creation (references available on request). The attempts I have seen
to do so are also speculative. Attempts by some religious scientists to fit BBC
with the first few chapters in Genesis have failed, quite badly, in my opinion.
So, as far as I am concerned, both the uncreated universe and the big bang
universe are interesting but equally speculative. Neither are able to provide a
credible explanation for our vast cosmos of unbelievable complexity fine tuned
for life and discovery.