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lpetrich
2001-Dec-15, 05:50 PM
Richard Carrier's "Was There a Big Bang? * I Honestly Don't Know", URL: http://www.infidels.org/library/modern/richard_carrier/bigbang.html

Any opinions on it? Too much of the article resembles classical crackpottery /phpBB/images/smiles/icon_frown.gif Like his approving mention of a conspiracy theory in which the Big Bang theory is supported mainly because BB supporters only allow other BB supporters to get telescope time. In such theories, Halton Arp often becomes a latter-day Galileo; RC also approvingly mentions HA. Here I'll analyze his critiques point-by-point:

RC: "(1) Expansion does not entail that it all began at a point."

RC: "We have absolutely no evidence that the universe began at a point--that is entirely a theoretical invention, as yet untested, and unlikely ever to be testable, yet it is the essence of the very "Big Bang" concept itself." and "... all too often big bang proponents confuse evidence for an explosion with evidence for the origin of all space and time."

LP:
A straw position -- and one unrelated to the bulk of the Big-Bang evidence.

He also mentions other causes of redshifts, such as contraction and scattering off of intergalactic dust and magnetic fields; however, contraction is extremely difficult to take seriously as an explanation for cosmological redshifts, and when scattering causes frequency shifts, it obscures the original direction of the light.

He mentions Eric Lerner's discussion of radiation pressure as a Universe-expansion mechanism, but it's rather easy to show that it would produce too small a "kick".

RC: "(2) The microwave background radiation has too many other explanations."

He mentions approvingly the theory that it is the scattered light of very distant stars; however, it looks like something optically thick at nearly constant redshift. He also mentions the discovery of intergalactic dust and magnetic fields; however, these do not significantly obscure a variety of distant objects, which implies that they are optically thin over Hubble sizes.

RC: "(3) The proportion of light elements to heavy is far too muddled to stand as a proof."

Actually, it's reasonably consistent with Big-Bang nucleosynthesis. And there are indirect ways of estimating how much helium could have been formed in the cores of stars, by comparing heavy-element and helium abundances; they fall on a straight line that hits zero heavy elements at about 25% helium by mass.

RC: "(4) Observations of differences in aggregate cosmic phenomena over time are inconclusive."

RC: "That things were different in earlier epochs is not inconsistent with an oscillating steady state theory or multi-bang theory or phase-change theory, or theories involving cosmic cycles, or still other possibilities that are too plausible to be simply dismissed, and that no one is even trying to eliminate. ..."

LP:
However, that does mean that the galaxy era, as it might be called, has been very Big-Bang-like. One problem for many of these theories is that they end up including Big-Bang-like phases, making them difficult to distinguish from a single Big Bang.

RC: "(5) The 2nd law of thermodynamics does not entail a Big Bang."

Straw position.

RC: "(6) A flat universe is entailed by almost every other possible theory. "

Not to mention other resemblances to the single-BB theory that successful alternatives end up having.

And here is some of his evidence against the Big Bang:

RC: "(1) How can there be galaxies that are older than time?"

RC's first examples suggest one of the problems with dealing with popularizations; they like to translate reported results into familiar terms, such as a redshift into a distance. However, the derived distance depends on the dynamics of the Universe's expansion such as the value of the Hubble constant, and a distant galaxy's present distance may be significantly greater than its time-of-observation distance.

A more serious problem is that Big-Bang-based estimates of the Universe's age are sometimes less than the estimated ages of the oldest stars.

RC: "(2) Where is all the mass?"

True, a lot of the mass in the Universe appears to be material that interacts only very weakly with its readily-observable material, but I don't think that that's a fatal difficulty, because some weakly-interacting particles are already known to exist (neutrinos), with additional such particles being an expected consequence of various Grand Unified Theories.

RC: "(3) Where did all the superscale structure come from?"

True, getting that right has been somewhat difficult, but there are some promising leads, such as frozen quantum fluctuations from an exponential-expansion inflationary era, the side effects of cosmic strings, and so forth.

But counter to that is abundant support for the standard Big Bang model to at least the nucleosynthesis era and theoretical reason to believe that it had continued from a quantum-gravity epoch (Hawking's singularity theorems).

Speaker 4 the Death of Go
2001-Dec-15, 07:21 PM
Excellent post, Lpetrich. If you haven't already, will you post this in the secular web so Carrier can defend himself?

~Ender~

DStahl
2001-Dec-16, 01:18 AM
I agree, excellent post. It's worth noting that a number of things that could have crippled the Big Bang theory or even killed it outright are instead consistent with the theory. (Hydrogen/helium ratio and cosmic background radiation's blackbody spectrum are two that spring to mind.) Add inflation, and we can reasonably explain the several more things. (Flatness of spacetime, absence of magnetic monopoles, scale of variations in the cosmic background radiation, and possibly the origin of large-scale structure.)

For me, the fact that the Big Bang offers reasonable explanations for more observations about the Universe than any other theory gives it some weight. It may be wrong, but unless I hear of something with similar explanatory power I'll continue to think it's probably right. Just my opinion.

--Don

GrapesOfWrath
2001-Dec-16, 01:53 AM
On 2001-12-15 14:21, Speaker 4 the Death of God wrote:
If you haven't already, will you post this in the secular web so Carrier can defend himself?
What do you mean by "secular web"?

Speaker 4 the Death of Go
2001-Dec-16, 07:13 AM
Hello Grapes of Wrath!
The secular web is a cesspool of infidels, located at http://www.infidels.org
I am a regular there, and so is Lpetrich, and the historian carrier (i for the life of me cannot fathom why Carrier is playing at a astrophysicist) is one of the founding fathers of that site.
~Theothanatologist~

lpetrich
2001-Dec-20, 07:54 PM
I had also started a thread on this subject in the Internet Infidels forum "Science and Skepticism".

Richard Carrier's favorite alternative to the Big Bang is the Quasi-Steady-State Cosmology pushed by Geoffrey Burbidge, Jayant Narlikar, and Fred Hoyle. However, that cosmology looks like a complicated kludge in comparison to the Big Bang or the original Steady-State model.

GrapesOfWrath
2001-Dec-20, 07:59 PM
So we're kinda sloppy seconds?

lpetrich
2001-Dec-23, 06:26 AM
What's "sloppy seconds"?

And to clarify, the Big Bang does not require anything grotesquely ad hoc the way the Steady State or the Quasi Steady State cosmologies do, with their "creation field". The only physics it requires is either well-known physics or plausible extrapolations of well-known physics, like massive weakly-interacting particles or an inflation-inducing scalar field. And the only place it seriously breaks down is at the beginning -- and that is because we do not have a good understanding of quantum gravity.