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Topic: Rich Halvorson: Questioning Cosmological Superstition - Separating science from ...
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posted 13. August 2004 12:22
Questioning Cosmological Superstition:
Separating science from myth in our theory of the universe
by Rich Halvorson
Abstract: For decades the two aspects of the cosmological principle, isotropy and homogeneity, have been held as inseparable and invaluable foundations for cosmology. As observational evidence has improved, however, it offers empirical support only for the claim of isotropy, and continues to disprove homogeneity even at large multi-galactic scales. In examining the origins of the two principles, we note that isotropy was an ingenious insight that managed to connect a few disparate data points into a helpful and accurate theory. Homogeneity, on the other hand, was considered a necessary correlate to isotropy not for any scientific reason, but because it seemed necessary to make isotropy compatible with a secular view of the universe. As such, homogeneity became a founding principle of cosmology not for scientific merit but as a philosophical perspective preferred by some scientists. This essay argues that this has proven to be unhelpful—and even an outright hindrance—to the advance of cosmological theory. As Stephen Hawking admits, a similar secular bias kept scientists from accepting the big bang theory in spite of much evidence. And, as this paper argues, cosmology may be suffering from yet another case of myth hindering science.
To read the entire paper, click here.
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Evan
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posted 14. August 2004 09:17
I am puzzled by this paper - maybe I am missing something, but it seems to me that “homogeneous” is being used in two different ways here without the author being aware of it.
First, after explaining isotropy, which, as he explains, is well-established by the evidence, he states,
quote:
(2) The universe is homogeneous – from any other galaxy, the universe would also appear isotropic.
That is, if the universe looks the same to us in all directions, then it would look the same in all directions from any other place in the universe also.
On the other hand, throughout the entire paper this is not the meaning of “homogeneous” that he discusses - rather he is discussing the fact that the universe is “lumpy” rather than having stars (or galaxies, or evenly clusters of galaxies) uniformly distributed.
This is an entirely different matter. We see the universe as lumpy, and cosmologists have offered explanations for this (which like much of cosmology is a mix of speculation and evidence - this is a tough subject to nail down), so by the principle of homogeneity in the first sense (looking the same from other places in the universe), we would expect the universe to look lumpy from other locations also, which seems an entirely reasonable conclusion.
That is, the principle of homogeneity in the first sense (looking the same ...) would imply that if the universe does not look homogeneous in the second sense (entities not uniformly distributed), then it would not look homogeneous in this sense to others either. This seems to me to be a wholly unremarkable statement.
The author confesses to being a “philosopher dabbling in the sciences.” However, he’s also in graduate school at Harvard - surely this issue of the one word being used in two different ways should have been apparent to him.
Now, a meta-question. The moderator posted this paper, not Halvorson himself. Will Halvorson appear and reply? This is common here - the moderator posts a paper by someone else rather than the person them self. Does the moderator do this by request - no questions asked?, or does the moderator apply some criteria? Given that this is Brainstorms, why doesn’t the author (Halvorson, Dembski, Wells, whoever) just post their paper them self?
I ask because I am puzzled by the background implication of Halvorson’s paper. On the surface he is implying that perhaps scientists are holding on to the homogeneity principle because of an anti-theistic bias. But, given his confusion over the two meanings of homogeneous, it looks like Halvorson might be guilty of exactly the reverse problem - trying to somehow (and I really don’t get how) make some kind of tenuous implied case for a theistic interpretation of the universe’s origin.
Now maybe I have really missed something here, and this interpretation of Halvorson’s confusion is all wrong, but it sure seems clear to me. I also note that this paper was written for a professor of astronomy - I wonder if Halvorson has gotten feedback from his professor on this paper?
So I am puzzled, and would appreciate knowing whether anyone else (including Halvorson) sees the problem in the paper that I have pointed out.
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Evan
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posted 21. August 2004 11:42
It's been a week since I last posted, and there has been no activity on this thread.
I am still curious about a question that I asked earlier: assuming that this paper was posted with the knowledge and/or at the request of Rich Halvorson, I am wondering if he is interested in or intends to discuss it here. I know people are quite busy, and I know traffic here at ISCID has fallen off quite a bit, but I don't understand why a paper would be posted here and then the author would not return to discuss it.
Just my feelings about this.
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Rich
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posted 23. August 2004 19:51
Evan –
Here is the author’s response you requested. Thank you for taking the time to respond. Although I wrote this response over a week ago, it took me a few days for ISCID to approve my posting access. I’m grateful that you took the time to read the paper. My response to your criticism is as follows:
Even a cursory browsing of the cosmological literature reveals the logical and evidential tension within the field over scientists’ initial expectations for homogeneity and the observed reality.
This tension is just as plain in the writings of Hawking as in various astronomy textbooks. The only difference is that here, I am willing to admit and explore the possibility that the initial supposition of homogeneity may have been based on the unscientific grounds of a secular philosophy.
The careful reader will note that nowhere does my paper insist on a theistic interpretation. Instead, I simply notice that the actual evidence (rather than a philosophy of “modesty”) points in that direction, and it is explained away for the sake of secularism. The principle of simplicity (Ockham’s Razor) dictates that homogeneity should be included only if it is necessitated by the simplest possible interpretation of the evidence.
Further, readers should pay careful attention as to how the working definition of homogeneity has evolved and changed within the field itself. It’s not that I am using different definitions, but that scientists themselves have expanded the scale of expected homogeneity more and more until they have arrived at the oxymoronic idea of “lumpy homogeneity.” What they now call “homogeneity” would have been called heterogeneity just a few decades ago … it’s only that the definition of homogeneity has been re-worked to maintain the principle in light of the unexpected (and perhaps undesired) conclusions of observational astronomy.
Instead of revising the hypothesis based on observed evidence, cosmologists have amended the meaning of “homogeneity” to retain a principle introduced out of philosophical rather than scientific necessity.
I would encourage any readers still confused about my explanation to look up my citation of Hawking or an introductory text on cosmology. One will see authors over and again explaining the tension between theory and observational data. As I quoted Hawking: “We have no scientific evidence for, or against, this assumption. We believe it only on grounds of modesty.”
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Darel R. Finley
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posted 27. August 2004 16:19
I think Evan is onto something. Click here to view six diagrams/descriptions of hypothetical universes (simplified to two dimensions) that illustrate the confusion over what exactly is meant by "homogeneity."
It seems that there is a loose link between the "smooth vs. lumpy" definition and the "isotropy everywhere" definition, but it is not absolute.
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The Deuce
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posted 28. August 2004 08:42
Actually, Rich did acknowledge the distinction between the "isotropy everywhere" and the "no lumpiness" definitions, although it comes late in his paper, on page 15:
quote:
Other scientific investigation has suggested that homogeneity and the Copernican principle are actually two different parameters. This research suggests that the Copernican principle could be true (that all observers in the universe would see the same degree of isotropy), without homogeneity being true (the universe remains “lumpy”). It was previously assumed that if the Copernican principle were applied, a homogeneous universe would then be a given.
Based on this, I don't think that he was arguing that a non-lumpy universe implies a non-isotropic universe. Rather (and I think he could have been a little bit more clear about this throughout most of the paper), he was arguing that the same assumed principle lead to both assumptions, and that in the case that we're able to test (the non-lumpy assumption), the principle has lead us wrong.
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Evan
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posted 28. August 2004 11:00
Thanks, Darel - those are very good illustrations that help make my point.
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