Tuesday, April 03, 2007

Cosmology

What's the difference between the following statements:

1. The universe depends on a force that "our five senses can’t detect," that "doesn’t interact at all with electricity or magnetism," and that is compared by those who work in the field to the "tooth fairy."

2. The universe depends on God.

12 comments:

  1. Your comment has zero persuasive value unless you can explain in what way the "summary needs a little work."

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  2. I'm not sure what you mean by "abstracting" here. Anyway, my point is that it seems very odd that scientists are invoking something that they themselves equate to the "tooth fairy" -- something that for now is unobservable even by the most powerful detectors, and may forever be unobservable for all we know -- and that is posited only because it helps to fill a gap in certain (but not all!) equations. If these scientists used the letters "g-o-d" to describe this unobservable force, rather than the letters "d-a-r-k -m-a-t-t-e-r a-n-d e-n-e-r-g-y," people would immediately say, "Hey, this is just a God of the Gaps argument. Science can't rely on some mystical force just to fill a gap in the equations."

    Right?

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  3. The word "equation" doesn't mean equating dark matter with God. It's this: From what I can tell (as a non-scientist), the only reason anyone even suggests such a thing as dark matter or dark energy is because of certain equations regarding the expansion of the universe or the brightness of supernovae, and these equations don't make sense unless you add in some additional factor for "dark" something or other, even though no one has any idea what that is or how to detect it.

    More quotes from that article:

    "The term doesn't mean anything," said David Schlegel of Lawrence Berkeley National Laboratory this past fall. "It might not be dark. It might not be energy. The whole name is a placeholder. It's a placeholder for the description that there's something funny that was discovered eight years ago now that we don't understand." . . . As one summarized the situation, "We don't even have a hypothesis to test."

    So forget "God." This whole situation seems equivalent to the Far Side cartoon where two scientists are staring at a lengthy equation on the blackboard, and one says regarding a blank spot, "And here, a miracle occurs."

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  4. Anonymous2:08 PM

    Dark matter/energy theory (usually known as the standard cosmological model), like string theory, isn't empirical. Einstein, at least, had the professional integrity to be very uncomfortable positing the existence of something that could not be observed or disproven.

    You can't say "If we had this, then everything would fall into place" and call it science, unless you can test it and disprove its existence. That's where both fail the test of science.

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  5. "the only reason..."

    I think that's just factually wrong. But even if it were right, I still wouldn't understand the criticism: The "neutrino" was a placeholder, as were "atom," "force," and "gravity." These concepts all started off as inchoate ideas that later became refined by further observations, follow-up hypotheses and theoretical change. (Another way to put it is that such terms are only "partially denoting" at the start of their careers.)

    If "God" were as semantically elastic, perhaps science could make some good use of the term!

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  6. OK, good point about the various concepts that weren't fully understood at first.

    But speaking as a non-scientist who is out of my depth as to the technical side of things here, it seems to me that your Wikipedia link shows only that there are observations indicating that the universe's expansion is accelerating -- not direct observations of dark energy. Thus, what I said seems to be right: whatever equations that describe the universe's expansion need some "miracle" or "God" or "dark energy" to be plugged in at a certain point -- even though we may never be able to observe (and no one even has a good guess) what that is.

    Maybe (but this can only be a completely wild guess on your part) "dark energy" or "dark matter" will turn out to be akin to the "atom" -- inchoate now, but to be fleshed out with future observations and theorizing. But what if it's not? What if theorists in 2100 or 2200 realize, for some reason, that dark energy will never be observed in any fashion, and that the only rationale for dark energy that we're ever going to get is that it makes certain equations work out more nicely. Would that be different from saying, "A miracle happens here"?

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  7. "Would that be different from saying, "A miracle happens here"?

    I think it would be different because even in your scenario the relevant constant would function in an equation that bares out empirically; and the presumption would be that that constant represents something empirical.

    Again, too, keep in mind that we don't "directly observe" gravity, either; rather, it's inferred from direct observation of certain kinematic phenomena. (Which is why it took so long to discover it, despite its conspicuous effects.)

    Whether dark energy goes the way of gravity (and becomes integrated into physical theory) or the luminiferous aether (and becomes a footnote in the history of physics) remains to be seen. As one at least as out-of-his-depth as you, I don't feel qualified to have an independent opinion on which it's likely to be.

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  8. What if theorists in 2100 or 2200 realize, for some reason, that dark energy will never be observed in any fashion, and that the only rationale for dark energy that we're ever going to get is that it makes certain equations work out more nicely. Would that be different from saying, "A miracle happens here"?

    This won't happen Stuart. The reason is that to even be able to make the statement that "dark energy will never be observed" implies that we have some knowledge that transends the need to observe it. In other words, to be able to say that we won't be able to observe dark energy is to say that we understand it well enough to know why we won't be able to detect the source. If we know that, then we must know the nature of the source, at least to some degree.

    To make another point, your notion that we posit dark energy just to make the equations work out is actually something that happens commonly in physics. This is precisely how quantum mechanics and many other branches of physics first started, by writing down some equations that describe what we see. Then we extrapolate from those equations and make new predictions of new things that we might expect to see, that is how the scientific process bootstraps itself.

    For a more esoteric example, see string theory. Here is a theory that makes predictions that are potentially observable but completely beyond our means to do so technically. So, the big debate in physics today is "Is string theory right?" Well no one knows, because no one has the capability to constrain it with experiments. However, no one has concluded that we will never be able to detect strings or the effects of strings simply because we don't know enough about them to be able to say one way or the other.

    Finally, the fact that the expansion is accelerating is itself a direct observation of dark energy. Even if we don't understand exactly what it's source is, we know it's there because the acceleration itself cannot occur without energy in the first place.

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  9. As for your original question.... I think the real problem is in the question itself. The question equivocates a point of scientific knowledge with a point of religious faith, and they really aren't the same thing, even though many people try to make them so. It's an invalid comparison from the very beginning.

    I think that far too many Christians today have become jealous of the successes of science and have attempted to invoke a kind of scientific like thinking as substitute for faith. This will ultimately fail miserably.

    The reason it will fail is that in trying to be the equal of science by science like means makes faith subservient to science rather than it's equal. Folk such as Phillip Johnson and Bill Dembski are not doing any good for the Faith, they are doing far more damage than good by turning Christians into laughingstocks.

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  10. 4. Stuart Buck asks: What's the difference between the following statements:

    1. The universe depends on a force that "our five senses can’t detect," that "doesn’t interact at all with electricity or magnetism," and that is compared by those who work in the field to the "tooth fairy."

    2. The universe depends on God.

    The difference is that the set of possibilities #1 describes includes #2 but is much broader. Take 'dark matter' or 'dark energy'. Neither would qualify as God yet they would seem to fit #1.

    You could repharse this to see the difference more clearly:

    1. There happens to be an American living on the USA's east coast.

    2. George Bush lives on the USA's east coast.

    #2 fits nicely with #1 but #1 is much more broad since it could be talking about any American who happens to live on the east coast.

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  11. Anonymous7:23 PM

    From 2004: "He's had several opportunities by now to explain what scientists mean when they rule out the supernatural "by definition," but he still refuses even to attempt an answer."

    It's now 2007 and you still have problems distinguishing between the natural and the supernatural.

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  12. That's a complete non sequitur. Even if you think I have trouble distinguishing the natural and supernatural, that has nothing to do with my 2004 debate against Brian Leiter, who was either unwilling or unable to explain what numerous scientists meant when they said that science rules out the supernatural "by definition."

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