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Does a now solved Problem on Galactic Spiral Arms Noted in 1925 support a Young Earth?

Post of the Month: September 2011


Subject:    | Answers From Genesis
Date:       | 11 Sep 2011
Message-ID: |

Brett Schubert opens with a question:

> I am very interested in evidence that proves the age of the earth.
> I've looked on both sides of the argument, and wanted to ask you at
> about your response to the points raised in the link
> below. Sometimes it's difficult to know which statements are accurate,
> based on good measurements, and which are sensationalized. Several of
> the arguments made at the link below are not addressed on your page
> about evidence for an old Earth. Please let me know where I can go to
> find information about these arguments, or if are able to find debates/
> arguments against them. Thanks!

Garamond's reply is POTM:

It's been a while since I checked in on Answers in Genesis. Let's take a look.

The stars of our own galaxy, the Milky Way, rotate about the galactic center with different speeds, the inner ones rotating faster than the outer ones. The observed rotation speeds are so fast that if our galaxy were more than a few hundred million years old, it would be a featureless disc of stars instead of its present spiral shape.[1] Yet our galaxy is supposed to be at least 10 billion years old. Evolutionists call this "the winding-up dilemma," which they have known about for fifty years. They have devised many theories to try to explain it, each one failing after a brief period of popularity. The same "winding-up" dilemma also applies to other galaxies. For the last few decades the favored attempt to resolve the puzzle has been a complex theory called "density waves."[1] The theory has conceptual problems, has to be arbitrarily and very finely tuned, and has been called into serious question by the Hubble Space Telescope's discovery of very detailed spiral structure in the central hub of the "Whirlpool" galaxy, M51.[2]
[Humphreys, June 2005]

[1] Scheffler, H. and Elsasser, H., Physics of the Galaxy and Interstellar Matter, Springer-Verlag (1987) Berlin, pp. 352–3 53, 401–413.

[2] D. Zaritsky, H-W. Rix, and M. Rieke, Inner spiral structure of the galaxy M51, Nature 364:313–315 (July 22, 1993).

First: this is about as good as young-earth creationism is going to get. The HTML is professional-grade, the text has a calm, reasonable tone and even cites the peer-reviewed literature. To someone who doesn't have science as a fairly serious hobby, this might look plausible. I have no trouble appreciating this for the PR work that it is.

A few observations:

  1. The "winding problem" was first noticed by Bertil Lindblad in 1925.
  2. The astronomical community promptly concluded that the spiral arms could not be "rigid", and so set out trying to find what was going on.
  3. The "density wave" model was proposed in the 1960s and has continued to be refined.
  4. One of the refinements came from Zaritsky's et al. work on M51. He concludes his abstract by stating:

    "We suggest that a combination of several mechanisms, such as the interaction of M51 with the neighbouring galaxy NGC5195, forcing by the central 'bar', or distortions from density waves, is required to generate the observed structure."

Humphreys would like you to read that and conclude the "density wave" hypothesis has failed.

  1. M51 has proven to be a fertile testbed for refinements to the "density wave" hypothesis.

    "We present hydrodynamical models of the grand design spiral M51 (NGC 5194), and its interaction with its companion NGC 5195. Despite the simplicity of our models, our simulations capture the present day spiral structure of M51 remarkably well, and even reproduce details such as a kink along one spiral arm, and spiral arm bifurcations."

    C. L. Dobbs et al., "Simulations of the grand design galaxy M51: a case study for analysing tidally induced spiral structure", 2010.

So, Humphreys has grossly misrepresented the state of the research. He has a Ph.D. in an unrelated area; I have a Ph.D. in an unrelated area. If I can track down this record in 30 minutes on a lazy Saturday afternoon there's absolutely no reason he couldn't have done the same.

Whether or not he was deliberately lying I'll let him sort out with his God.

Humphreys begins by proposing that the spiral arms of galaxies are "material", despite the fact that he has no evidence of this and despite no working astronomer holding this position. In order to support his point of view, he then has to get rid of everything we know about physics, nuclear chemistry, geology, cosmology and astronomy.

Once we've done all this, do we at least have a greater understanding as to why spiral (and other, more strangely shaped) galaxies are the way they are? Humphreys is silent here as well, as he must be. Making the universe younger does not solve the problem of the origin of these structures.


Here is the choice that Humphreys does not want to spell out. You may accept as true an idea rejected in 1925 and not picked up since in order to reject the idea of an old universe, while reducing our ability to explain the world we see around us, or...

You accept that spiral arms are not "rigid", thus no "winding problem" exists, and that by the application of lots of "complicated" math we're now able to generate computer models of not only single galaxies in isolation, but how galactic interaction affects the shape of galaxies.

This isn't two side of a question. There's nothing to debate here. Humphreys relies on the fact that most of his readers either can't or won't consult the peer-reviewed literature. Once you invalidate that assumption the magic of his words dissipates.

The rest of Humphreys's arguments are equally bad. If there's one in particular you're curious about, please post it.

For a good summary of density waves, consult wikipedia:

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