More Dark Matters

Friend and reader Rob Dodson sends in a link to an interesting story on some astronomers proposing a new model of gravity, prompted by the anamoly of that orbital speed of many stars is much greater than the currently accepted theory predicts, the same puzzle I described several posts back.

I suggest that this story nicely illustrates the point I was making: it often is not obvious whether to regard some observation(s) out of line with a particular theory as refuting it, or as simply indicating the presence of some as yet undetected factor influencing the situation(s) that will be seen to fit the theory once it is recognized. There is no automatic procedure for correctly deciding between devoting one's (limited) time and energy to searching for a way to explain the anamoly within the current theory and the alternative of attempting to supplant it. When faced with such a situation, a scientist is always forced to rely on her intuition as to which course is more promising. In doing so, I think it is quite sensible to take into account the extent to which the existing model is supported by other evidence -- in other words, positive results should lend a theory added weight.


  1. All the theories fly in the face of the Genesis account which explains that there are waters above and waters below. The whole universe is surrounded by ice, and none of the stars can be more than 6000 light years away. Observations to the contrary must be wrong.

  2. I discussed the same thing in my comment to your original post but reached the opposite conclusion to you.

    I suggest a much simpler explanation as to why, ceteris paribus, scientists will tend to accomodate apparent refutations of a theory by adapting it, rather than chucking it out and starting all over with a new theory. It is nothing to do with induction. It is simply because it's a lot cheaper!

  3. OK, Julius, but the tendency to adapt an existing theory seems to me to be strongly correlated with how many previous observations support that theory. Why else is it "cheaper" to endorse one theory rather than another?

  4. Because theories have ramifications; so the disruption to science caused by chucking out an existing theory will tend to be greater than that caused by merely adapting it.

  5. I still suggest that those ramifications involve confirming uses and tests of the theory. If Newton's theory of gravity is used to send ships to the moon, that is both a ramification and a confirmation.


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