Time-Varying Constants

Two serious questions crossed my mind during Friday’s very interesting talk about the redefinition of SI units. One is that the changeover to the new system takes place on 20th May, which is right in the middle of the examination period at Maynooth University. We will therefore have to supply two differents set of physical constants, one to go with examination papers taken before 20th May and the other for those taken afterwards. This will even affect those of us who like to use natural units in which, for example, Planck’s Constant is set equal to unity: after the redefinition of Planck’s constant on 20th May 2019, we will have to set its value in natural units to be equal to 0.99999999987.

The other question is that the new system of SI units presupposes that the constants of physics are actually constant and can therefore provide a stable framework. Many theories have been suggested in which the fundamental constants change with time. In the present context I feel obliged also to point out as an example the classic paper of Scherrer (2009) (PDF available here) the abstract of which reads:

We examine the time variation of a previously-uninvestigated fundamental dimensionless constant. Constraints are placed on this time variation using historical measurements. A model is presented for the time variation, and it is shown to lead to an accelerated expansion for the universe. Directions for future research are discussed.

This casts grave doubt on the motivation for the new system of SI units, at least until 12 noon.

6 Responses to “Time-Varying Constants”

  1. Undoubtedly my most widely-read paper. Thanks for taking another look at it.
    Bob Scherrer

    • Thanks for linking to your blog! It looks like I have some catching up to do. Expect many comments. Cosmology, science fiction, Wernher von Braun, Batman—I’m surprised that we’ve never met.

    • Life as we know it is impossible without RSS feeds. Is your RSS comment feed working? (Addressed to Bob, not Peter.)

      • I’m afraid that my blog is on a bit of a hit-or-miss status right now.

      • Yesterday I couldn’t subscribe to the comments feed. Today I could, and there was one new comment, by someone else: “Please don’t ever stop!”.

        I added about 10 comments yesterday.

        I remember reading “The Return of a Static Universe and the End of Cosmology” when it came out.

  2. My apologies – I just discovered that while I thought blogger was emailing me comments for moderation, these emails were, in fact, falling into a black hole. All has been fixed. As you can see, I am no Peter Coles (and thanks, Peter, for letting us use your blog as a personal chat room).

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