# Fundamental physical constants

1. Jan 19, 2004

### Nereid

Staff Emeritus
In a thread in PF's Special and General Relativity ("What if the speed of light was slower") there is a discussion on physical constants, including c.

lethe pointed out that there are only 26* truly fundamental constants, and posted a link to a John Baez page with a discussion of these (Ambitwistor also posted a link to this Baez page, much earlier):
http://math.ucr.edu/home/baez/constants.html

These constants matter, at least in the sense that if any were different, the universe would be very different.

Baez says: 'All other dimensionless constants (aside from those built into the initial conditions) can in principle be derived from these, if our best theories of physics are correct - by which I mean general relativity, which covers gravity, and the Standard Model, which covers all the other forces. Of course, "in principle" means "not necessarily by any simpler method than by simulating the whole universe"!'

What's the current status of deriving 'all other dimensionless constants' from these 26? Are there any hints of discrepancies?

A quick look at Baez' list and I'm thinking that the values of quite a number of these fundamental constants aren't known. What's the current status on their values (most aren't on the NIST website)?

*from the Baez page:
-> the mass of the up quark
-> the mass of the down quark
-> the mass of the charmed quark
-> the mass of the strange quark
-> the mass of the top quark
-> the mass of the bottom quark
-> 4 numbers for the Kobayashi-Maskawa matrix

-> the mass of the electron
-> the mass of the electron neutrino
-> the mass of the muon
-> the mass of the mu neutrino
-> the mass of the tau
-> the mass of the tau neutrino
-> 4 numbers for the Maki-Nakagawa-Sakata matrix

-> the mass of the Higgs boson
-> the expectation value of the Higgs field

-> the U(1) coupling constant
-> the SU(2) coupling constant
-> the strong coupling constant

-> the cosmological constant

2. Jan 19, 2004

### pallidin

Great question! Looking forward to responses.