Are The Constants Of Physics Actually Constant?

The foundation of science are the constants. Literally. If we could not rely on them being invariant then we really would not have science. Even more fundamentally I think that we would not have stars, planets, reliable chemistry and even life.

So are the constants of physics truly constant or do they change with time? Were they different in the past and will they evolve into something else in the future?

A Search For The Evidence

• The Oklo Reactor is a uranium deposit in Gabon that became a natural nuclear reactor about 1.8 billion years ago. The isotopic composition of fission products have been studied in detail to see if there were changes in nuclear interactions with present day reactors. The analysis showed that there did not seem to be alteration in the physics of nuclear reactions since then.
• The ratio of the mass of a proton to the mass of an electron is an important one. It dictates, among other things, the chemistry that goes on in out bodies. A study of the emission spectra of clouds of methanol in distant galaxies (and therefore far back in time) has shown that the change is less than one hundred thousandth of a percent or less over the past 7 billion years (essentially zero change).

• The ratios of spectral lines of distant quasars that come from different types of atomic transitions such as the fine structure and the hyperfine structure (due to redshift from the expansion of the Universe the ratios and not the absolute value need to be compared). The frequency ratio have dependencies on the electron charge and mass, the speed of light, and Planck's constant, and can have been used to compare these parameters to their present values on Earth. No shifts have been detected.

In Closing

We can only look back to the time that ionized gases became neutral and allowed the sky to permit light to travel freely through the Universe. It seems that since then the constant of physics have remained just that, constant.

Now you can sleep at night.

Sources and Further Reading

1. Article on Scientific American here. An overly wordy article that is not direct and does not go that deeply into the topic but it is where I got the idea for this post.