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Comment by dj-wonk | Hacker News Reader

> Davis and co point out that the Oklo data can also constrain changes in other constants, such as the ratio of light quark masses to the proton mass. To date, this work is consistent with these constants being constant.

In the history of science, how many 'constants' have, so far, been shown not to be constant?

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To my knowledge none, but there do exist problematic constants that we can't measure consistently. Famously, measurements of the gravitational constant G vary in a pattern that repeats every 5.9 years. There are a few theories about this systematic error but no solid supporting evidence in experiment form.

tl;dr No constants have been proven not-constant but there are some that might be pending further research

This is quite interesting, is there a paper or some source of information related to this?

http://www.researchgate.net/publication/274780565_Measuremen...

Here's a relevant link: http://phys.org/news/2015-04-gravitational-constant-vary.htm...

There was some concern that the rate of radioactive decay was altered based on the Earth-Sun distance, but that's been disproven: http://phys.org/news/2014-10-textbook-knowledge-reconfirmed-...

I wonder if this variation in G is similar.

Not to my knowledge. It's not an idle question, though -- the suggestion that physical constants might have changed over time arose not arbitrarily, but as a result of work in theoretical physics (Dirac's large number hypothesis, as well as a number of models that predict non-constant constants).

Remember that just over a hundred years ago one might equally well have asked "in the history of science, how many things have been shown to have constant velocity in all reference frames?"

Depends on what you mean. There have been a lot of implicit constants that change, F = (k) * MA. So, saying constant changes really just means there is another term in the equation that people are ignoring and lumping in with some constant.

The fine structure "constant," mentioned in the article actually varies with energy scale (although that's not the concern in the article).

Could you explain what you mean here? I can't tell what you're referring to.

Well, from my non-physicist's understanding of the matter: the fine structure constant is associated with the strength of electromagnetic interactions. The value we call the "fine structure constant" that's about ~1/137 in the equations is the lower bound of that strength, the strength of the interaction when you're dealing with energies about the same size as the electron mass. However, when you're dealing with higher energies, the interaction is stronger.

The interesting question as far as I can tell isn't related to how electromagnetism's strength varies over different energy scales, but whether the strength of electromagnetism at a given energy scale varies over time or space.

This is more or less correct, ~1/137 corresponds to zero momentum transfer (or equivalently infinite distances). This is because of screening by particle-antiparticle pairs at larger distances. See e.g. the first few slides of http://www.fysik.su.se/~clement/teaching/emparfys/2010-2011/... (one of the first things I found in a quick search).

It sounds specious but some ‘parameters’ are sometimes taken to be constant and then turn out to vary in relation to other parameters (such as time). This distinction between what we ”take to be” constant and that which is stringently and formally defined as being a specific value is a vast cognitive chasm.

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