> 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?
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
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.
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.
It would be like someone calling Orlando, western USA. It's on a west coast, and if you were to head west you would likely hit Mexico (maybe Texas...) but it's obviously not western USA.
Just curious, but what would the accurate geographic descriptor of a west coastal, but not on the western subcontinent be called? The Congo is generally called central Africa in my experience, but that wouldn't really be accurate for Gabon/Angola, would it?
One interesting thing about this is that it represents a race, between the concentration of Uranium in high-grade ores through geological processes (which requires the Earth to have formed, and so on and so on) on the one hand and the reduction in abundance of U-235 in natural Uranium over time due to radioactive decay.
> The one exception was a shallow reactor zone at a place called Bangombé, some 30 kilometres from Oklo, although this has largely been washed out by ground water.
I don't necessarily want to start a giant derail here, but this thing has some social significance in that it resuscitated some pseudo-scientific claims about advanced ancient human civilizations ala Atlantis, that suffered cataclysm and disappeared from history.
Not human civilizations. 2 billion years is a lot of time... but it might be weak evidence that we are not the first technological species in this planet. If you consider that we are probably not the only intelligent species on the planet just now, it sounds at least plausible to me.
What's truly amazing is the emergent properties of nature that lead to natural structures such as this.
It makes me wonder if we can create cellular automata made from materials at a nano-scale to mimic this process. Then you're one step away from a Von-Neumann Universal Constructor.
It did change it, that's how I noticed in the first place. In my case I went back and re-edited the title and that seemed to make it stick to "million" instead of "M."
In the history of science, how many 'constants' have, so far, been shown not to be constant?