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Comment by mtviewdave | Hacker News Reader

The most fascinating part about alpha to me is the implication that it isn't actually constant, and varies over time and/or distance. I once read a suggestion that perhaps the observed universe is simply the portion of the greater universe where alpha has a value that lets things like stars, planets, and life exist.

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Being actually a derived quantity, alpha's non-constancy actually implies that one or more of the underlying ‘constants’ vary non-homogeneously — which is what you said, but slightly different in import... observing alpha is actually just a convenient way of observing the others indexed together.

You've got this backward. Alpha is the fundamental physical constant: c, e and \hbar are the derived quantities. I'll quote part of another comment that I left on this thread:

> Now for a piece that's more interesting. The fine-structure constant (alpha) is the coupling constant that sets the strength of electromagnetism. This means that its value is the thing that matters in the equation: e^2/\hbar c. Each of the other values is a derived quantity. Further, to speak a bit loosely, only changes in alpha matter -- in the sense that if the speed of light (c) changes, but the other constants (e and \hbar) change in a way that keeps alpha the same, then you wouldn't be able to tell with an experiment that anything has changed.

> Contrast this situation w/ a change in alpha -- a table-top experiment would be able to detect the change (given that it's large enough, and we have methods of measuring changes on year-time scales that are a few parts in ~10^-18 (Rosenband, 2008)), as it would mean that physics has changed in a fundamental way.

> http://phys.columbia.edu/~millis/1900/readings/Science-2008-...

A further layman explanation by a researcher in this field: http://astronomy.swin.edu.au/~mmurphy/research/are-natures-l... specifically the section titled "Aside: Is it e or c varying?"

Thanks for explaining it to me.

This is also similar in the BSM-SG model:

Alpha could be different in different galaxies. It will not vary in a galaxy but maybe vary between galaxies. This is not clear, most likely not. It has much to do with the early stages of galaxy crystallization which could be the same for all galaxies.

It has a geometrical underlying principle in BSM-SG. c is also derived, e more or less, not so sure with h, guess you could.

Most of the 'constants' from the standard model are derived in BSM-SG, there are only very few underlying constants.

Physics experiments have ruled theories like this out. They can put a very very small upper bound on how much the constants can change over a volume the size of the universe, and over the lifetime of the universe.

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