This question is motivated by sheer curiosity. I certainly do not expect that the free parameters we use in the standard model have changed in value since we started measuring them with a "modern" degree of accuracy.

It would seem to me however, that as our experimental data accumulates in both quality and quantity, that it is important to know the physical constant values we input into our models as precisely as we can.

My question is, as I know very little about experimental physics, (and to working physicists this is probably an obvious question I am asking), but is there a law of diminishing returns in knowing the value of say, the mass of an electron to the 21st decimal point?

Is it important to continually refine the constant values to make the most, for example, of seemingly minor discrepancies in the results from the Large Hadron Collider?

I hope I am making myself clear and I apologise if I am not.

My point is: if the LHC produces an unexpected, repeated but extremely subtle result in an experiment, are we confident enough in the correctness of our present measurements of physical constants that we can draw conclusions other than measurement errors in them?

I am pretty sure the answer is yes, and that perhaps some of the results from the LHC actually serve to refine the values of the constants to reduce the error bars of the current values even more.

  • $\begingroup$ @dmckee I certainly don't want you to go to the bother of searching or listing duplicates, when I should definitely be doing it myself, but this is the 4th , at least, question I have asked in which no duplicates came up under the title of the question, otherwise I would not have posted. I will search deeper in future using the search box on the right. Rant over, sorry. Thanks very much for your listing. $\endgroup$
    – user81619
    Aug 3, 2015 at 16:12
  • $\begingroup$ The automatic duplicate suggester is not particularly good. Nor are those obviously duplicates in my mind, they just touch and similar issues and might help you to see the bigger picture. $\endgroup$ Aug 3, 2015 at 16:15

1 Answer 1


Every few year the Committee on Data for Science and Technology (CODATA) publishes recommended values of the fundamental constants, see http://www.codata.org/. They use the most accurate experimental results available, so yes, the values of the fundamental constants can -- in principle -- change. But what is more likely, is that the number of significant digits in these values increases.

What is important to note is that not only high-energy experiments are used to determine these constants, but also "low-energy" spectroscopy experiments or a combination of the two.


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