In the January 13th issue of New Scientist was a report about a series of measurements designed to determine the mass of protons. Despite the extreme precision of the equipment [designed to be accurate to one part in ten billion] the discrepancy between the various sets of measurements by different laboratories was even greater – something like four standard deviations, which, according to the article, has a probability of less than 3/10 of one percent. Part of the problem in measuring protons is that their mass varies depending on the configuration of the nucleus of the atom being measured, so that, although both a deuteron and a helium-3 atom contain two protons, one neutron, and one electron, the total mass differs as a result of the internal configuration of the nucleus.
What I find interesting about this seemingly rather pedantic discussion about the accuracy of determining the mass of a proton is the assumption, which underlies the entire basis of science, that a proton should have the same mass in the same configuration at all times. So far, repeated measurements are suggesting that this may not be so.
Einstein’s theory of relativity works on a cosmic scale, but not on a sub-atomic scale, while quantum mechanics work on a sub-atomic scale but not on a cosmic scale, and for almost a century scientists have been working on a “theory of everything” that would unify the two.
Now… add to that the problem of dark matter. Way back in 1970, the astronomer Vera Rubin discovered that the stars in the Andromeda Galaxy revolve around the galactic center at the same speed, unlike the planets in our solar system, where the inner planets move much faster than the outer planets. This research was the basis for the confirmation of dark matter, but the problem remains that while a huge variety of measurements indicates that dark matter exists, to date no scientist has been able to identify or measure any individual constituent of dark matter, although the sterile neutrino is considered one of the possible components.
A similar problem exists with dark energy. According to the standard model of cosmology, the universe cannot be expanding at its present rate without the contribution of dark energy, and the best current measurements indicate that dark energy contributes 68.3% of the total energy in the universe. The mass–energy of dark matter and ordinary matter contribute 26.8% and 4.9%, respectively, and other components such as neutrinos and photons contribute a very small amount. But, again, no one has been yet able to detect or measure such energy.
One of the reasons that scientists have theorized the existence of both dark matter and dark energy is the assumption of uniformity, i.e., that the speed of light, the force of gravitation [or in Einstein’s terms, the mass-warping of spacetime], and the various “atomic” weights and forces are constant throughout the universe. So far as light and gravity are concerned, they certainly have seemed to be uniform in our small section of our galaxy.
Except now… there’s a real question of the uniformity of the mass of the proton, and I have to ask whether that might suggest that on a vast cosmic scale there’s not the standard uniformity that scientists have assumed.
It seems to me that the mass of the individual constituents of atoms will only be the same if and only if the structure of the atoms is the same.
Change the configuration of atoms (without changing the number and type of the constituent elements) and the elements will have to have different energy/mass because the differently configured elements will have a different force pattern thereby changing energy/mass of the elements.
If one maintains the same environment to the nth degree then one should get the same mass for the proton (unless there is a fluctuation of the balancing forces in the energy/mass of the element itself).
Uniformity has to be defined and balanced with the method of measurement. If either is not specific enough then one can expect a variable amount of tolerance in the result. Performing a test to one part in ten billion would require an environment that is the same to the that degree.
So I am not surprised with the results found.
Supposedly, the conditions were similar, and the atoms measured were the same elements. That’s why the deviation was considered significant.
You are probably correct although other articles state that the measurement methods differ and that explains the difference in mass found. The New Scientist article states that they measured H3 and Deuterium; hence my non-physicist attempt at explaining the different experimental results. In addition I note that there appears to be a similar difference in determining the radius of the proton ( but here there is a clear difference in how this can and is measured). Interesting.
Since a proton is composite rather than fundamental, there may be enough complexity to allow for either incompleteness of theory or incompleteness of application (even if theory could in principle explain the difference).
It’s always good to remember how much we don’t know, and that there probably is even more that we don’t know that we don’t know. But whether this is putting theory, application, or experiment in question, remains to be seen, IMO.