By the 1940s, it became clear that the value of the fine-structure constant deviates significantly from the precise value of 1/137, refuting Eddington's argument. With the development of quantum chemistry in the 20th century, however, a vast number of previously inexplicable dimensionless physical constants were successfully computed from theory.
The reason for this is that the choice of units is arbitrary, making the question of whether a constant is undergoing change an artefact of the choice (and definition) of the units. For example, in SI units, the speed of light was given a defined value in 1983.
Thus, it was meaningful to experimentally measure the speed of light in SI units prior to 1983, but it is not so now.
For the fine-structure constant, this upper bound is comparatively low, at roughly 10−17 per year (as of 2008). The gravitational constant is much more difficult to measure with precision, and conflicting measurements in the 2000s have inspired the controversial suggestions of a periodic variation of its value in a 2015 paper.
For the fine-structure constant, this upper bound is comparatively low, at roughly 10−17 per year (as of 2008). The gravitational constant is much more difficult to measure with precision, and conflicting measurements in the 2000s have inspired the controversial suggestions of a periodic variation of its value in a 2015 paper.
For the fine-structure constant, this upper bound is comparatively low, at roughly 10−17 per year (as of 2008). The gravitational constant is much more difficult to measure with precision, and conflicting measurements in the 2000s have inspired the controversial suggestions of a periodic variation of its value in a 2015 paper.
Similarly, with effect from May 2019, the Planck constant has a defined value, such that all SI base units are now defined in terms of fundamental physical constants.
All text is taken from Wikipedia. Text is available under the Creative Commons Attribution-ShareAlike License .
Page generated on 2021-08-05