:::: The linked article says there may have been a change in the fine structure constant, α, not necessarily the speed of light, c. Also, it hardly seems like a variable α is currently well-established. It's just the result from one set of data. But even accepting that there has been a change in α and that this means a change in c, the amount seems minuscule. The article says that α "had increased by a few parts in 10<sup>5</sup> in the past 12 billion years", which would correspond to a similar change in c. Therefore, even if c is not exactly constant it would be very nearly constant and relativity would still be a great approximation. That's ignoring that there may be a mundane explanation for this apparent change. | :::: The linked article says there may have been a change in the fine structure constant, α, not necessarily the speed of light, c. Also, it hardly seems like a variable α is currently well-established. It's just the result from one set of data. But even accepting that there has been a change in α and that this means a change in c, the amount seems minuscule. The article says that α "had increased by a few parts in 10<sup>5</sup> in the past 12 billion years", which would correspond to a similar change in c. Therefore, even if c is not exactly constant it would be very nearly constant and relativity would still be a great approximation. That's ignoring that there may be a mundane explanation for this apparent change. |