Ars Technica: Some theories about the nature and history of the universe suggest that certain physical constants have varied in value over time. Observations of light from a galaxy 7 billion light-years away have shown that one of those constants has not changed for at least the past 7 billion years. The light that was observed showed methanol absorption lines that differed from Earth absorption lines by only 1 part in 10 million. Methanol’s chemical structure is heavily dependent on the ratio of proton mass to electron mass. If that ratio, which is considered one of the fundamental universal constants, had been different 7 billion years ago, then the absorption lines would have been significantly different. Although the observation doesn’t explain why the physical constants have the values they do—the fine-tuning calculations—it does help confirm that physical constants don’t vary in time or space.