Fine structure constant may vary with space, constant in time

Enlarge / At these sorts of distances, images of quasars don't have many details. (credit: NASA, ESA and X. Fan (University of Arizona))

One of the most exciting prospects in physics has been discovering that fundamental constants are not actually constant at all. When I first started writing, physicists and astronomers were just figuring out how to build instruments and statistical tools that would allow highly accurate measurements of fundamental constants from the distant Universe. The results have been consistently disappointing: the constants appeared to remain constant over time.

But that still leaves open the possibility that the fundamental constants may be subtly different in space rather than time. Now, new observations examine this possibility back to just about 750 million years after the Big Bang.

Frustrating constants

The fundamental constants are one of the mysteries of modern physics. These constants are not predicted by theory; instead, their values are measured and put into the equations. Our physical theories will accept pretty much any value for the fundamental constants, but if the values were even the tiniest bit different, our Universe would be unrecognizably different—to the extent that we would not exist. This is often referred to as the "fine tuning problem."

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