Constant Changes

If a constant of nature can vary, then so might laws of physics

Sometimes it’s the tiniest differences that change everything. This summer, astrophysicists reported tantalizing evidence of just such a discrepancy.

As light from a distant quasar pierces a gas cloud billions of years ago, atoms absorb some colors. The precise wavelengths of the lost colors suggest to astronomers that the seemingly constant strength of light’s interaction with matter has not, in fact, always been the same.