An order of magnitude sensitivity gain is described for using quasar spectra to investigate possible time or space variation in the fine structure constant . Applied to a sample of 30 absorption systems, spanning redshifts , we derive limits on variations in over a wide range of epochs. For the whole sample, . This deviation is dominated by measurements at , where . For , . While this is consistent with a time-varying , further work is required to explore possible systematic errors in the data, although careful searches have so far revealed none.
- Received 13 February 1998
©1999 American Physical Society