CHAMPAIGN, Ill. — Ancient light absorbed by neutral hydrogen atoms could be used to test certain predictions of string theory, say cosmologists at the University of Illinois. Making the measurements, ...

Absorption spectroscopy is an analytical chemistry tool that can determine if a particular substance is present in a sample by measuring the intensity of the light absorbed as a function of wavelength ...

A new study documents an inexpensive, spark-free, optical-based hydrogen sensor that is more sensitive -- and faster -- than previous models. Hydrogen as a clean, renewable alternative to fossil fuels ...