Letter: LIGO measures gravitational radiation, not light

In his Oct. 12 letter, Charles Robinson states “It has been proven that light actually travels exponentially faster in space, therefore, reducing the time for it to reach the earth from the black holes.” The implication here is that somehow, LIGO overestimates the distance to the binary black holes we have detected.

First, no such proof indicating light travels at variable speeds exists.

Secondly, LIGO observes not light from black holes, but gravitational radiation. There is no assumption of the distance to these binary black holes, and the distance is instead extracted from the nature and amplitude of the gravitational waves themselves.

Lastly, we too congratulate the new Nobel laureates in physics. However, they are not resident at LIGO Hanford Observatory: Barry Barish and Kip Thorne are at Caltech, and Rai Weiss is at MIT.

This story was originally published October 25, 2017 at 4:42 PM with the headline "Letter: LIGO measures gravitational radiation, not light."