Question

Scientists at a collaboration called LIGO were recently able to use very large interferometers to measure gravity waves, which are predicted by Einstein’s theory of General Relativity. Einstein’s theory predicts that dramatic events in faraway space, such as black holes colliding, would cause the space between two objects 1 km apart to shrink or expand by approximately 2.5*10-19m. Imagine one arm of an interferometer using a laser with a wavelength of 1064 nm is placed in the direction of the expansion of space due to a cosmic event, while space in the direction of the other arm remains unchanged. How long would the interferometer arms have to be for the cosmic event to cause the interference at the interferometer detector to switch from constructive to destructive? Explain your reasoning, and comment on the result and its implications.

Thanks!

Answer 1