Visit 2019-04-08

We were very happy to be able to Visit the VIRGO site given that one has to wait for many month to get an appointment.

Interferometer arms

The two arms are each 3 km long the laser beam is split and then passes each beam multiple times for a total of some 120 km of travel. Then the two beams meet again and in theory the waves should be perfectly "in sync" and black each other out. Only if some disturbance like a gravitational wave passing changes the distance travelled by the light then there will (hopefully) be a signal with a signal to noise ratio that will allow to talk analyze what might have caused the disturbance. In the past a few very interesting astronomical events have been detected this way. See e.g. GW150914