Harry Collins


On his book Gravity’s Ghost: Scientific Discovery in the Twenty-first Century

Cover Interview of June 21, 2011

In a nutshell

How do physicists decide that some data might constitute a discovery?

The way to find out is to watch.  For 18 months I watched physicists arguing about a burst of data that turned up around the Fall Equinox of 1997 and became known as the “Equinox Event.”

What they saw was a little jump in the output that happened at the same time on both of the giant interferometers that make up LIGO –the Laser Interferometer Gravitational-Wave Observatory.  Each of these interferometers has two arms at right angles that are two-and-half miles long.  They are sighted around 2,000 miles apart, one in Washington State and one in Louisiana.  So if they both go off together it suggests that something coming from a long way away was the cause.

But that’s only the start.  Maybe the bursts were just coincidental noises on both devices.  Maybe there was an earthquake or an electrical storm 1,000 miles from each.  Maybe everyone got up and switched on the coffee-maker at exactly the same time when the ads came up during an exciting television program, causing a sudden glitch in the power grid.

It took 18 months for the physicists to argue out what they should say about the effect and during all this time they also knew the signal might be a fake put in deliberately to test them.