Putting Einstein to the test in a small glass tube

The most accurate test to date of Einstein’s theory of special relativity is taking place at the University of Sussex. The investigation of Einstein’s 1905 theory could change the face of modern physics. It will examine quantum gravity, a theory which introduces very small modifications into the accepted 1905 theory.

Examination of Einstein’s theory is usually a costly and time-consuming exercise. Existing experiments involve multi-million dollar space projects. Physicist Dr Ben Varcoe has devised a way of bringing the science down to earth.

Dr Varcoe said: “I have created a new means of looking at the problem without the hassle and cost of sending large spacecrafts away from the planet. We shall gain better results here at Sussex by shining lasers through a small glass tube and measuring the effects.”

The experiment looks at quantum gravity, a theory which introduces very small modifications to the Einstein’s theory. The experiment is designed to accurately measure any changes to the speed of light during testing. The aim is to find out whether light really is “c”, a constant, in the famous equation E=mc2. Einstein decreed the speed of light must be a the same regardless of how fast the observers of the experiment are moving. New physics disciplines, such as quantum gravity and string theory, often introduce small changes to Einstein’s theory.

Light has two properties, the time it takes to go between two points and the distance between its waves. Quantum physics makes it possible to alter the time it takes for the light to travel between two points whilst leaving the speed of the waves the same. Dr Varcoe’s experiment involves slowing down the speed of a flash of light so it takes a very long time to travel through the experiment in a laboratory at the University campus. By slowing the speed of the light flash to a manageable level it is possible to examine the associated light waves and test Einstein’s theory to a higher precision than ever before.

Dr Varcoe said: “No one in the UK has ever tried slowing down light for this purpose. The speed of light is incredibly fast at about 30 million metres a second which is why great distances in space are used for testing. We will be able to use a 5 cm glass tube with gas inside to slow the light from three lasers down to 10 metres a second. It is a simple practical method for tackling a major intellectual challenge.”

The tests will be carried out by Dr Varcoe assisted by two undergraduate students. Initial findings are expected within six months with full results by late 2005. The project has been funded by a grant from the Particle Physics and Astronomy Research Council.