Brussels, 11 Jan 2006
The most famous equation in all of science, E=mc2, appears to be broadly accurate, more than a century after Einstein published his special theory of relativity in 1905.
Researchers from the Laue-Langevin Institute (ILL) have found that E=mc2 is accurate to four parts in ten million following tests carried out in conjunction with the Massachusetts Institute of Technology (MIT).
The test of the theory is based upon what happens when an atomic nucleus captures a neutron, giving rise to an isotope with a mass of +1 compared to the original atom. However, the resulting isotope ought to have slightly less mass than the original nucleus and neutron before they merged. The mass difference is emitted as gamma-rays (energy).
The experiments were conducted in parallel on each side of the Atlantic. At the MIT, the differences in mass of isotopes of silicon (masses of 28 and 29 respectively) and sulphur (masses of 32 and 33 respectively) were measured with very high accuracy.
Meanwhile, here in Europe, an international group from the ILL and the French National Institute of Technologies, measured the energy from gamma-rays emitted by both silicon and sulphur when additional neutrons were captured.
The combination of the ILL's reactor and the world's highest-resolution gamma-ray interferometer - GAMS4 - meant that the level of gamma radiation could be measured to an accuracy of close to four parts in ten million.
All that was left was simple arithmetic - compare the values taken on each side of the Atlantic and determine the differences in mass, and establish the level of energy released.
And - Einstein was right all along, but this has now been verified with an accuracy 55 times higher than in previous measurements. The results are important, as any significant deviation would have serious implications for the world of physics and influence the way in which we interpret the world. Fortunately, the world seems to be just is as Einstein said it was 100 years ago.
Institut Laue-Langevin (ILL)
Tel: +33 4 76 20 71 07