Albert Einstein

An image of one of the most accurate man-made spheres, as it refracts the image of Einstein in the background. This sphere was a fused quartz gyroscope for the Gravity Probe B experiment, and differs in shape from a perfect sphere by no more than 40 atoms of thickness. It is thought that only non-rotating neutron stars are smoother[citation needed]. It was announced on 1 July 2008 that Australian scientists had created even more perfect spheres, accurate to 0.3 nanometers, as part of an international hunt to find a new global standard kilogram.