Even with man's advancements in developing increasingly intricate microprocessors and ever taller skyscrapers, there's one thing we cannot do. We cannot make a completely perfect sphere. Sure, we can get close. But a new problem has provoked a more perfect execution. The kilogram needs to be standardised across many countries as the 120-year-old physical platinum standard is changing in mass. And deviations in measurement have screwed up the value of a kilogram across the globe.
Luckily one man could create the perfect sphere. And he could do it by hand.
Achim Leistner was an optical engineer from the Australian Centre for Precision Optics, pulled out of retirement to create two perfect spheres.
Another team started by creating a pure batch of silicon-28, spun in ex-Soviet centrifuges that were once used for uranium. Then in Germany, a team grew a pure crystal from the silicon, which was sliced into blocks and sent to Leistner.
Leistner and his crew used two spinning rotors to grind the spheres by hand—a process that took several months to complete. Their resulting spheres were accurate in smoothness to 0.3 nanometers and curvature to 60 to 70 nanometers. New Scientist explains that if these spheres were increased to Earth proportions, you'd see smoothness deviations of only 12 to 15 mm and roundness variation of 3 to 5 meters.
For the full remarkable story, be sure to hit the link. [NewScientist]