History

A small cylinder called Le Grand K has defined the kilogram for more than a hundred years.

Le Grand K was forged in 1879 and is held in a locked vault outside Paris—revered and kept under lock and key because its mass, a little over 2 pounds, is the official definition of the kilogram.

If Le Grand K gets heavier or lighter—or absorbs atoms of something from the air—the definition of the kilogram literally changes.

Bill Phillips, a Nobel laureate from the National Institute of Standards and Technology in Maryland, told the assembled delegates at the international General Conference on Weights and Measures that basing the kilogram's official definition on a hunk of metal held in a vault was "a situation that is clearly intolerable." His colleagues clearly agreed, as no country voted to keep the old definition. 

Coffee is among the most commonly consumed beverages worldwide. Because of its popularity, it has attracted a great deal of research over the years.

Scientists have now stacked up a fair amount of evidence proving that coffee can protect against certain diseases and may even extend lifespan. Studies have shown that moderate coffee consumption might protect against cardiovascular disease, diabetes, and Parkinson's disease, to name but three.

But the findings to date leave some unanswered questions. For instance, certain people have genetic variations that alter the way in which they metabolize caffeine. How are they affected? Similarly, does the type of coffee — ground, instant, or decaffeinated — make a difference?