Sir

Cosmologists are now getting data at rates greater than those conveniently measured in bits per millennium. Nature and Science have recently presented many interesting articles on the subject. But otherwise well written articles seem to have difficulty describing the effects of a greater than zero cosmological constant. Phrases such as “energy density of empty space”1, “cosmic repulsion”2, “large scale repulsive force”3, “vacuum energy”4, “mysterious repulsive force”5 and “cosmic antigravity”6 are inconsistent with each other, and less than clear.

I would like to propose that the effects of a greater than zero cosmological constant be referred to as ‘levity’. In the vernacular, levity is rather the opposite of gravity. It starts with ‘l’, the Latin equivalent of the Hellenistic lambda. And, while I make no great claims of being a wordsmith, ‘levity’ or ‘levitational force’ seems to read better than any of the alternatives above.

In a field where there are terms such as ‘black hole’ and ‘big bang’, and where many researchers report feeling uneasy with a greater than zero cosmological constant, surely a little levity wouldn't hurt.