Madam, – William Reville (Mystery of matter is behind the great darkness of our universe”, May 21st) writes, “In the 1990s, to the great surprise of astronomers, it was discovered that, far from slowing down, the expansion of the universe is accelerating, propelled by a mysterious dark energy that acts like negative gravity”.
Ahem. Negative gravity? Surely the paper of record is no place for the introduction of such unquantified levity? – Yours, etc,