Physicists have an embarrassing problem, says Andrew Derrington . They can't measure gravity Imagine that every time you weighed yourself you got a different result. At first it might seem quite convenient to know that if your weight looks a bit too high you can try again and get a better answer. But if you really want to know the right answer it can be a nuisance.
Physicists trying to measure gravity have a similar problem.
It is more than 300 years since Newton, allegedly inspired by a falling apple, proposed his universal law of gravity. The problem is that the value of G seems to be different every time it is measured. An international meeting will be held in London in November to discuss gravity measurements. If the differences are real this could be really exciting, or even alarming. Gravity does more than make apples fall to earth.