Thank you for your kind comments Bernard.

You are, of course, correct and eom is incorrect. While we know the lifetime of the proton is in excess of 10^32 years (that's a 1 followed by 32 zeros) and believe that antiprotons have the same lifetime, we have not explicitly measured the lifetime of the antiproton to such accuracy. As I recall, the existing measurement on the lifetime of the antiproton is it will live for at least 10,000,000 years. This is not to say that it will decay in that time, but rather the lifetime is no smaller than that.

This disparate set of numbers reflects the fact that we measure the lifetime of protons using vast detectors, comprising some 50,000 metric tons of water. Antimatter lifetime experiments are much more difficult and are done using 0.00000000001 grams. Hence the huge difference in our knowledge.

Current theory suggests that an antiproton, far from any normal matter, will live as long as a proton, far from antimatter. That is a very reasonable inference, taken from complex experiments which compare how the laws of physics govern matter as compared to antimatter. But as a matter of a specific measurement, we can only definitively state the lifetime of an antiproton must exceed 10,000,000 years.

Cheers...

Don Lincoln