Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have learned about the existence of positrons as a decay product from uranium fission - if I'm not mistaken. Is there any evidence for higher 'mass' anti-matter, or is that mere speculation or rationalisation? i.e. Is the argument that there anti-matter based planets in the universe, or just a soup of positrons?

share|cite|improve this question
Possible duplicate: – Qmechanic Aug 16 '12 at 7:21

Your question suggests that you think positrons are the only form of anti-matter, but as far as we know every particle has a corresponding anti-particle (some particles like the photon or Z are their own anti-particle). The positron weighs about 0.5MeV while the heaviest known anti-particle is the anti-top quark at 173 GeV i.e. 346,000 times as heavy as the electron.

Anti-hydrogen atoms have been made. These contain a positron bound to an anti-proton, so these are the simplest form of anti-atoms. The anti-hydrogen atoms are too hard to handle to assemble into anti-molecules so we haven't seen any form of anti-matter more complicated than a hydrogen atom yet.

The final part of your question, whether there are anti-matter planets, is addressed in the link Qmechanic posted in his comment. The headline is that there is no evidence for any sizable (i.e. bigger than a hydrogen atom) aggregation of anti-matter anywhere in the universe.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.