• Question: What is the difference between anti-matter and dark-matter ?

    Asked by lala to Louise, Michaela, Steve on 24 Jun 2010 in Categories: .
    • Photo: Louise Johnson

      Louise Johnson answered on 24 Jun 2010:

      Antimatter is like the opposite of matter – so an electron has a negative charge but an antielectron has a positive charge and is called a positron. Small amounts of antimatter have been synthesised in particle accelerators – about six atoms of antihydrogen – but whenever antimatter touches matter, they cancel each other out releasing huge amounts of energy. There doesn’t seem to be much antimatter in the universe but nobody knows why.

      Dark matter is normal matter but we don’t know where it is! The reason physicists talk about dark matter is that the universe seems to behave as if there’s more matter in it than we can detect in the usual objects (like stars and planets and dust clouds). It’s called “dark matter” as a way of saying we can’t find it with telescopes.

      Some ideas for where it could be are that there might be more black holes than we know about, or that particles called neutrinos might have a very small mass – which adds up to a lot over a whole universe because there are so many neutrinos.

    • Photo: Michaela Livingstone

      Michaela Livingstone answered on 24 Jun 2010:

      Anti-matter can be thought of as matter’s “mirror image”. What this means is you get equivalent particles, but which have opposite charges. In practice, this means that they are annihilated if they come into contact their “normal” matter counterparts and are converted into huge amounts of energy.
      Dark matter is theoretical type of matter that doesn’t give off any light, so we can’t see it using telescopes. However, we think it must be there because all the matter we can see is not enough to hold the galaxies together. Dark matter is the unaccounted matter that we’ve calculated must be there to hold everything together.

    • Photo: Steven Kiddle

      Steven Kiddle answered on 24 Jun 2010:

      we know what anti-matter is, we have no idea what dark matter is only that we can’t see it.

      Anti-matter is identical to normal matter, except particles have opposite charge, when anti-matter meets matter they annihilate releasing pure energy obeying e=mc squared.

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