• Question: Thoughts on antimatter???

    Asked by Annabelle Gill to Stewart on 9 Nov 2018.
    • Photo: Stewart Martin-Haugh

      Stewart Martin-Haugh answered on 9 Nov 2018:


      Anti-matter is extremely cool!

      1)Antiparticles are almost exactly the same as particles, but they have opposite electric charge. So positrons (=positive electrons) go the opposite way round a wire than electrons.

      2)Antimatter was added into the theory of fast + small things (relativistic quantum mechanics) because the equations don’t work without it (equations from Bristol native Paul Dirac).

      3)Then people saw it in cosmic rays hitting the Earth FROM SPACE, confirming the equations work

      4)Antimatter annihilates to form pure energy when it touches matter. This is how particle colliders work: we collider together matter and antimatter and it annihilates. That creates new particles which we measure in big detectors (kind of like cameras).

      5)Since matter and antimatter are opposites and the universe seems to be symmetric, we expect as much matter as antimatter. But we don’t see much antimatter in the universe.

      6)Since we can make antimatter at the Large Hadron Collider, we can see if there are any differences between it and antimatter – this might explain why there isn’t much of it in the universe.

      7)There is an experiment at CERN that creates and traps small amounts of antimatter (far too little to be dangerous). We think antimatter falls to the ground under gravity, but it might fall upwards! The experiment is hoping to measure whether it falls up or down.

      8)If you (God forbid) get injured and go to the hospital, they might give you a PET scan. This stands for Positron Emission Tomography and uses antimatter to image the human body!

      TL;DR – antimatter is cool, useful and mysterious. Something to aspire to…

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