• Question: What is the smallest thing in the world? Because people say an atom but they can break down into smaller things.

    Asked by iexterminateyou to James, Marcus, Martin, Rob, Suzanne on 19 Mar 2012.
    • Photo: James Boone

      James Boone answered on 19 Mar 2012:

      Atoms are comprised of a nucleus and a number of orbiting electrons. The electrons are what we call fundamental particles, in that they aren’t made up of anything smaller. The Nucleaus however is made up of Protons and Neutrons and these are made up of three constituent particles called quarks, the proton is made up of two “UP” quarks and one “DOWN” quark and the Neutron is made of one “UP” quark and two “DOWN” quarks. The quarks are fundamental particles in that, as far as we know, are not made up of anything smaller. Hope that’s answered your question 🙂

    • Photo: Marcus Gallagher-Jones

      Marcus Gallagher-Jones answered on 19 Mar 2012:

      I think in terms of mass it’s the electron though I could be wrong. Particle physics gets a bit crazy at the subatomic level.

    • Photo: Suzanne McEndoo

      Suzanne McEndoo answered on 19 Mar 2012:

      Hmm, I’m not sure. I guess it’s quarks, but I don’t know enough about particle physics to say for sure what their stats are.

      I think the lower limit on size is the plank length http://en.wikipedia.org/wiki/Planck_length which is 1.616199(97)×10−35 metres but that’s a bit outside of my range of knowledge.

    • Photo: Martin Zaltz Austwick

      Martin Zaltz Austwick answered on 19 Mar 2012:

      There is no smallest thing, really. Electrons can spread out through a lump of metal, or be concentrated into a tiny, tiny volume depending on the local conditions. How big do you think an electron is? How about a proton? A proton is much heavier, but normally exists in the centre of the nucleus, a much smaller space than the electron. But a proton can take up a lot of space under the right conditions. So, there is no answer to this question. A neutrino is probably the lightest particle of matter though.

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