• Question: Is it true that a photon can be at everywhere at one time?

    Asked by 06chrste to James, Marcus, Martin, Rob, Suzanne on 16 Mar 2012.
    • Photo: Martin Zaltz Austwick

      Martin Zaltz Austwick answered on 16 Mar 2012:

      Yes, in theory, Quantum physics allows matter and light to behave like a wave (so a particle can be everywhere at once) or a particle (so it’s in one particular place). But it can’t really be both at once – once you’ve observed a particle in a specific place it can’t be everywhere else as well!

    • Photo: Marcus Gallagher-Jones

      Marcus Gallagher-Jones answered on 16 Mar 2012:

      I believe this one has something to do with someone putting a cat in a box?

    • Photo: Robert Thompson

      Robert Thompson answered on 16 Mar 2012:

      Well funny you should ask this, I’ve spent all day explaining to people how things can be in two places at once and how things can be in two states at once.

      http://www.thebigbangfair.co.uk/viewitem.cfm?cit_id=384673

      Some experiments show that when you measure it then previously it must have been in two places at exactly the same time.

      Its pretty cool and pretty mind blowing.

    • Photo: Suzanne McEndoo

      Suzanne McEndoo answered on 18 Mar 2012:

      Sure. There are a few ways that quantum mechanics lets something be everywhere (or at least several places) at once. One way is the Heisenberg uncertainty principle. It basically tells us that the more you know where something is, the less you know about how fast it’s going. Similarly, the more you know it’s speed, the less you know about where it is. So if we know pretty much exactly how fast the photon is going, it will be spread out completely.

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