• Question: Would a study of quantum physics mean people could be in 2 places at once?

    Asked by katienelson to Chris, Dave, David, Fiona, Jack on 21 Jun 2013.
    • Photo: Chris Mansell

      Chris Mansell answered on 21 Jun 2013:

      If a human were to run towards a wall with two doors in it, the probability of us going through both doors would be very small. This is because we extremely large (compared to particles, like electrons, that can go through two holes in a screen at the same time). This effect also depends on the speed at which you (or the comparatively tiny particle) travel towards the doors (or holes). The smaller you are and the slower you move the better your chances of going through both openings at once.

      To be mathematical about it (but without taking relativity into account), we can say that you want the product of your speed and mass to be as small as possible. This is because all objects have a wavelength associated with them. If your wavelength is about the same distance as the distance between the openings, you may be able to go through both at once. The product of your speed and mass is inversely proportional to your wavelength. The wavelength of a human is extremely small, much smaller than the distance between two doors, so the chance of going through both at once is extremely tiny.

      The wavelength is called the De Broglie wavelength. You can have a go at calculating your wavelength at:

      http://hyperphysics.phy-astr.gsu.edu/hbase/debrog.html#c5 .

    • Photo: David Freeborn

      David Freeborn answered on 22 Jun 2013:

      Hi katienelson,

      Probably not. Quantum physics means that the position of every particle is uncertain, and is described by a certain probability of being in different places, but it doesn’t mean that at any particular moment in time the particle is in two places at once.

      And for people, the probability distribution is very small, because people are very big (very far from the quantum scale). In practice, even with quantum mechanics, we can pinpoint precisely where a large object is.

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