• Question: Is there another dimension?

    Asked by lucasjacobs to Meeks, Pete, Stephen, Steve, Tom on 16 Jun 2010 in Categories: . This question was also asked by bubbles123.
    • Photo: Stephen Curry

      Stephen Curry answered on 15 Jun 2010:

      You mean apart from the three of space and one of time that we already know about (thanks to Einstein)?

      I hear that string theorists insist that there must be 10 or 11 dimensions in total and that the ones we can’t see are ‘folded up’ so that we can’t, um, see them.

      I don’t know enough about string theory to know if it’s any good. I have yet to hear about an experiment that has been designed to test it – and what good is a theory if it doesn’t influence experimental design?

      I’m probably being too harsh on the theorists but on this issue, I’m with the cartoonist, XKCD. 😉

    • Photo: Marieke Navin

      Marieke Navin answered on 15 Jun 2010:

      This is a fab question.

      OK, look at it like this. Imagine you are a tight-rope walker balancing along a rope. You can only move backwards and forwards, not up, down, left, or right. So you’re only experiencing one dimension.

      Now an ant on the rope can move all over the place in an extra dimension, circularly around the rope.

      So maybe there are extra dimensions, like i’ve just described, but we can’t see them or we’re not looking on small enough scales. Some of our theories, like string theory, require extra dimensions and just because we don’t see or experience them doesn’t mean that they don’t exist.

    • Photo: Steve Roser

      Steve Roser answered on 16 Jun 2010:

      There’s lots. Einstein took us up to 4 with time included as an extra dimension, and the string theorist seem to suggest 11 or so

    • Photo: Tom Hartley

      Tom Hartley answered on 16 Jun 2010:

      This is not my area and the physicists will certainly give you a better answer. I am fascinated by space and dimensions, but I don’t have the training (in Physics) needed to think about it carefully without making mistakes.

      In my own work I often think about higher dimensions as it is a good way of thinking about what a neuron does in the brain (bear with me). Each cell sends a signal (or fire”) when a certain set of circumstances is met. For example, some cells in the brain fire when you are looking at a particular person’s face. Imagine that there are some properties of the face that make it unique or nearly unique – those might be the features (detected by other cells connected to the face cell) that make the cell fire. For example, distance between eyes, size of nose, thickness of eyebrows, width of mouth etc. We can think of these different measurements as making a kind of space (called “face space”) in which each faces has its own location. If there are just two features we’re interested in, we could draw face space on a piece of paper, and decide where each of our friends would be. Usually there are more than three dimensions, so the space is hard to imagine, but you can still do the maths e.g., to figure out how far apart different faces are. That’s faces, but the same approach could work for anything else which has features that can be identified – then you would call it “feature space” I suppose.

      And there are tricks for modelling neurons and how they “learn” that work on this principle. It turns out that similar things are often represented by neurons which are near to each other in the brain. The brain forms maps which roughly preserve the distances in the feature space – or at least this is a useful theory which could explain how the maps could be learned through experience, rather than inherited.

      This is difficult to explain, but you can find out more on this web page – some school students visited York and I showed them how to make brain maps.

      http://www-users.york.ac.uk/~th512/nagty/

    • Photo: Pete Edwards

      Pete Edwards answered on 16 Jun 2010:

      We already know our universe has four dimensions up/down, left/right, forward/backward and the time at which you are standing in a given position, but some theories that describe the building blocks of everything around us suggest that the dimensions we can experience are not the whole story.
      String theories suggest that there may be hidden dimensions in the universe that are too tiny for us to notice. The Large Hadron Collider at CERN ( http://www.lhc.ac.uk/ ) may well provide evidence for these extra dimensions by producing mini black holes which will exist for a tiny fraction of a second before vanishing in a puff of particles.
      We don’t know if extra dimensions really do exist or are just a prediction of a theory that may well be proved incorrect, but the LHC may provide an answer to this question in the next few years.

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