Curved space-time

I love this demo, but it’s one of those oddly bimodal ones – you can interact with it in two different ways:

  1. You throw marbles at it yourself, and stare at them. This is delightful, though rarely very informative.
  2. You’re led through a structured exploration by a demonstrator, as here. This is informative, but less delightful.

The challenge for the demonstrator is to balance their audience’s natural inclination to roll the marbles themselves with their inclination to retain control and direct attention. That is: play vs. lecture, or perhaps more appropriately here, interactive exhibit vs. demonstration.

We explore this a little in the forthcoming Demo film, which starts with a candle flame. We all love staring at the flames of an open fire, but we don’t necessarily learn very much about combustion by doing so. How we use a demonstration is perhaps more important than the demonstration itself. That’s certainly the case for teaching, and I suspect also true for storytelling.

Video found via The Kid Should See This, which also links to this useful video showing assembly.


3 thoughts on “Curved space-time”

  1. It is very hard to communicate an analogy in an interactive exhibit, unless it is extremely accurate, there are no conceptual jumps and it looks like the real thing. This doesn’t work in any condition as it suffers from a 3D model of 4D universe which is pretty hard core, it doesn’t really look like spacetime (what does spacetime look like?) and the energy losses are far too high so orbits don’t even work properly.

    So to make it work you need the showman at the front moving the cups over the balls fast enough that you don’t get lost in the holes in the model.

    Though I guess this is a good interactive exhibit to teach you how a weight on a rubber sheet works, which is useful if someone later uses a rubber sheet analogy for space time.

  2. Yes I spent many happy hours when revising for my GCSEs writing this kind of simulator, then again my A-levels, and again when I was supposed to be doing a PhD
    being my most recent effort, which works better on modern computers than it ever did.

    I love the protoplanetary disc mode on the one you suggest. Withe the right, big enough interface it would make a really nice interactive – especially as touch screens are now coming of age.

    There are a couple of ways of doing 2 body orbits using magnetism which would be nice too.

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