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Q & A: light and the Planck scale

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Most recent answer: 06/14/2015
Q:
Why don't we see measurable differences in the speed of light due to variances of the flatness of space at Planck length scale?
- Neil Richins (age 48)
Dublin Ireland
A:

We don't really know what's happening on the Planck scale, except that it happens very fast, compared to the period of visible light, and that within a volume of a cubic wavelength of light, it's happening in different ways at zillions of different spots. So the light just sees a well-averaged medium Perhaps the light behavior that we see already shows effects of those small-scale variances. We'd still just see an average behavior.

Here's a bit of an analogy. Liquid water has all sorts of fluctuations going on at the scale of molecules and picoseconds. Still, light travels through it without a whole lot of scattering. Any Planck-scale fluctuations in spacetime are much faster and smaller-scale so averaging should smooth them out far better than it smooths out the proeprties of liquid water.

Mike W.


(published on 06/14/2015)

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