4 ms·
Well, that's not quite true. The normal distribution maximizes entropy for a finite mean and variance. But it's not guaranteed that certain physical processes
by antognini 9y ago
Well, that's not quite true. The normal distribution maximizes entropy for a finite mean and variance. But it's not guaranteed that certain physical processes have well defined means and variances. A power law is the maximum entropy distribution with a well defined mean, but undefined variance, on the range (0, infinity). [1]
Of course in reality, at some point, some other physical process starts to dominate and cuts off the power law. this then turns it into a power law with a different slope or an exponential cutoff.
Edit: I forgot to add that a star's light profile on an image is actually approximately Gaussian. But it isn't exactly Gaussian --- I seem to remember that the core more closely resembles a Lorentzian. I am obviously not an observer, otherwise I would have thought of that immediately!
[1]: https://en.wikipedia.org/wiki/Maximum_entropy_probability_distribution https://en.wikipedia.org/wiki/Maximum_entropy_probability_di...
- kgwgk 9y ago> A power law is the maximum entropy distribution with a well defined mean, but undefined variance, on the range (0, infinity). The maximum entropy distribution with a given mean is the exponential. I think to define power law distributions you will need additional constraints more concrete than "undefined variance".
- antognini 9y agoThat's if you require the range to be [0, infinity). If you don't require 0 to be a valid point in the distribution then a power law is the maximum entropy distribution. A power law just diverges if you try to integrate to zero, so you have to find a lower entropy distribution.
- kgwgk 9y agoI think that if the power law cannot be integrated on [0,infinity), it cannot be integrated on (0,infinity) either.