anchor.diff:  == What does non-Gaussian mean?
   
   === What does non-Gaussian mean?
  - - \( \alpha_2 = \frac{\left< x^4 \right> }{3 \left< x^2 \right> } - 1 \)
  - - For a Gaussian distribution, \( \left< x^4 \right> = 3\left< x^2 \right> \), so \( \alpha_2 = 0 \) 
  + - \( \alpha_2 = \frac{\left< x^4 \right> }{3 \left< x^2 \right> } - 1 \) is the "non-Gaussian parameter"
  + - For a Gaussian distribution, \( \left< x^4 \right> = 3\left< x^2 \right> \), so \( \alpha_2 = 0 \)
  + - Can be calculated from particle-tracking
   
   === What does non-Gaussian mean?
    - A random walk (diffusion) is Gaussian _at any given time_:
  
positive.code: 
  * Corey O'Hern, Mark Shattuck, Christine Jacobs-Wagner
  * Brad Parry, Ivan Surovtsev, Eric Dufresne, and everyone I talked to
  
  == Acknowledgments
  
  * Corey O'Hern, Mark Shattuck, Christine Jacobs-Wagner
  * Brad Parry, Ivan Surovtsev, Eric Dufresne, and everyone I talked to
  * Sackler, PEB, and HHMI
  
negative.code:  - So if the particles aren't diffusing, then \( \alpha_2 \neq 0 \)
     * For caged particles, \( \alpha_2 \approx -\frac{1}{5} \)
   - Closely related to caging and cage-breaking behavior
     * In a cage, particles move very small distances
     * Cage-breaking would involve much larger jumps
     * The distribution of "step sizes" would be very non-Gaussian
     
  === What does non-Gaussian mean?
  
  