deletions | additions       diff --git a/Payam.tex b/Payam.tex  index 58b3a80..9cd3cf9 100644  --- a/Payam.tex  +++ b/Payam.tex 
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\begin{itemize}  \item No! They are measuring different things. Payam's $t_{\rm h}$ is considering the diffusion of momentum information about a particle (I think this is the characteristic time in the decay of the velocity autocorrelation). My $t_{\rm h}$ is about pure information flow.  \item Sound speed shouldn't depend on viscosity at except for near-supersonic flow. (\href{http://iopscience.iop.org/0370-1301/66/5/303/pdf/0370-1301_66_5_303.pdf}{Or does it?} \href{http://www.engineeringtoolbox.com/sound-speed-water-d_598.html}{Speed of sound table}, \href{http://resource.npl.co.uk/acoustics/techguides/soundpurewater/content.html#LUBBERS}{$c(T,P)$ fits}.)     \item Some reading about propagation of hydrodynamic information:  \citet{1995PhyA..214..185E},  \citet{Espanol_Rubio_Zuniga_1995} for evidence of sound-wave propagation; 
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\citet{nderson_Mitchell_Bartlett_2002} describe an experiment where sonic communication is observed.  \end{itemize}  \item Sound speed shouldn't depend on viscosity at except for near-supersonic flow. (\href{http://iopscience.iop.org/0370-1301/66/5/303/pdf/0370-1301_66_5_303.pdf}{Or does it?} \href{http://www.engineeringtoolbox.com/sound-speed-water-d_598.html}{Speed of sound table}, \href{http://resource.npl.co.uk/acoustics/techguides/soundpurewater/content.html#LUBBERS}{$c(T,P)$ fits}.)     \end{itemize}  \item Payam has (equation 12) $v_{\rm DNA}=F_{\rm ext} \ln(\ell/d)/\eta\ell - \lambda E\ln(1+r_{\rm D}/d)/\eta$, which we use to calculate $t_{\rm D}$. He finds $t_{\rm D}\sim \ell\eta/E\lambda$ -- whence this simplification?  \end{enumerate}