Re: Two neutron stars on a collision course?

Russell Wallace wrote:

> The density at maximum scrunch can't be much greater than that of the 
> already-formed neutron star, can it? Also, I've seen the mean free path 
> of neutrinos in lead quoted as a light year (1e16 m); if neutronium is 
> 1e14 times as dense as lead, that would imply a mean free path on the 
> order of 100 m, a couple of orders of magnitude smaller than the 
> diameter of a neutron star.

There is also the issue that as the density increases, the neutrinos 
themselves become semidegenerate and have trouble travelling freely. 
Keep in mind this is also happening _during_ the catastrophic collapse 
which forms the neutron star, and, after its rebound, the 
electromagnetic blast of the type II supernova.

Only at these extreme densities, during the supernova collapse, do 
neutrinos become "trapped."  At normal neutron star densities and 
conditions, they're much more transparent to neutrinos.

The details and numbers are in _Black HOles, White Dwarfs, and Neutron 
Stars_ by Shapiro and Teukolsky.

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