Recent content by BobGom

I'm looking for an explanation for the fountain effect in superfluids using the 'two fluid model'. However the explanations I've come across are not very satisfactory From the NASA website http://cryo.gsfc.nasa.gov/introduction/liquid_helium.html But why does superfluid Helium flow...

Does the use of the MB distribution actually imply that? Surely the reason why the MB distribution sometimes works is because the issue of distinguishability does not arise since the occupancy is low enough that the chance of finding two electrons in the same state is small.

Interactions between electrons in a solid are very complicated and anything close to an exact Quantum Mechanical solution is pretty much impossible. Yet you can get pretty good results in many cases by treating the electrons as a nearly free gas which only interacts with a periodic lattice of...

Mathematical Methods for Physics and Engineering by Riley, Hobson and Bence is the standard choice at my uni.

Surely it is more or just as likely that these "Boltzmann Brains" would have false memories of a low entropy universe rather than observing the disordered universe they actually exist in. Especially as presumably a fluctuation which allows for some sort of sensory input of the 'actual' universe...

I am having difficult finding the meaning of the term 'fracture strength'. http://en.wikipedia.org/wiki/Flexural_strength" it means the flexural or bending strength but that is unsourced and marked as dubious. I was also wondering if it could be synonymous with fracture toughness or something...

Also curiously looking at the http://www.nndc.bnl.gov/sigma/getInterpreted.jsp?evalid=4208&mf=3&mt=2" for hydrogen, the data point for 0.0253eV has a cross section of 20.44b with all the low energy cross sections being in this area. However it appears to be 30.14b in the plot. There is an...

Ah ok. Do you know whether or not when the scattering cross section is normally quoted, is that the elastic scattering cross section or does it include inelastic scattering events aswell?

An overview of the materials for the ITER reactor is given here if this is what you mean. http://lhc-collimation-project.web.cern.ch/lhc-collimation-project/ph2_meeting_files/Barabash%20ITER%20Materials%202007.pdf

Thanks. I'm assuming the desired quantity from the site above is the total bound scattering cross section. The value for hydrogen quoted above is 82.02b and appears to be taken from a 1992 publication. However two textbooks (one from 1977, one from 1994) both put the thermal value for...

I am looking for thermal neutron scattering cross sections (0.025eV) for individual isotopes, having found non isotopic data for most elements in a textbook. The most comprehensive cross section database appears to be http://www.nndc.bnl.gov/sigma/index.jsp?as=238&lib=endfb7.0&nsub=10"...