113,632 reputation
5175303
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 10 months
seen 4 mins ago

Semi retired old time computer nerd who started programming on a Commodore Pet.

Since I'm also active in the Physics forum I should add that I started as a theoretical chemist, moved into solid state photochemistry and finally worked in industry as a colloid scientist. I only became a full time computer nerd in 1997.


Jul
15
comment When they say that the universe cooled after the big bang, where did the heat go?
@garyp: not that it's relevant but see Why does deodorant always feel cold?.
Jul
15
answered What was the density of the universe when it was only the size of our solar system?
Jul
15
revised Future of a universe with scalar field
Correct typos
Jul
15
comment Absorption cross section and absorption coefficient
I don't have access to HITRAN, but if you look on HITEMP you'll see data on molecules like CO$_2$, CO, NO, OH, etc. You need to use the number density of these molecules e.g. the number of CO$_2$ molecules per unit volume. Note that while the answer I've given is generally true it wouldn't hurt to check the FAQs on the database just to make sure they don't use some other convention.
Jul
15
reviewed Approve suggested edit on Regarding luminosity monitor of particle collider
Jul
15
reviewed Approve suggested edit on Why does the Walecka model not include pions?
Jul
15
reviewed Approve suggested edit on Why can charges outside be ignored in Gauss's Law?
Jul
15
reviewed Close About Stellar Evolution
Jul
15
reviewed Close Does the Higgs boson give mass to ALL other particles?
Jul
15
comment Calculate electricity generation
@user7063: the potential energy change for any object of mass $m$ falling through a height $h$ is given by $\Delta U = mgh$. How much of this potential energy change can be extracted is down to engineering.
Jul
15
comment Space Warps & Frame Invariance
@LoganR.Kearsley: No-one is going to win a Nobel prize for theoretical calculations of FTL drives (unless of course you actually create one :-) so for physicists it's the sort of thing you do on a Friday afternoon. The interferometer experiment isn't designed to build an FTL drive, it's designed to see if that type of curvature can be created by a non-exotic stress-energy tensor. This seems to me to be an interesting experiment and the relationship to the Alcubierre metric is incidental.
Jul
15
comment What was the density of the universe when it was only the size of our solar system?
The universe may well be infinite in size, in which case it was always infinite in size even at the moment of the Big Bang. So there was no point when the universe was the size of the Solar System.
Jul
15
comment Absorption cross section and absorption coefficient
@jokersobak: if you use the number density of molecules of CO$_2$ you get the scattering cross section for a CO$_2$ molecule. If you use the number density of atoms you get the cross section for an atom. So it depends on what cross section you want to calculate.
Jul
15
awarded  Enlightened
Jul
15
awarded  kinematics
Jul
14
awarded  Nice Answer
Jul
14
comment BBC radiation: What is it?
Can you provide a link or links to examples of these acronyms
Jul
14
comment Would computers accelerated to high speeds compute “faster” from our point of view?
For any object moving relative to you time moves slower not faster. The computer you send off into space would do the calculation slower than the one on your desk. For more info search this site for time dilation
Jul
14
reviewed Close Electrical force between two objects
Jul
14
reviewed Close Day/night cycle in Greenland