136,377 reputation
9229379
bio website ratsauce.co.uk
location Chester, United Kingdom
age 54
visits member for 4 years, 4 months
seen 1 hour 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.


May
19
comment How black hole lose mass?
Have a look at the duplicate I've suggested. If if you insist on the virtual particle metaphor then the black hole swallows particles with a negative energy, so its total energy decreases. The escaping positive energy particles make up the radiation.
May
18
comment Why do virtual particles form at black hole horizon?
Also related: Are vacuum fluctuations really happening all the time?
May
18
comment Are magnetism and electricity the same thing?
Hi Sohaib. At the moment your question is too broad to be usefully answered. Can you make it more precise? For example can you pick a particular example of the difference between the two that is puzzling you.
May
18
comment Why do virtual particles form at black hole horizon?
Hawking radiation is not really due to pairs of virtual particles. See for example Black holes and positive/negative-energy particles and Why doesn't Hawking radiation cancel itself out?. In fact virtual particles don't exist in the sense most people think. See Matt Strassler's article.
May
17
comment Momentum conservation in FRW spacetime
I'm guessing this is related to Valter's answer to your previous question, but it seems to me that Valter's answer answers most if not all of this question too. Can you clarify what you're asking that isn't covered by the previous question?
May
17
comment Polarization and Reflection
Also Calculate the polarization vector on reflection or refraction from a dielectric interface, and probably other questions as well.
May
17
comment Polarization and Reflection
possible duplicate of Polarization of light upon reflection
May
17
comment Correlation energy - is it the difference between the Hartree-Fock energy and exact energy, or Hartree-Fock PE and exact PE?
@user1126849: Yes, it does refer to the difference in total energy. However bear in mind that the total energies have a global gauge symmetry so what exactly they mean is debatable. When we're doing an HF/SCF calculation we're almost always calculating the difference between two systems e.g. comparing the energy of a molecule with the energy of isolated atoms. We're normally also calculating the energy at absolute zero so no rotational or vibrational modes are excited.
May
17
comment How can we calculate the standard deviation of multiple values with different uncertainties each?
possible duplicate of How to combine measurement error with statistic error
May
17
comment “Derivation” of Minkowski metric?
Aha, yes, good point! I now wish I had included that in my answer :-)
May
16
comment Momentum and spacetime
@StuartW: yes, except that the temporal comonent increases with velocity. That's because $|v|^2 = -c^2v_t^2 + v_x^2 + v_y^2 + v_z^2$. Note the minus sign. This comes from $|v|^2 = -g_{\alpha\beta}v^\alpha v^\beta$.
May
16
comment If proton spin emergence from quarks and gluons is mysterious, why is silver atom spin not?
@TerryBollinger: We think of electrons in atoms as falling into pairs in atomic orbitals. However this is an approximation that ignores electron correlation. The correlation mixes up the atomic orbitals, however in atoms this effect is relatively small because the electrons are relatively far apart. In dense strongly interacting systems the correlations are so strong there are no separate orbitals that you can populate in pairs. You cannot just pair up the particles and see what's left.
May
15
comment If radiation didn't exist, would everything live longer?
I'm voting to close this question as off-topic because it's about biology not physics
May
15
comment a question about work needed to move a charge towards another one
The question I've linked refers to a gravitational potential not an electrostatic potential, but it's still basically the same question with the same answer.
May
15
comment Intuitive understanding of the elements in the stress-energy tensor
@Calmarius: oops, yes. I'm too used to working in the rest frame where $\gamma$ is one :-)
May
15
comment Fibre bundles and space-time
I've included an image of the relevant figure. Apologies for the poor quality but the book is a bugger to scan because it's so thick!
May
14
comment What is the pressure at the center of the Earth? (Or a neutron star)
No, the pressure is dominated by the matter far from the centre where the gravity is not zero.
May
14
comment Polarization in LCDs why the light need to be polorized twice?
I'm voting to close this question as off-topic because is shows insufficient prior research.
May
14
comment Polarization in LCDs why the light need to be polorized twice?
Have you done a basic Google search? The Wikipedia article on LCD displays seems to answer all your questions.
May
14
comment Using the uncertainty principle to estimate the ground state energy of hydrogen
Thanks gonenc, I was curious to see how close to $\hbar/2$ the hydrogen atom got. As soon as the question is eligable for a bounty I'll post one and award it to you.