109,131 reputation
4166295
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 9 months
seen 9 hours 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.


Oct
15
comment Are there any radiation emitted from the cameras?
All electrical equipment radiates some electromagnetic waves. Can you be a bit more precise about what you think a video camera might be radiating and why?
Oct
15
comment Normalization of a wavefunction that's superposition of two unknown energy eigenfunctions
CuriousOne's point is that $<u_i|u_j> = 0$ and $<u_i|u_i> = 1$, so your integral is simply $25A^2$.
Oct
15
comment How can we assume that reaching the speed of light slows down time?
Though the question is phrased in an unclear way I'm guessing it's asking about the physical reality of time dilation. In that case there are several questions that address this issue.
Oct
15
comment What does the “size of the universe” mean if the Universe is infinite?
This question appears to be off-topic because it is asking about the meaning of a commonly misused phrase.
Oct
15
comment What does the “size of the universe” mean if the Universe is infinite?
The phrase size of the universe is used in two ways: (1) to mean the size of the currently observable universe, or (2) to indicate that the speaker has no understanding of general relativity.
Oct
15
comment Why does a dish cloth absorb liquid better when it is damp?
@awendt: PES is probably polyester, and PP is polypropylene. These are both quite hydrophic and do not interact with water, so the behaviour is being dominated by the viscose component.
Oct
14
comment Why does a dish cloth absorb liquid better when it is damp?
@Floris: indeed. Physics is more fun though - would you rather answer questions on black holes or doing the washing up? :-)
Oct
14
comment Is ice a type of glass?
@fullmooninu: impurities in the water tend to act as nuclei and trigger crystallisation. Eliminating impurities retards crystallisation and makes it easier (though it's still hard!) to make an amorphous phase.
Oct
14
comment Why is it legitimate to only observe motion, but call it time, such that concepts like “the relativity of simultaneity” are seen as possibly genuine?
I'm not convinced that's a duplicate, at least partly because I'm not sure the OP is clear what they're asking.
Oct
14
comment Why wouldn't a room temperature superconductor violate the laws of physics?
The downvote is harsh - not all of us are hard core physics nerds.
Oct
14
comment What is the difference between the compact U(1) group and non-compact U(1) group?
See What is the meaning of non-compactness in the context of U(1) in gauge theories?. Assuming I understand Luboš correctly the non-compact theory allows continuous, i.e. not quantised, charges.
Oct
13
comment Speed, Velocity and Acceleration
$v^2 = u^2 + 2as$ possibly?
Oct
13
comment What are hadronic uncertainties?
I'm not sure that the phrase has a precisely defined meaning. I've seen it used where QCD calculations are difficult, e.g. because the system is strongly interacting, so the properties of the system can't be calculated with much accuracy.
Oct
13
comment Why can't de Broglie waves be electromagnetic in nature?
Yes ${}{}{}{}{}{}$
Oct
13
comment Why can't de Broglie waves be electromagnetic in nature?
Doesn't this prove that matter waves are em waves? - no, it only proves that photon waves are light waves. Why should this apply to anything other than photons?
Oct
13
comment Why in PN junctions the octet rule is dominating electrostatic repulsion?
@Sparkler: You say electrons from N diffuse towards P and complete an octet but this is not true. The electrons in the $p$ type semiconductor valence band are delocalised so any particular electron is not associated with any particular atom. The electrons are not grouped into octets around a particular silcon atom. Similarly any charges created by movement of electrons are spread out over the whole system.
Oct
13
comment Plank stopping time (Continuation and Physical meaning)
The system only obeys the harmonic oscillator equation while some of the plank remains on the smooth surface. Once the plank has completely crossed onto the rough side the equation of motion changes to $\ddot{x} = -\mu mg$ i.e. the dceleration is constant. There will be a critical value of $v_0$ above which the plank crosses completely onto the rough surface. That's whay as you take $v_0 \rightarrow \infty$ your SMO derived equation of motion gives silly answers.
Oct
12
comment Why we take two focuses in concave and convex lenses before the lens and behind the lens
I'm still not absolutely sure what you're asking, but I think it's because concave lenses always produce a virtual image, and (as drawn) a virtual image is always to the left of the lens.
Oct
12
comment Using Cosine Law to Find Net Electric Force on Charge Always Results in Positive Number?
Can you edit your question to show exactly what calculation you are doing when you use the cosine law.
Oct
11
comment Can the diffraction/interference pattern behind the slit (double slit) be calculated with Feynman path integrals (QED)?
See also Young's Double Slit Experiment in Quantum Field Theory