136,117 reputation
9228378
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
20
comment Moving Around Space Without Propellant
See my answer to Intuition as to why the orientation (of a 3D object) is not a conserved quantity? for a proof that the position of the centre of mass of an isolated system cannot change.
May
20
comment Luminous flux density by using Lambert's cosine formula
Hi Harish and welcome to the Physics SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems.
May
20
comment what size puddle does a gallon of water produce?
@jameslarge: in that case the contact angle will be approximately $\pi$ so $\cos\theta \approx -1$. You just need to Google for the surface tension and density of coffee (the density will be very close to the density of water).
May
20
comment String wrapping around a motionless cylinder
Hi and welcome to the Physics SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems.
May
20
comment A Relativity question about radial acceleration?
Hi Sophie. The question I've linked is calculating the weight, but it calculates the norm of the 4-acceleration as an intermediate step.
May
20
comment Free-falling from rest into a Kerr black hole
@PeterShor: forgot to divide by 2? :-)
May
20
comment Does the Holographic Principle explain Dark Energy?
I'm voting to close this question as off-topic because it is founded upon a misapprehension
May
20
comment Compare phase spectrum and magnitude spectrum
That's an awfully broad question. Can you be a bit more precise about what you want to know?
May
20
comment Stern-Gerlach experiment need for collimated beam?
Any angular spread in your beam will blur out the spots and maybe even make them merge so they can't be seen.
May
20
comment Electric Flux through cube
I'd be inclined to consider the flux through the eight cubes surrounding your point charge then divide by eight.
May
20
comment Does the Holographic Principle explain Dark Energy?
Hi Dennis. As it stands I don't think your question means anything. On the scale of the universe holography normally refers to the AdS/CFT idea, and in this case the universe is a 4D boundary to a 5D bulk. The origin of the cosmological constant in AdS/CFT is still an open question.
May
20
comment Electric Flux through cube
Hi Ashu and welcome to the Physics SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems.
May
20
comment Why bodies lose heat faster in water than in air?
@whistles: Yes, I think that's a reasonable way to put it.
May
20
comment Free-falling from rest into a Kerr black hole
@PeterShor: no, the singularity is always at $r < r_s$. Can you flesh out your comment to show what calculation you're referring to e.g. which equation?
May
20
comment How come the concept of an instant of time is such a controversial topic with relativity, but with entanglement it's completely acceptable?
@YogiDMT: Your first question: in an absolute instant of time wouldn't everything be stationary relative to each other? is (I think) just another varient on Zeno's paradox and has already been discussed to death hereabouts. I'm not sure what your second question: why cant we say that the universe exists in a definitive state at any given point in time? is asking.
May
19
comment Does General Relativity imply loops in space?
@Golz: in GR you cannot make a unique split between time and space. You might say that a planet has returned to the same point in space (at a different time) therefore it has moved in a loop. However other observers would disagree. Even the simple case of an observer moving relative to you would claim the planet moves in a helix not a loop.
May
19
comment Why bodies lose heat faster in water than in air?
@whistles: yes, but how much heat those currents can carry away depends in part on the specific heat. If the specific heat is very low the current warms rapidly to your body temperature without removing much heat.
May
19
comment Why does a heavier mass of the higgs boson support a theory of a multiverse? and what spiritual impications will this have?
The simplest supersymmetric extensions of the Standard Model predict a Higgs significantly lighter than 125GeV. I'm not sure there is a simple way of explaining this. You'd need some appreciation of how the calculation works, and this is far beyond the layman (far beyond many physicists actually :-). I'm not sure that the observed Higgs mass suggests a multiverse. It's borderline for the Standard Model vacuum remaining stable all the way up to the Planck energy, but I'm not sure I see the connection with multiverses.
May
19
comment surface tension force problem
The obvious Google search has as it's very top hit this Wikipedia page, with this section describing exactly the calculation in your question. One more cynical than I might think you haven't tried very hard before asking someone else to do your homework.
May
19
comment ionising atom(s) with gamma rays
@JonCuster: Hmm. I've always regarded Compton scattering as re-emission of a new lower energy photon. I see your point though.