100,741 reputation
4146258
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 7 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.


Mar
10
comment Density as a function of Temperature?
For what system? For an ideal gas you have the equation of state $PV = nRT$ so the molar density is $n/V = P/RT$. For other systems there will be corresponding but more complicated expressions.
Mar
10
comment Quarks are now considered to be fundamentals, but so were atoms some time ago. So the way we see is only limited by our technological advances?
have a read through en.wikipedia.org/wiki/Preon. As it stands your question is a bit too broad to be usefully answered here, but if you have any specific questions arising from reading the preon article please ask them.
Mar
10
comment Is it possible that the universe in its entirety is discrete rather than continuous?
possible duplicate of Does the Planck scale imply that spacetime is discrete?
Mar
10
comment Do neutron stars reflect light?
Thanks. The link must have been broken when the Astronomy SE closed then reopened as a beta.
Mar
8
comment Entropic force in polymers
Yes. The point is that you are stretching the rubber and therefore changing the conformation of all the polymers in it. You aren't stretching the string, you are just rearranging it.
Mar
8
comment Where is the Higgs Field?
@user3394040: your statement implies water is caused by fish
Mar
8
comment Initial conditions of the origin of the universe
possible duplicate of Before the Big Bang
Mar
8
comment Entropic force in polymers
Yes, but you aren't changing the entropy of the molecules in the string. You're only changing the entropy of the string itself.
Mar
8
comment Entropic force in polymers
Entropy is a molar quantity i.e. the total entropy is proportional to the number of molecules present. In a piece of rubber there are an enormous number of molecules, but with a piece of string you have just one molecule of string. The entropy change when you straighten the string is too small to produce a detectable force - if you had $6.023 \times 10^{23}$ pieces of string it might be a different matter.
Mar
7
comment Why am I wrong about how to view gauge theory?
@gatsu: no, that's due to a global gauge symmetry
Mar
7
comment Rolling disk in inclined plane and flat plane?
possible duplicate of Static as opposed to Kinetic Friction in Rolling Motion
Mar
7
comment Confused about length contraction and aberration
possible duplicate of What does a sphere moving close to the speed of light look like?
Mar
7
comment Math formula for crystal glass resonance
Your question is a duplicate, though I have to admit the previous question hasn't got any really good answers. You might be interested in this paper on singing wineglasses. There isn't a simple formula to predict the resonant frequency.
Mar
7
comment Math formula for crystal glass resonance
possible duplicate of Science behind the singing wine glass
Mar
7
comment Naive visualization of space-time curvature
Full marks for effort :-) However this is still far from a non-nerds explanation of why we see geodesics as curved. Maybe an intuitive explanation (intuitive for non-nerds that is) is just not possible.
Mar
7
comment How long does it take for a black hole to form?
@jaskey13: No (I seem to starting all my answers with "No" :-). The whole point of infinity is you can never reach it. When we say the event horizon takes an infinite time to form we mean there will never be enough time to observe it.
Mar
7
comment Why am I wrong about how to view gauge theory?
Well, we have to impose the symmetry because it works. To pretend it isn't there, or is a coincidence, as in your option 2 seems unnecessarily obstinate. I don't think the choice you present is appropriate. The choice is just to say either (1) we don't know why the symmetries are there or (2) to go looking for reasons why the symmetries are there. Obviously physicists prefer option (2).
Mar
7
comment How long does it take for a black hole to form?
@jaskey13: No. For an external observer the event horizon never forms. The best we see is an apparent horizon.
Mar
7
comment Why am I wrong about how to view gauge theory?
The problem is that there is no reason or justification for imposing the U(1) local gauge symmetry. It would be nice if there was some fundamental reason why a U(1) gauge symmetry had to exist. For example various models of string compactification generate these local symmetries, though none of these models are a full description of the Standard model. Still, this is an example of what we mean by a hidden (i.e. hidden at Standard Model energies) degree of freedom.
Mar
7
comment How long does it take for a black hole to form?
@jaskey13: No, we have theories that describe the universe (the bits we can see) very well. But those theories predict some parts of the universe are inherently unobservable. That doesn't mean we've stopped trying. For example some of the firewell theories predict spacetime simply ends at an event horizon.