112,667 reputation
5171301
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 10 months
seen 5 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.


Nov
10
comment Why doesn't frequency change?
possible duplicate of Why frequency doesn't change during refraction?
Nov
10
comment If the Universe reaches the state of heat death scenario, could it produce a new Big Bang?
and the universe no longer expands - assuming dark energy is what we think it is the universe will continue expanding forever. What you describe is basically Penrose's idea of conformal cyclic cosmology. You might want to read up on this and maybe post a more specific question.
Nov
10
comment Time dilation in outer space vs in a gravitational field?
Hi Ranjith. This site isn't well suited to broad questions like yours. You might be interested to look around this site for related questions, for example Is gravitational time dilation different from other forms of time dilation? is related.
Nov
10
comment Is there a physical reason for colors to be located in a very narrow band of the EM spectrum?
@AntonTykhyy: snakes use continuous spectrum absorption as a primitive form of vision, and that's why I mentioned it. I agree it's not useful for anything we would normally describe as an eye.
Nov
10
comment Can the half-life of rubidium 87 be theoretically estimated?
If the system is amenable to a perturbative treatment than yes in principle. In practice I suspect the problem is too hard.
Nov
9
comment How much impact would it make in science if the speed of light is discovered to be variable?
This is too broad a question. Have a read throught the Wikipedia article on VSL theories and google variable speed of light cosmology then come back to us if you have a specific question.
Nov
9
comment Relativity and acceleration-acceleration
@brightmagus: no. In one frame an accelerometer will show a non-zero reading while in the other frame it will show a zero reading. There is a fundamental asymmetry.
Nov
9
comment Death by entropy
Your body isn't a closed system. Humans (all living organisms really) keep their own entropy roughly constant by increasing the entropy of the regions of the universe around them.
Nov
9
comment Relativity and acceleration-acceleration
@brightmagus: no. There is no way to determine the velocity of an accelerating observer, only the relative velocity compared to another observer. However an accelerating observer can determine their acceleration by a local measurement (e.g. using an accelerometer) without reference to any other frame. Note FenderLesPaul's comment above, which I agree with.
Nov
9
comment Why does water rise through a hole in ice
@kaka: capillary action only has much effect in very small holes i.e. up to a few millimetres in diameter. Assuming we're talking about the sort of holes you could catch fish through there would be no significant contribution from capillary action. If you were fishing through the hole would that be carpillary action? :-)
Nov
8
comment Why do electrons eject only if the frequency of incident ray is greater than the threshold frequency?
@Vinayak: your statement the energy is given to a large area is not true. The whole point of the experiment is that light is exchanged between the EM wave and the metal in quanta. Quanta called "photons". The exchange of energy is localised, and a low intensity just means fewer photons per second.
Nov
8
comment What is the link between observation wavelength and spatial resolution of an instrument?
Nicholas, your question is too broad to be usefully answered here. It's more like an essay question you'd get in an exam.
Nov
7
comment Beam of electromagnetic wave, with radius of 3cm or less
@CarlWitthoft: thanks, good point!
Nov
7
comment Can we get the refractive index of a prism by using white light?
@Floris: this is obviously more of an exercise for the student that a real measurement. I can rarely resist the temptation to prod students into looking into the subject that bit more deeply :-)
Nov
7
comment Why does water rise through a hole in ice
@Floris: snap :-)
Nov
7
comment Why does water rise through a hole in ice
Rob, can you clarify exactly what happens to the water. Does it (a) rise flush with the top of the ice, (b) rise to a bit below the top of the ice, (c) overflow the top of the ice, or (d) something else?
Nov
7
comment Moving From Schwarzchild Geodesic Equations to Equations of Motion
@Mr.Frobenius: $\tau$ can be any affine parameter that parameterises the curve. For massive particles we normally take it to be the proper time i.e. the time shown on a clock carried by the freely falling observer. However it need not have a physical significance. For example the same equation applies to light, but light has no proper time so in this case $\tau$ has no physical significance.
Nov
7
comment Why does water rise through a hole in ice
@Floris: you have assumed Rob means the water rose to lie flush with the surface of the ice. My own interpretation of the question was why doesn't the water remain flush with the bottom of the ice, i.e. why does it rise up in the drilled hole at all, and I'm assuming the 7cm different between the top of the ice and the water level is insignificant. Really you need to ask Rob to clarify what he means. As it stands both your and my answers are accurate descriptions of the physics that is potentially involved. Whose interpretation is correct you'd have to ask Rob.
Nov
7
comment What is the physical intuition behind the fact that 'energy is not continuous'?
Holger, your answer confuses virtual and real photons and this is not helpful. The interaction between electrons happens by the exchange of virtual photons.
Nov
7
comment Gravitational work
The change in gravitational potential energy between two points is independant of the path between them, but this does not mean the net work must be zero. For example your object starts with no kinetic energy but ends up with non-zero kinetic energy (well, until the contact with the ground stops it). There may also have been work done on internal degrees of freedom in the object. For us to answer your question you'll need to be a lot more specific about precisely what you're asking.