129,824 reputation
8215355
bio website ratsauce.co.uk
location Chester, United Kingdom
age 54
visits member for 4 years, 2 months
seen 43 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.


Mar
19
comment Why is momentum conserved in inelastic collisions? How is it related to momentum-impulse theory?
@mariam.. the argument I've made above doesn't depend on whether the collision is elastic or inelastic. In all cases the forces on the two bodies are equal and opposite so the momentum changes must be equal and opposite.
Mar
18
comment Limitations of Redlich-Kwong equation of state
@jakemcgregor: but do feel free to click the tick symbol to mark the question as answered if you're happy with my suggestion.
Mar
18
comment Limitations of Redlich-Kwong equation of state
@jakemcgregor: discussing code is frowned upon hereabouts as it should really be done on the Scientific Computing SE. I only answered because I was curious about the problem. Please don't post any more code in your question.
Mar
18
comment Limitations of Redlich-Kwong equation of state
@jakemcgregor: the binary chop is an elementary technique I'm afraid. I learned it at my mother's knee (seriously: she was a scientist! :-). If you're going to be doing any scientific computing then you need to read up on basic numerical techniques. You get the scrolling code by indenting by four spaces.
Mar
18
comment Derivation of natural frequency of free vibration equation
What is $m_s$? The mass of the string? We need to see a diagram showing what is oscillating to have any chance of answering this.
Mar
17
comment Water Waves in the Wake of a Boat
Hi John. I've added a diagram that I think represents what you're asking about. I agree that the Youtube video does look as if the wake is curved. If I've got it wrong or you don't like the diagram shout and I'll delete it.
Mar
17
comment Complex numbers in Circuits
This is really too broad a question to be usefully answered here. You need to go off and Google for phasor. The tl;dr answer is that a complex number allows you to simultaneously represent the amplitude and the phase of an electric signal.
Mar
17
comment Thought experiment on graviton breaking the speed of light
Why would two entangled gravitons be different to two entangled photons? Since the latter doesn't involve superluminal communication, why should the former?
Mar
17
comment Can the Sun capture dark matter gravitationally?
I suppose some dark matter will slingshot around the planets and reduce its velocity that way.
Mar
17
comment Will a hot object have more gravity than a cold object?
@ChrisWhite: a real object is neither time independant nor the only object in the universe
Mar
17
comment Will a hot object have more gravity than a cold object?
Related, though surprisingly I can't find an exact duplicate, Will heating up an object increase its mass? and the links therein.
Mar
17
comment Gödel's solutions to Einstein's relativity equations and their consequences
@Hypnosifl: I mean I can't imagine any mechanism that could produce an infinite rotating fluid. An infinite expanding fluid is easy because expansion is a local phenomenon. But rotation is not.
Mar
17
comment Is dark matter really present around the sun?
@RobJeffries: if the dark matter starts at an (effectively) infinite distance from the Sun then unless it can shed kinetic energy it will execute a parabolic/hyperbolic orbit around the Sun and finish an infinite distance away from the Sun. It's the shedding kinetic energy that's difficult to achieve for weakly interacting matter.
Mar
16
comment Force between charges when there's a slab of dielectric between them
possible duplicate of Forces between charged particle
Mar
16
comment Gödel's solutions to Einstein's relativity equations and their consequences
@Hypnosifl: I can't think of a way to actually construct a Gödel universe. It is not just a case of taking our universe and spinning it around some arbitrarily chosen axis.
Mar
16
comment Gödel's solutions to Einstein's relativity equations and their consequences
@Sean: hmm, well, possibly. The thing is that the Gödel universe is not just what you get if you take our universe and spin it on some axis. The Gödel universe is homogeneous in the sense that wherever you are in the universe you will observe it to be rotating about your position. There is no special point in the universe that is the axis of rotation. Whether this is actually physically possible is not at all clear to me.
Mar
16
comment wavelike properties of massive objects
See also Why doesn't a marble rolling on a table ever reflect back at the edge?. I'm sure there are other related questions, but these are the two I remember.
Mar
16
comment What is time, with respect to universe?
Related, and possibly a duplicate: Is there a proof of existence of time?
Mar
16
comment Will an object always fall at an infinite speed in a black hole?
@Danu: yes, I agree. I've expanded my answer to explain where we get the formulae from if not exactly how they're derived.
Mar
16
comment Interpretation of a singular metric
@Oscar: that suggests my final comment is true i.e. that the Big Bang is not part of the manifold and therefore the question "did the Big Bang happen at a point" is meaningless.