meta user
network profile
| bio | website | |
|---|---|---|
| location | United Kingdom | |
| age | ||
| visits | member for | 2 years, 4 months |
| seen | May 19 at 17:20 | |
| stats | profile views | 325 |
Have D.Phil in Mathematical Physics from 25 years ago.
I also like to work in the mathematical foundations of Computer Science and AI. I would be interested to find a merger of work in all three areas....
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Jan 30 |
comment |
From differentials to differential equations @Guido, Actually your discrete problem looks like a kind of "one way diffusion". I wonder whether modelling it on a Cellular Automata framework would be possible? |
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Jan 30 |
answered | From differentials to differential equations |
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Jan 28 |
comment |
Deriving group velocity I have extended this answer to cover some background to the calculation. |
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Jan 28 |
revised |
Deriving group velocity added 1389 characters in body |
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Jan 28 |
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Does the Banach-Tarski paradox contradict our understanding of nature? Ron, Does not the Solovay model require assuming the existence of an Inaccessible Cardinal? If (mathematical) physics is to be described better with Solovay, then do you have an interpretation for this Inaccessible object? |
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Jan 28 |
answered | Deriving group velocity |
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Jan 19 |
awarded | Yearling |
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Jan 8 |
awarded | Nice Question |
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Jun 8 |
awarded | Constituent |
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Jun 8 |
awarded | Caucus |
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Jan 19 |
awarded | Yearling |
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Apr 12 |
comment |
Can “big rip” rip apart an atomic nucleus? So to summarise this conclusion in terms of the actual question:(1) The Big Rip will happen (up to atom scale at least);(2) Cosmological isotropy assumptions dont make any difference - the basic theory is sound;(3) Nuclear Rip may or may not happen. Is this the "correct picture"? |
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Apr 12 |
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Investigating damped Harmonic Motion in a Spring? These two questions are obviously linked: physics.stackexchange.com/questions/8402/… |
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Apr 12 |
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Reactionless Drives "photons have no mass" - some formulae: photon frequency $\omega$, Energy = $\hbar \omega$= pc. So momentum p=$\hbar \omega/c$. One could even associate the "mass" m=p/c = $\hbar \omega/c^2$. Rest mass is zero. |
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Apr 12 |
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Is there an energy density limit in GR? Here is a scientific discussion of density with SI units and some actual values: en.wikipedia.org/wiki/Density. So the claim that you appear to make that this concept (density - mass density $\rho$) has no invariant or physical or laboratory meaning doesnt make sense to me. |
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Apr 12 |
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What am I doing wrong when I try to make this unit conversion? @David, I agree with the last sentence. The question (which I cannot answer) is whether George just took the results from figure 3 (presented as they were against actual ground temperatures of around 15C) as the basis of doing the conversion. |
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Apr 12 |
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Is there an energy density limit in GR? Furthermore it was not John, but you who introduced $T^{00}$ into this question - only to prove that $T^{00}$ was coordinate dependendent and non-invariant. Great! So the original question still stands unanswered. |
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Apr 12 |
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Is there an energy density limit in GR? @Edward, I did not mention coordinate systems, because I agree they are arbitrary too. The Lab will have a fixed length say. A tensor-coordinate question here is about the range of representations of that length. A physical question would be "can an an object of unlimited length enter and be placed in the lab"? I agree that there are at least two types of questions around here: ones on tensor-coordinate properties, and ones on actual physical properties. The challenge of this question has been to address the phyisical question: I dont think that it is a tutorial on tensors. |
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Apr 11 |
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Is there an energy density limit in GR? This latter question isnt my question; it is the original question: Is there an average energy density limit over this volume beyond which a blackhole will always form? I am just emphasising physical to get away from references to tensors, which has been distracting. |
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Apr 11 |
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Is there an energy density limit in GR? @Edward, the physical value of a quantity is its measurement in a lab. So physical mass density would be its measurement in a lab. Use E=mc^2 to convert to physical energy density measured (E=m if c=1). The question then is whether this can become arbitrarily high without a BH forming (in the Lab). |
