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ajb

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Everything posted by ajb

  1. Thats my point exactly Atheist, the equations are just Gobble-Dee-Gook. I am sure you have "good intentions" elas, but without careful explanation of where these equations come from (they may be empirical of course) and the units involved no one will be able to follow your logic. I am thinking you don't mean "force" but work done, by something or on something. Work has the same units as energy.
  2. Majid does quantum groups and related stuff if I remember rightly. I know about loop quantum gravity, but it is not my research topic. My understanding (not being an expert) is that including matter was an issue. My supervisors are Hovik Khudaverdyan and Ted Voronov. I would call their work supermathematics and supergeometry. Recient work of interest has been on odd-symplectic geometry and odd Laplacians. These things are all connected with the antifield formulism. Topological field theory was something that we might look at also. Not sure exactly what, but probabily something to do with exactly solvable models and gravity in 3 and 2 dimensions. I expect my research will be something related to this.
  3. I have come across Freidel, but i have never actually read any of his papers. I take it you are talking about the noncommutative geometry workshop at the Newton Institute. I won't be going, but i do know some of the participants. Also as a side note, my supervisor did his PhD under A. Schwarz, who is one of the invited speakers.
  4. The title of my PhD topic is "geometric constructions in quantum field theory". I was told to go away and read up on fibre bundles and gauge theory, which I have done now, up to a few proofs etc. So thats why I want to be VERY clear on trivial bundles etc. We are also interested in the BRST symmetries, these are a clever way of dealing with gauge theories by promoting the gauge parameter to be a dynamical anticommuting field. It is particulary useful when dealing with gauge fixed actions and quantum gauge theory. There is a lot of (super)geometry behind this which is of interest.
  5. you wrote r = F/M so provided I am reading your equation right, the units are [meters] = [Newtons]/[kilograms] = [meters][kilograms][seconds]^{-2}[Kilograms]^{-1} = [meters][seconds]^{-2} ??????? which is just wrong. Unless your F is not a force, but some other constant with units [meters][kilogram]^{-1}. Im not sure what that would physically correspond to.
  6. Thanks Martin, I will have a look at the PDF you suggest. I know how to prove it using the homoptopy axiom, it is quite simple really. I have no idea how you would prove the axiom. AJB
  7. With the USA I keep thinking about CSI, Law and Order, NCIS, things like that. So america is full of pedophiles, murderers, gangsters and gun carrying nuts! It can't be true? AJB
  8. I was thinking about R^n as I had manifolds as the base space in mind. Once I assume the homoptopy it is easy to prove. Basically, it allows you to identify a bundle over a contractable space with a bundle over a point, which is trivial. I will look at the website you suggest Matt. Cheers
  9. Rocket man is talking about the Athena project at Cern. http://athena.web.cern.ch/athena/ All the theory points to the fact that matter and anti-matter behave the same. This is due to some deep theorems of quantum field theory like the CPT theorem. It is a good test of quantum field theory and the standard model. However, these ideas need to be tested and so Athena was born. On a personal note, Mike Charlton is head of the physics department at the university of swansea. I did my undergrad studies at swansea. I think he joined in my final year.
  10. I am not convinced by the basic formula you wrote down. Check the units carefully. The following site will helpyou http://units.nist.gov/cuu/Units/units.html
  11. Does any one know who to prove that fibre bundles over contractible spaces are trivial? One method woud be to use the Homoptopy axion for bundles. Do you know how easy that is to prove? I was wondering if there is a more geometric method of proving it. It seems obvious that on say R^n we could use the global coordinates of R^n as a local trivialisation. Thus only one trivialisation would be needed and hence we have a trivial bundle. Can this be proved? Any ideas and references welcome. Cheers AJB:confused:
  12. It is not something I have thought much about. Everett to me seems a "waste of space", the number of so called parallel universes would be huge. The Copenhagen interpretation relies on the obsever to much, it is difficult to think about quantum mechanics of the whole universe in this way. So I really don't know what one to vote for, both have pros and cons. Yet again maybe the answer is something else.... I will vote for the Copenhagen interpretaion. I think it is the most useful when dealing with most quantum systems in which you can define a classical observer.
  13. To understand something I think you should have both a "mental picture" and be able to understand the mathematics and compute things. Without the mathematical framework, you cannot say that you understand something. Most crackpots and people with "new theories" simply do not understand the mathematics of current thinking and hence dispute them. But at the end of the day, physics (to me at least) is an attempt to describe the natural world using mathematical models. Some of these models are hard to describe, such as quantum mechanics.
  14. I have also been able to make it compatable with the add-on "VariationalMethods" by adding a few more lines of code. By doing so, I have been able to get the equations of motion for (N=2) one dimensional supersymmetric quantum mechanics. I am sure more complex systems could be studied, of personal interest are BRST symmetries in (pseudo)clasical mechanics.
  15. If your mathematics are correct, then I think you have interpreted it wrong. As far as the mass m1 is concerned, the lower mass m2 behaves as if it were part of the larger mass M. So I don't see why the velocites would be the same anyway. The equivalence principle states 1) Inertial Mass = Gravitational mass. 2) Space-Time is locally flat (i.e. a manifold). 3) The laws of physics reduce locally to that of special relativity. there are weaker versions, where 3 is removed. So far the equivalence principle has passed every test thrown at it.
  16. I have written a package for Mathematica that alters the noncommutative multiply to take into account Grassmann parity. I have also written some basic functions that may be of use. It can expand expressions over the noncommutative multiply, collect terms involving Grasmann odd elements, it can give you the even and odd parts of a superfunction, it can give you the body and soul of a superfunction. I have also defined differentiation of odd variables from the left. At some point I would like to extend the package to include supermatrices and calculate the supertrace and Berezinian. Is there anyone on here that would like to test the package for me?
  17. Bignose is right. One appliction of the gamma function is in the path integral formulation of quantum field theory. I am sure there are many many other situations in which the gamma function comes up.
  18. The Euler Gamma function can be thought of as the extension of the factorial function to complex arguments. The gamma function crops up in many different areas of mathematics. For example, the gamma function arises when calculating the volume of a n-sphere. Have a look here for more details http://mathworld.wolfram.com/GammaFunction.html
  19. The answer is no. In the early universe equal amounts of matter and anti-matter were present. It is thought that there is some asymmetry in the interactions so that after all the anti-matter has combined with the matter there is some matter left. As far as I know there is no established theory which explains this asymmetry. However, assuming that this mechanism does exist every one billion and one protons would have to annihilate with one billion anti-protons to produce one proton to one billion photons. If you want to know more you should look up baryogenesis in a cosmology book. I recommend the book by Andrew Liddle "An Introduction to Modern Cosmology".
  20. I am studying toward a PhD in mathematical physics. My interestes are in geometry and topolgy in physics; 1) Geometry and quantum field theory 2) BRST symmetries and the antibracket 3) Supermathematics Severian, what areas of theoretical particle physics are you working on?
  21. I have spoken to several scientists about this in the past. Some think it is very important to have an interpretation and other not so important. One problem with interpretations is that they can be misleaing. This is often the case in popular science. Personally, I think that an interpretation is important and useful, but no substitute for mathematics.
  22. I don't think you will be able to do any original work. Do you know about differential equations and how to solve them numerically? If so, a nice project could be to solve the time-independant Schrodinger equation for some well-known potentials.
  23. By viewpoint do you really mean a physical interpretation of a theory? If this is so, I am unsure if it is important. Clearly, having some kind of interpretation if useful for explaining results and calculations to a wider audience or to present hand-waving arguments. However, it could never be a substitue for hard calculations. That said some physical insight can be very useful when doing mathematics.
  24. Physics cannot put and answer to "why", but tells you "how". Gravity is observed in nature, falling apples, the motion of planets etc.. What coures gravity is mass/energy. It plays the same role as electric charge does in electrostatics. If things have no net charge then their is no electric force between them. The same is true of gravity, no mass or energy then no gravitational force. Or are you really asking "why gravity is not just electromagnetic in nature"?
  25. In physics and mathematics we have pre-print servers. Most of the articles posted are then summitted to journals, but now some people only post online. I think it is a great thing, as well as being very easy to find papers it allows everyone to get access to scientific results for free. http://xxx.soton.ac.uk/ http://www-spires.dur.ac.uk/spires/hep/ http://cds.cern.ch/ http://www.ma.utexas.edu/mp_arc/ http://www.ictp.trieste.it/~pub_off/ http://www.sm.luth.se/~norbert/home_journal/electronic/elect.html
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