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the argument you have stated is against accelerating a massive particle to the speed of light. This means that you cannot have "faster than light" time travel.

It is however, not an argument against time travel in general.

Glad to be of help.

In fact I did a module on modern physics as part of my MPhys which included time-machines. I wonder how may university courses can boast that?

What I would say is that it is not obvious that time travel is not permitted within the frame work of general relativity.

Generally, when ever we have a rotating space-time the angular and temporal coordinates get mixed up we have a time-machine. Due to this mixing it is posible to find paths for which time becomes periodic. These are the so called Closed Timelike Curves, or CTCs.

This is how Malletts time-machine works. The rotating cicular beam of light produces the phenomena of inertial frame dragging. This courses the space-time to rotate and we have a time-machine!

Similar time-machines have been suggested involving rotating cylinders of dust, rotating black-holes, spinning cosmic strings, or even a rotating universe.

The other kind of time-machine involves apparent faster than light motion. Things like worm-holes work like this. Essentially it is because there is more than one path that a light beam could be sent, one shortrer than the other. In this way you can make it look like you have sent a message faster than light and hence have a time machine.

One conjecture you should know about is Hawking's "chronological protection conjecture". It simply states that the universe does not allow time-machines. As far as I know, just about every time-machine ever concidered can be shown to be flawed when investigated further.

The question with Mallett's time-machine could be "what is stopping it working?"

I think you mean Ronald Mallett

http://www.physics.uconn.edu/~mallett/main/main.htm

http://www.physics.uconn.edu/~mallett/main/time_travel.htm

For more information on other time machines search SPIRES for time machines or time travel

http://www-spires.dur.ac.uk

This should convince you that time travel is a "real" area of research. However, I think that most people are not trying to create a real time machine, but rather push known theories to the limit. In this way we learn more about the theories (mostly general relativity) and point towards new physics.

G.M. Shore (my MPhys supervisor) wrote a review of some time machines. http://arxiv.org/abs/gr-qc/0210048

Does anyone know any references about fluid dynamics as a field theory? In particluar I wanted to know more about the symmetries of fluid dynamics and possible Lagrangians.

The only references I know are HEPPH-0407101 and papers by the same people. Are there any others out there that I don't know?

Cheers

I was just wondering if there are any regular Mathematica users on this forum?

I use Mathematica all the time, mostly for fun. I wanted to know about how to write packages. Any advice?

Cheers.

The main area of mathematics behind quantum mechanics if the theory of Hilbert spaces and their operators. Hilbert spaces are infinite dimensional complex vector spaces and the operator are infinite dimensional matrices.

So, before looking at this I suggest you get familiar (if your not already) with linear algebra, things to do with vector spaces and matrices in finite dimension.

You can also use a Monte Carlo method for calculating pi, but is it rather slow. I once wrote a programe in BASIC to do it several years ago now. I do not suggest that it is a "good" method of calculation but it does work.

You can see how it work here

http://www.eveandersson.com/pi/monte-carlo-circle

The book by A Das & T Ferbel would give you an overview of nuclear and particle physics. It doesn't use any quantum field theory but assumes that you know some quantum mechanics. It might be the sort of book you are looking for.

http://www.worldscibooks.com/physics/5460.html

Halzen and Martin comes highly recommended, it was the bases of a course I did last year on further quantum mechanics. Like Severian said, it stops short of using quantum field theory, but does deal with relativistic quantum mechanics and Feynman diagrams. I never used the book myself, but I know people who have.

If you want more advanced stuff there are plenty of book out there. I like Ryder, Kaku, Nash and Ramond.

Hope that helps

Hello all,

I am new to this forum and would like to introduce myself. My name is Andrew and I am a PhD student at the university of Manchester UK.

My research interests are in geometry and mathematical physics. Of interest lately has been the BRST transformations, the antibracket and (odd-)symplectic geometry. These things are all to do with how to treat general gauge theories correctly when quantising them. The underlying structures involved are all "super". That is they all involve anti-commuting objects.

Before that I obtained a MSc in theoretical particle physics with a distinction at the university of Sussex. Mt final year project was on anomalies. And before that I did my undergraduate studies at the university of Swansea where I obtained a MPhys degree.

To find out more, have a look at my website

http://www.angelfire.com/geek/susy/index.html

Thank you

Andrew