Modern and Theoretical Physics

As some of you probably know, quantum gravity theory depends on background independant geometry and the idea that space is discrete, as opposed to continuous. So for observation purposes this means probing scales and energys of the planck order, which in particle accelerators is impossible. Even creating a mini black hole, AFAIK is nowhere near the energies required to witness space around the planck epoch of the universe. I listened to the interview Martin provided with Lee Smolin, and the subject was brought up in 'Three Roads to Quantum Gravity' in that by studying gamma ray bursts, it's possible to probe such energies. This makes sense to a point, but surely all w…

Best radio interview I've heard so far, short (15 minutes) clear, relaxed, and understandable. The CBC science program "Quirks and Quarks" http://www.cbc.ca/quirks/media/2006-2007/mp3/qq-2006-09-23e.mp3 Also this article at the New Yorker website http://www.newyorker.com/printables/critics/061002crat_atlarge which will be published in the 2 October issue of the magazine. Called "Unstrung", critic Jim Holt reviews Smolin's and Woit's books Also a Scientific American article, dated 25 September, free online here http://www.sciam.com/article.cfm?articleID=00000749-259B-1514-A59B83414B7F0133 "Is String Theory Unraveling?" It has links to earlier SciAm…

Let's have a (oneshot at least) BOOKCLUB this is what a bookclub is: http://www.book-club.co.nz/bookclubs/tips.htm it says you need 5 or more people and you pick a book and all read it and discuss it. I'm proposing for our first selection the book currently at the top of this bestseller list: http://www.amazon.com/gp/bestsellers/books/14560/ref=pd_ts_b_nav/102-4540543-7840144 which is Smolin The Trouble with Physics...and What Comes Next I am especially interested in his discussion of what comes next, in section III "Beyond String Theory" which starts around page 200 It's an intelligently written book. Although it doesnt use equations it talks…

I have an idea on how to make a perpetual motion device/machine. Imagine a hollow doughnut made of see-through plexiglass under a vacuum . Inside is a magnetic floating car thing, and along the side and bottom are magnets holding it up. You could get it turning by kind of turning the contraption until the car starts moving, and then just set it down. It'll just keep moving and moving and moving, never ending. The only thing that could stop it is photons emitted by whatever light source affects it. In fact you could use these photons by putting a piece of metal at the top with one side white and the other black. The light would be reflected on one side, and absorbed…

i'm going through a bit of a stargate obsession phase just now and i was reading up about wormhole on the web. nearly every site(well, sites that actually correspond to the physics we all know and love) says that a wormhole violates causality because the information arrives before it is sent. now, i've thought about this and done some maths and i must be missing something because i can't figure out how that would happen. lets say we have a colony on some planet around alpha centauri and we've either discovered or made a wormhole. and we'll say c=300000000 ms^-1 to keep the math simple. normal radio communication would require 4 years to reach the colony and anoth…

perceptive is said advisedly he is not a physicist----more on the humanities side----and he makes some trivial technical mistakes that don't matter to the main issues. a generalist shooting from the hip, but he gets some things right. I'll put up some exerpts later today when I've time. Here's the review in yesterday's Slate (14 September): http://www.slate.com/id/2149598/ Here is some background on Gregg Easterbrook http://en.wikipedia.org/wiki/Gregg_Easterbrook Brookings Institute fellow, senior editor at the New Republic, often writes for Atlantic Monthly, NY Times... author of several books

From wikipedia: I was just wondering if this really has any scientific merit....

has anyone come up with a theory on how tachyons would be created if they were to exist? could tachyons be part of the dark matter? if they exist, their imaginary mass energy may prived predictable effects in the gravity around galaxies. i don't know any of the GR equations, so i wouldn't be able to see what happens when you put an imaginary term in for mass\energy.

as most of us know the conventional rail gun uses 2 rails and an armature to complete the circuit causing the 2 rails to repel and shoot the armature at very high velocities. whati want to know is why thishappend. the force is applied perpendicular to the rails and not parallel to it. why would a force that is acting perpendicular be able to force out the armature at such speeds. :confused:

best audio I've heard in some time covering current status of QG research (in first 10 minutes) plus Barrett's work on 3D http://www.newton.cam.ac.uk/webseminars/pg+ws/2006/ncg/ncgw02/'>http://www.newton.cam.ac.uk/webseminars/pg+ws/2006/ncg/ncgw02/ also great talk by Alain Connes on how he realized the standard model of particle physics and gravity in a non-string approach to unification he calls NCG---but Urs Schreiber calls "spectral geometry" both these talks are in MP3 I think both are worth listening to----they are hour talks given at the 4-8 September workshop at Newton Institute Cambridge http://www.newton.cam.ac.uk/ John Barrett is at N…

How true is this.... Can the LHC produce a particle that could be dangerous? I know the tiny black holes would evaporate pretty quickly but what about some unknown particles not thought of. Like some surprise that won't go away. http://cosmiclog.msnbc.msn.com/archive/2006/09/10/3371.aspx Bee

The Foundation of Pure Motion Movement (PMM) And The Super SBDP Polyshifts In the world we now live in, scientist and engineers have been asking a few basic questions. For example, Give a good and detail explanation of how current flows in a wire, why is there friction, do we really know the answer too many question pertaining to elementary Physics, thermodynamics. We really have never seen electrons flow, and never see the atom. In fact there are so many unanswered questions. We are basing many calculations on facts that are not facts. We are leaving out the main variables that need to correct them for what I call the Super SBDP (Super Blue Domain Polyshift, a cer…

Who do you guess? It is among those living today---Einstein and Newton don't count There is a chance that you wont even recognize the name. http://physicsweb.org/articles/news/10/8/13/1 It is interesting how they developed this measure of physics creativity and then used it to get a list of the top ten living physicists. I probably would not have guessed who came out #1, but I knew of him and have been impressed earlier by things he has said---like in reply to the 2005 Edge question.

a maths building at Cambridge has a new convenience a blackboard, with chalk and eraser, in the lavatory see picture: http://ppcook.blogspot.com/2006/09/to-commute-or-not-to-commute.html

Hi everybody. I guess I just feel like I should make a contribution to this website, and now I have such an oppurtunity; and have attached a piece of work to this thread. I did this coursework a while back called an "Introduction to Quantum theory", where I covered and eleaborated on the initial steps covered in the development of the theory and its logical origins. I would not say this is an excellent piece of work, but as I have received my A level results; I feel no inhibitions about posting this now(I was a little concerned if the exam board would raise a word or too). I hope this helps anyone interested in the subject, and I apologise in advance if it is a …

Can someone please explain to me why it is that we consider the electromagnetic and weak forces to be 'unified' but not the strong and electroweak? As far as I understand it (and I probably don't understand it very far at all) the electromagnetic and weak forces are the same thing at higher energies. I also understand that there is a 'unification energy' at which all the forces are one single force. So why the special status of 'unified' for the electroweak? Is it some relic of past, less complete understandings? Or (more likely) am I missing something? Thanks for any light shed!

If theories like the Superstring and Loop Quantumn Gravity can never be tested directly (except from predictions made by them) would that mean they have the qualities usually attributed to descriptions of "faith"? If so, would this make advances in theoretical physics similar to the advent of new religious convictions? Perhaps a topic for discussion?

So I found this article on New Scientist: http://www.newscientist.com/article/mg19125645.800.html Talking about spacetime braiding and a form of loop quantum gravity where the universe is just an enormous quantum computer. And well, obviously, the idea struck a chord with me. Here's their paper: http://www.arxiv.org/abs/hep-th/0603022

Saw this in Time: (har har on the pun Time) http://www.time.com/time/magazine/article/0,9171,1226142,00.html So, can anyone provide a take on this? I really liked Brian Greene's books but have certainly been more drawn to Smolin/LQG lately, namely because of the fecund universes hypothesis.

http://www.sciencefriday.com/pages/2006/Aug/hour2_081806.html the second hour of "Science Friday", a weekly feature on NPR (US national public radio) hosted by Ira Flatow will include a chat between Lee and Brian about the current situation in fundamental physics----st***g theory and all that. If you live in the US and can get NPR, you might want to tune in. ============== I just learned that Discover magazine has a review of the two new books by Lee Smolin and Peter Woit that are causing a stir by criticizing institutional concentration on string theory (to the exclusion of non-string alternative approaches). http://www.discover.com/issues/sep-06/de…

personally I don't like it, but I do have a question on it. I know that there are many many many different versions of string theory, but recently I've heard that it may be possible to construct one to fit any universe, is this science popularization crap or is it true or relatively true? Also would it be possible to construct a thought experiment that would show whether string theory could be made to fit our universe? essentially a bell inequality for the string theories. Even if such a though experiment seemed untestable it could eventually lead to an experiment similarly to how the bell inequality eventually led to experimentation.

September 2006 issue of Sci Am has a review by George Johnson of the new book by Lee Smolin, called The Trouble With Physics George Johnson is a good one to get reviewed by. http://www.santafe.edu/~johnson/ http://www.santafe.edu/~johnson/gravestone.jpg Time magazine just had a review of Smolin's book by Michael Lemonick (senior science writer for Time for past 15+ years). The Time magazine review is already posted on web, free for download. http://www.time.com/time/magazine/printout/0,8816,1226142,00.html

hello was wondering if the laws of physics apply across all dimensions. or do certain laws only exist in certain dimensions, and futher if a law does exist only in certain dimersions how would a change brought about by that physical property that would only exist in say the eight dimension be reflected in the 3rd dimension. strange thought mr d

Here is an article I think you might enjoy about a topic that has challanged us for years. Its on paradoxes in time travel explaining a lot of the problems involved. Here is the link...http://ezinearticles.com/?Paradoxes-in-Time-Travel&id=224204

So I read this "explination" which uses two analogies, one where there definately are hidden variables and one where I don't see why there shouldn't be. And so, I don't understand what Bell's theoem is getting at. So in short, how can the absense of hidden variables be proven?