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  #41  
Old 05-14-2011, 10:39 AM
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Lol yeah. We briefly touched on string theory but it's only the first year of a degree course so nothing too deep. I'm naturally suited to physics but tbh i get bored so fast of it I'm not sure if I'll continue. I sort of enjoy maths as well, or used to, but again it's one of those things that requires effort and I'm not sure it's what I want to do right now.
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  #42  
Old 05-14-2011, 01:58 PM
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I do think the nature of study is changing!

You have these marvellous Stanford University lectures at YouTube, and you can pause while you look up stuff at Wikipedia with Google. I get annoyed at books that spend the first half doing the old historical stuff. Do it properly with advanced modern methods! I want to see the overall pattern from the higher ground!

Here's a nice function called the Dirichlet Eta Function which is related to the Riemann hypothesis and the natural logarithm. It converges nicely, better than the zeta function, and the even terms can be quickly eliminated, leaving the physically interesting odd terms for conformal mapping.


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Now there may be a mere 6 compactified dimensions in our space, which suggest SO(32) symettry will apply. And yes, Eta(6) has factors of 31 and 32 in it. It's a contender for doing something interesting in Physics! I shall look out for it in Prof Susskind's lectures.
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  #43  
Old 05-14-2011, 02:23 PM
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It is changing. Earlier in the year my head was blown by ATP and glycolysis and I found KhanAcademy on youtube which helped me a ton. It's so easy to just go into autopilot when reading from books.
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  #44  
Old 05-14-2011, 02:50 PM
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It saves so much time being able to Google up what you want. I scarcely keep notes any more, though I do work stuff out on paper for interest until I totally get it. Here's something about maths that gets clearer as you go further. Complexity doesn't increase exponentially as you go to higher powers and dimensions. Usually you just have a few more terms to add. That's all.

Remember the old x squared quadratic problem. Hard enough. The Cubic and Quartic problems are a bitch. The Quintic is actually impossible as Abel proved. That problem can give you the wrong idea. Because electrical filters are easy. There are really only first and second order elements. Third order and higher filters are just the product of simpler ones, and generally you just lay poles and zeroes around a unit circle to get them symettrical and solve them.

Dimensions are the same, just the matrices become bigger, but computers eat these for breakfast! So what I'm saying, is it really doesn't get too much more difficult. Having said that, these Calabi-Yao 6D shapes are a bit unfathomable currently, which seems to be the holdup in String Theory right now. But I expect that it can all be done with 3 special doughnuts!
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  #45  
Old 05-15-2011, 04:06 PM
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OK, S/A Physicists and interested parties, I have finished Leo Susskind's course on STRING THEORY, so here is the CURRENT answer to visualising 10 Dimensions AFAIK!

Firstly Quantum Chromodynamics (Gluons binding nuclei) in 9 spatial dimensions, 6 of which are compactified:



Take 3 D2-Branes labelled RED, GREEN and BLUE (making 6 dimensions) and fix open strings to the three planes to generate the gluons with their colour charge. This leaves 3 dimensions for the strings I reckon.

Or you can create a D3-Brane like our 3D space, then run open strings fixed at one end into it.



The usual open string is an electron or in the case of a heavy D1 brane (which is like a heavy string) a MONOPOLE. The twist/orientation on the string determines charge, and unlike attract. A doubly attached string would be a photon. Hope I've got all that right. That's it really!
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  #46  
Old 05-16-2011, 11:39 AM
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Quote:
Originally Posted by system7 View Post
OK, S/A Physicists and interested parties, I have finished Leo Susskind's course on STRING THEORY, so here is the CURRENT answer to visualising 10 Dimensions AFAIK!

Awesome. Thanks!
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  #47  
Old 05-17-2011, 11:21 AM
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Yup, I think I nailed it there. Strings may just be a mathematical way of applying some conditions to what is essentially geometry in 10, 11 or 24 or 26 dimensions. But they have relevance.

What does a neutron or a proton (Consisting of 3 quarks) look like? Well, there is a configuration in mathematics known as a Tight Borromean Ring which may help. It is really 3 Tori with an elliptical property.



There is much subtlety in BORROMEAN RINGS, including a hidden 5 symettry, the Golden ratio and the fact that you can make one with 3 ellipses, two ellipses and a circle, an ellipse and two different size circles, but not 3 circles, which describes the possible combinations. I don't know if that describes gluons, quarks or hadrons, but Nature would be stupid to pass that one up. It exists somewhere.
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  #48  
Old 05-17-2011, 11:50 AM
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"Relevance" is a relative term. String theory is a mathematical description of a model for physics that hasn't made a truly testable prediction in its 50 years of existence. It is interesting if not elegant and I do think it deserves to be pursued further, but its usefulness and applicability is extremely limited.

As for what a proton "looks like", that's pretty inconsequential, isn't it?
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  #49  
Old 05-17-2011, 12:52 PM
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I've gotta agree that String Theory is at an early stage. I don't know if it's right. But it is impressive in the way it unites the photon of light in the tiny atom with the graviton in the huge Black Hole. It is making the World think about geometry again. No other theory comes close.

6 dimensional Calabi-Yau shapes? 3 holes or a maximum of 480?


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Deeply fascinating stuff that makes a Physicist or Mathematician's little Heart sing. Rock on, Leonard Susskind!
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  #50  
Old 05-17-2011, 04:19 PM
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Aw Heck! Do you wanna know what a closed string really is? (Remember the MASS is the LENGTH SQUARED.)

Do you wanna know what an open string really is? (Remember it's often attached at one end, in the case of an exchange particle, it's attached at both ends.)

Anyone figured it out yet? It's easy! I know. It's a question of looking at them the right way.

Geometry and symettry are another matter, of course.
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Last edited by system7; 05-17-2011 at 04:36 PM.
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