The last few days some interesting physics articles about string-net liquids have popped up. It began with Robert Laughlin's Nobel Prize for the discovery of particles with a fractional charge, a completely new type of matter. It was shown that sometimes several electrons can congregate in a way that they appear to have fractional charges.
Xiao-Gang Wen studied these particles together with Michael Levin and they came up with a theory they call string-net liquids. The theory suggest that all fermionic particles are endpoints of long open strings and that light is represented by fluctuations in a closed string. Simulations of vibrations in nets made of these strings gave rise to Maxwell's Equations and to other kinds of fundamental particles.
The slides from his presentation at a quantum computer conference early March can be found here. It includes some very complicated equations, but what he wants to show in the end is that fermions and light emerges from the collective motion of strings that fill the vacuum of space. A condensed string will be have like a single particle.
Interesting stuff, and hopefully this way of looking at the fundamental particles could get us another small step closer to figure out what this whole place is all about.
Showing posts with label physics. Show all posts
Showing posts with label physics. Show all posts
2007-03-18
2007-03-08
TED talks to watch...
2007-02-20
The Fabric of the Cosmos
Last night I finished Brian Greene's excellent popular physics book The Fabric of the Cosmos: Space, Time, and the Texture of Reality. I would recommend it to any one interested in theoretical physics or just curious about how far the scientists have come in trying to understand our universe.
The book is quite a heavy read, 493 pages plus a lot of endnotes and references. Having read The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory I can say that The Fabric of the Cosmos (TFotC) is an even better book. It takes up some of the same theories mentioned in Elegant Universe, but includes a lot more about The Big Bang and general relativity. In TFotC Greene starts out with water in a spinning bucket hundreds of years ago, through the discoveries of general relativity, the uncertainties involved in quantum mechanics to the latest super string theories, finding the key to "the arrow of time" along the way.
It's not easy to describe all this in a way that makes in understandable to people who aren't theoretical physicists, but Greene does a great job. It's barely any mathematical formulas or equations, instead he relies on similes and methaphores to get the point through.
Overall it's a very thought provoking book. In the middle of the book there's a lot of discussion about spacetime and the implications of quantum mechanics and general relativity. The more you learn about these things, the more obvious it seems that there is no such thing as free will. I find this very difficult to accept and my mind opposes it, but it's hard to contradict his logic reasoning.
I find the chapter on entropy and the arrow of time to be well written and the examples he is using are very fitting. Sometimes he gets a bit too excited over the numbers, printing a page or two with zeroes trying to describe the enormous values of some probability or metric. It's still well beyond what you can grasp.
Even if Greene is a strong supporter of string theory, he does a fair comparison between that and Loop Quantum Gravity in the last chapter of the book. But I still think that the way the book is written, most people will convinced that Branes in superstring and M-theory is the way to go.
As a final grade, I'll give it 8/10. It's a great book, but you really need to focus and think while reading.
The book is quite a heavy read, 493 pages plus a lot of endnotes and references. Having read The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory I can say that The Fabric of the Cosmos (TFotC) is an even better book. It takes up some of the same theories mentioned in Elegant Universe, but includes a lot more about The Big Bang and general relativity. In TFotC Greene starts out with water in a spinning bucket hundreds of years ago, through the discoveries of general relativity, the uncertainties involved in quantum mechanics to the latest super string theories, finding the key to "the arrow of time" along the way.
It's not easy to describe all this in a way that makes in understandable to people who aren't theoretical physicists, but Greene does a great job. It's barely any mathematical formulas or equations, instead he relies on similes and methaphores to get the point through.
Overall it's a very thought provoking book. In the middle of the book there's a lot of discussion about spacetime and the implications of quantum mechanics and general relativity. The more you learn about these things, the more obvious it seems that there is no such thing as free will. I find this very difficult to accept and my mind opposes it, but it's hard to contradict his logic reasoning.
I find the chapter on entropy and the arrow of time to be well written and the examples he is using are very fitting. Sometimes he gets a bit too excited over the numbers, printing a page or two with zeroes trying to describe the enormous values of some probability or metric. It's still well beyond what you can grasp.
Even if Greene is a strong supporter of string theory, he does a fair comparison between that and Loop Quantum Gravity in the last chapter of the book. But I still think that the way the book is written, most people will convinced that Branes in superstring and M-theory is the way to go.
As a final grade, I'll give it 8/10. It's a great book, but you really need to focus and think while reading.
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