Advertisement Hide. Progress in String, Field and Particle Theory. Front Matter Pages i-xiii. Front Matter Pages Pages The Holographic Principle. Christopher P. Herzog, Igor R. Klebanov, Peter Ouyang. I love the new blog, even the posts about dimwitted movies e. Mr and Mrs Smith Only, where are the poems? Where are the pictures? But I do love the new blog, and all of your accomplices. Cameron— Gauge theories are basically generalizations of electromagnetism. It can be generalized to more complicated kinds of symmetries, e.
SU 2 etc. The Standard Model makes heavy use of gauge theories, to describe the strong and weak forces as well as electromagnetism. Ignore Dan. Not only are people who try to tell others what to write about annoying, your politics posts provide a nice counterpoint to the physics. It creates a richer blog. Stop whining, Geoff. I still like to argue, debate and comment.
Particles vs. strings
I fell asleep somewhere in the second or third paragraph of this post. Anyhow, I guess publicly going to bat for string theory is not a bad move when you find yourself on the job market. I watch string theory from the sidelines as a journalist and read about if often. There are some aspects that are often a oversold and the scientist should probably frame their comments a little differently. I understand the math is well worked out and waiting for confirmation.
Does anybody know when quantum mechanics and general relativity went from hypothesis to theory? Your new blog is interesting so far. Our understanding of string theory is far from complete. Holding up a tentative observation as evidence that string theory is wrong or, worse, unscientfic is…silly. As Sean mentions you can start writing down field theories and never finish.
Gauge invariance allows us to reduce an infinite number of ostensibly different theories into a single theory imagine writing down all of the gauge fixed versions of a theory with a continuous gauge fixing parameter. Or suppose, after making some obscene number of measurements, we still find ourselves with an infinite number of field theories consistent with our observations. Ideas like this completely change our original goal, which was to identify the unique field theory out of an infinite number that describes the results of our experiment.
Instead, we make due with the fact that our tools measurements up to some scale for picking out a particular theory will never completely pin things down above that scale. Understanding a theory means, among other things, knowing what kind of questions you can ask and how to ask them. With respect to the landscape, string theory is in a similar situation.
We have ideas about how to formulate string theory, but certainly not with the degree of generality that we would like. We know what the proper observables are in some situations, but not others. The landscape may be an important question for string theory, or it may just be an artifact of our own ignorance.
Can I prove it? What Sean says still applies. As you might guess, I strongly disagree with some of your claims about string theory, more specifically:. Well, what exactly is the prediction? What will the detectors see? OK, this is just one parameter, and if one could make predictions that just depend on one parameter that would be great. Why do you believe this is true?
The existence of an infinite number of very different vacuum states around which you can build perturbative string theory expansions makes the issue more pointed. If you believe that perturbative calculations are valid and so the theory can make predictions, you also have to believe in the infinite number of vacuum states, which makes the theory radically non-predictive at energies we can ever hope to measure. Most string theorists I know would prefer to believe that perturbation theory is no good for determining the vacuum state, that non-perturbative effects will pick out a vacuum that looks like our world.
Bob McNees is ignoring the long response I wrote to him on my blog explaining the problem with his analogy about QFT and string theory. You can read it there, but the fundamental point is simple. QFTs make an infinity of well-defined predictions about low-energy physics. You can go out and compare them to the real world. You then see that one of the simplest QFTs agrees precisely with everything experimentalists have seen.
Experimentalists do more experiments and get results agreeing with what this QFT predicts. This is a beautiful example of the scientific method. The utter lack of any connection between string theory and experiment makes it something completely different, and raises real issues of whether it is a science at all, especially if anything like the landscape exists. First of all, until recently there was very little of this. Until the last couple years, the reaction I got from most string theorists was that I was an idiot, too stupid to understand the theory.
I made attempts to publish some rather moderate criticisms of string theory, and found these thwarted, generally by non-string theorists who were pretty convinced that only a crackpot would be claiming that string theory was completely on the wrong track. Things have changed a lot during the past few years. First of all, because of the internet, venues have appeared in which the problems with string theory can be laid out extensively and in public.
Secondly, despite what Sean says, progress on string theory has virtually come to a halt, and many of the people doing it have become discouraged or even left the field. Finally, the apparent existence of the landscape has led to a large number of prominent string theorists engaging in what is obviously pseudo-science.
The words many physicists, string theorists and non-string theorists, use to describe what is going on are not printable in a family-type blog like this one.
About this book
The theory groups at Harvard, Princeton, Stanford, etc. The incredible degree of over-hyping of the theory that has gone on is part of this. If so, please either tell me what this expression is, or direct me to a paper where one is derived. Not sure if that was an intentional pun..
Particles vs. strings
Interesting post and interesting blog! Few astronomers would take very seriously an astrophysical theory whose tests required, say, million-kilometer-diameter telescopes, or observations over a period of several thousand years. The test could have been done with earlier eclipses, but World War I got in the way.
I will get around to it. Black hole theory provides an important testing ground for the quantum theory of gravity and in recent work significant progress has been achieved in explaining black hole entropy and Hawking radiation from a more fundamental point of view. Work on quantum black holes has led to new relations between strings and non-Abelian gauge theory.
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This application of string theory has already provided new insights into strongly coupled gauge theories, and it continues to be an exciting area. Members of the high energy theory group are also involved in cross-disciplinary research, applying field theoretic techniques to a variety of problems, including turbulent flow, dissipative quantum systems, the quantum Hall effect, and heavy-ion collisions, to name a few.
Jump to main content. Hamilton Colloquium Series Donald R.
- String Theory For Dummies!
- Introduction to algebraic geometry.
- Regions and the World Economy: The Coming Shape of Global Production, Competition, and Political Order: The Coming Shape of Global Production, Competition and Political Order;