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Current Thoughts in String Theory
DrLudicrous writes "The NYTimes is running a nice little synopsis of the current ideas in string theory. Apparently, there is still quite a bit of disagreement about how to interpret the various theories, with some string theorists supporting a semi-deterministic worldview a la Einstein (God does not play dice), while others believe our universe is just one possibility among many, with respect to various physical parameters."
From the article:The new calculations suggest that this dark energy cannot last forever, that it will disappear sometime in the far future
how can it disappear? does dark energy not follow the laws of conservation? (energy can neither be created, nor destroyed, only changed) any one have an answer?
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I think that quote (or rather, truncuated paraphrases thereof) is much abused. What Einstein is saying (which is much clearer in a fuller context) is that while the probabalistic equations that comprise much of quantum theory are valuable as descriptive and predictive tools, they do much less to further Einstein's cherished ideals of really understanding the fundamental basis of physical reality. The statement "I am convinced that He does not throw dice" is a statement that while the equations of quantum mechanics might behave like statistics, they did not mean that the underlying reasons for why these equations work were simply artifacts of random, statistical processes - mere throwing of dice. Our ongoing failure to connect all the dots of the various paradigms could indicate that he was on to something...
It Is the Nature of Information to Transgress Artificial Boundaries
forget for a moment the moral implications of God playing a gambling game.
An all-knowing and all-powerful God would have no problem predicting the outcome of dice. They are physical objects governed by all the physical relationships that govern things like gravity, collisions and such.
The magnitude of the complexity of the outcome of dice seems to be too complicated for any human or machine to calculate a result.
Random outcome of dice is just a concept to help us deal with extremely complicated situations.
Hey! Turtle Theory is really a much better theory than you think. Turtle Theory says that there are no fundamental distinctions, but as soon as you pretend there is a fundamental distinction by coming up with a word -- any word at all, such as 'turtle' -- then it's turtles all the way down. It's a comment upon mistaking the map for the territory. (It is also an old Buddhist cosmology, I think from the 1st century A.D. It was a joke even then.)
Big Brother Bush is doubleplus ungood.
"God does not play dice with the universe. He plays an ineffable game of His own devising, which might be compared, from the perspective of any of the other players [i.e. everybody], to being involved in an obscure and complex variant of poker in a pitch-dark room, with blank cards, for infinite stakes, with a Dealer who won't tell you the rules, and who smiles all the time." (Terry Pratchett, Good Omens)
I'm not so sure they are barking up the right tree. We don't have the TOE (theory of everything), but I'm not sure if it can be found. That is, I'm not sure if string theory can be valid. Or if it is valid it is not a TOE. I do not have time or energy to prove, but I Belive a TOE violates the 2nd Law of thermodynamics. Granted, some might argue that a TOE would take precedence over the grand 2nd law, but it so reliable and prevents so many stupid things from happening on a big scale that I have faith in it.
Well.. maybe. Or Maybe not. But Definitely not sort of.
I'm pretty sure quantum computers will only allow us to simulate quantum systems. String theory is at a more fundamental level. Sure, we can compute (numerically) the mathematics behind string theory, but we can do that on classical computers as well.
Physics: Making the universe open source.
There are several overlooked points in the discussion. Someone above has already pointed out that the Einstein quote about divine gambling is over and misquoted.
String theory was proposed by Lord Kelvin, who started to investigate by developing a theory of knots, which was expanded by Reidmeister, and blossomed in the 20th century.
Einstein's special and general relativity were created to explain observed phenomenon that could not be explained by current theories. For special relativity, this was the constant velocity of the speed of light given by electromagnetism and confirmed by the Michaelson-Morley experiments. General relativity is a result of formulating Newtonian gravity in the field theoretic language used for unified electromagnetism. There were bits of data around indicating its necessity, though, such as errors in the perihelion of Mercury.
Quantum mechanics was similarly developed because of an incredible plethora of data. Thanks to Bell, we now know that (unless theory takes some really extreme turns), before an interaction with a "classical" apparatus, a quantum particle not only has unknown position and momentum, it actually doesn't have either. It's a subtle argument, but it's pretty well tested.
The motivation for string theory was to remove infinities in the fields which result from point-like particles. There is no physical motivation. String theory was not formulated as a theory of gravity or a grand unification theory. Those were bolted on afterwards as people noticed they could have sufficient degrees of freedom: you can build similar theories with straight up quantum field theory, and many people do for their life's work. So far the theory has produced one observable, which we already knew to far higher accuracy from quantum field theory. Pure number theorists get more physics as a by product than do string theorists. Supersymmetry and the Higgs boson are attempts to clean up mathematical holes, but they seem almost well motivated compared to the morass that is string theory.
String theory has driven a wedge between theorists and experimentalists in particle physics, and made it "unfashionable" to do serious theory that actually deals with reality. However, the popular press loves it: you can quote big sounding names and no one can nay-say them. Most areas of particle physics abjectly fail when it comes to explaining what you're doing to the layman.
Thankfully the pendulum seems to be swinging. At Caltech, their one phenomenologist has recently been absolutely swamped with pupils: string theory seems to be dying off at last.
The observation is that there are two fields of physics that have been rigorously tested and widely accepted, but are only really valid in their own domains. The problem that faces modern physics is how to reconcile this disagreement. The difference between string theory and turtle theory is that string theory is reduces down to quantum theory and relativity when suitable constraints are placed on it. Stop me if I'm wrong, but I don't think turtle theory can do that. The fact that current technology is unable to verify the theory through experiment is a temporary situation (and a unique one. Through most of history, experimental observations have triggered theoretical research.)
String theory might be pushing the limits of science, and it might be completely wrong, but it has a strong foundation, and it attempts to address a big question, and that should be reason enough for scientists to keep working on it.
Yes I do have a physics PhD and I have done a lot of quantum mechanics in my time (low energy electron-molecule collisions). Yet, I don't have a clue about the string theory. Popular articles on the subject do not help at all (at least for me).
I guess this is just an extreme example of the typical slashdot discussion. A lot of people are "insightful" and "informative" particularly if the topic is esoteric enough.
Isn't the first experimental proofs of the relativity theory (special and/or general) came from astronomy? We don't necessarily need to do the experiment here on Earth... all we have to do is to find a place were the experiment is already taking place and observe it...
Just because I don't care, it doesn't mean I don't understand. Homer J. Simpson
This is not in the realm of science or physics. This is philosophy - hence the term "metaphysics". Modern science presupposes certain axioms about existence (uniqueness, identity, persistence, objectivity, etc.). If you can't test/prove something, then it's a hypothesis and not a theory. This point is frequently missed by pop science culture that assigns the term "theory" to any random brainfart of Hawking or Greene or the others, but a bona fide theory requires tests and must have demonstrated predictive value.
Hence it was a philosophical issue and not a scientific one until we developed the capability to test the atomic hypothesis.
Have you heard of the problem of underdeterminism? There will *always* be multiple theories that have *exactly* the same predictive power and yet are mutually incompatible. What do you do when two theories with different fundamental 'entities' predict exactly the same results but by totally different 'mechanisms'?
Nobody said in string theory that "billions and billions of universes are needed for ours to exist by random chance". That is far from known, in string theory or any other theory.
Every universe is "rare" and "unique" in some way. Just maybe not the anthrocentric way that people who appeal to Intelligent Design usually mean.
In the meantime, while you seek an answer that is emotionally satisfying, I'll keep looking for one that is true.
Some semantics:
A theory is a systematization of ideas.
An hypothesis is a claim about the relation
between a theory and reality.
Reality is really real.
Fringe means "not popular with the in-crowd yet".
"Untestable" means you haven't figured out the
right experiment yet.
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