The Man Who Invented the 26th Dimension 259
StartsWithABang (3485481) writes Based on all the experiments we've ever been able to perform, we're quite certain that our Universe, from the largest scales down to the microscopic, obeys the physical laws of three spatial dimensions (and one time dimension): a four-dimensional spacetime. But that's not the only possibility mathematically. People had experimented with bringing a fifth dimension in to unify General Relativity with Electromagnetism in the past, but that was regarded as a dead-end. Then in the 1970s, an unknown theoretical physicist working on the string model of the strong interactions discovered that by going into the 26th dimension, some incredibly interesting physics emerged, and String Theory was born.
Re:String theory is voodoo physics (Score:5, Insightful)
Proposing an idea that explains a previously unexplained observation isn't pseudoscience. It can certainly be wrong, and should be treated as such until experimentally tested.
But pseudoscience lives in a special realm, where it wraps itself in the verbiage of science, while not sharing the methods and intent. String theory very clearly falls into the "not testable yet" category, rather than the "designed to resist testing" category that weapons grade bullshit enjoys.
Re:String theory is not science! (Score:5, Insightful)
"String theory is untestable" is one of those easy to remember phrases that keeps you away from a great amount of interesting information:
1) "String theory" is actually a family of related theories that make different predictions, where they're advanced enough to do so
2) They're neither as a class, nor individually, a priori untestable
3) They're theories of high energy physics, so what predictions they do make will be difficult to test on currently existing hardware
4) The mathematical tools to make sense of the theories and make predictions are novel themselves
String theory is at a stage kind of like parachuting early-20th-century physics into the 15th century. It's not relevant at length scales where we can easily make observations, but we don't have the necessary cognative or physical tools to write it off either. Have we been handed relativity, or the aether? We can't say because we're not smart enough yet.
Now, as a matter of expediency I'd argue that any self-respective physicist should dedicate himself to advanced models that are a little closer to home and might act as stepping stones to string theory's energy scales, but since when has any self-respecting scientist been led away from a beautiful hypothesis by pragmatism? Much less a physicist?
Re:Gotcha covered... (Score:4, Insightful)
26 base 10 = 42 base 6
Re:Why are they all space dimensions? (Score:4, Insightful)
I can look up/down, North/South, and East/West, but I can not look past/future. So it makes sense that I also can not look t2+/t2-.
You can't do anything except for analyze the signals of photons presently impinging on your retina. You have no direct means of experiencing the space ahead of and behind you any more than you do the time directly ahead of and behind you. But assuming those photons travelled in straight lines in space and time and have spectra which depend on the object they last interacted with, you can make some good inferences about what objects were there a short time ago. Just as you can make the inference that those objects may have also been there at an earlier time, or may continue to be there longer than that.
It's only because the speed of light is so fast that we act like we are making direct spatial observations. Slow it down enough and you might not say your eyes were very good for finding the position of things at all -- just for telling you what they were like in the past.
Re:While we're at it (Score:3, Insightful)
The GP was talking about "emperical phenomenon".
So that's the unexplained phenomenon and:
Those aren't emperical phenomenon. They're not phenomenon at all. It's just a mathematical artefact from an incorrect theory.
That's the resolution that requires 26 dimensions. My linalg-fu is weak, so I'm actually not checking the math myself. Happy?
Not really, no.
Currently there are no actual phenomenon (i.e. real things) which string theory yet explains.
Re:Crazy Parakeet Man (Score:5, Insightful)
String theory became extremely dodgy for a while there - in fact, it went totally off the rails IMO. There were physics journal articles with long philosophical rants and no equations. When the "get random nonsense published" prank war hit physics, it's no surprise it was a string theory journal that fell for it.
This is what happens to any science without new data coming in. When the Superconducting Supercollider was cancelled, particle physics began getting a little nutty, and by the time you had mid-career physicists with who had only published works never to be challenged by experiment, well, it's an object lesson in how not to do science.
But the LHC was the needed fix. Theory and experiment are now re-coupled, and I hear that sanity is returning aggressively. Meanwhile the other end of physics, cosmology, has the most accurate data ever to work with, thanks to the CMBR probes, and has been making huge strides for a decade now (cosmology with significant digits, who'd have thought?).
Re:Crazy Parakeet Man (Score:5, Insightful)
What she's saying is that there is no known practical test which requires string theory as an explanation -- the other theories are sufficient. That doesn't contradict the idea that there are tests which could disprove string theory.
Consider the claim that a man who stands before you was created just outside your front door 5 minutes ago, fully formed with enough knowledge to communicate and a local accent, etc., but no evidence of any prior existence was created along with him. Your alternative explanation is that he's lying and was born 30 years ago, as his appearance suggests. You could disprove his theory by finding his house with pictures of him growing up -- that's prior evidence of his existence. It's extraordinarily doubtful that you could ever prove his claim, even if it were true -- it's just much more likely by virtue of simplicity that he was born and you can't find evidence of where he grew up prior to 5 minutes ago, because there's certainly no less evidence of that.
It's not enough for a theory to stand up to attempts to disprove it -- that's a necessary but insufficient condition. It also has to explain something, anything, in a way that is either simpler or more complete than other known theories.
Newton's Laws stand up because they are simpler but less complete than theories like relativity. Relativity stands up because it is more complete than Newton's Laws -- there are known situations when Newton's Laws simply give the wrong answer and relativity gives the right one. QM stands up because it explains something that relativity does not, so it's more complete in a different sense. Aristotelian cosmology failed because it was simply wrong. Geocentrism failed not because it was "wrong" (a geocentric frame of reference is a perfectly valid, albeit non-inertial, frame of reference, and you can absolutely make accurate calculations about the universe with Earth defined as its geometric center), but because it was incredibly complicated compared to heliocentrism and provided no discernible scientific benefits. That leads to the question: is string theory like geocentrism, in that it's not strictly disproven but it's an unnecessary pain in the ass?
The request here would be for a situation that String Theory explains, and QM and Relativity either do not explain, or explain inaccurately, or explain in a more complicated fashion. It's useless until it provides one of those things, other than the joy of pure mathematics. Science does not state "all proposed theories are true until disproven" -- rather, it says "don't assume a proposed theory is true until you fail to either disprove it, or come up with an easier answer".
I'm not personally in a good position to evaluate the merits of string theory anymore, and neither is anybody with merely the knowledge in that wikipedia article (though it helps). You should note, though, that the wikipedia article you yourself cited, cites Feynman, Penrose, and Sheldon Lee Glashow as making an even stronger argument Jane Q. Public is making -- saying that it simply is a failure as a theory, because it doesn't provide practical novel experimental predictions (in other words, it's not more complete than existing theories).