String! Theory! What is it good for ?!?

And all this, amazingly, before we even got to Woit and Smolin. Peter Woit - WikipediaWoit runs the blog mentioned, which discusses disciplines and ideas he and his supporters class as pseudoscience, using an organizational theme derived from Pauli's comments regarding useless speculation. Not Even Wrong Not even wrong - WikipediaLee Smolin's story seems a little more complex. He originally wanted the demogorge of String Theory to eat his ideas about Loop Quantum Gravity just as it had eaten Relativity, Quantum Mechanics, Supersymmetry, and the most substantial amount of the LHC schedule. But when the elitist academic aristocracy sniffed at his little preciousss and said "No thanks, Man" he vowed to bring their ivory towers down around their ears. Lee Smolin - Wikipedia

Here's a bit more Smolin. Interestingly, for someone who says superstring is unfalsifiable, he sounds like he's proposing two ways to test it Lee Smolin - WikipediaIs this just nonsense though? The "wormholes as magic breaking causality" sort of problems I'm vaguely familiar with all seem to start with building your wormhole with both ends local and then dragging one end around spacetime to the place or relative date that you want to be able to stargate to. Obviously that won't work in this case. Is there something in string theory that would imply we could get our negative mass or perfect vacuum or whatever configured in such a way as to punch a hole through to another brane?Here's what Susskind says about Smolin now, having sparred with him Leonard Susskind - Wikipedia

... is suffering acute topic splay in a couple of places. I'm culling these remarks from Message 119 of Speed of LightLet's answer this stuff here where it belongs.Just off the top of my head, the other dimensions in M-theory aren't fictitious, they are theoretical. In physics the word "fictitous" has a specific meaning, as in the case of fictitious forces like centrifugal force. These are effects that we find convenient to describe as if they were forces, but are actually inertia acting in resistance to real forces.Also, I can't find anyone who is credible who says that string theory is in principle untestable. They just say that it will cost a lot, same as Relativity and the Standard Model have so far. Feel free to post references, though ...

This isn't totally out of line as an analogy, in that it's similar to the way that dealing with extra dimensions actually affects the math.My favorite example for explaining cube-square effects is King Kong. If we take a normal 5-foot tall gorilla and make him "ten times bigger" -- ie 50 feet tall, and proportional -- we are actually increasing his total volume a thousand times. He's not just ten times as tall, he's ten times as wide, and ten times as deep, see?So the first thing that happens is, he falls over. His feet support him based on a ratio of surface to weight, and while the weight has increased at least a thousand times, the surface has only increased one hundred times. In order for his feet to support him at "ten times bigger" (cubed, a thousand times) they themselves are going to have to instead be a smidge less than 32 times bigger (squared, 1024 times) to hold him up. And they won't fit on top of the Empire State Building anymore, will they? (The second thing that will happen is, his bones shatter, because they would need to be 1000 times as dense to support his weight, and changing size won't get you that, he needs a whole different kind of bone structure, but that's enough of this.)So now let's consider Mr. A Square, of Flatland, who is only aware of two dimensions. The things he thinks of as volume are what we consider surfaces, the things he considers surfaces are what we would call borders. But he has some genuinely 3-dimensional objects penetrating his reality, of which he is only directly aware of a cross-section of. These are alive, for the sake of argument, or some kind of crystal perhaps, that he can effectively "double" the size of by feeding or watering or whatever. Because he is aware of two dimensions, he understands that this is really making them "4 times bigger" from his viewpoint. But in experimentation, by trying to move them around, for example, he determines that they are actually becoming 8 times heavier.If he thinks about this enough, and extrapolates, he may come to understand that there must be an unexpected third dimension, that he cannot experience in the normal way that he experiences the two he has. If he keeps investigating more and more of these crystals or whatever they are and experimenting, he can become pretty sure of this.Other phenomena that might alert him to this state of affairs are, if things somehow flip into mirror images of themselves from his point of view. This can happen to 2d objects because of rotation through the 3rd dimension. Another might be, if there are things that seem to appear and disappear, due to the fact that they sometimes penetrate his plane and at other times do not. Stuff falling down onto Flatland and bouncing off, for example. And so on ... He may even figure out a way to move himself in this newly-discovered unsenseable direction!Now, with quantum mechanics we have long suspected the existence of more dimensions than the 4 we know. We get a lot of effects that seem to indicate this. When we split a photon, we don't get two half-photons, we get two complete photons at half the amplitude. When we break up fermions we get even more astounding results! Fractional spin is another great example, we have to turn a quantum particle around not once but twice to get back to our original state.Just as a side note, almost everyone tends to use a 6 dimensional view of reality to get through their day: 3 of space, 3 more of time. That is, we believe we can make real decisions about the future, some aspects of which are objectively better or worse (up-down in time) and some of which are just personal preferences (left-right in time.) This has a lot more to do with conceptualizing Wheeler's "Many Worlds" than it does with genuine M-theory, but I think it's relevant to the discussion of whether other dimensions are useful or not, real or not.

I see part of where this conversation is going wrong. You are eager to assert that the other worlds or "branes" of M-theory are unprovable, purely theoretical, do not exist, cannot be observed, or a similar argument along those lines.This debate, like many of the debates you try to engage in, is getting bogged down in semantics. Media saturation in the form of things like Twilight Zone, comic book universes, and yes Star Trek, have confused the question of these other worlds or spaces or realities with the concept of "other dimensions". I will go into why this happens in more detail in a bit, but for now here's this quote from the wiki Catholic Scientist linked you to Dimension - WikipediaA dimension is just a linear measurement, like length, width, or depth. A single linear measurement, like the length of a pole, is one-dimensional. Two linear measurements which meet at some point, like the length and width of this screen, define a plane, which is two-dimensional. Add depth, which we do not see directly because our eyes are surfaces, but can infer by touch and have learned to see via a convenient optical illusion that we create by focusing two eyes, and you have defined the three-dimensional space we pretty much all admit to. "3-d" movies operate by presenting slightly different images to each of our eyes, taking advantage of this illusion to make us see depth that isn't really there.Note that these are what we could call real, non-fictitious dimensions. This isn't a bad point to argue. Temperature, on paper, is certainly a linear measurement. We can do a lot of good math by treating it as such. For example, imagine a graph showing distance from the sun as length (y) and average temperature as width (x). The line we draw on this graph correlating our measurements tells us a lot about radiation levels. We do geometry with numbers like this all the time, it's very useful.But as far as we know so far, temperature in this sense is what we could definitely call a fictitious dimension. That is, while we find it convenient for some work to treat it this way, it does not appear to represent an actual direction at right angles to the space we conceive ourselves as existing in. We cannot point at temperature using a constant and say, this many degrees equals this many feet, uniformly.Time, as it turns out, is different. Our experiments with light revealed, to our dismay, that there is such a constant in this case. 1 second of time equals about 186,000 miles (300,000 kilometers) of space. Yes, that means that as you sit there, your perception or identity or "soul" is moving at about 300 million meters per second into the future! This is a very disturbing and counter-intuitive concept. But that doesn't make it untrue. Every experiment so far confirms this, it's the way things really are.Real science is full of facts like this. Most people understand, or think that they understand, that the earth is rotating. But when I point out that that means that they are traveling east at about a thousand miles per hour, give or take a few hundred depending on their real distance from the equator, some of them get physically ill. They tend to crouch a little, and ask why the thing doesn't rip itself apart. (The answer is, it does, in the form of earthquakes, continental drift, hurricane winds, etc.)That's enough of this for now. If you want to attack the branes, call them branes. Don't confuse them with the extra dimensions (linear directions) which separate them from our own alleged brane.Edited by Iblis, : linkEdited by Iblis, : &spelng

False. It is one of the most successful equations in physics. Message 75False. The smallest quantum of length (Planck length) that appears to be possible in a spacetime shaped the way ours is is about 1.616 x 10^-35 meters. (The negative exponent there represents an exponential fraction. 10^-4, for example, would be 1/10,000 so 10^-35 is 1/(a 1 followed by 35 0s).)As 1 second is demonstrably about 300 million meters, the minimum quantum of duration (Planck time) is about 5.391 x 10^-44 seconds.Planck units - WikipediaEdited by Iblis, : spelligEdited by Iblis, : &punctuation

Brilliant post! I'm still confused, of course (it comes from being a bit of a moron, you know.)Does M-Theory consist of the tiny 2d pipes of simple string theory, plus the 3d+1 normal spacetime, plus 5 more? Or, if M-Theory is still uncertain, does real String Theory consist of the 2d pipes plus 9d+1 plus perhaps this extra one to make Supergravity work?What I'm asking really is, are the 2 dimensions of the String Theory tubes a part of, or in addition to, the count of spacetime + extra stuff that makes a total of 10 or 11? In other words, should the real total be 13 or 12, or not?Feel more than free to throw in anything that helps define what the extra dimensions do for a living in a practical sense, the way gravity, magnetic poles, rotation, and entropy give us markers to help describe what the normal 4 dimensions are about. Please.PS: OK, on closer examination and repeated attempts to imagine, I believe I see that one of the dimensions of the tubes is just normal time, and the other is the extremely curved "circles", considered as 1-dimensional. I think. So maybe what I'm asking is, is this 1 dimensional circularity in addition to, or part of, the count of 10 or 11. And anything I can get to help imagine what the other dimensions are doing, of course. Thanks!Edited by Iblis, : No reason given.

So it's more like f(2d)=10d, and/or f(??}=11d; where the function in question is the stuff being discussed (very sparsely) in HOLOGRAPHIC UNIVERSE? .I loved that stuff in Warren Ellis's Planetary. Of course it's brilliantly ironic there, in the sense that they really obviously are an array of 2 dimensional representations extrapolated out to a full-scale multiverse (ie, a comic book.)
circumstantialAnyway, this is a minor disappointment, in that I seriously thought I understood what at least one of the allegedly so-curved-as-to-be-irrelevant-outside-quantum-mechanics extra dimensions was up to, and now I guess I don't. Oh well, che sera, sera ...

OK, I'm going to skip over what I've been trying to digest about the pipes (and also spin) for the moment, and try again. This is the sort of place I want to start, yes. This extra 5th dimension, unlike the other 4, which may or may not be curved inward such that they theoretically lead back around to wherever you started from, but it's all academic, because you could never live long enough or even go fast enough to ever actually make the trip in any way; this guy, this 4th spatial dimension, is curved inward on itself so much that it is only recognizable as a direction at all in the very small motions and interactions of the subatomic waveforms/particles. Yes?But that smallness doesn't have anything to do with its location. Like North, or Up, or Left, I can move in these 7th and converse 8th directions from anywhere in the universe I happen to be. I just get right back where I started from so fast I never even know I'm gone, unless I happen to be a Micronaut of some kind. To a photon, however, motion or force or spin to or from this tiny direction is a noticeable thing which has a real effect on its relationship with the other dimensions. Good so far?So Ok, that covers electromagnetic fields and photons. Is there one for each field? One for each boson? Various combinations? And which of them are big enough to significantly allow room to fit in these many branes, some of which may be similar to, and others wildly different from, our own spacetime?

I love this stuff Sadly, I have to point out to you that Mr. A Square cannot see the top and the bottom of the square. He can only see the edges. This is because, for him to see things, light has to pass through the 1-dimensional lens at the front of his eye and strike the 1-dimensional rods/cones inside his eye. This means he can only properly see light that travels directly along the plane he is in, and such light can only show him the edges of things, never the surfaces. The surfaces of stuff in his world are similar to the volume of things in our larger world, we cannot see inside each other, can we?A better example might be if he and his fellow Flatlanders had an opening on one edge that they used as a mouth, and then to the left of it, an outcropping that they used as a nose. If we were to take one of his buddies and flip him over, his nose would now be to the right of his mouth! This is the sort of thing that would be impossible in a 2-dimensional world view, it would be like someone in our 3d space suddenly having their heart on the right instead of the left. If such a person also became dyslexic, trying to write from right to left for example, and had a gold filling on the left side of their mouth instead of where the dentist put it on the right, we would be bound to eventually start theorizing about a 4th dimension that they had somehow been rotated in.This is the sort of thing that makes the magic of n-dimensional geometry work. It's what could allow us to do surgery on someone without piercing their skin, or to "walk through walls". Take a coin to represent your flatlander, and stick it in a brownie pan. Move it forward and backward, left and right, it has no way out of the closed area it is in. This is Timmy Leary in San Luis Obispo County Jail, or John Dillinger in Crown Point. There is no way he can possibly escape!Now, reach down, lift him out, deposit him outside the pan somewhere. Wow! Looks like teleportation, don't it? But really it's just an ordinary day in the third dimension. Meanwhile, his little coin guards are coming up with a story about inside help or a fake gun made out of cardboard to explain this "impossible" feat.Now, back to the way his eyes work. Interestingly, light travels in all directions, so it IS possible for some light to reach his rods and cones without traveling through his lens properly. This light could give him vague glimpses of worlds near him, but because its dim and unfocused, it will be screened out by his brain entirely as long as his eyes are open and focused on things. If he closes his eyes, he may see vague spots and flashes though, indicating there is still some light coming from somewhere. If he becomes totally relaxed, and stops focusing altogether on what he thinks the world is limited to, he may even be able to get vague cross sections of the other "flatlands" nearby which are quite similar to his own. What he would see though, even under the best circumstances, wouldn't conform to the laws of nature he knows; because, being a composite, effects would not naturally seem to follow their causes and many unreal things would appear that were not really part of any 1 plane, but rather a combination of things happening on many planes.Now, try this experiment. First, close your eyes. Report what you see? Good, keep them closed for a while, becoming more and more relaxed. 6 to 10 hours ought to do. When you wake up, report what you saw. Keep doing this for some time off and on, decide what it might mean about the universe you appear to be living in