Here is a quotation from Smolin's description of the development of a theory called "string theory" (p. 64):
What was even more significant is that in the cases where the program worked, physicists--beginning with Yochiro Nambu, Holgar Nielsen and Leonard Susskind--realized that the solutions they found did not correspond to the traditional conception that a fundamental particle is a point that has no extension or dimension. Rather than behaving like mathematical points, they behaved more like stretched, one dimensional objects, something like rubber bands.
This led to the idea that perhaps atomism is right, because there are fundamental things in the world. Only these things are not to be visualized as point particles; they are instead one-dimensional. These fundamental one dimensional objects are what we call now strings. Just as a point has no size, these also take up no space, as their diameters are zero. But they do have length.
OK, let's analyze this for a moment. What it sounds like Smolin is saying is that there were two ideas of what the world is fundamentally made of being discussed. One idea was that the world is made up of point particles which take up no space and have no size, which have no length, height, or depth. The other idea was that the world is made up not of point particles but of one-dimensional strings. These strings take up no space, being one-dimensional, but they do have length.
Here's the problem: Taken at face value, both of these ideas are meaningless nonsense. In case you haven't noticed, material objects take up space. They have size. They have dimensions--height, width, length. So how could they be made up of particles which have no size and take up no space? And what even is a "particle" which has no size or dimensions and takes up no space? It is exactly equivalent to "nothing." Material objects, by definition, have size and dimension and take up space. That's just what "matter" is. If you remove size and space from a material object, you remove its very essence, its very substance. So why in the world are we talking about material particles which have no size and take up no space?!
The idea of "strings" is even better. They, too, take up no space. They have only one dimension (length, I guess), but no height or width. But this concept, too, makes absolutely no sense taken at face value. What in the world is an object that has length but no height or width? If a supposed "material object" has no width, it has no substance at all. But these amazing objects, which have no material substance at all and take up no space, yet are of definite length. "Nothing" now has a definite length, and is the fundamental building block of all material objects!
What in the world is going on here? I think we're still in the world of serious scientists. I don't think these ideas are intended as an elaborate practical joke. But, taken at face value, they are meaningless gibberish, utter nonsense. Yet these scientists talk about them as if they make perfect sense, and they claim that the ideas make predictions that can be tested, etc. One possibility to explain this bizarre situation is that the physicists have developed mathematical formulas that work to describe in mathematical form the sorts of observations they are making. Perhaps the whole thing makes sense as math, and they are simply using extremely odd and misleading ways of communicating these math concepts as descriptions of objects and functions in the real world. Perhaps they have failed to distinguish between mathematical ideas that work in mathematics and descriptions of physical reality. For example, 2-4=-2 works just fine in math. It is a very useful idea. But as soon as you start to think that the formula is describing an actual material state of affairs ("I had two apples on the table, and I took four away, so now I have negative two apples on the table."), you run into serious trouble. Not all mathematics describes material objects and functions. Sometimes mathematics works at a purely logical and theoretical level--which is very useful, but not to be confused with one-to-one descriptions of what can exist or go on in the physical universe. In the case of some of these ideas in modern physics, I really don't know what is going on. My guess is that there is something of value here in terms of mathematics, and that either the scientists are using language I simply do not understand or they are using the wrong language (either because they are simply misusing language or because they truly are confused about the distinction between mathematical formulas and descriptions of physical reality).
Here's another example of the same sort of thing, from the same Lee Smolin book. This time, we are talking about the odd characteristic of string theory to require more than three dimensions to exist in the universe. If this seems like a problematic situation to you, welcome to my club. But, have no fear, string theorists think they can solve this problem (p. 67):
The idea is to postulate that our world does have nine dimensions, but that six of them are rolled up, so that the diameter of the universe in these directions is not much more than a Planck length. There would then be no way for any of the elementary particles, such as the protons--which are twenty orders of magnitude larger than the diameter of these curled up dimensions--to know about anything other than the three remaining dimensions.
Feel better? I hope not. If I'm understanding correctly, what I just heard was this: "String theory has the unfortunate characteristic of adding six dimensions to the universe in addition to our usual three, which seems to be a problem. But not to worry! The other six dimensions are all rolled up into tiny little balls, so they don't get in the way."
It will be helpful here to remember what a "dimension" is. The three dimensions are height, width, and length. They are nothing other than directions in space. There are three fundamental directions you can go (or grow) in space. Imagine yourself standing in the middle of a room. You can go 1. forwards and backwards, 2. left and right, 3. up or down, or 4. a combination of these. Those are the only possibilities in the physical universe. There just aren't any other directions to go, if you think about it. But string theory is telling us that there are six other directions things can go (or grow) in. Perhaps you are wondering why you haven't noticed them? Well, it's because they're itty-bitty and rolled up into little balls. What?! We're talking about directions, right? What in the world does it mean to say that there are six directions that are rolled up into tiny little balls?! Directions are not material objects. I can roll playdough up into little balls. I can roll paper up into little balls. These are physical objects or substances. But directions aren't that sort of thing. You can't pick up a direction, put it in your pocket, drop it on the floor, put it in some water to see if it floats or not ("Look, dad, I just put 'up' into a glass of water, and it floats!" "That's really neat, son!").
Again, I don't think I'm the victim of an elaborate practical joke. These PhD scientists seem to really mean what they're saying. But how can they? How can anyone with the smallest modicum of an ability to think in a logical and intelligent manner speak seriously this kind of complete nonsense? Again, I suspect that there is some mathematical truth at the heart of these things, and that something is going seriously wrong in communication or translation. But I wish I could figure out what it is, because they're driving me nuts!
I'm sure I'll be writing more on this in days to come, and it will end up under the label "Modern Physics". So stay tuned.