SPIN CYCLE: I’m slowly going through my “Great Minds of the Western World” CD lectures from The Teaching Company. I’ve made it to the 17th Century, and just heard the story of Sir Isaac Newton. The great minds of the 16th and 17th Centuries were quite amazing, and Sir Isaac was the amazing of the amazing. In just a few months, mostly as a spare time project, Newton thought up the basic concepts and math for what we now call “physics”. And after he finished it, he stuffed his notes in a drawer and forgot about them until 20 years later, when astronomer Halley paid him a visit to discuss the motion of planets. Newton suddenly remembered that he had previously sketched out some math, but he wasn’t sure just where those notes were anymore. Luckily, he eventually found them and published them, and the world took a huge step out of the dark mists of ignorance and misunderstanding (i.e., a world where things moved according to “magic”).

Yea, you’ve gotta have a pretty big mind to put together the idea of “force equals mass times acceleration” and “momentum equals mass times velocity” and “the force of gravity is inversely proportionate to the square of the distance between two objects”. Put all that together with the recently invented Cartesian 3-dimensional coordinate grid, as Newton did, and you could relate force and mass and time and motion in one neat little package. Quite a useful thing, as it turned out. (Unfortunately, as always, the military was one of the first groups to see the value of this new idea; using Newton’s system, they could figure out with great accuracy where a cannon ball or an artillery shell would land).

Well, I don’t have a mind anywhere near as big as Newton’s, nor do I remember much about the math behind basic physics, despite having studied it in engineering school many years ago. But I was tempted to do a bit of ersatz “big thinking” myself after watching Brian Greene’s PBS special about superstring theory, “The Elegant Universe”. I was intrigued by the simple exposition of hidden dimensions that Greene presented — recall that one of superstring’s biggest conceptual challenges is its need for 10 or 11 dimensions, well beyond the 3 space dimensions and one time dimension that we perceive in our daily life.

Greene said that as far as we are concerned here in our day-to-day world, the extra dimensions of superstring are rolled up into tiny little balls, and thus they can’t take us anywhere relative to our three dimensions. He made an analogy to a long wire cable. You could step back and look at a long, straight piece of cable, and it looks like something that has only has only one dimension, i.e. length. However, if you zoom in on the cable, down to the perspective of an ant, it has two “degrees of freedom”: length, given that the ant can walk along the cable; but also, the cable has a circular dimension … the ant can walk in circles around the cable. That ant would hardly get anywhere if it just keeps on spinning round and round the cable; the circular dimension isn’t doing it much good, just as the hidden dimensions of superstring theory don’t allow us to do any hyper-dimensional transporting. (Hyper dimensional transporting would be really cool … if there were to be a linear hyper-dimension, you could disappear and show up a few seconds later in an entirely different place; imagine the fun you could have … here I am, now I’m on the other side of the room, now I’m across the street, now I’m back again, where will I show up next?).

Greene then said not to take this example too literally … it’s a “sort of” analogy, because the concepts behind superstring are much weirder and harder to understand. Well, doing some Newtonian big-think, but on a more literal basis (well below the level of superstring mathematics, which I’ll never come close to understanding, and not even up to Einsteinian relativity), it occurred to me that you might be able to come up with a different way of looking at day-to-day physical matter and movement. I wondered if Newton could have decided that there are six dimensions by which we should describe the movements in time and space of all matter. The first three are the highly apparent ones: length, width and depth. The extra three are circular dimensions that are wrapped around the big three linear dimensions, just as in Greene’s example of the ants walking around the cable. The first three dimensions are used to describe an object’s relative position and its linear movement. The next three couldn’t tell you a thing about an object’s position or linear movement, but they could tell you what it’s doing with regard to spin.

When you think about it, spin is a strange thing (I’m talking about regular spin, not the totally abstract and weird concept of “spin” for elementary particles … or the totally down-to-earth and weird concept of political spin). You airplane pilots are very familiar with spin; you call it roll, pitch and yaw. When you’re up there in the clouds, either on a Piper Cub or a jumbo jet, roll, pitch, and yaw are life-and-death issues for you. But for us non-pilots, well … try thinking about a spinning top (that is, if anyone still spins tops, like I did when I was a kid; one year it was yo-yos, the next year it was tops … I guess today it’s skateboards). A spinning top definitely has some interesting characteristics, all of which can be adequately described in three-dimensional space through Physics 101 concepts like “angular momentum” and “center of gravity” and “moment arms”. But still, back when I was studying basic physics, these concepts seemed like some sort of “retro-fit” to make a distinctive type of physical behavior (i.e., spin) comprehensible to our three dimensional system. So why couldn’t our physics have been based on six dimensions instead (plus time as the seventh), to better accommodate the reality of spin?

My mind is too old and weak to come up with what the math would have looked like in such a system. But I can take a guess here … it would describe every point on a grid based on it’s length, width and height relative to the starting point, then would also describe what that point was doing with regard to spin along the length, width and height axes (i.e., roll, pitch and yaw). Of course, those extra three descriptions would get pretty complex; when an object is spinning along an axis, one set of points in it is experiencing “true spin”, like the stillpoint center of a spinning wheel. The other points of a spinning body are flying around through length, width and height according to their radial distance and angle relative to that stillpoint axis. I’m not sure if all this would be a better way to describe a spinning object than the way that our 3D basic physics works. It might have been much more convoluted. But still, I wonder if it could have worked, if we could have gotten used to it, had spin been personally judged as something distinctive by the person who founded physics (i.e., Newton)?

Well, there isn’t any practical value in my ponderings here. None whatsoever. But nevertheless, it’s fun (for me anyway) to put one’s self in Newton’s shoes, and see what other approaches he might have taken to describing how things work in our “regular world”. Things are the way that they are for historical reasons, but it’s interesting to ponder whether they could have been different. Not necessarily for better, not necessarily for worse … but different! Who knows, maybe someday we will make contact with an extra-terrestrial life form, and maybe their basic physics will use three linear dimensions, three
spin dimensions, and one time dimension (just as their number systems may not be based on multiples of ten, as ours is). But then again, they may be so advanced that our theoretical 11 “superstring” dimensions will be accepted doctrine to them. Or maybe they will be up to 47 dimensions or some crazy number … who knows!!!