Tuesday, January 23, 2007

Time as a spatial dimension

How is my "way of imagining" ten dimensions different from what a student of physics or string theory would be taught? The simplest answer is this: I start from the assumption that time is part of a full spatial dimension. Most of us have gotten used to the idea that time can be called the fourth dimension, and Einstein's theories of spacetime have shown us that we can imagine time as a dimension which can be bent by large masses or concentrations of energy to create gravity, or stretched by near-speed-of-light travel to create twins who are no longer the same age. However, even though a dimension which can be bent and stretched may sound like a spatial dimension, the traditional scientific position has always been to keep time as a separate quality which is overlaid on the other spatial dimensions: when string theorists have talked about a reality created in ten dimensions, they were really referring to nine spatial dimensions, plus one temporal dimension. Likewise, M-Theory's eleven dimensions are actually based on ten spatial dimensions, or eleven dimensions when time is added in.

When I propose that time is part of a full spatial dimension which we third-dimensional creatures are experiencing in a limited way because we are built from chemical reactions and processes that obey the thermodynamic laws of entropy, I go out on a limb where some are not willing to follow. By blending concepts from Edwin Abbott's famous book "Flatland: a Romance of Many Dimensions" with concepts from string theory, quantum physics, the anthropic principle, and Everett's "multiverse", and then throwing in concepts from Minsky's Society of Mind, Dawkins's theory of memes, and metaphysics/New Age concepts of souls/ghosts/reincarnation, I fully realize I am trying to blend schools of thought which to some might appear to be completely incompatible. Nonetheless, the feedback I have gotten on my book has been generally very favorable: I believe that this is in part because I have always been quick to acknowledge my position as a generalist, and that my framework for discussion extrapolates beyond what you would be taught in a physics class today. That is one of the reasons I was so pleased to have famous author Greg Bear give me his endorsement for my book: "a fascinating excursion into the multiverse--clear, elegant, personal and provocative". Having a Hugo and Nebula winning science fiction author acknowledge what I've created as being an interesting take on the nature of reality puts, to my way of thinking, just the right spin on the project: this is a work of imagination which many have found thought-provoking, but no one should feel they are being tricked into believing that this proposed framework is the currently approved teaching of mainstream science.

To be clear, the supposition that time and space are part of a larger system which we are experiencing in a unique way is not just science fiction. To quote from my book: "string theorists have been expressing concepts which we once expected to hear only from yogis and gurus. Nathan Seiberg, of Princeton’s Institute for Advanced Studies was quoted in the Los Angeles Times as saying 'I am almost certain that space and time are illusions'. Edward Witten (one of the most respected researchers in modern physics, and the man who first advanced M-Theory) has said that 'time and space may be doomed'. Viewpoints such as these hint that the way of looking at the dimensions we are exploring in this book may not be a outlandish as some might think."

What about the fashionable groundswell that has arisen lately saying that string theory is unprovable conjecture, and "not even wrong"? Where does that leave my way of imagining reality? Since the concept I am proposing was only distantly related to mainstream string theory in the first place (as a few string theorists have pointed out online), the question is not really relevant. I have proposed a way of imagining higher dimensions, based upon the unusual assumption that "time" is really just the way you move within a particular dimension from one state to another: for us, we experience time as the fourth dimension, but for a two-dimensional Flatlander, "time" would be the third dimension, and so on. Time exists in no dimension in particular, then, it is just a way of moving within whatever dimension you are currently examining, from one state to another.

One of the conclusions I reach in the book is that our reality is based upon a series of points that are no less than the planck length apart from each other, drawing the line that we experience as time. The simultaneous wave/particle nature of subatomic particles, then, would be a result of this process: waves of probability are observed in the assembly of slices that we are moving through, each "slice" representing a three-dimensional state of our universe, and each slice being a point on the fourth-dimensional line we are drawing from the available fifth-dimensional choices (and in quantum terms, each slice being an observed/collapsed state of those probability waves).

Last June, Scientific American released a wonderful special edition issue called "A Matter of Time". Lee Smolin's article in that issue, "Atoms of Space and Time" introduced me to "loop quantum gravity". I found this article very interesting because I could overlay it on my "way of imagining" quite easily. Loop quantum gravity is based upon the same supposition as mine: that our reality is defined by discrete packets of time and space, creating the illusion of continuous reality that we see around us (which in no way, of course, is intended to say that Lee Smolin would endorse my way of imagining the ten dimensions!).

Last week I started reading Mr. Smolin's book "The Trouble with Physics", which discusses some of the other theories of reality apart from string theory, and I would recommend this book highly as an excellent alternative to the books by Kaku, Greene, and Randall that I have recommended on my website.

Enjoy the journey,



Anonymous said...

I've never understood why time was singled out for special treatment. It has always seemed so odd, but I've assumed that trained physicists must have some rationale. It's nice to see someone willing to embrace what is, I think, the most reasonable position. Your approach to imagining 10 dimensions is wonderful. Nice work.

Nick James said...

I'd just like to thank you for your little animation. I won't pretend that I can actually visualise what these dimensions look like because that would simply be hubris. However, working up to them in a logical manner at least gives me the illusion of understanding, which is good enough for me.

Anonymous said...

You are correct time is not a spatial dimension, it is instead our limited perception of linear movement through the fourth spatial dimension. Time in 'n' spatials dimensions is a byproduct of linear 'n+1' dimensional movement, and accordingly time within a given dimension is theroretically independant of time in any other dimension. I'm still trying to work out how this plays into key forces in our dimension. (gravity, electromagnatism, etc) I'm also still trying to figure out what significance velocity in 3 dimensions (c in particular) has in terms of the fourth.

Anonymous said...

Being a layperson of physics I know doesn't really qualify me to spout off at the top of my head, but I just can't help saying something about this topic. Which is, that time must have some dimensionality to it to behave as it does in Einstein's theory of relativity. Whereby time slows the faster an object moves (relative a stationary observer.) So that one could begin to think of it a something spatial? Which I couldn't express in terms of height, width, and length, but more as a line extending straight ahead that slowly bends back on itself as if to retrace itself or to move in opposite parallel motion. Perhaps in the shape of a loop? Or again, as in the horizontal sweep of a TV image that creates a two dimensional image that appears real but is more an illusion of three dimensions?

randwulff said...

I always wondered: if time is a spatial dimension, where did we get the momentum to move along it in the first place? If time is like the traditional three dimensions and we are travelling through it, some force must have been applied somewhere, no?

Rob Bryanton said...

Hi randwulff, there definitely does seem to be something drawing us forward with the arrow of time, and there are many scientific opinions about why this is. With my project I insist that it's because you and I derive our energy from thermodynamic chemical processes which move towards higher entropy, and that is the way most physicists describe the timeline of the universe: the beginning had the lowest entropy, the end will have the highest entropy, so that's the direction we observe as living things.

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