Monday, 14 March 2011

Is time a dimension?

In my previous post I described the 10 spacial dimensions proposed by M-theory but the theory says there are actually 11 dimensions. The 11th dimension isn't spacial (or space-like) - it's time.

When I dare to think that I'm beginning to understand the bigger picture of reality, the definition of time always messes with my mind! When I try to consolidate my ideas about time, I always hit a new obstacle or paradox that perplexes me. This post is no exception! I am just about to publish and I still seem to have more questions than answers about time!

Question: What IS time?

The following video shows how the greatest minds in physics have still not tied down an answer to the question "What is time?".

(video 5 of 5)

Question: Does time behave like it is a dimension?

We speak of our perceived reality as "space time" and time is often referred-to as the 4th dimension.

But does time qualify as a dimension? Is it at right angles to space? Well, in order to be orthogonal to space, it must be possible to move in the direction of time without changing your co-ordinates in any of the other dimensions. So time satisfies that condition: standing on the spot, you move through time without moving through space.

In the Brian Cox video above (at 03:56) Dr. Fay Dowker describes time as "granular". She is proposing that time works as a series of finite 3D snap-shots - lets call them "now-points" - that evolve or grow from the current moment. She says that, in order that the future can evolve in an infinite number of possible different ways, it has to consist of discrete now-points at which choices can be made. If time were continuous, then there would be no now-points and no opportunities to choose. In other words, if time were continuous, that is the same as saying that the future is pre-determined and there is no such thing as free will.

This description of time as an infinite number of now-points stacked side by side is a similar to my previous description of a 1D line as a collection of zero-D points stacked side-by-side. Again, this supports the idea that time is a dimension.

Question: So, what IS time then?

I have just discovered this short video which introduces a new gravity model called "Quantum Gravity From Causal Dynamical Triangulation". The computer simulation of this model reproduces interesting "quantum foam" effects on the small scale and yet on the large scale, generates a universe that resembles our own.

(Utrecht University)

Renate concluded (at 09:35) with two preliminary findings:
(1) Time is fundamental: time and causal order exists at the smallest scale
(2) Time persists: it existed before the Big Bang when there is no space.

I interpret the first point to contradict Fay Dowker's idea that, at the Planck scale, time is granular. However, Renate did not expand on her conclusion so I'll have to come back to this point when I've had a chance get more information.

The second point seems to be saying that time lies outside of space and you could conclude from that that she is suggesting time is pan-dimensional. That would mean that time is infinite and does not have a beginning and an end as the Big Bang theory implies.

Renate says (at 11:32) that to fully understand time, we need a consolidated theory of quantum gravity and a theory of how we perceive reality. I hope to see others take up this philosophical challenge in the near future.

Question: Should time be the 4th dimension or the 11th?

I'll let my Twitter friend, Canadian philosopher Rob Bryanton tackle that one for me:


Rob points out how time is a bit tricky to deal with since it only seems to go one-way. He resolves this conundrum by stating that time is just a direction in the dimension that he calls duration and we have time and anti-time in the fourth dimension just as we have the directions up and down in the third dimension.

I like Rob's deductive reasoning and I will return to the elusive nature of time in future posts. By placing time at only the 4th level, we are saying it's a subset of the 5th and that the higher dimensions are therefore beyond time. Renate Loll (above) seems to be suggesting that we need to rethink this point and indeed our whole perception of time.

Question: Is time just a human construct?

This is a big question and I'll try to offer a few clues to the answer in my next post "A Subjective View of Time"

From the perspective of THIS universe, I am "The REAL" Jeff Hall

More Information
In the following link, a new theory of space time suggests that time does not exist as a dimension. It's interesting to see the level of angst in the comments to this post

You'll need to take a deep breath before watching the following video in which Rob explores some of the implications of time lines and granularity