March 2013 Archives

March 3, 2013

Flame Challenge

I've entered the Flame Challenge.  The challenge, specifically, is to answer the following question, scientifically (i.e. not poetically), for an 11 year old, in 300 words or less or as a graphic or video entry.  The entries will be judged by 4th-6th graders in schools in the USA.  It was too much of a challenge for me to resist, and now that the deadline has passed I can reveal my answer:

What is time?

Imagine looking at every slice of a loaf of bread, one by one, starting with the crust at one end and progressing towards the other. First you'd see the crust, then you'd see all the slices from the middle of the bread. If the loaf had an air bubble inside, then you'd see a hole in some of the slices. The slice from right at the edge of the bubble would have a small hole, and the ones which were cut right through the middle of the bubble would have bigger holes. On your way through the slices, you'd see a small hole first, then a bigger one, then another smaller one, then no hole at all.

The passing of time from moment to moment is like moving from one slice to another. Many things stay the same, just like every slice of a loaf of bread looks roughly the same, but some things change --- like the sizes of the holes in the bread slices. Things that change quickly, like an explosion, look very different from one "slice" to the next. Things that aren't changing at all look exactly the same in every slice. Something that's moving, like a car, changes its position from one slice to another.

When you think of time this way, you see that the passage of time is quite similar to moving along in distance. This is actually how scientists often think about it, too. Have you heard of Einstein's Theory of Relativity? That's based on treating space and time as very similar things. The main difference is that we have no choice but to move forwards in time. You can choose to stop moving through the slices of bread and spend longer looking at a particular slice, but you can't stand still in time!

My approach was to make the link between the dimension of time and the dimensions of space by using a familiar household object.  There's so much more that I could've added with a longer word limit, like how things can be measured in time and space by creating an object that changes its appearance regularly along the dimension of interest.  A ruler is just a stick which looks slightly different as you move along its length (the numbers go up), and a clock is just an object which looks slightly different as you move through time (the hands go round).  You can even extend the concept of a crystal to dimensions of time as well, making a space-time crystal.  What I find most interesting of all is how our perception of time is linked to its physical reality: exactly why are we compelled to advance through time, while having apparent free will concerning our movements in other dimensions?  Is it all in our heads?  Perhaps somehow related to the second law of thermodynamics applied to the physical and chemical processes in our brains?

The winners will be announced at the World Science Festival in June this year.  In the unlikely event that I win a trip to NYC at that time, I'll be flying in a highly sleep-deprived state from an experiment at the Linac Coherent Light Source.