We all know what it is… right up to the moment when we really think about it. Then, for me, it all falls apart. The more I think about it, the less sense it makes. Physics talks about space-time as a 4-dimensional thing but one of those dimensions, time, is very strange. In that one dimension we can’t stand still and the appearance is that everything moves in that dimension in ways and rates that we can’t control. Bidirectional motion is allowed in the other 3 dimensions but, apparently, only one way in the fourth. And so it goes… time is a very strange thing. Thinking about this topic both fascinates me and makes my brain hurt. 😉
There have been a couple of good books, talks and TV programs about the nature of time. One was a NOVA program and a few days ago I ran across the talk linked below. I found it first on the TED site but it’s better watched on the University of Sydney (Australia) site that actually hosts it.
Given in December 2009, the talk is The origin of the universe and the arrow of time by Dr. Sean Carroll, a theoretical physicist at the California Institute of Technology. His talk is in two parts, each of which is just under 30 minutes, so this one will need a fairly serious investment of time. But I found it well worth it–there’s a reason it made TED’s “Best of the Web” selections. Sean’s an excellent speaker (good example in fact of a presentation), an extraordinarily well qualified lecturer and the author of a couple of books about cosmology.
The talk is given at roughly the level of a high school or undergrad college physics class, so you’ve got the background for the talk. Yeah, I’ve got the background but that doesn’t keep it from stretching my brain a lot. And even if you hated that physics class, Sean’s good enough that he might even change your mind!
So, go let Sean tell you about time and enjoy.