Meme Engine

David McDermot, Brian Greene
"There is no Time"
Radiolab

In this two minute clip, we hear the speakers grappling with language, trying to say that time should be thought of differently.  They can’t help using the words before, always, or never, even though they’re arguing for a point of view where those words aren’t appropriate.

As they repeat over and over that “this instant has always existed”, it sounds to me that they want to claim the time dimension is really just another space dimension (see an excellent post on this topic from the blog “See Things Differently”).  A nice layman’s way to think of dimensions in space is to realize that each extra dimension gives more room.  Room to maneuver, or just room for more stuff.

• 1-dimension: an infinitely long thread.
• 2-dimension: line up a zillion of these threads beside each other, so they form kind of a huge sheet of streched out fabric, one that stretches infinitely.
• 3-dimension: now take a zillion of these 2-dimensional sheets, and stack them on top of each other - so many that it starts to get thick like a mattress, then two mattresses, and on and on until it’s infinitely thick.  The result is 3 dimensional.

Notice how each higher dimensional space needed infinitely many copies of the previous dimensional space.  So, if you have room to draw a cartoon on your 2d sheet, then you can draw infinitely many cartoons (or 3d cartoons) within the fabric of your 3d infinitely thick matress.

The reasoning can be extrapolated one dimension more in an almost spacial seeming way:

• 4-dimension: take a zillion copies of your thick 3d mattress, and insert one into each tick of the clock, so you get a full 3d space each second.  If you had room for a sculpture in one mattress, you now have room for infinitely many sculptures in your 4d spacetime fabric.

So you see, time just adds more room for more stuff.  If you can get your head around viewing time spatially, then you have to admit that it’s just a huge hyper-mattress, and no one point is special enough to deserve being called the present.  Events happen at various points, but whether they are future or past depends where you look from, and which way you are oriented in the 4d mattress.

The 3d analogy is this… though I am sitting in my house, it would be silly to say that my current location is “special”.  Though I might say that my neighbor’s house is “ahead” of me, I don’t mean it objectively.  It would no longer be ahead if I were to face the other way, or walk over to the neighbor’s house, etc.  The neighbor’s house exists independant of any subjective directionality I impose on my 3d reality.

Does this translate to 4 dimensions?  More than we’d think at first.  But not so much we should throw away our watches.

Some credits: the audio is from my current favorite episode of Radiolab, hosted by Jad Abumrad and Robert Krulwich.  We also hear from David McDermot and Brian Greene.