Now you see it, but what — and when — is it, really?

From Dec. 26, 2004:

I have wondered about this for a long time. Since sight involves light, do we see things at the speed of light or is there a time delay? If I look at my wife, am I seeing her instantaneously or as she appeared to be some undetermined amount of time ago?

Well, I don’t know. I’ve never seen your wife so I can’t tell how quickly she changes.

I’m sorry. That was just a dumb joke. This is actually a very good question. I just don’t know how you people keep coming up with such interesting stuff.

Did you know that it might be that elephants weep? As in cry from sorrow. I don’t know for 100 percent sure that this is true, but I came across it while I was looking up the answer to this howquick-do-we-see thing. Personally, I think an elephant crying its eyes out from sorrow would be just about the saddest thing in the world, don’t you?

And speaking of eyes reminds me that I once told this one guy I would mention his name here someday. Clive Sell. There you go.

OK, when you see something, light hits your cornea, goes through your pupil, goes through a bunch of other stuff like blood vessels and nerves and watery stuff, hits the lens and ends up on the retina. That’s where the real work gets under way. The retina converts the light into electrical impulses and shoots them off to the brain. Apparently the information the brain gets is not especially detailed, so it dips into your memory, such as it is, to fill out the details.

For example, your eye might see your wife, but the information your brain gets is just sort of generally wife-ish looking, but your brain kind of remembers seeing her around before so it just announces to the rest of your body that the eyes picked up on the little woman.

I could throw in a cheap-shot wife joke here, I suppose, but I like to think I’m bigger than that.

So how long does all this take? I am told it’s about 50 milliseconds — considerably less than a blink of the eye.