YOU LIVE IN THE PAST

Hey, Vsauce, Michael here, and today we are going to be talking about the past. But not like history—in fact—we will be talking about what we call now. This very newest moment in time, and the fact that we can never really be aware of or live in what we call now, because it takes time for our brain to process the information about what's happening now, and it takes time for that information to get from the rest of our body to our brain.

In fact, the taller you are, the further back from now, the further back from the past you live. But more importantly, why do we call emotional, relationship-based movies targeted at females chick flicks? Well, for the answers to these questions, we're going to start with the flash lag effect. David Eagleman has done some amazing research on this effect. It's what occurs when a participant looks at a ring moving around in a circle. A light is flashing exactly in the middle of the ring.

This is exactly what the photons landing on their retinas represent. But when asked what they saw, participants responded they saw this. Now, for the longest time, it was hypothesized that people said this because our brains guess ahead. Our brain assumed that the ring would continue doing what it had been doing, and figured it would be safer to go ahead and say that the ring was already a bit ahead of the light.

But Eagleman wanted to know what would happen if when that flash of light occurred in the middle of the ring, the ring all of a sudden reversed direction and spun around the other way. If our brains really are guessing ahead, participants should still say that they saw this, because the brain figured that the ring would be there and were surprised when it went the other direction. But instead, participants said that they saw this.

Now, how could they have seen this if they had no way of knowing that the ring was going to reverse direction? Were their brains clairvoyant? Can our brains see into the future? As it turns out, no. What's really happening here is that our eyeballs are receiving an image—an image of a flash of light inside a ring. But then our brains wait a little bit to make sure that we have the full story.

And as the ring begins to reverse direction, that new information is incorporated into what we actually sense, and we become aware of the wrong version of now. By doing more studies with rings traveling at different speeds, Eagleman was able to determine that what we are aware of as now, what our brain tells us is happening actually happened 80 milliseconds in the past!

Now, 80 milliseconds is not a lot of time, but it's a little scary to think that our brain has no physical way of knowing, being aware of, or even living anywhere but slightly in the past. Nerve impulses travel through our body at a top speed of around 250 miles per hour. But now, look at Bill Warner on a motorcycle. He's going really fast. In fact, he's going 278 miles per hour, which means that this guy on a motorcycle is traveling faster than my brain can even figure out what now is.

Keep in mind that 250 miles per hour is the top speed for neural impulses within our body. If I tap my nose and tap my toes at the exact same time, it feels instantaneous, even though there is no physical way that the brain could actually be receiving that, because when I tap my nose, the message goes right into my brain. But when I tap my toes, the message has to travel across the entire length of my body.

The brain waits momentarily to make sure that there's nothing else going on or coming in, and then corroborates all that information and we become aware that the taps were indeed instantaneous. But we don't become aware of that tap until the brain is sure, which means that the taller you are, the longer the brain has to wait for that physical message to come from your toes, the further behind you technically are in actually feeling the touch—the further back in the past you're living.

When there's a delay like that between sensory information or brain processing, we become used to that delay and begin to just see them as instantaneous events, which leads to some weird behavior. If participants are pushing a button that causes a light to flash with a delay between the two actions of about 80 milliseconds, they will learn that it's instantaneous.

But if the researchers shorten that distance so that now when the button is pushed, the light flashes in only—let's say—40 milliseconds, the participants, even though they are actually causing the light to come on, will deny it and they'll say, "No way! That came on before I pushed the button! I didn't do it!" That was also a flash of light.

But light bulbs don't receive a continuous direct stream of electricity through the wire. Instead, they receive alternating current in most businesses and households. So the filament is actually being excited and left alone about 50 to 60 times a second. But our eyeballs don't notice any flicker for a few reasons. One, it's happening really fast, but mainly because that filament continues to be super hot during that little gap in time.

The only way to really see this flicker is to use a high frame rate camera when a light bulb is being turned on or off so it's cooler. There's the flicker. You know what else flickers? A film projector. It's easy to think that a film projector works merely because a roll of film is dragged across a light source, but if that were the case, a movie screen would be a blur of fast moving images.

Instead, a shudder is used. The shudder opens and closes to let an image hit the screen, and then when shut, the next image comes into place and it opens and puts that on the screen. Now, early films were shot at only about 16 frames per second. So sitting in the theater, you would see a bright image flashed 16 times on the screen, which was not fast enough to not be noticeable.

So, movies flickered, which is why they were called flicks, which is where we get the word chick flick. All right, I'm gonna go now. And of course, by now, I mean I will leave 80 milliseconds before you become aware that I've left. I put three links to previous Vsauce videos in the description that are related to this one if you haven't seen them yet. One is about why time feels like it's going faster as we get older.

Another is about the frame rate of the eyeball, and the other is about the stopped clock illusion. Have fun, and as always, thanks for watching.