How do you film the Speed of Light?

In a building there, there is a camera that leaves me absolutely speechless. Is this camera capable of

film

ing the

speed

of

light

? - Yes. - Dan: Damn. - Very high-tech stuff, guys. - The maximum

speed

we can do is 10 billion frames per second. This is the reason we came here. Turn it up to the maximum? - Yes that's fine. I feel like no human should have seen this. We have

film

ed the fastest. We have hit our ceiling. It won't be soon that we film something faster, so... Not this year, maybe. Should we just invent some things that are faster?

Let's start inventing things. Yes, this camera weighs like 50 trillion... Clearly you haven't seen super

light

. The setup was really interesting. It shows that thousands of hours of research have been invested in the creation of that camera. I mean, in the pictures you can't really tell what's going on. When you think about what's really happening, what you're seeing, it's more impressive than the actual images. Yes, it's one of those things where the idea is much more impressive than the visual. Because the visual looks like a slightly dated film effect. With an image of a bottle. (synth music plays) I would say that of all the videos we shot, this one, as we were filming it, I was struggling to understand how the camera was acquiring those images.

And you also have to think about the time scale involved. I can't understand how short a picosecond is. - It's absolutely crazy. - Well, nothing else happens on that scale. Well, while we're struggling to figure it out, we thought we'd better ask one of the people who invented the technology. We are here with Lihong, one of the inventors of the camera. Do you think you could explain to us exactly how it works, and we can try to understand it, because I just don't understand it right now? Sure. For the first time, humans can see how a pulse of light propagates in space.

But before we talk about our camera, let me talk about the standard streak camera. A standard streak camera gives you a 1-D movie that's really fast. You only allow the X dimension, or horizontal dimension, to pass, and then you see a horse race through a slit. - It won't be as fun. - Good. We are very used to our smartphone cameras seeing at least the world in 2D, if not 3D. Yes, it is a world you can identify with. Exactly. And let me talk about how our camera works. Let's say we start with this object. But before we send you to a standard streak camera, we'll direct you to this digital micromirror device.

We write this code, and that is an important step, because it allows us to then decode everything to generate a 2-D movie. And this encoded object goes to this streak camera. Unlike the standard streak camera usage, we allow either the wide dimension or the vertical dimension to enter. On the back, you can use a slower motion to capture whatever you want. detect. It is a great invention. This technology allows us to look at really short time intervals. Why do we have to use a laser instead of a simple light bulb or a normal flashlight? A flashlight turns on too slowly for us to observe it.

A laser, we can make it very short. We then use a state-of-the-art laser pulse, which is turned on on a femtosecond scale. So the laser pulse is on the femto scale? Well well. Yes. But our camera works so fast... - Yes, I was going to say. - ...even nanoseconds seem like an eternity. This camera makes it look like the light is off forever, but in reality it is still on the peak scale. Lihong: Well, you're literally watching the slowest slow motion movies right now. The hope is that our camera can be used to study some fundamental physics.

We've all heard of sonar, but there is an optical counterpart to sonar called lidar. It also looks a lot like radar. Basically you detect a round trip time. So from time, you can measure distance. Could it be used to see in corners? Yes, it is feasible, although we have not physically done it. - That's like a superpower. - Yes. For now, we are doing something very similar to that. Let's say you have a foggy situation or a cloudy situation. With the naked eye you wouldn't see the plane at all. So we can look through the cloud and get a movie like this.

You can see this little plane. Gav: And I see that you can also see the detailed information this way. Lihong: You get detailed information. In reality, this would be much more precise than our eye. And this could be useful, perhaps even in the future, for self-driving cars. We want to drive in a cloudy situation, a foggy situation, and you can see objects through the fog. - Another superpower. - Yes. We are also thinking about something more biological. We know that our brain is probably the most complex machine in the universe. I want to find out how our brain calculates even one plus one.

By using our camera, we can potentially see that. Would this be useful in detecting brain damage? If someone had had a stroke, could you see it in this? That is certainly our hope. Does that mean that in the future people will be able to read my mind? That is a possibility. I feel like it must be a great achievement to have seen the fastest. It was a surreal moment when we got the first movie at the speed of light. Because that's the ceiling as we know it. We never thought it would be possible, yes. Well, thank you very much, Lihong, for showing us all these fascinating things.

I'll be thinking about this on the way home. I'm going to be watching this and trying to understand it. - Repeatedly. - Alright, back to you, Gav and Dan. Thanks to us. This is our time cheat sheet, just a list of all the different time scales. Normally we stay in milliseconds. Many of our exposures come down to the microsecond. - Yes. - Sometimes when we use the 2511, we will have exposure times that exceed hundredths of nanoseconds, but that is as far as our Phantoms go. - Yes. - We were down here with this camera and in this stadium.

But before, of course, I had everything understood. I had it all in my mind, like, “Yeah, this is the amount of time.” - Now I've lost it again. - Well, what... - So many zeros? - What surprises me is that we had a femtosecond long piece of light - hanging around... - Yes, we did. ...filming it with picosecond differences between frames. What is this all about? Yoctosecond? Surely, that would make the light look like you're blinking. At this point, I feel like you could also say infinite. In fact, we've received a lot of feedback over the years about how to do this asking us to film the light with our Phantom.

For example, filming a torch, a laser beam, a light bulb or something like that. And I always have to explain to them that light is so fast that our Phantom camera sees light exactly the same way our eyes do. So just for the fun of it, I thought I'd demonstrate it here. Here is the light. Here's a piece of paper. Let's play. Booop. Alright. There it is, instantly. I just left it to show that it was in slow motion. - Because otherwise... - Dan: They wouldn't believe us. Gav: Otherwise, they wouldn't believe us. I thought a good way to demonstrate how fast over 100 billion frames per second is would be to simply look at some of our old images and determine how long they would have taken at 100 billion frames per second, or 10 trillion.

Okay, let me get something out. Ray. One of the fastest things we've ever filmed before we were immediately over it. If we filmed this at 100 billion frames per second. Watching the full clip played at age 24 would take almost four months. - Four months? - Yes. And it's just happening right there. Gav: And there it is. And if we could somehow film this at 10 billion frames per second, the entire strike, from start to finish, would take 32 years. Imagine the duration of that storm. In fact, I can simulate exactly what that would look like if it were filmed at 10 billion.

Here we go, and it's playing now. This is exactly what it would look like. - Flippin'-A. - Very good, another clip? No no. See everything. Well. - 32 years. - That should take us to retirement. Yes I think so. (no audible dialogue) Next clip. Do you remember this bad boy? Dan: Yes. Ronda Sherman. Gav: We filmed this at 12,000 frames per second. There it is flying through the air. If we had filmed this at 100 billion frames per second, from the start to the end of the frame it would take eight years. Well, that would kind of defeat the purpose of having a tank shooting at something.

They were just like, "I guess I'll just get out of the way." You could serve two presidential terms before it was out of the frame. Now, just for laughs, it's pretty easy math: you just add two zeros. If we filmed it in 10 billion, 800 years from start to finish. So, quite a few Queen Elizabeths. And finally, the human blink... specifically, yours. You can tell it's mine because of the rebellious forehead. - Gav: Look at that. - Yes. Gav: Filmed at 1000 frames per second, if it were filmed at 100 billion, it would take you 19 years to close and open your eyes. (Dan gasps) Gav: The things you wouldn't have seen.

It would be like I was about to celebrate the millennium and then I would say, "Wow!" "3, 2, 1! 2019?" You blinked and you missed the millennium. And, absurdly, if we filmed this at 10 billion frames per second, the most boring video ever seen, it would take 1,900 years to open your eyes again. Then it would start flashing when Jesus was cutting. I would open them and it would be World War I. - More or less. - Good. That's a great way to imagine it. And think, in all that time, a few photons of light would say, "Ah, here we go," as if it were nothing.

Honestly, that was an absurd episode. To take something that... you know, every day, we're used to, but to take it to that extreme level, you can barely understand it. I liked it quite a bit. I liked how much it bothered my head. Me too. I quite liked how they told us about the real-world applications it could be used for in the future, like the police might want to use it to see around corners with that lidar. Like sonar where they shoot light and it bounces off all surfaces and they see people around the corner. Yes, or being able to easily see through the skin with a single image.

Yes, you can watch a wound heal or you can basically perform an MRI with your cell phone. I'm a little terrified of the future of surveillance technology, but, you know, we'll see what happens. I hope you enjoyed that video. Be sure to check out other episodes of “Planet Slow Mo.” and you can subscribe to us, the Slow Mo Guys, if you want. The episodes aren't usually that heavy, I promise. Those guys were very smart and wore lab coats. I feel like I should be like... - We should take ours off. - Just take it.