If you’ve ever wondered just how fast the speed of light is, and how to film it, The Slow Mo guys have an answer.
The famous YouTube duo, Gavin Free and Daniel Gruchy, have spent over a decade showing the world what incredibly fast things look like in slow motion, from C4 explosions deflecting bullets to a man in a 6ft giant water balloon.
In their latest experiment, documented on their YouTube channel which has 14.9 million subscribers, the pair wondered if they could capture the speed of light, “the fastest thing we as the human race know of”.
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And then they also explained how they managed to do it.
First off, they would need to film the speed of light at 10,000,000,000,000 frames per second - which is 10 trillion - and they’ve explained how they did it.
“A lot of times in our YouTube comments, we get asked to film the speed of light. And I have to always reply to people letting them know that the speed of light, it's almost incomprehensibly fast, and even our cameras, under a million frames a second, will never see anything like that,” Gavin said in their video.
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However, with the help of Peng Wang, a postdoctoral scholar at Caltech, The California Institute of Technology, in California, the pair were able to film the speed of light passing through the length of a water bottle to help us visualise just how insanely fast it is.
Peng, armed with an incredibly high-tech camera which uses compressed ultrafast photography, explained how he could show the speed of light with a laser, saying it would take “about 2,000 picoseconds” for the beam to travel from the top of the bottle to the end.
Gavin explained: “So for the audience, it goes milliseconds, microseconds, nanoseconds, picoseconds, femtoseconds. So we're on the sort of pico/femto scale with this stuff.”
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Donning goggles for safety, the trio took to a dark room to capture various images of the light passing through the bottle at 10 trillion frames per second - the speed of light.
Lihong Wang, a professor at Caltech and one of the inventors of the camera, said: “For the first time, humans can see how a light pulse propagates in space,” adding that the technology “allows us to look at really short time intervals.”
“I feel like no human should ever have seen this,” Gavin said.
Lihong went on to talk about a "standard streak camera", explaining: "A standard streak camera gives you a 1-D movie that's really fast.
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"You only allow the X dimension, or horizontal dimension, to pass through...", he said, equating it to watching a horse race through a very small slit on a screen.
For more context on it all, he added: "We're so used to your smartphone cameras seeing at least the world in 2-D, if not 3-D."
Explaining it further, he said: "Let's say we start with this object. But before we send it to a standard streak camera, we're going to route it to this digital micromirror device.
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"We write this code, and that's an important step, because that allows us later on to decode everything to generate a 2-D movie.
"And this encoded object is routed to this streak camera. Unlike the standard use of the streak camera, we allow the wide dimension, or the vertical dimension to come in.
"At the back end, you can use a slower camera to capture whatever you want to detect. It's a great invention. This technology allows us to look at really short time intervals".
So there you have it.
Featured Image Credit: Credit: YouTube / The Slow Mo Guys