This is one of the most mind-blowing things you’ll EVER see. (And I swear to G-D if this post only gets a few thousand views on X, then X is simply not fit for purpose for anything. Because this is something everyone should see and be blown away by) You’re watching a laser beam move in real time… at 2 billion frames per second. Light only travels about 15 cm (6 inches) in each frame. That’s why you can actually see the beam crawl across the room, bounce off the mirrors, and come back. Now watch carefully when the camera position changes… The light going away from the camera suddenly looks slow. The light coming toward the camera looks almost instant. It looks like the speed of light is changing. It’s not. You’re seeing the finite speed of light itself. The camera is literally recording the PAST at different moments depending on how far the light has to travel to reach the sensor. This isn’t CGI. This isn’t a simulation. This is a homemade camera filming actual photons. Full credit, and huge respect, to @Alpha__Phoenix Alpha Phoenix Channel