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A laser pointer at 2 billion fps makes the speed of light look... kinda weird

AlphaPhoenix · 6M views · 2025-10-17 · 29:22

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Overview

AlphaPhoenix shows off a new camera that films at two billion frames per second and uses it to film a laser pointer pulse. He investigates a strange quirk in how the speed of light appears on camera.

On Hacker News

Referenced in threads about the two-billion-fps camera and equivalent-time sampling as an example of filming light moving.

Discussed on HN; no positive recommendation is recorded in this export · HN mentions 2025–2026

Topics

Everyday physics & science demosFundamental physics
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speed of lighthigh-speed cameralaserequivalent-time samplingphysics demo

What people said

apt-get · 2026-08 · Reference

Related - filming light at 2 billion fps with a somewhat similar setup in concept (at the single pixel scale): [VIDEO]

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nomel · 2026-03 · Reference

By definition, you can't interpolate a sample. A sample is a measured value. What you can do, if and only if you have an exactly repeating signal triggering at the same point within a cycle, is change the delay between the trigger and sample, and repeat. In other words, sample at different times within the same signal (since it's exactly repeating), to build up samples in time, of that waveform, to whatever time resolution you want. Of course, you're limited to any noise in the trigger, variation in the signal, etc. This is how you can record light moving through your garage [1]! [1] [VIDEO]

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westurner · 2025-10 · Reference

OT video: "A laser pointer at 2 billion fps makes the speed of light look... kinda weird" (2025; AlphaPhoenix) [VIDEO]

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Sources

Video by AlphaPhoenix, played through YouTube.

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