# Video: water appears frozen in sine wave

A beautiful video of sound curiously affecting a stream of water, visible thanks to a camera recording at 24 frames-per-second. The speaker generates a 24 hz sine wave that vibrates the water while the camera recording at 24 fps make the stream appear to "freeze." (Thanks, Koshi!)

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1. eldritch says:

I would have appreciated a comparison of how it looks at a much higher framerate, to roughly simulate what our eyes would actually see. It’d help to reinforce the physics of what is happening.

2. That’s too cool.  I wonder if the effect would work IRL if your lit a room with a matching frequency strobe…

1. Marius van Voorden says:

Yes, it would :)

3. Brainspore says:

Remember when that thing made friends with Ed Harris?

4. xzzy says:

Too bad James Cameron didn’t know about this trick back in the 80’s or he’d have abused the shit out of it for his T-1000 melting scene.

5. TacoChuck says:

If I am understanding this correctly, it is the hose bouncing that is making the water appear like, the water itself is not being held in that pattern by the sound waves. What is happening is that the end of the hose is being bounced which is making the water fall in that pattern.

1. GlyphGryph says:

Yes. Each “piece” of water is following a set curve, but since we only see that piece every so many fractions of a second…

2. SamSam says:

Yes, it’s called the Wagon wheel effect, where the spokes of a wagon wheel — or the propellors of a helicopter or jet engine — appear to slow down, become stationary, and/or reverse.

We see this so often with propellors in movies that I know many people who think that real propellors actually look like this to the naked eye — they don’t, it’s just an effect of the movie frame-rate.

In this case the water is waving back-and-forth, but each frame of the camera happens to sync up to when the wave was exactly where it was last time, so the wave appears to be stationary.

6. SomeGuyNamedMark says:

Now just install this in a men’s room.

7. PhasmaFelis says:

This loses a lot by not showing us (something approximating) what it would look like in person. Just an ordinary hose spray?

1. The video does show us what it’s like in person. The frame of the video doesn’t add to the effect. And there is no strobe. Just the house bouncing in response to sound waves from the speaker.

1. SamSam says:

…no, the effect you’re seeing is precisely because of the video frames. See my post above about the wheel wagon effect, or the video below with the helicopter.

In real life this would just look like a hose waving back and forth, and wouldn’t look odd at all..

8. SvenOrtmann says:

It’s quite the same effect as with the helicopter whose main rotor doesn’t seem to move (same frequency as camera, again).

9. autark says:

“Any sufficiently advanced technology is indistinguishable from magic.” – Arthur C. Clarke

10. jheiss says:

I thought it was interesting that when the actual speaker sound leaked through briefly it sounded rather like a film projector, cause, well 24 frames per second…

11. Boston’s Museum of Science had (still has?) a similar interactive demonstration where you can “freeze” an arc of water droplets in midair by adjusting the frequency of a strobe light. Or you could tweak the rate to make them slowly march to the left or right. I remember playing with this 30+ years ago.

12. I was hoping to see what would happen if he moved his hand or a stick through the water, to try and get a sense of how it would look IRL.

13. cabalist says:

OMG, MAGIC!

…and the Arthur C. Clarke quote, of course…