Amazing optical illusion or "glitch in the Matrix"?

By: Will Goodman
Topics: Viral Video

(CBS News) Watching this video is a bit like seeing a "glitch in the Matrix". Is it impressive? Without a doubt. Is it science? You know it. Will you possibly start questioning reality? Watch and find out.

The video was posted by YouTube user brusspup , who has been featured here on The Feed a few times for amazing optical illusions and art, and who writes about it:

This is really simple but has such an awesome effect. Fill a bucket full of water and place it about 5 feet off the ground. Place a subwoofer about 1 foot lower than the bucket. Run a plastic tube from the top bucket down in front of the subwoofer. Tape the tube to the front of the speaker. Then aim the end of the tube to an empty bucket on the floor. Get the water flowing from the top bucket. Now just generate a 24 hz sine wave and set your camera to 24 fps and watch the magic happen. Basically your cameras frame rate is synced up with the rate of the vibrations of the water so it appears to be frozen or still. Now if you play a 23 hz sine wave your frame rate will be off just a little compared to the sine wave causing the water to "move backward" or so as it appears. You can play a 25 hz sine wave and cause the water to move slowly foward.

Another amazing video that has earned a big triple-rainbow salute from all of us here at The Feed! To check out more videos by brusspup, you can go to her YouTube page by clicking here.

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by TampaBayTed April 23, 2012 9:28 AM EDT: Sorta reminds me of what goes on at my 3 a.m. visit to the bathroom.; Reply to this comment


by Melissahinkler April 22, 2012 3:37 PM EDT: Wow. Pretty cool.Isn't that the same sort of thing as when you see a wheel on a moving car and it looks like it's going backwards?; Reply to this comment


by Capismama April 22, 2012 1:01 AM EDT: I have to admit....that was cool.; Reply to this comment


by theNarrowWay April 21, 2012 1:11 PM EDT: This is just aliasing. A neat example of it, but not something I would call amazing.; Reply to this comment


by NorthernPaladin April 21, 2012 3:06 AM EDT: Neat, but as the story hints, it's really a "camera illusion" moreso than an optical illusion. The difference being that if you were standing there in person you would just see water flowing into a bucket. (Although you could probably make it into a true optical illusion with the aid of darkness and a strobe light...); Reply to this comment

by zavatone April 20, 2012 11:06 PM EDT

Do you guys even spell check?

It's "camera's frame rate", not "cameras frame rate". We're supposed to learn this by fourth grade. Please spell check; mistakes like this are embarrassing.

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by retroplayer April 21, 2012 3:49 PM EDT: Umm... inanimate objects do not have possession, therefore the apostrophe is never used. (ie. it is its, not it's)

Man that is so embarassing when you do something so stupid while calling another person stupid.


by jaykay3141 April 21, 2012 6:06 PM EDT: The carton of glassware my daughter and her husband received for their wedding bore the warning "USE CAUTION WHEN CUTTING FRAGILE GLASSES INSIDE".

A local hospital advertised "Our Emergency Room will accept any body".

Or better yet, read "Eats, Shoots, and Leaves". Punctuation does matter.


by markosoft82 April 22, 2012 11:47 AM EDT: Whilst zavatone does appear to be slightly anal about it... inanimate objects still have possession. A house will still have windows, and a bike will still have wheels. However to say "camera's frame rate' which is correct... is slightly awkward so it's more common to say "the frame rate of the camera", thus removing the problem itself.


by Rod_Smith May 15, 2012 12:34 PM EDT: Umm...Retroplayer, inanimate objects do have possessives. The "camera's frame rate" is the frame rate "belonging to" or "possessed by" the camera.

It's so embarrassing to do some thing so stupid while calling someone else stupid for calling another person stupid.

by Yellowbird12 April 20, 2012 2:32 PM EDT

Do you think perhaps this principal is being used to cloak some of our latest military flight machines? I do know the principal is in use for military weapons where they can blast back a crowd if they become "unruly". This type of sound weapon will pop eardrums and stop hearts from beating too. Believe it. If you play sub-woofers around heart patients, you can stop their hearts... or at least send them into defib.

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by assman April 21, 2012 1:14 AM EDT: What.. are you talking about? Nothing you said here was even close to reality.

by Freedom7Capsule April 20, 2012 1:16 PM EDT

Author, "...sine wave...? Huh?

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by Joe4242 April 20, 2012 5:00 PM EDT: Freedom, a sine wave is simply a pure tone, with only one frequency component.


by jaykay3141 April 20, 2012 8:31 PM EDT: Freedom, please pick up a high school trigonometry book. There should be some graphs that show what a sine wave looks like and how it can be generated.

In fact, when you get far enough along to play with Fourier transforms it's possible to break up nearly any repetitive wave form into combinations of sine waves. You can think of them as the building blocks of more complex sounds.


by tmittelstaed April 21, 2012 12:59 AM EDT: jaykay I think that depends on your definition of how you do it - a pure square wave has infinite number of sine waves - but can you really have an infinite amount of something enclosed in the universe? Towards the border the mathmatics starts to fail at describing reality.


by jaykay3141 April 21, 2012 6:32 PM EDT: tmittelstaed, I was thinking in terms of the underlying conceptual mathematics rather than the specific physics. Because you mentioned square waves I assume you have a background in math or engineering too. Remember deltas and epsilons from freshman calculus? They don't exist in reality but are a convenient device for explaining things like velocity and acceleration.

One example that's physically simple but conceptually difficult is figuring out the area under a curve, where infinitely many "little tiny pieces" add up to something finite. E.g. a rectangle has a finite area but that area can be mathematically expressed as the infinite sum of infinitely many infinitesimally small pieces - i.e. a definite integral(*). After all, scientists and engineers have been using the concepts since Newton's time.

(*) FWIW I had one heck of a time getting my head around that idea when I first took calculus and physics so I know how weird it sounds.


by Scimajor April 20, 2012 1:04 PM EDT: Very cool effect. I doubt I'd have figured out the process (apart from reading the article) except that the video gave away the frequencies which were suspiciously similar to typical frame rates used video.

Very inventive.

I'm curious whether this effect would be possible with an old style tube video camera (rather than the newer CMOS/CCD cameras). My guess is that one wouldn't get the same effect (i.e. scanning lines for each frame would ruin it?).

The wonder of science man! You have to love it.; Reply to this comment