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Folding Space-Time Using a Music Box

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In science fiction, folding space-time leads to jump drives and other modes of interstellar travel (spin up the FTL Drive, Mr. Gaeta!). But there are other reasons you might want to fold space-time -- like making music.

In this video, mathemusician Vi Hart demonstrates a down-to-earth method of folding space-time. All she needs is paper, a music box, and a basic knowledge of music notation. Got seven minutes to learn a little about space, time, and music? Tune in:

So what else can you do with this concept? In 2009, Hart created a Möbius strip containing a theme from the Harry Potter Septet. Because it's a strip, it can be played indefinitely (as long as the cranker keeps cranking), but each pass through inverts the notation due to mathemagic.

And while we're talking about the relationship between space and time, here's a Minute Physics video exploration of the question how far is a second?

See also: Vi Hart Makes a Video About Making a Video About Making a Video.

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Watch How Computers Perform Optical Character Recognition
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Optical Character Recognition (OCR) is the key technology in scanning books, signs, and all other real-world texts into digital form. OCR is all about identifying a picture of written language (or set of letters, numbers, glyphs, you name it) and sorting out what specific characters are in there.

OCR is a hard computer science problem, though you wouldn't know it from its current pervasive presence in consumer software. Today, you can point a smartphone at a document, or a sign in a national park, and instantly get a pretty accurate OCR read-out...and even a translation. It has taken decades of research to reach this point.

Beyond the obvious problems—telling a lowercase "L" apart from the number "1," for instance—there are deep problems associated with OCR. For one thing, the system needs to figure out what font is in use. For another, it needs to sort out what language the writing is in, as that will radically affect the set of characters it can expect to see together. This gets especially weird when a single photo contains multiple fonts and languages. Fortunately, computer scientists are awesome.

In this Computerphile video, Professor Steve Simske (University of Nottingham) walks us through some of the key computer science challenges involved with OCR, showing common solutions by drawing them out on paper. Tune in and learn how this impressive technology really works:

A somewhat related challenge, also featuring Simske, is "security printing" and "crazy text." Check out this Computerphile video examining those computer science problems, for another peek into how computers see (and generate) text and imagery.

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Can You Solve This Fish Riddle?
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Transporting cargo by boat doesn’t usually require solving tricky brainteasers. That’s not the case with this fishy riddle from TED-Ed.

For this scenario, imagine you're a cargo boat director who’s charged with shipping several tanks of rare fish to an aquarium. The tanks are tossed overboard during a rough storm and it’s your job to retrieve them. There’s a mini-sub onboard that might be of assistance, but there’s a problem: You only have enough fuel for it to make one quick trip. Before launching your rescue mission, you need to figure out exactly how many tanks fell into the water and where they landed.

After referring to sonar data, thermal imaging, and your shipping notes, you come up with this list of information to help narrow down your search.

1. There are three sectors where the cargo landed.

2. There are 50 animals in the area, including the lost fish and deadly sharks.

3. Each sector contains between one and seven sharks and no two sectors have the same amount of sharks.

4. The tanks each have the same amount of fish.

5. There are 13 tanks at most.

6. The first sector has two sharks and four tanks in it.

7. The second sector has four sharks and two tanks.

So how many fish are there? If you came up with 39, you’re right. There can only be 39 fish spread out across 13 tanks, which means there are three fish in each.

In case you’re feeling more confused now than you were before, you can refer to TED-Ed’s full explanation in the video below.

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