By Scott Kim|Monday, January 01, 2001

Also Sprach Frank and Dave

At a critical point in the movie 2001, astronauts Frank Poole and Dave Bowman consider disconnecting the intelligent computer HAL. They try to conceal their plan by talking in a soundproof chamber, but crafty HAL is able to read their lips. Each number below is followed by a sequence of mouth positions that add up to a single word of Frank and Dave's dialogue (also below). Can you match each set of mouth positions with one of the words? To help you, we've italicized five of the 10 words. For a discussion of the science behind HAL, including the lip-reading scene, see Hal's Legacy, edited by David Stork (MIT Press).

"I don't think we'd have any alternatives. There
isn't a single aspect of ship operations
that's not under his control. If he were proven to
be malfunctioning I wouldn't see how we'd
have any choice but disconnection."
"I'm afraid I agree with you."

Screen Play
To create the spectacular corridor of light at the end of 2001, special effects supervisor Douglas Trumbull turned to a photographic technique called slit scan, developed by filmmaker John Whitney.

A slit-scan machine has three moving parts: an illuminated table that displays the art vertically; a camera mounted on a track facing the art; and, just in front of the art, an opaque screen with a thin vertical slit. To expose a single frame of film, the camera shutter opens, the slit moves slowly across the artwork from left to right, and then the shutter closes. If the camera and table don't move, the resulting image looks just like the original art (Figure A, below). But if the table or camera moves during the exposure, the image will be distorted. The table can move horizontally or vertically within the plane of the art; the camera can move back and forth, perpendicular to the plane of the art. Moving the camera forward makes the picture appear to get closer from left to right, as shown in Figure B.

Can you describe the simplest way the camera and art table might have moved to create the images below?

One Man's Monolith Is Another Man's Tetrahedron
Arthur C. Clarke's short story "The Sentinel," which inspired 2001, features an alien artifact shaped like a tetrahedron (a solid bounded by four triangles). In the movie, the artifact— the mysterious monolith— is a hexahedron (a solid bounded by six quadrilaterals).

1.  [tricky] Slice a 1x4x9 rectangular hexahedron to reveal an equilateral triangle cross section. Slice a regular tetrahedron to reveal a square.

2.  [tougher] Draw a tetrahedron within a hexahedron so that all six edges run along the hexahedron's surface. Draw all 12 edges of a hexahedron that has two opposite, 4x9 rectangular faces within a tetrahedron.

3.  [really difficult) Cut a solid hexahedron into five tetrahedrons. Cut a solid tetrahedron into four nonrectangular hexahedrons.


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For all things Kubrick, including links to other sites and discussion groups on the Web, surf to

Go to for a discussion of the special effects in 2001. The site includes a detailed description of the slit-scan technique.

© Copyright 2001 The Walt Disney
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