Speaker 1: Welcome to brain Stuff from how Stuff Works dot com
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Speaker 1: today's question. If you could spin a carousel fast enough
Speaker 1: to get its rim moving at nearly the speed of light,
Speaker 1: would time stand still for people on the carousel. At
Speaker 1: least in the theoretical sense, this idea is reasonable. If
Speaker 1: the carousel were spinning so that the outer edge of
Speaker 1: the carousel moved at nearly the speed of light, then
Speaker 1: time would appear to slow down for people on the carousel.
Speaker 1: When the carousel writers looked out at the world spinning by,
Speaker 1: the days would pass very quickly, so the people on
Speaker 1: the carousel would age very slowly relative to people not
Speaker 1: on the carousel. This would create essentially a time machine
Speaker 1: that lets the passengers on the carousel travel into the future.
Speaker 1: In a practical sense, this idea has problems because of
Speaker 1: the centripetal force that the carousel would generate. Some of
Speaker 1: the fastest rotating objects in existence today are high speed flywheels.
Speaker 1: High speed flywheels float on magnetic bearings in a vacuum chamber,
Speaker 1: so there's very nearly zero friction on them. These flywheels
Speaker 1: are able to achieve speeds up to about two hundred
Speaker 1: thousand rotations per minute. The main problem with flywheels running
Speaker 1: this quickly comes in the form of rotor disintegration. The
Speaker 1: outward forces on the rotor are huge. Even if you
Speaker 1: assume that the flywheel has a twelve inch diameter running
Speaker 1: at a million rpm, the outer edge of the flywheel
Speaker 1: would be traveling at only about thirty four thousand miles
Speaker 1: per hour, nowhere even close to the speed of light
Speaker 1: at a hundred eighty six thousand mile per second. The
Speaker 1: other option would be to create an extremely large carousel.
Speaker 1: Say you built a ring as big as Earth's orbit,
Speaker 1: or about a hundred eighties six million miles in diameter.
Speaker 1: This ring would only have to spend at a rate
Speaker 1: of about one revolution per hour compared to the Earth's
Speaker 1: one revolution per year to achieve something near the speed
Speaker 1: of light. Building this ring and then accelerating the entire thing,
Speaker 1: of course, would be a big project. Do you have
Speaker 1: any ideas or suggestions for this podcast? If so, please
Speaker 1: send me an email at podcast at how stuff works
Speaker 1: dot com. For more on this and thousands of other topics,
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