Speaker 1: Welcome to Brain stop from house Stuff Works dot com
Speaker 1: where smart Happens. Hi, I'm Marshall Brain with today's question,
Speaker 1: what is a VAC train and when will they appear
Speaker 1: in reality? In the middle of the eighteen hundreds, the
Speaker 1: United States built the Transcontinental Railroad to get people and
Speaker 1: products across the country. By today's standards, it was a
Speaker 1: slow way to go, about eight days to get from
Speaker 1: Omaha to San Francisco. At the time, however, the Transcontinental
Speaker 1: Railroad was a technological marvel. The same trip in a
Speaker 1: covered wagon took six months if things went well. When
Speaker 1: they didn't go well, it often meant death. Compared to
Speaker 1: a dangerous six months journey, eight days in a train
Speaker 1: seemed like late speed. In the middle of the nineteen hundreds,
Speaker 1: trains were replaced by jet airplanes. Now a person could
Speaker 1: fly from New York to Los Angeles in six hours
Speaker 1: at fifty miles per hour. At the time, this too
Speaker 1: seemed like a technological marvel. But here we are fifty
Speaker 1: years later and nothing has really changed. The obvious question
Speaker 1: is what's next. One possibility is supersonic travel. Supersonic passenger
Speaker 1: airplanes currently cannot fly overland in the United states because
Speaker 1: of sonic booms, but new technologies could soon give us
Speaker 1: supersonic planes that don't have sonic booms, opening up this possibility. However,
Speaker 1: supersonic planes aren't really the answer. First, they'll be limited
Speaker 1: in their speed to a thousand or fifteen hundred miles
Speaker 1: per hour. While that's much faster than today's jets, it's
Speaker 1: not revolutionary. The second problem, though, is the cost per passenger.
Speaker 1: As the speed of the plane increases, so does the
Speaker 1: amount of fuel required to overcome air resistance. When the
Speaker 1: supersonic Concord jet was flying, it took six times more
Speaker 1: fuel per passenger than a seven forty seven to get
Speaker 1: through the air. Thus, the Concorde was too expensive for
Speaker 1: most people to afford. The ultimate solution is likely to
Speaker 1: be a vac train, also known as evacuated tube transport
Speaker 1: or e t T. In a vactrain system, a magnetically
Speaker 1: levitated train moves through a vacuum sealed tube. The vacuum
Speaker 1: means no air resistance, and the magnetic levitation means no
Speaker 1: resistance from wheels or tires. Removing these two sources of
Speaker 1: drag creates two huge benefits. First, it means that the
Speaker 1: train can go incredibly fast, with a top speed of
Speaker 1: five thousand miles per hour second. It means that the
Speaker 1: amount of energy required to move the train is very small.
Speaker 1: There are new energy costs to maintain the vacuum and
Speaker 1: to cool empower the magnets, but these energy costs are
Speaker 1: minimal compared to a jet. The bottom line is that
Speaker 1: a VAC train between New York and Los Angeles would
Speaker 1: allow how people to commute from one city to the
Speaker 1: other if they wanted to. The travel time would be
Speaker 1: less than an hour, and the price of a ticket
Speaker 1: would be very low. The only real constraints on a
Speaker 1: VACT train system are first the need to construct the tube,
Speaker 1: and second the need to keep the track straight. At
Speaker 1: five thousand miles per hour, only the gentlest of turns
Speaker 1: are possible, or passengers would feel the g forces. A
Speaker 1: right turn, for example, might cover several big states. On land,
Speaker 1: a vactrain system could be put underground in tunnels, or
Speaker 1: it could go and steal or concrete tubes above the
Speaker 1: ground to cross an ocean. The tube might be anchored
Speaker 1: with cables on the ocean floor, with the tunnels floating
Speaker 1: mid ocean. The idea of a VAC train system that
Speaker 1: crosses the United States is exciting, but the global picture
Speaker 1: is even more interesting. With a vactrain system circling the planet,
Speaker 1: it's easy to imagine travel from the US to China
Speaker 1: taking only two hours. New work to London might take
Speaker 1: only an hour or so. The system could carry both
Speaker 1: passengers and cargo, so shipping times and costs could be
Speaker 1: reduced drastically. A VACT train system circling the globe might
Speaker 1: sound far fetched today in the same way that transcontinental
Speaker 1: jets would have sounded far fetched in nineteen hundred. Keep
Speaker 1: in mind that the Right Brothers didn't fly until nineteen
Speaker 1: o three. But there is already research underway in China
Speaker 1: to bring an early version of a VACT train to market.
Speaker 1: This first system would only have a partial vacuum, but
Speaker 1: would allow trains to travel up to six hundred miles
Speaker 1: per hour. China already has hundreds of miles of high
Speaker 1: speed rail traveling at two hundred miles an hour, and
Speaker 1: a VACT train would lower travel times significantly. With China
Speaker 1: working on the problem, we can expect the United States
Speaker 1: in Europe to follow, and VACT train systems could be
Speaker 1: a reality in just ten to twenty years. For more
Speaker 1: on this and thousands of other topics, is that how
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