WEBVTT - What is a vactrain?

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<v Speaker 1>Welcome to Brain stop from house Stuff Works dot com

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<v Speaker 1>where smart Happens. Hi, I'm Marshall Brain with today's question,

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<v Speaker 1>what is a VAC train and when will they appear

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<v Speaker 1>in reality? In the middle of the eighteen hundreds, the

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<v Speaker 1>United States built the Transcontinental Railroad to get people and

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<v Speaker 1>products across the country. By today's standards, it was a

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<v Speaker 1>slow way to go, about eight days to get from

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<v Speaker 1>Omaha to San Francisco. At the time, however, the Transcontinental

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<v Speaker 1>Railroad was a technological marvel. The same trip in a

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<v Speaker 1>covered wagon took six months if things went well. When

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<v Speaker 1>they didn't go well, it often meant death. Compared to

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<v Speaker 1>a dangerous six months journey, eight days in a train

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<v Speaker 1>seemed like late speed. In the middle of the nineteen hundreds,

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<v Speaker 1>trains were replaced by jet airplanes. Now a person could

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<v Speaker 1>fly from New York to Los Angeles in six hours

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<v Speaker 1>at fifty miles per hour. At the time, this too

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<v Speaker 1>seemed like a technological marvel. But here we are fifty

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<v Speaker 1>years later and nothing has really changed. The obvious question

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<v Speaker 1>is what's next. One possibility is supersonic travel. Supersonic passenger

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<v Speaker 1>airplanes currently cannot fly overland in the United states because

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<v Speaker 1>of sonic booms, but new technologies could soon give us

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<v Speaker 1>supersonic planes that don't have sonic booms, opening up this possibility. However,

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<v Speaker 1>supersonic planes aren't really the answer. First, they'll be limited

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<v Speaker 1>in their speed to a thousand or fifteen hundred miles

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<v Speaker 1>per hour. While that's much faster than today's jets, it's

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<v Speaker 1>not revolutionary. The second problem, though, is the cost per passenger.

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<v Speaker 1>As the speed of the plane increases, so does the

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<v Speaker 1>amount of fuel required to overcome air resistance. When the

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<v Speaker 1>supersonic Concord jet was flying, it took six times more

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<v Speaker 1>fuel per passenger than a seven forty seven to get

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<v Speaker 1>through the air. Thus, the Concorde was too expensive for

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<v Speaker 1>most people to afford. The ultimate solution is likely to

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<v Speaker 1>be a vac train, also known as evacuated tube transport

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<v Speaker 1>or e t T. In a vactrain system, a magnetically

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<v Speaker 1>levitated train moves through a vacuum sealed tube. The vacuum

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<v Speaker 1>means no air resistance, and the magnetic levitation means no

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<v Speaker 1>resistance from wheels or tires. Removing these two sources of

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<v Speaker 1>drag creates two huge benefits. First, it means that the

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<v Speaker 1>train can go incredibly fast, with a top speed of

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<v Speaker 1>five thousand miles per hour second. It means that the

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<v Speaker 1>amount of energy required to move the train is very small.

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<v Speaker 1>There are new energy costs to maintain the vacuum and

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<v Speaker 1>to cool empower the magnets, but these energy costs are

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<v Speaker 1>minimal compared to a jet. The bottom line is that

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<v Speaker 1>a VAC train between New York and Los Angeles would

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<v Speaker 1>allow how people to commute from one city to the

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<v Speaker 1>other if they wanted to. The travel time would be

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<v Speaker 1>less than an hour, and the price of a ticket

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<v Speaker 1>would be very low. The only real constraints on a

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<v Speaker 1>VACT train system are first the need to construct the tube,

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<v Speaker 1>and second the need to keep the track straight. At

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<v Speaker 1>five thousand miles per hour, only the gentlest of turns

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<v Speaker 1>are possible, or passengers would feel the g forces. A

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<v Speaker 1>right turn, for example, might cover several big states. On land,

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<v Speaker 1>a vactrain system could be put underground in tunnels, or

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<v Speaker 1>it could go and steal or concrete tubes above the

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<v Speaker 1>ground to cross an ocean. The tube might be anchored

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<v Speaker 1>with cables on the ocean floor, with the tunnels floating

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<v Speaker 1>mid ocean. The idea of a VAC train system that

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<v Speaker 1>crosses the United States is exciting, but the global picture

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<v Speaker 1>is even more interesting. With a vactrain system circling the planet,

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<v Speaker 1>it's easy to imagine travel from the US to China

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<v Speaker 1>taking only two hours. New work to London might take

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<v Speaker 1>only an hour or so. The system could carry both

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<v Speaker 1>passengers and cargo, so shipping times and costs could be

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<v Speaker 1>reduced drastically. A VACT train system circling the globe might

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<v Speaker 1>sound far fetched today in the same way that transcontinental

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<v Speaker 1>jets would have sounded far fetched in nineteen hundred. Keep

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<v Speaker 1>in mind that the Right Brothers didn't fly until nineteen

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<v Speaker 1>o three. But there is already research underway in China

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<v Speaker 1>to bring an early version of a VACT train to market.

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<v Speaker 1>This first system would only have a partial vacuum, but

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<v Speaker 1>would allow trains to travel up to six hundred miles

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<v Speaker 1>per hour. China already has hundreds of miles of high

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<v Speaker 1>speed rail traveling at two hundred miles an hour, and

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<v Speaker 1>a VACT train would lower travel times significantly. With China

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<v Speaker 1>working on the problem, we can expect the United States

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<v Speaker 1>in Europe to follow, and VACT train systems could be

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<v Speaker 1>a reality in just ten to twenty years. For more

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