1 00:00:00,520 --> 00:00:03,560 Speaker 1: Welcome to Brain stop from house Stuff Works dot com 2 00:00:03,560 --> 00:00:14,640 Speaker 1: where smart Happens. Hi, I'm Marshall Brain with today's question, 3 00:00:15,080 --> 00:00:18,640 Speaker 1: what is a VAC train and when will they appear 4 00:00:18,840 --> 00:00:22,360 Speaker 1: in reality? In the middle of the eighteen hundreds, the 5 00:00:22,480 --> 00:00:26,360 Speaker 1: United States built the Transcontinental Railroad to get people and 6 00:00:26,440 --> 00:00:30,200 Speaker 1: products across the country. By today's standards, it was a 7 00:00:30,400 --> 00:00:33,600 Speaker 1: slow way to go, about eight days to get from 8 00:00:33,600 --> 00:00:38,000 Speaker 1: Omaha to San Francisco. At the time, however, the Transcontinental 9 00:00:38,080 --> 00:00:41,960 Speaker 1: Railroad was a technological marvel. The same trip in a 10 00:00:42,040 --> 00:00:45,720 Speaker 1: covered wagon took six months if things went well. When 11 00:00:45,760 --> 00:00:49,239 Speaker 1: they didn't go well, it often meant death. Compared to 12 00:00:49,280 --> 00:00:52,479 Speaker 1: a dangerous six months journey, eight days in a train 13 00:00:52,640 --> 00:00:56,360 Speaker 1: seemed like late speed. In the middle of the nineteen hundreds, 14 00:00:56,560 --> 00:01:00,240 Speaker 1: trains were replaced by jet airplanes. Now a person could 15 00:01:00,240 --> 00:01:02,920 Speaker 1: fly from New York to Los Angeles in six hours 16 00:01:02,960 --> 00:01:06,880 Speaker 1: at fifty miles per hour. At the time, this too 17 00:01:07,000 --> 00:01:11,000 Speaker 1: seemed like a technological marvel. But here we are fifty 18 00:01:11,080 --> 00:01:14,760 Speaker 1: years later and nothing has really changed. The obvious question 19 00:01:14,880 --> 00:01:21,240 Speaker 1: is what's next. One possibility is supersonic travel. Supersonic passenger 20 00:01:21,280 --> 00:01:25,240 Speaker 1: airplanes currently cannot fly overland in the United states because 21 00:01:25,240 --> 00:01:28,920 Speaker 1: of sonic booms, but new technologies could soon give us 22 00:01:28,959 --> 00:01:34,640 Speaker 1: supersonic planes that don't have sonic booms, opening up this possibility. However, 23 00:01:34,959 --> 00:01:39,160 Speaker 1: supersonic planes aren't really the answer. First, they'll be limited 24 00:01:39,160 --> 00:01:41,880 Speaker 1: in their speed to a thousand or fifteen hundred miles 25 00:01:41,880 --> 00:01:45,000 Speaker 1: per hour. While that's much faster than today's jets, it's 26 00:01:45,000 --> 00:01:49,680 Speaker 1: not revolutionary. The second problem, though, is the cost per passenger. 27 00:01:50,120 --> 00:01:52,640 Speaker 1: As the speed of the plane increases, so does the 28 00:01:52,640 --> 00:01:56,080 Speaker 1: amount of fuel required to overcome air resistance. When the 29 00:01:56,120 --> 00:02:00,240 Speaker 1: supersonic Concord jet was flying, it took six times more 30 00:02:00,360 --> 00:02:03,280 Speaker 1: fuel per passenger than a seven forty seven to get 31 00:02:03,280 --> 00:02:06,960 Speaker 1: through the air. Thus, the Concorde was too expensive for 32 00:02:07,080 --> 00:02:11,000 Speaker 1: most people to afford. The ultimate solution is likely to 33 00:02:11,040 --> 00:02:15,800 Speaker 1: be a vac train, also known as evacuated tube transport 34 00:02:16,000 --> 00:02:20,320 Speaker 1: or e t T. In a vactrain system, a magnetically 35 00:02:20,440 --> 00:02:25,040 Speaker 1: levitated train moves through a vacuum sealed tube. The vacuum 36 00:02:25,080 --> 00:02:28,720 Speaker 1: means no air resistance, and the magnetic levitation means no 37 00:02:28,840 --> 00:02:32,800 Speaker 1: resistance from wheels or tires. Removing these two sources of 38 00:02:32,919 --> 00:02:36,840 Speaker 1: drag creates two huge benefits. First, it means that the 39 00:02:36,919 --> 00:02:40,320 Speaker 1: train can go incredibly fast, with a top speed of 40 00:02:40,400 --> 00:02:43,680 Speaker 1: five thousand miles per hour second. It means that the 41 00:02:43,720 --> 00:02:47,320 Speaker 1: amount of energy required to move the train is very small. 42 00:02:47,720 --> 00:02:50,680 Speaker 1: There are new energy costs to maintain the vacuum and 43 00:02:50,680 --> 00:02:53,960 Speaker 1: to cool empower the magnets, but these energy costs are 44 00:02:54,000 --> 00:02:57,000 Speaker 1: minimal compared to a jet. The bottom line is that 45 00:02:57,040 --> 00:02:59,800 Speaker 1: a VAC train between New York and Los Angeles would 46 00:02:59,800 --> 00:03:02,280 Speaker 1: allow how people to commute from one city to the 47 00:03:02,320 --> 00:03:04,840 Speaker 1: other if they wanted to. The travel time would be 48 00:03:04,960 --> 00:03:07,160 Speaker 1: less than an hour, and the price of a ticket 49 00:03:07,160 --> 00:03:10,560 Speaker 1: would be very low. The only real constraints on a 50 00:03:10,639 --> 00:03:14,320 Speaker 1: VACT train system are first the need to construct the tube, 51 00:03:14,480 --> 00:03:18,079 Speaker 1: and second the need to keep the track straight. At 52 00:03:18,120 --> 00:03:21,520 Speaker 1: five thousand miles per hour, only the gentlest of turns 53 00:03:21,520 --> 00:03:24,880 Speaker 1: are possible, or passengers would feel the g forces. A 54 00:03:25,000 --> 00:03:29,639 Speaker 1: right turn, for example, might cover several big states. On land, 55 00:03:29,760 --> 00:03:33,240 Speaker 1: a vactrain system could be put underground in tunnels, or 56 00:03:33,240 --> 00:03:35,960 Speaker 1: it could go and steal or concrete tubes above the 57 00:03:35,960 --> 00:03:39,280 Speaker 1: ground to cross an ocean. The tube might be anchored 58 00:03:39,280 --> 00:03:42,520 Speaker 1: with cables on the ocean floor, with the tunnels floating 59 00:03:42,560 --> 00:03:46,160 Speaker 1: mid ocean. The idea of a VAC train system that 60 00:03:46,240 --> 00:03:50,080 Speaker 1: crosses the United States is exciting, but the global picture 61 00:03:50,200 --> 00:03:54,360 Speaker 1: is even more interesting. With a vactrain system circling the planet, 62 00:03:54,600 --> 00:03:57,720 Speaker 1: it's easy to imagine travel from the US to China 63 00:03:57,840 --> 00:04:01,280 Speaker 1: taking only two hours. New work to London might take 64 00:04:01,360 --> 00:04:04,280 Speaker 1: only an hour or so. The system could carry both 65 00:04:04,360 --> 00:04:07,800 Speaker 1: passengers and cargo, so shipping times and costs could be 66 00:04:07,880 --> 00:04:11,800 Speaker 1: reduced drastically. A VACT train system circling the globe might 67 00:04:11,960 --> 00:04:15,400 Speaker 1: sound far fetched today in the same way that transcontinental 68 00:04:15,480 --> 00:04:18,640 Speaker 1: jets would have sounded far fetched in nineteen hundred. Keep 69 00:04:18,640 --> 00:04:21,520 Speaker 1: in mind that the Right Brothers didn't fly until nineteen 70 00:04:21,520 --> 00:04:25,039 Speaker 1: o three. But there is already research underway in China 71 00:04:25,120 --> 00:04:27,840 Speaker 1: to bring an early version of a VACT train to market. 72 00:04:28,160 --> 00:04:31,120 Speaker 1: This first system would only have a partial vacuum, but 73 00:04:31,120 --> 00:04:34,000 Speaker 1: would allow trains to travel up to six hundred miles 74 00:04:34,000 --> 00:04:37,200 Speaker 1: per hour. China already has hundreds of miles of high 75 00:04:37,240 --> 00:04:40,039 Speaker 1: speed rail traveling at two hundred miles an hour, and 76 00:04:40,080 --> 00:04:43,760 Speaker 1: a VACT train would lower travel times significantly. With China 77 00:04:43,839 --> 00:04:46,440 Speaker 1: working on the problem, we can expect the United States 78 00:04:46,440 --> 00:04:49,440 Speaker 1: in Europe to follow, and VACT train systems could be 79 00:04:49,480 --> 00:04:54,560 Speaker 1: a reality in just ten to twenty years. For more 80 00:04:54,600 --> 00:04:56,840 Speaker 1: on this and thousands of other topics, is that how 81 00:04:56,880 --> 00:04:59,200 Speaker 1: stuff works dot Com and don't forget to check out 82 00:04:59,200 --> 00:05:01,080 Speaker 1: the brain stuff block on the house stuff works dot 83 00:05:01,120 --> 00:05:03,719 Speaker 1: com home page. You can also follow brain stuff on 84 00:05:03,720 --> 00:05:07,440 Speaker 1: Facebook or Twitter at brain stuff H. 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