You've just made your way out of a really frustrating traffic jam, and you're looking around for the reason, maybe an accident or roadworks, but you can't see anything. So, what in the world just happened?
你才剛脫離一陣著實惱人的車潮，而你正四處查看塞車的原因，也許是車禍或是道路施工，但你卻看不到任何線索。那麼，剛才究竟發生啥事了？
Mathematicians use different models to explain these so-called phantom traffic jams. One popular model likens traffic to a flowing liquid and traffic jams to a shockwave.
數學家們使用不同模型來解釋這些所謂的「幽靈塞車」。一種最普遍的模型將車潮譬喻成流動的液體，而塞車譬喻成震盪波。
To investigate this, Japanese researchers put 22 cars on a circular track, and ask them to drive around at a steady 30 kilometers per hour. For a little while, all goes well, but it takes just one car to slightly change speed to cause problems, making the car behind slow down further, and the next car back to slow down even more again.
要研究這現象，日本研究人員安排 22 輛車在一條環形跑道上，並要求他們以穩定的時速 30 公里繞圈行駛。過了一會兒，一切都很順利，但只要一輛車稍微改變車速就能造成問題，使得後方的車進一步慢下來，而下一輛車又甚至慢更多下來。
The cars begin to clump together, and this clumping effect reverberates backwards around the track like a shockwave, even leaving to brief halts at points.
車輛開始擠在一起，而這相擠的效應就像震盪波一般向後回傳到整個跑道，甚至在某些地方帶來短暫的停止狀態。
Theoretically, if traffic remains heavy, this traveling wave could just keep going and going forever. These invisible waves of congestion also occur in real-life traffic jams. They create a ripple effect which doesn't go away until all cars return to the same pace.
理論上來說，如果交通維持繁忙狀態，這種行進波能就永遠不停持續下去。這些隱形的壅塞波動同樣也在現實生活的塞車中發生。它們產生一種在所有車輛回到相同車速前都不會消失的漣漪效應。
To prevent a jam, you should maintain a steady speed, so no changing lanes, no slowing down to look at things, and using your cruise control. And you can always carpool or use public transport to reduce congestion in the first place.
要避免塞車，你應該要維持穩定的車速，所以那代表不要變換車道、不減速看其他東西，並使用你的定速巡航。還有你永遠可以共乘或是利用大眾運輸來在一開始就減少壅塞情形。
Another potential solution is driverless cars, which are better at keeping a constant pace, and which can wirelessly communicate with each other to respond to changing traffic conditions.
另一個可能的解決方式是無人駕駛汽車，那更能維持固定的車速，且那可以和彼此無線通訊以應對不斷變化的交通狀況。
Mathematicians help, too, by improving the algorithms that control our traffic lights, and predicting when and where traffic jams will occur.
數學家也有幫忙，藉由改善控制交通號誌的演算法，還有預測塞車狀況在何時何地會發生。
And now, four fast facts about pesky traffic:
現在，有四則關於惱人車潮的趣味資訊：
Traffic light timings optimize movement for the majority of traffic, meaning that if you're driving against the flow, you could hit a frustrating run of red lights.
交通號誌的時間點盡可能配合大多數的車潮動向，表示如果你往不同方向前進，你可能就會碰上一連串煩人的紅燈。
Traffic psychology studies show that women cyclists are given more space on the road than men, and you're more likely to let a car in front of you if you have passengers.
交通心理研究顯示，女單車騎士比起男性在路上會被讓出更多空間，而如果你車上有乘客的話，你更有可能讓車輛開在你的前面。
Using theoretical physics to understand traffic congestion is creatively called "jamology."
利用理論物理學理解塞車，被很有創意地稱為「塞車學」。
And in 2010, a 100-kilometer stretch of highway between Beijing and Tibet came to a standstill for two weeks, possibly the greatest traffic jam in history.
2010 年，在北京和西藏間高速公路上一條綿延 100 公里的車流停滯了兩個禮拜，也許是史上最厲害的塞車。
Stuck for ideas about traffic jams? Check out our website where we have some links, and we'll see you around back here next week.
腦袋堵太多塞車資訊嗎？看看我們的網站，那兒我們有一些連結，我們在下週會回到這裡與你相會。
- 「到底」- In The World
So, what in the world just happened?
那麼，剛才究竟發生啥事了？ - 「陷入停滯狀態」- Come To A Standstill
And in 2010, a 100-kilometer stretch of highway between Beijing and Tibet came to a standstill for two weeks, possibly the greatest traffic jam in history.
2010 年，在北京和西藏間高速公路上一條綿延100 公里的車流停滯了兩個禮拜，也許是史上最厲害的塞車。
