字幕列表 影片播放 列印英文字幕 Hey, Vsauce, Michael here. 93% of all the humans who have ever lived are dead. For every person alive right now, there are 15 people who are no longer alive. The Earth is dangerous...but where is the most dangerous place on Earth? Ignoring freak occurrances, where is the most persistently perilous place on the surface of our planet? Well, let's being with temperature. Extreme heat and extreme cold can kill within hours, if not minutes. In cold environments, without clothing, the human body, by itself, doesn't do a very good job of maintaining a high enough temperature to live. It just takes too much work. Even when you feel comfortable and warm, nearly half of your daily caloric intake is used merely to keep your body's temperature where it should be. If you took a human and stripped them naked and put them in an environment at 0 degrees Celsius, they would die from having too cold of an internal temperature within about 20 minutes. We need warmth. But one thing we need more immediately than that is Oxygen. And that brings us to the summit of Mount Everest. This place, on the surface of Earth, has incredibly thin air. At the top of Mount Everest there is only 1/3 as much breathable Oxygen as there is down at sea level. Climbers can endure the conditions for short periods of time if they acclimate for months, but, if you were to teleport from wherever you are right now directly to the summit of Everest, you would most likely die within only 2-3 minutes because there isn't enough Oxygen. Death would come even more quickly if you were at the bottom of the Mariana Trench. There, you would be submerged under nearly 7 miles of water, about 11 km, causing the pressure around your body to exceed 15,000 pounds per square inch. At normal swimming depths you could always hold your breath, but that far down, with that much pressure, your lungs would collapse immediately, and without Oxygen, your brain would go unconscious in 15 seconds, and you'd be dead in under 90. You would die pretty much just as quickly as someone who walked into outer space without a suit on. But falling into a molten lake of lava is probably the most spectacular way to go. Contrary to what you see in many movies, your body wouldn't just burn a little bit and slowly sink as if it were in quicksand; instead, there would be a lot of fireworks. Hot, molten lava is liquid rock, 4 times as hot as your oven can ever get. And the human body is mainly made up of water which, when exposed to that kind of heat, turns into steam...explosively. There's a fantastic video right here on YouTube where a guy throws a bag of organic material containing a lot of moisture into hot lava. It doesn't just sink in- it causes a miniature eruption. I highly suggest you go watch it. But, what if we want to measure danger not by how quickly you would die, but by the actual total number of fatalities caused. Well, for this, we're going to need to get much, much smaller. Like, microscopic. In 1918, influenza killed nearly 100 million people, which, at the time, was 3% of the world's entire population. But places where, and when, the plague has spread rapidly are even scarier. Between 1347 and 1353, a third of everyone in Europe died because of the bubonic plague, an infection caused by Yersinia Pestis. It's easy to think of the plague as something from way back in the past, but it is still here. Of course, now we have antibiotics which can help in most cases, but, believe it or not, in America alone, 5-15 people still get the plague every year. In terms of total fatalities, however, the plague and influenza are nothing compared to the danger caused by this guy: plasmodium. It's a micro-organism that can get into our blood because of mosquito bites, and causes Malaria. Across the totality of human history, the number of deaths attributed to Malaria is unbelievable. Researchers like Nobel Laureate Baruch Blumberg have studied the history of the human genome and human migration, and determined that of all the humans who have ever existed, it is likely that half died from Malaria. So, in terms of total fatalities across all of human history, a place where plasmodium could enter the blood stream because of a mosquito bite, statistically speaking, could be called the most dangerous place on Earth. But let's switch gears for a moment and talk about places that are dangerous not because of Earth, or Earth's creatures, well, actually, just one specific creature: us. La Oroya is a mining town in Peru where the murder rate is low but pollution is high. The town's smelter emits pollution into the air, and temperature inversions in the atmosphere above the town trap gasses within, causing the town to have 85 times more arsenic in its air than is deemed safe. But that's nothing compared to Lake Karachay in Russia. It was named the most polluted spot on Earth by the World Watch Institute on Nuclear Waste. The lake contains so many radioactive pollutants that you can receive a lethal dose of radiation merely by standing for one hour near certain parts of the lake. The Global Peace Index ranks countries by how safe they are. It takes into account a number of factors including crime and political corruption. The safest country, according to the Index, is Iceland. And the least safe is Somalia. But for the highest murder rate, you'll have to go to Juarez, Mexico, where out of every 1 million inhabitants, each year, 1,477 of them are murdered. I've always found it amazing just how many serial killers Miami seems to have on the show "Dexter," but Miami is a big city, and so, despite all those serial killers, it's murder rate in the show is not the highest of any fictional town from a TV show. That honor goes to Cabot Cove, the town where "Murder She Wrote" occurred. An analysis of "Murder She Wrote" episodes revealed 274 murders, but a population in the town of only 3,500, making Cabot Cove's murder rate 1,490 per million inhabitants. Until recently that number was unmatched by reality, but last year, the city of San Pedro Sula in Honduras reported a murder rate of 1,588 murders per million inhabitants. Let's conclude by revisiting pollution, specifically the Chernobyl accident, and a certain oxymoronic danger. For 10 days in 1986, radioactive isotopes spilled out of a blazing reactor core, forcing mass evacuations. It's more than 25 years later now, and many parts of the exclusion zone remain incredibly lethal. But, without humans there, many parts of the exclusion zone have seen wildlife flourish, especially endangered species which can go to the exclusion zone, live, reproduce, and be safe...from us. We managed to ruin a place to the point at which it endangered our lives and we had to leave, and, in doing so, we left parts of it a little bit safer for other forms of life. You can read more about all of these topics by following links down in the description below. Keep learning, and, as always, thanks for watching.
B1 中級 你知道地球上最危險的地方在哪裡嗎? What's The Most Dangerous Place on Earth? 1621 44 VoiceTube 發佈於 2013 年 06 月 27 日 更多分享 分享 收藏 回報 影片單字