科学常识中的十大错误

英语自学网

There is nothing better than a bit of mythbusting (which accounts for the popularity of the television program of the same name), so here we are again, presenting you with a new list of terribly common misconceptions and myths – this time about science.
没有什么比“揭秘”更能吸引我们了（这也是为什么类似“大揭秘”这样的探索节目能够如此受到欢迎的原因）。所以今天这里将继续为大家介绍一些普遍存在的误解。这一期是关于科学上的误解。
Evolutionary Improvements


The Myth: Evolution causes something to go from “lower” to “higher”
While it is a fact that natural selection weeds out unhealthy genes from the gene pool, there are many cases where an imperfect organism has survived. Some examples of this are fungi, sharks, crayfish, and mosses – these have all remained essentially the same over a great period of time. These organisms are all sufficiently adapted to their environment to survive without improvement.
Other taxa have changed a lot, but not necessarily for the better. Some creatures have had their environments changed and their adaptations may not be as well suited to their new situation. Fitness is linked to their environment, not to progress.
误解十：进化是从“低级”向“高级”发展
虽然自然选择将劣势基因从基因库中筛去是事实，但在有些情况下，不完美的基因存活了下来。比如菌类、鲨鱼、小龙虾、苔藓——这些生物在长时间内都保持基本不变。它们对自己的生存环境已经足够适应因此没有什么进化。
其他种类的生物也许改变了很多，但并非一定进化得更高级了。有些生物改变了它们自己的生存环境，但它们的进化发展未必适合它们的新环境。适合与否与环境有关，而不是与是否向高级进化有关。
Humans Pop In Space


The Myth: When exposed to the vacuum of space, the human body pops
This myth is the result of science fiction movies which use it to add excitement or drama to the plot. In fact, a human can survive for 15 – 30 seconds in outer space as long as they breathe out before the exposure (this prevents the lungs from bursting and sending air into the bloodstream). After 15 or so seconds, the lack of oxygen causes unconsciousness which eventually leads to death by asphyxiation.
误解九：人在真空中会爆炸
科幻小说和电影为了加强作品的戏剧性而将这一误解强加给我们。事实上，只要在暴露于真空之前中呼了气（这可以阻止肺部破裂和向血液输入空气），人体可以存活15至30秒。但过了这一时间段，由于缺乏氧气，人体将迅速失去意识，最后窒息而死。
Brightest Star


The Myth: Polaris is the brightest star in the northern hemisphere night sky
Sirius is actually brighter with a magnitude of ?1.47 compared to Polaris’ 1.97 (the lower the number the brighter the star). The importance of Polaris is that its position in the sky marks North – and for that reason it is also called the “North Star”. Polaris is the brightest star in the constellation Ursa Minor and, interestingly, is only the current North Star as pole stars change over time because stars exhibit a slow continuous drift with respect to the Earth’s axis.
误解八：北极星是北半球夜空中最亮的星星。
北极星并不是北半球夜空最亮的星星。最亮的星星是天狼星,它的视星等有-1.47等,北极星则只有1.97等（视星等越低，亮度越高）。北极星的重要性在于可以用来导航。它的位置十分接近北方，所以被称为“北方之星”。北极星是小熊星座最亮的星，更有意思的是，它是目前发现的唯一跟随地球的地轴不断改变位置的的恒星。
Five Second Rule


The Myth: Food that drops on the floor is safe to eat if you pick it up within five seconds
This is utter bunkum which should be obvious to most readers. If there are germs on the floor and the food lands on them, they will immediately stick to the food. Having said that, eating germs and dirt is not always a bad thing as it helps us to develop a robust immune system. I prefer to have a “how-tasty-is-it” rule: if it is something really tasty, it can sit there for ten minutes for all I care – I will still eat it.
误解七：如果食物掉在地上后五秒内被拾起，则该食物可以安全地食用
这种说法简直是胡说八道。如果地面有细菌，一旦食物掉在地上，细菌将立刻粘附到食物表面。当然，食用细菌并非都是坏处，起码它可以增强人体的免疫系统。我这里倒有另一种说法：“美食法则”.如果手中的食物确实美味，它可以待在地上十分钟或更久——我还是会吃了它。

            
            

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Dark side of the Moon


The Myth: There is a dark side of the moon
Actually – every part of the moon is illuminated at sometime by the sun. This misconception has come about because there is a side of the moon which is never visible to the earth. This is due to tidal locking; this is due to the fact that Earth’s gravitational pull on the moon is so immense that it can only show one face to us. Wikipedia puts it rather smartly thus: “Tidal locking occurs when the gravitational gradient makes one side of an astronomical body always face another; for example, one side of the Earth’s Moon always faces the Earth. A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner. This synchronous rotation causes one hemisphere constantly to face the partner body.”
误解六：月球表面有明暗之分
事实上月球的每一面都会被太阳照射到。之所以产生这样的误解是因为月球总是以同一半面向着地球。而这则是由潮汐造成。因为地球的引力对月球影响很大，所以我们只能看到月球的一面。

Brain Cells


The Myth: Brain cells can’t regenerate – if you kill a brain cell, it is never replaced
The reason for this myth being so common is that it was believed and taught by the science community for a very long time. But in 1998, scientists at the Sweden and the Salk Institute in La Jolla, California discovered that brain cells in mature humans can regenerate. It had previously been long believed that complex brains would be severely disrupted by new cell growth, but the study found that the memory and learning center of the brain can create new cells – giving hope for an eventual cure for illnesses like Alzheimer’s.
误解五：脑细胞无法再生。如果脑细胞死亡了，将不会有新细胞取而代之。
长久以来，这一说法都被科学界认同并且加以传播。但1998年瑞典和美国加利福尼亚沙克研究所的科学家们发现人类的脑细胞具有再生的功能。此前科学家们一直认为新细胞的生长会严重破坏大脑， 但研究却表明大脑的记忆和学习神经具有再生细胞的能力。这也给了治愈类似老年痴呆的疾病带来了希望。


Pennies from Heaven

The Myth: A penny dropped from a very high building can kill a pedestrian below
This myth is so common it has even become a bit of a cliche in movies. The idea is that if you drop a penny from the top of a tall building (such as the Empire State Building) – it will pick up enough speed to kill a person if it lands on them on the ground. But the fact is, the aerodynamics of a penny are not sufficient to make it dangerous. What would happen in reality is that the person who gets hit would feel a sting – but they would certainly survive the impact.
误解四：一枚从高处落下的硬币会砸死人
这一说法相当普遍以至于经常被搬进电影里。 意思是说如果你从一幢高楼的楼顶（比如帝国大厦）掷下一枚硬币，由于高速下坠，它所带来的冲击力将会致人死亡。事实上，根据空气动力学，这样一枚硬币还不足以对人构成任何威胁。无非就是让这个不幸的过路者感到一阵刺痛罢了，但肯定不会被砸死。

            
            

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Friction Heat

The Myth: Meteors are heated by friction when entering the atmosphere
When a meteoroid enters the atmosphere of the earth (becoming a meteor), it is actually the speed compressing the air in front of the object that causes it to heat up. It is the pressure on the air that generates a heat intense enough to make the rock so hot that is glows brilliantly for our viewing pleasure (if we are lucky enough to be looking in the sky at the right time). We should also dispel the myth about meteors being hot when they hit the earth – becoming meteorites. Meteorites are almost always cold when they hit – and in fact they are often found covered in frost. This is because they are so cold from their journey through space that the entry heat is not sufficient to do more than burn off the outer layers.
误解三：流星进入大气层发生摩擦而燃烧
流星体闯入地球的大气层（变成流星之前）时，由于高速飞行，它的前端与空气强烈摩擦发热。当作用于空气的压力产生一定的热量，流星体便会发光燃烧，最后变成令人赏心悦目的流星。另外，关于流星还有一个普遍的误解：当流星撞击地球时（变成陨石之前），它会逐渐变热。事实上，几乎所有的陨石都是冷的，而且大多数的表面都覆盖着一层霜。这是因为陨石本身非常冷，摩擦所产生的热量不足以蒸发它的外层。

Lightning

The Myth: Lightning never strikes the same place twice
Next time you see lightning strike and you consider running to the spot to protect yourself from the next bolt, remember this item! Lightning does strike the same place twice – in fact it is very common. Lightning obviously favors certain areas such as high trees or buildings. In a large field, the tallest object is likely to be struck multiple times until the lightning moves sufficiently far away to find a new target. The Empire State Building gets struck around 25 times a year.
误解二：闪电不会在同一个地方打两次
下一次你遇到闪电想找个地儿躲躲时，千万要记住这一点：闪电会同在一个地方打两次。这其实非常常见。闪电显然特别青睐一些地方，如参天大树，或者高楼建筑。在较大的区域里，最高的建筑物经常被选为目标。闪电往往几击中其数次后才悻悻然地离开去寻找下一个。仅帝国大厦每年就被闪电击中二十五次之多。

Gravity in Space

The Myth: There is no gravity in space
In fact, there is gravity in space – a lot of it. The reason that astronauts appear to be weightless because they are orbiting the earth. They are falling towards the earth but moving sufficiently sideways to miss it. So they are basically always falling but never landing. Gravity exists in virtually all areas of space. When a shuttle reaches orbit height (around 250 miles above the earth), gravity is reduced by only 10%.
误解一：太空无重力
事实上 太空中存在着重力，而且还不小。之所以宇航员看起来无重力是由于他们在绕着地球旋转。一方面他们处于向地球持续下落中，另一方面他们又沿着地球水平运动。这使得他们始终保持着一种下落却又不可能着地的状态。重力其实无处不在。当飞船达到轨道点（大约离地球250英里），重力也不过才减少10%。
实习生：李帅男