FALLING WITH HELIUM
氦气球降落伞
Q. What if I jumped out of an airplane with a couple of tanks of helium and one huge, un-inflated balloon? Then, while falling, I release the helium and fill the balloon. How long of a fall would I need in order for the balloon to slow me enough that I could land safely?
Q．如果我背着几罐氦气和一个巨大的未充气的气球从飞机上跳下来会怎么样？如果我在下坠的过程中给气球充氦气，那么我需要从多高的高度跳下来，才能使气球让我减速到可以安全落地的速度呢？
A. AS RIDICULOUS AS IT sounds, this is-sort of-plausible.
A．虽然这听上去有点滑稽，不过这种方法还是……可行的。某种意义上。
Falling from great heights is dangerous.[citation needed ] A balloon could actually help save you, although a regular helium one from a party obviously won 8217;t do the trick.
从极高的高度跳下来是非常危险的。一个气球也许能够保证你摔不死，但派对上常用的那种氦气球显然不管用。
If the balloon is large enough, you don 8217;t even need the helium. A balloon will act as a parachute, slowing your fall to nonfatal speeds.
如果你的气球够大，甚至连氦气都不用，气球本身就能充当降落伞，让你减速到非致命的速度。
Avoiding a high-speed landing is, unsurprisingly, the key to survival. As one medical paper put it . . .
毫无疑问，避免高速触地是保证存活的关键所在。正如一篇医学论文所说的那样：
It is, of course, obvious that speed, or height of fall, is not in itself injurious . . . but a high rate of change of velocity, such as occurs after a 10 story fall onto concrete, is another matter.
很显然触地速度，或者说下落的高度本身并不致命……但极大的速度变化率（比如你从10楼摔到底楼的水泥地上带来的变化）可就是另一回事儿了。
. . . which is just a wordy version of the old saying “It 8217;s not the fall that kills you, it 8217;s the sudden stop at the end.”
……这个表述太啰嗦，还是古语来得简洁：“害死你的不是下落过程，而是最后的突然停止。”
To act as a parachute, a balloon filled with air-rather than helium-would have to be 10 to 20 meters across, far too big to be inflated with portable tanks. A powerful fan could be used to fill it with ambient air, but at that point, you may as well just use a parachute.
为了能产生降落伞那样的效果，充满空气而不是氦气的气球的直径需要有10～20米——这么大的体积光靠便携式的储气罐可是充不满的。虽然一个马力强劲的风扇可以用环境空气把气球充满，但这样你还不如直接用个降落伞呢。
Helium
氦气
The helium makes things easier.
有了氦气，事情就变得容易多了。
It doesn 8217;t take too many helium balloons to lift a person. In 1982, Larry Walters flew across Los Angeles in a lawn chair lifted by weather balloons, eventually reaching several miles in altitude. After passing through LAX airspace, he descended by shooting some of the balloons with a pellet gun.
用不了几个氦气球就能把人“抬”起来。1982年，拉里•沃尔特斯在庭院椅上绑上了许多气象气球，乘着他的“飞椅”升到了几千米高的空中，并横跨了整个洛杉矶。在飞过洛杉矶国际机场空域后，他用随身携带的气枪打爆了几个气球用以降落。