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Hey guys, Matt here with Science or Fiction.
嘿，大家好，我是Matt，这里是《科学还是虚构》栏目。
Is there a speed that would harm humans?
有没有什么速度是会伤害到人体的呢？
There are a bunch of human speed records that are going to be broken in the coming decades
在未来的几十年内，一堆人类的速度记录将会被打破，
as we develop the technology to travel thousands of miles in minutes by land,
因为那时我们研发出的技术可以将我们在陆地上行进的速度提高到分分钟数千英里，
send commercial flights into low-earth orbit, and attempt to get humans to Mars.
将商业航班送入近地轨道，并尝试将人类送上火星。
So with all of these possibilities on the horizon,
因此，有了所有这些可能性，
a question you might be asking yourself is “How fast is too fast?”
你可能会想，“多快算太快呢？”
Well, first of all, wherever you are, no matter what you are doing, you are traveling nearly 67,000 mph around the sun.
首先，无论你身在何处，也无论你在做什么，你每时每刻都在以每小时6.7万英里的速度围绕太阳公转。
It just doesn’t feel that way because the Earth,
你没有察觉只不过是因为地球，
and therefore humans, have been traveling at that constant rate for, well, you know, kind of a while.
也包括地球上的人，以这样的速度周转已经，你知道的，有段时间了。
We can actually survive any speed, as long as it remains constant.
实际上，我们是可以适应任何速度的，只要它保持不变。
It’s when acceleration enters the equation that things can get pretty tricky.
只有当速度方程中涉及到加速度的时候，问题才会变得比较棘手。
In fact, if you accelerate at a high enough rate, you will pass out and very possibly die.
事实上，如果加速度足够大，人是会晕过去甚至死亡的。
This is because of what happens to the human body when it experiences g-force, or the unit of measure for acceleration.
因为人体在受到重力加速度G，也就是加速度的度量单位，的作用的时候会发生一些变化。
It’s based on Earth’s gravitational pull.
重力加速度的来源是地球的引力。
One “G” is the force applied to an object by gravity while on the Earth’s surface.
一个“G”就是在地球表面上地球引力对物体施加的力。
It’s also the force that determines how much we weigh.
重力也是决定我们体重的作用力。
So, simply put, if a human experiences three Gs, they experience a force on their bodies that is three times their weight.
所以，简单地说，如果一个人承受了三个G，就是说他们承受了三倍于他们体重的一个力。
We can experience the G force in different ways.
重力加速度作用的方式很多。
If we accelerate horizontally like in a car or train, we can experience g-force either front-to-back or side-to-side.
如果我们像汽车或火车一样水平加速，我们会体验到水平向或者侧向的重力加速度。
We can actually withstand quite a bit of g-force when it’s hitting us horizontally.
实际上，我们在水平方向上能够承受较大的重力加速度。
It’s when things go vertical,
是当作用力变换为垂直方向的时候，
which mostly happens only on airplanes, roller coasters, or during space launches,
一般情况下只有在飞行，过山车或空间发射时才会出现，
that things get much more dangerous much more quickly.
情况才会迅速朝危险发展。
Vertical g-force can be experienced negatively (foot to head) or positively (head to foot).
垂直的重力加速度可以是负向的（从脚到头），也可以是正向的（从头到脚）。
Both can be experienced in an airplane or rocket,
两种情况都能在飞机上或火箭上体验体验到，
and both can pose serious threats to our health because of what happens to all the liquid in our bodies under these circumstances.
而且这两种情况都可能对我们的健康构成严重威胁，因为在这种情况下我们的体液会发生一定变化。
With a high level of negative Gs, blood can end up collecting in our heads.
如果负向的重力加速度很大，我们的大脑就会充血。
Sometimes a “red out” will occur, with the lower eyelids swelling up so much that they cover the pupils.
有时还会造成下眼睑过度膨胀以致覆盖瞳孔，也即所谓的“红视”。
If enough blood pools in the head, which can happen around 2 or 3 negative Gs, a person will lose consciousness. Yikes.
如果头部充血太多，这种情况可能发生在大约2-3个负G的时候，人就会失去意识。爽吧。
And other scary stuff happens when force is applied from head-to-foot and blood starts to pool in the lowest parts of our bodies.
而承受从头到脚的正G，人体下半身开始充血时，还可能发生其他的危险。
At 1 G, or normal conditions, our bodies require 22 millimeters of mercury blood pressure to pump blood from the heart to the brain.
在1G也就是正常情况下，我们的身体需要22毫米汞柱的血压才能将血液从心脏泵入大脑。
That requirement doubles at 2 G, triples at 3 G, and so on.
这一数值在2G时要翻倍，在3G时就要翻3倍，以此类推。
There’s a certain point at which our bodies can no longer muster the energy needed to pump the blood, which happens around 4 or 5 Gs.
当加速度到达一定水平，我们的身体将无法继续获得将血液从心脏泵出所需的能量，这种情况一般发生在4-5G左右。
Blood ends up pooling in the feet,
血液最终就会流向脚部，
and the rest of the body receives such a lack of oxygen that a person first loses vision due to a lack of blood flow to the eyes
身体其他部分由于过于缺氧，人就可能因为眼部供血不足而暂时失明，
and then consciousness altogether when the brain loses enough of its blood flow.
然后是大脑供血不足引起整个人失去意识。
This phenomenon is known as G-LOC, or G-induced loss of consciousness.
这种现象被称为G-LOC，也就是重力加速度诱发的意识丧失。
Both head-to-foot and foot-to-head vertical g-forces can eventually lead to death if they last long enough.
只要持续时间够长，正G和负G都可能引起死亡。
So, given that humankind is on the precipice of breaking many speed records,
所以，鉴于人类即将打破多项速度记录，
and given that many of the airplanes and spacecrafts that will be involved could one day fly your average Joe across the country at record speeds,
鉴于终有一天，很多飞机和宇宙飞船都能以破纪录的速度载着你我这样的普通人飞行，
how can we make sure that we, you know, don’t die?
我们如何才能确保我们……你们懂的……不会挂呢？
Pilots do a number of things to train for serious g-s.
为了适应高G，飞行员需要进行一系列训练。
The better shape they are in, the more able they are to control their body’s blood flow with their muscles.
飞行员体型越好，用肌肉控制血液流动的能力就越好。
Leg and abdominal muscles must be particularly strong so that when pilots tense these muscles, they can keep the blood from draining to their legs while experiencing positive g-force
腿部和腹部肌肉必须格外结实，这样飞行员才能在承受正G肌肉收缩时防止血液大量流向腿部。
Well, it’s sort of unrealistic to expect everyone to have abs of steel,
要指望每个人都有钢铁般的腱子肉是不现实的，
so other solutions might be needed if we are to expect average people to eventually accelerate at rates currently only safe for fighter pilots.
所以，要想最终普通人能够承受得住目前战斗机飞行员才能承受的加速度，我们就要想别的办法。
One solution could be anti-g suits, which pilots have been using since World War II.
一种可能的解决方案就是二战以来飞行员一直在穿的抗荷服。
They utilize air bladders to keep the blood in our bodies where it should be.
抗荷服能够利用气囊保证血液的正常输送。
Fortunately, we haven’t quite reached the point where people like you
幸运的是，我们现在还没有达到像你我这样的人，
or unless there are a lot of fighter pilots watching this episode, then I take that back
除非咱们的观众中间有很多战斗机飞行员，是的话我就收回我这句话，
are going to be accelerating at deathly rates.
都要承受致命的加速度的地步。
There is still time for us to figure out how to manage all that.
所以，我们还是有足够的时间来解决这些问题的。
For more epic stories of innovation that shaped our future check out theageofaerospace.com.
欲了解更多超赞的缔造未来方面的创新故事，请查看theageofaerospace.com。
Did you know we learned a lot about how g-force affects the body from one guy shooting himself down a track in a rocket sled?
你知道吗，我们对G载对于人体的影响的很多知识都是从一个坐着火箭雪橇嗖的一下子滑下去的家伙那里了解到的吗
It’s true, check it out here.
真的，不信你看这里。
Before you do that, make sure to subscribe and be sure to keep coming back to Seeker for more videos.
在那之前，请记得订阅我们的频道，并定期回来观看我们的新视频噢。
