Has Earth’s Gravitational Pull Been Changing?
地球的引力改变过吗？
Don, why are you slouching? Don’t you know it’s bad for you?
唐，为啥你无精打采？你不知道这对你不好？
Did you know that about 200 tons of debris strike the Earth every day? So I was thinking! Although most of this stuff burns up in the atmosphere, the resulting dust still settles and adds to the Earth’s mass. That’s about half a million tons per year!
你知道每天大约200吨的碎片来到地球？所以我在思考。虽然这些东西中的大部分在大气中烧掉了，但是烧完后的灰尘仍然沉淀并增添地球的质量。大约每年有50万吨。
All right, but what does all this have to do with your posture?
好的，但是所有这些与你的仪态有啥关系呢？
Sit Up Straight
笔直端坐
So if the earth keeps accumulating mass, doesn’t that mean that the Earth’s gravitational pull has been increasing? After all, gravity is directly proportional to mass.
所以如果地球持续累积其质量，那不是意味着地球的引力也正在增加？毕竟，引力与质量是成比例的
Are you saying you can’t sit up straight because gravity is stronger now than it used to be?
你说你不能笔直端坐是因为地球引力比以前更强了？
Admit it, Yaël–it’s a good one.
承认这一点吧，耶尔，这是件好事。
Earth’s Mass
地球的质量
Earth’s mass in metric tons is approximately six followed by twenty-one zeroes. So assuming that your estimate is correct, and the Earth accumulates a half a million tons of debris every year, this means that in the sixty million years since dinosaurs existed the Earth would have accumulated approximately thirty trillion tons of meteoric debris. That’s thirteen zeroes.
地球的质量按照公制吨位来衡量大约是6后面加21个0.所以假设你的估计是正确的，并且每年地球积累50万吨的碎片，这意味着自从恐龙存在以来的6000万年，地球已经积累了大约30万亿吨的流星碎片。那是13个0。
The point is that a number with thirteen zeroes is minuscule relative to a number with twenty-four zeroes. While thirty trillion tons sounds impressive, it is nothing compared to the Earth’s total mass. So it’ s definitely not all that extra gravity that’s making you slouch
关键是13个零相对24个零而言是非常小的。虽然30万亿吨听起来很震撼，但是它与地球总的质量相比还是微不足道的。所以很明确的是额外的重力不会使得你无精打采。 |