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量子论的起源背景 – 译学馆
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量子论的起源背景

The Origin of Quantum Mechanics (feat. Neil Turok)

量子理论是从何而来的呢
Where did Quantum theory come from?
它并非源于空想
It started, not as a crazy idea,
而是因为一个灯泡
but with a light bulb.
19世纪90年代初
In the early 1890s,
德国标准局请教马克斯•普朗克
the German Bureau of Standards asked Max Planck
如何让电灯更高效
how to make light bulbs more efficient,
这样他们就可以用最少的电产生最强的光
so that they would give out the maximum light for the least electrical power.
普朗克面临的第一个任务就是预测
The first task Planck faced was to predict
一条热灯丝能发出多少光
how much light a hot filament gives off.
他了解到光是由不同颜色的电磁波组成
He knew that light consists of electromagnetic waves
而这些电磁波又由不同频率的波传送
with different colors of light carried by different frequency waves.
问题是 要确保尽可能多的光
The problem was to ensure that as much light as possible
由可见波而不是紫外线或红外线发出
was given off by visible waves rather than ultraviolet or infrared.
他曾试着算出每种颜色的热源能释放多少光
He tried to work out how much light of each color a hot object emits,
不过他的预测是基于与实验相悖的电磁理论
but his predictions based on electromagnetic theory kept disagreeing with experiments.
恰恰相反 后来它把这称为“绝望的行为”
Instead, in what he later called an “act of despair,”
他把现存的理论扔出窗外
he threw the existing theory out the window
然后一心投入到实验测试中
and worked backwards from experimental measurements.
研究出的数据让他发现了物理界的一个新法则:
The data pointed him to a new rule of physics:
光波只在聚集成群时才会携带能量
light waves carry energy only in packets,
强能量包组成的高频光
with high frequency light consisting of large packets of energy
和弱能量包组成的低频光
and low frequency light consisting of small packets of energy.
光包 或称之为“量子”的想法
The idea that light comes in packets, or “quanta”,
可能听起来很疯狂 而且当时确实如此
may sound crazy, and it was at the time,
但爱因斯坦很快将它类比成一个更为通俗的问题:分享
but Einstein soon related it to a much more familiar problem:sharing.
如果你想哄小孩开心 只需给他们一块饼干
If you want to make a kid happy, give them a cookie.
但如果有两个小孩 而你只有一块饼干
But if there are two kids and you only have one cookie,
为了哄他们 你只能把饼干分成两半
you’ll only be able to cheer them up half as much.
可如果有4或8个 甚至160万个小孩
And if there are four, or eight, or sixteen hundred thousand,
如果只能分一块饼干给他们
you’re not going to make them very happy at all
你就不可能哄所有小孩开心
if have to share one cookie between them.
事实上 如果一个房间里有无数个小孩
In fact, if you have a room with infinitely many kids,
但饼干的数量是有限的
but not infinitely many cookies,
如果你想要平均地分饼干
if you share the cookies evenly,
每个小孩只能得到一块饼干碎屑
each kid will only get an infinitesimally small crumb,
他们没有一个会高兴
none of them will be cheered up.
并且会吃掉你所有的饼干
and they’ll still eat all your cookies.
光波和小孩的区别就是
The difference between light waves and kids is that
你不可能让无数个小孩在同一个房间里
you can’t actually have infinitely many kids in a room.
但因为光波各种波长都有
But because light waves come in all sizes,
你可以不断地产生小光波
you can have arbitrarily small light waves,
所以你可以将无限的光波放入一个房间里
so you can fit infinitely many into a room.
然后这些光波会消耗掉你的所有饼干……
And then the light waves would consume all your cookies…
我是说 能量
I mean, energy.
事实上 所有的无限小的光波
In fact, all these infinitesimal waves together
会有无穷大的能力吸收能量
would have an infinite capacity to absorb energy,
它们可以吸收你放在房间里任何东西释放的热能
and they’d suck all the heat out of anything you put into the room.
它们可以不断地吸收茶的热能
instantly freezing the tea in your cup,
或太阳的热能 甚至是超新星的热能
or the sun, or even a supernova.
幸运的是 宇宙并不是这样运转的
Luckily, the universe doesn’t work that way,
因为 据普朗克猜测
because, as Planck guessed,
微小的高频光波只能成群地释放能量
the tiny, high frequency waves can only carry away energy in huge packets.
它们就像只接受恰好第37块饼干
They’re like fussy kids who’ll only accept exactly thirty-seven cookies,
或第162000块饼干的挑剔小孩 不多不少
or 162,000 cookies, no more and no less.
因为它们很挑剔 高频光波不再起作用
Because they’re so picky, the high frequency waves lose out
大多数的能量都是由那些希望平均分享的
and most of the energy is carried away in lower-frequency packets
低频光波带走的
that are willing to take an equal share.
这些光包携带的普通 平常的能量
This common, average energy that the packets carry,
就是我们所知的“温度”
is in fact what we mean by “temperature.”
所以温度越高意味着平均能量越多
So a higher temperature just means higher average energy,
根据普朗克定律 那是由更高频率的光波发出的
and thus by Planck’s rule, a higher frequency of light emitted.
这就是物体工作时会变得更烫的原因
That’s why as an object gets hotter it glows,
首先是红外光 然后是红色 黄色 白色
first infrared, then red, yellow, white;
不断变热 蓝色 紫色 紫外光 等等
hotter and hotter towards blue, violet, ultraviolet and so on.
老实说 普朗克的量子论告诉我们
Specifically, Planck’s Quantum theory of fussy light tells us that
电灯泡的灯丝只有加热到3200开氏度
light bulb filaments should be heated to a temperature of about 3200 Kelvin
才能确保大部分能量作为可见波释放
to ensure that most of the energy is emitted as visible waves.
温度越高 紫外线越强 我们越容易晒黑
much hotter, and we’d start tanning from the ultraviolet light.
事实上 量子论自电灯泡和制革床出现前
Actually, quantum physics has been staring us in the face
就已摆在我们面前了
since long before lightbulbs and tanning beds.
一千年以来 人类一直在观察火
human beings have been gazing into fires for millennia
并且将火焰的颜色拼为“量子”
with the color of the flames spelling out “quantum” all along.
与THE CBC MASSEY LECTURES
Produced in association with THE CBC MASSEY LECTURES
以及PERIMENTER INSTITUTE FOR THEORETICAN. PHYSICS联合出品
And PERIMETER INSTITUTE FOR THEORETICAN. PHYSICS

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分饼干与量子论有什么关系?看看就知道!

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