Hendrix, Cobain and Page.
亨德里克斯，科本和佩奇。
They can all shred, but how exactly do the iconic contraptions in their hands produce notes, rhythm, melody and music.
他们都能速弹，不过他们手上的标志性玩意儿具体是如何产生音符、节奏、旋律和音乐。
When you pluck a guitar string, you create a vibration called a standing wave.
当你拨弦时，产生了一个振动，叫驻波。
Some points on the string, called nodes, don't move at all,
弦上的某些点，叫做波节，完全不动，
while other points, anti-nodes, oscillate back and forth.
而其它点--波腹，则来回振动。
The vibration translates through the neck and bridge to the guitar's body,
这个振荡通过琴颈和琴桥传递到琴身，
where the thin and flexible wood vibrates, jostling the surrounding air molecules together and apart.
琴身的细而有弹性的木头振动，将周围的空气分子搅动得聚集又分开。
These sequential compressions create sound waves, and the ones inside the guitar mostly escape through the hole.
这些连续的挤压产生了声波，吉他内部的声波大部分从洞中散播出来。
They eventually propagate to your ear,
它们最终传播到你的耳中，
which translates them into electrical impulses that your brain interprets as sound.
耳朵将它们翻译为电脉冲，你的大脑将它们转为声音。
The pitch of that sound depends on the frequency of the compressions.
声音的音调由压缩的频率决定。
A quickly vibrating string will cause a lot of compressions close together, making a high-pitched sound,
快速振动的弦会让压缩聚得更拢，造成高音调的声音，
and a slow vibration produces a low-pitched sound.
而慢速的振动则产生低音调声音。
Four things affect the frequency of a vibrating string: the length, the tension, the density and the thickness.
四个因素影响弦震动的频率：长度，张力，密度和厚度。
Typical guitar strings are all the same length, and have similar tension, but vary in thickness and density.
普通的吉他弦长度都相同，并且有相似的张力，但是密度和粗细不同。
Thicker strings vibrate more slowly, producing lower notes.
粗一些的琴弦振动得越慢，弹出的音符音调就越低。
Each time you pluck a string, you actually create several standing waves.
每次拨动琴弦的时候，你其实是在创造好几个驻波。
There's the first fundamental wave, which determines the pitch of the note,
其中有第一个基波，能决定音高，
but there are also waves called overtones, whose frequencies are multiples of the first one.
但是也有叫做泛音的波，它的频率是第一个波的好几倍。
All these standing waves combine to form a complex wave with a rich sound.
所有的这些驻波结合在一起就组成一个复杂的波，创造出浓厚的声音。
Changing the way you pluck the string affects which overtones you get.
改变拨动琴弦的方式能影响你创造的泛音。
If you pluck it near the middle, you get mainly the fundamental and the odd multiple overtones,
如果你在中间拨动琴弦，你听到的只有基波和奇数组的泛音的波，
which have anti-nodes in the middle of the string.
弦的中间有反节点。
If you pluck it near the bridge, you get mainly even multiple overtones and a twangier sound.
如果你在琴桥拨动琴弦，你听到的主要是偶数组的泛音的波和弦声。
The familiar Western scale is based on the overtone series of a vibrating string.
我们所熟悉的西方音乐中的音阶，就是基于琴弦振动时的泛音。

When we hear one note played with another that has exactly twice its frequency,
当我们听到一个音符的振动频率正好是另一个音符的两倍时，
its first overtone, they sound so harmonious that we assign them the same letter,
它的第一个泛音，它们听上去如此和谐，我们给它们分配了相同的字母，
and define the difference between them as an octave.
并且把它们之间的距离叫做一个八度。
The rest of the scale is squeezed into that octave
音阶中剩余的音符都在一个八度中间，
divided into twelve half steps whose frequency is each 2^(1/12) higher than the one before.
分成十二个半音，它们的频率比前一个音符高2^(1/12)倍。
That factor determines the fret spacing.
这个因素决定品之间的距离。
Each fret divides the string's remaining length by 2^(1/12), making the frequencies increase by half steps.
每个品把琴弦的长度分成2^(1/12)，使频率随着每个半音增加。
Fretless instruments, like violins, make it easier to produce the infinite frequencies between each note,
没有品的乐器，比如小提琴，可以在每个音符之间有无数个不同的频率，
but add to the challenge of playing intune.
但是给把握音调带来困难。
The number of strings and their tuning are custom tailored to the chords we like to play and the physiology of our hands.
琴弦的数量和它们的调音都是根据我们想要弹奏的和弦和我们的手的结构特制的。
Guitar shapes and materials can also vary, and both change the nature and sound of the vibrations.
吉他的形状和材料都不同，它们都可以根据振动的性质和声音改变。
Playing two or more strings at the same time allows you to create new wave patterns like chords and other sound effects.
同时拨动两个或者更多的琴弦，可以让你创造新的音波和其他的音效。
For example, when you play two notes whose frequencies are close together,
比如，当你同时弹奏两个频率相似的音符时，
they add together to create a sound wave whose amplitude rises and falls,
它们共同创造一个振幅不停地起落的声波，
producing a throbbing effect, which guitarists call the beats.
创造一种像脉动一样的效果，吉他手把这个叫做节拍。
And electric guitars give you even more to play with.
电子吉他可以创造的效果更多。
The vibrations still start in the strings,
振动从琴弦开始，
but then they're translated into electrical signals by pickups and transmitted to speakers that create the sound waves.
接下来拾音器把它们转换成电子信号，然后传送到扬声器，最后变成声波。
Between the pickups and speakers, it's possible to process the wave in various ways,
从拾音器到扬声器，有好多种方式处理声波，
to create effects like distortion, overdrive, wah-wah, delay and flanger.
去创造出失真、过速、“娃娃器”、延音、镶边等等的效果。
And lest you think that the physics of music is only useful for entertainment, consider this.
如果你觉得音乐中的物理原理只是为了娱乐而已，再仔细想想。
Some physicists think that everything in the universe is created by the harmonic series of very tiny, very tense strings.
有些物理学家认为宇宙中的一切事物都是由一系列和声的“能量弦”组成的。
So might our entire reality be the extended solo of some cosmic Jimi Hendrix?
难道我们的现实世界只是宇宙版吉米·亨德里克斯的扩展的独奏吗？
Clearly, there's a lot more to strings than meets the ear.
显然，弦不只有我们所听到的那么简单。