The information will travel like the compressional wave ahead of an earthquake, detectable only by special equipment.

这些信息将像地震前的纵一样传播，只有特殊设备才能检测到。

These are longitudinal waves that have to travel through a medium.

这些是必须通传播的纵。

In the case of a longitudinal wave, the back-and-forth motion is more of a compression-and-expansion.

纵的情况下，来回运动更像是压缩和膨胀。

Sound, you'll recall, is a wave: a 'longitudinal' wave.

如前所述，声音是一种： 纵。

But there are also longitudinal waves, where the oscillations happen in the same direction as the wave is moving.

但是也有纵，其中振荡发生移动的方向相同的方向上。

So the p wave and the s wave, and the different phases that move out from the site of rupture in the earth, are used by seismologists to locate the event.

地震学家用纵、横以及地球破裂部位移出的不同阶段来定位地震发生地点。

But sound is the other kind of wave: it’s a longitudinal wave, meaning that the wave’s back-and-forth motion happens in the same direction in which the wave travels.

但声音是另一种：它是一种纵，这意味着的来回运动发生传播相同的方向上。

Eventually, new experiments and ideas about light kept popping up — like that it's a transverse wave instead of a longitudinal wave like sound, and that it's a form of electromagnetic radiation.

最终，关于光的新实验和想法不断涌现——比如它是横而不是像声音一样的纵，它是电磁辐射的一种形式。