The world hums. It shivers endlessly.

It's a low, ceaseless droning of unclear origin that rolls imperceptibly beneath our feet, impossible to hear with human ears. A researcher once described it to HuffPost as the sound of static on an old TV, slowed down 10,000 times.

It's comforting to think of Earth as solid and immovable, but that's false. The world is vibrating, stretching and compressing. We're shaking right along with it.

“The earth is ringing like a bell all the time,” said Spahr Webb, a seismologist at Columbia University.

The hum is everywhere. Its ultralow frequencies have been recorded in Antarctica and Algeria, and — as announced this week by the American Geophysical Union — on the floor of the Indian Ocean. We still don't know what causes it. Some have theorized that it's the echo of colliding ocean waves, or the movements of the atmosphere, or vibrations born of sea and sky alike.

But if we could hear this music more clearly, scientists around the world say, it could reveal deep secrets about the earth beneath us, or even teach us to map out alien planets.

And the hum is getting clearer all the time.

Hmmm