Turns Out, the Earth's Inner Core isn't Solid After All

It used to be a popular theory that the Earth was hollow.

There are still believers. But the Hollow Earth theory had its heyday in the early 19th Century.

Among the most well-known was John Cleves Symmes.

He was credible – a U.S. Army officer. And he genuinely believed the Earth was hollow. In fact, he theorized that below the ground we stand were four concentric shells leading down to a hollow world underneath.

And he was convinced there were openings at the North and South poles providing access to this secret world. How do we know he truly believed? Symmes lobbied Congress in 1822 to fund an expedition to the North Pole so he could find the opening – and travel to the hollow world himself.

Congress didn’t buy into the hollow earth theory – not enough to fund an expedition. But a machinist in Illinois by the name of Marshall Gardner took notice.

When it was reported warm winds and red dust were found in the Arctic, Gardner saw this as proof: the hidden world below was releasing particles into the air. When he learned of migrating birds flying northward into the supposedly uninhabitable Arctic regions, he doubled down.

There must be warmer interior lands. And the aurora borealis?

Gardner was convinced these colorful lights in the sky indicated there was a second sun buried in the inner Earth core, and its rays were reflecting out to our world.

In 1913, Gardner published "A Journey to the Earth's Interior," making his case the Earth was hollow and contained this smaller sun, which gave heat and light to an inner civilization.

Most recently, Raymond Bernard picked up the argument. Again, a credible writer with a Ph.D. in Education from NYU. Bernard not only agreed with the hollow earth theory, but in his 1964 book he claimed this inner world was the true source of UFOs.

Of course, mainstream science was never on board with these ideas. The accepted theory of the Earth's center was that, below a molten outer mantle, the inner core is 100% solid. Exactly the opposite of hollow.

That was the accepted theory. The idea of a hollow Earth was dismissed.

Until now.

On February 10, 2025, scientists from the University of Southern California stumbled onto a surprising discovery about the Earth's core.

The purpose of their study had nothing to do with looking inside the core. They just wanted to chart the slowing of the inner core's rotation. Scientists knew this sphere oscillated over a 70-year cycle. And they suspected its rotation was slowing down, relative to the Earth's surface rotation.

How do they study something we can't see?

(To date, the entrances Symmes said were waiting for us at the North and South poles have not been discovered, so we can't take an actual journey to the center of the Earth.)

Scientists have another way to examine the core. They use seismic data – waves generated by Earthquakes – and analyze how these waves pass through the inner core. They've seen how the core spins, sometimes speeding up or slowing down – and even spinning in the opposite direction at times.

During all these tests, scientists assumed the core was solid. Specifically made of iron-nickel alloy.

But that may have all changed.

They were studying seismic waveform data from over 120 earthquakes in Antarctica that took place between 1991 and 2024.

As they analyzed the data from receiver-array stations in Fairbanks, Alaska and Yellowknife, Canada, one dataset included uncharacteristic properties the team had never seen before.

John Vidale, Professor of Earth Sciences at USC, said, "what we ended up discovering is evidence that the near surface of Earth's inner core undergoes structural change."

Said Vidale, "Later on, I'd realize I was staring at evidence the inner core is not solid."

The USC scientists found that the shape of the inner core changed, likely affected by the molten outer core. Until now, the outer core's molten, turbulent state was not thought to ever affect the inner core on a human timescale.

But it was the clearest cause to explain what the seismic waves indicated: that the inner core was changing shape, more like putty than an iron ball.

According to Vidale, this discovery showed the everyone we just don't understand this inner world like we thought. There are hidden dynamics within the Earth's core, with thermal and magnetic fields science doesn't fully understand.

The discovery opened a new door with more discoveries to follow, now that scientists know what they’re looking for.

On the gravestone of John Cleves Symmes in Hamilton, Ohio is a sculpture of a hollow earth. It's a tribute to his passionate belief that there was a mystery lying beneath us worthy of exploration.

We may have just found the first hard evidence that he was right.

More to come.

Sources:

https://today.usc.edu/earths-inner-core-is-less-solid-than-previously-thought/

https://www.sciencedaily.com/releases/2025/02/250210132238.htm