While trying to uncover how ancient Egyptians built the pyramids, a team of scientists found a hidden chamber in Khufu's Great Pyramid.
The monument is one of the world's oldest and largest marvels, but not everyone agrees how it was constructed. Some researchers argue we might figure that out if we look at its internal structure.
To get a better look inside, one team used the combined forces of two schools of thought: archaeology and particle physics.
The researchers imaged the pyramid using muons — those are particles produced when cosmic rays and Earth's atmosphere react. Muons have special properties that penetrate stone, which lets the team distinguish cavities in the pyramid from solid formations — like how X-rays image bones.
This interdisciplinary collaboration let the team discover a previously unknown void in the pyramid almost 100 feet long, similar to the pyramid's Grand Gallery.
The researchers suspect the new chamber might actually be one of several and was hidden on purpose when the pyramid was constructed. But the team can't physically get to the void right now.
And some questions remain — for example, about the chamber's exact structure and how it was used. Further studies could reveal more details about the void and might finally uncover how the Great Pyramid was built.