Cosmic-ray imaging finds hidden structure in Egypt's Great Pyramid

Scientists using an imaging method based on cosmic rays have detected a large and enigmatic internal structure in the last of the Seven Wonders of the Ancient World still standing, the massive Great Pyramid of Giza on the outskirts of Cairo.
Researchers announced the discovery on Thursday but said they did not know the purpose, contents or precise dimensions of what they are calling a “void” or “cavity” inside the pyramid, built as a monumental tomb around 2560 BC.
To peer inside the pyramid, the scientists used an imaging technique called muon tomography that tracks particles that bombard Earth at close to the speed of light and penetrate deeply into solid objects.

 Cosmic-ray imaging finds hidden structure in Egypt's Great Pyramid