Einstein's gravity passes new quantum test

Physicists from Ben-Gurion, Ulm and Oxford universities measured the quantum phase of a freely falling rubidium atom wave and compared it with a stationary one. The result matched Einstein's equivalence principle prediction, published September 2 in Science Advances, with Roger Penrose among co-authors.

• First direct quantum phase of a freely falling atom measured
• Rubidium atoms cooled near absolute zero on an atom chip
• Result matched equivalence principle prediction
• Co-author is Nobel laureate Roger Penrose