Is the universe finite or infinite?

Two possiblities exist: either the Universe is finite and has a size, or it's infinite and goes on forever. Both possibilities have mind-bending implications.

Physicists experimentally realize a quantum Hilbert hotel

(—In 1924, the mathematician David Hilbert described a hotel with an infinite number of rooms that are all occupied. Demonstrating the counterintuitive nature of infinity, he showed that the hotel could still accommodate ...

A new twist on quantum communication in fiber

New research done at the University of the Witwatersrand in Johannesburg, South Africa, and Huazhang University of Science and Technology in Wuhan, China, has exciting implications for secure data transfer across optical ...

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