The evidence has been growing that the universe is infinite but it may all come crashing down

In his masterpiece, On the Nature of Things, Lucretius (99 BC — 50 BC), a Greek Epicurean philosopher, proposed a thought experiment. He imagined a universe that is finite and a spearman standing at the edge of this universe. He throws the spear and it flies through the air. If the universe is bounded, he reasoned, it must hit something. Yet, if there is something there, that must be beyond where the spear can go and therefore the universe must be a little bigger than that.

By this, he reasoned that the universe is infinite.

Aristotle and later Ptolemy disagreed and proposed universes made up of concentric spheres centered on the Earth. Aristotle argued that if the stars were infinitely far away, they couldn’t rotate around the Earth in 24 hours. Ptolemy made the geocentric model work, and their arguments became the basis for Christian conceptions of the universe through the Middle Ages.

Nicholas of Cusa (1401–1464), the late Medieval German philosopher, started to challenge this view in his works on metaphysics. Although he had a geocentric model in mind, he argued that everything in the universe is in motion, including the Earth, with no well-defined center. He said even the “outermost sphere” is not a finite boundary. Therefore, the…