It was a reminder of the fact, which no scientist should ever forget, that human senses perceived only a tiny, distorted picture of the Universe. Tom Lawson had never heard of Plato’s analogy of the chained prisoners in the cave, watching shadows cast upon a wall and trying to deduce from them the realities of the external world. But here was a demonstration that Plato would have appreciated; for which Earth was ‘real’—the perfect crescent visible to the eye, the tattered mushroom glowing in the far infra-red—or neither?
