The science of cybernetics, of giant computers that could do much of Man's thinking for him on a specialized technological level, had transformed the face of the Earth and was continuing to transform it at a steadily accelerating pace. The rocket's four giant computers were of the newest and most efficient type--humanoid in aspect, with conical heads, massive metal body-boxes, and three-jointed metal limbs which had all of Man's flexible adaptability in the carrying out of complex and difficult tasks. Robotlike and immense, they towered in the chart room with their six-digited metal hands on their metal knees, their electronic circuits clicking, their tiers of memory banks in constant motion, but otherwise outwardly indifferent to the human activity that was taking place around them. Four metal giants in a metal rocket, functioning cooperatively with Man in the gulfs between the planets, might have made an imaginative fiction writer of an earlier age catch his breath and glory in the fulfillment of a prophecy. An H. G. Wells perhaps, or an Olaf Stapledon. But the reality was an even greater tribute to the human mind's inventive brilliance than the Utopian dream had been. The four giant computers were capable of solving problems too technical for the human mind to master without assistance, usually with astounding swiftness and always with the more-than-human accuracy of thinking machines whose prime function was to correlate without error the data supplied to them on punched metallic tapes, and to perform intricate mechanical tasks based upon that data. The robots were tremendous, by any yardstick you might care to apply, and if I'd had a son-- I stopped thinking about the robots abruptly and sat very still, listening. A sound I'd heard a moment before had come again, much louder this time--a chill, unearthly screeching. The chart room was just outside the eight-cabin section and I could hear the sound clearly. My nerves again, my over-stimulated imagination? In space strange and unusual sounds are as common as pips on a radar screen. It was queer how quickly you got used to them. You had to walk around with your ears plugged up, in a sense, but the plugs didn't have to be inserted. They were just natural growths inside your ears--invisible and without substance, but plugs notwithstanding. They produced a kind of psycho-somatic deafness which didn't otherwise interfere with your hearing. Just the very unusual sounds, the totally inexplicable raspings, dronings, creakings--usually of short duration--were blotted out. You didn't hear them unless something deep in your mind whispered: "This one is different. This is an emergency. Take heed!" The screeching was very different. It was like nothing I'd ever heard before, on Earth or in space.