But Rizzo wouldn't let up. "Suppose there's an intelligent race living on a planet near a Cepheid variable star. They figure that any other intelligent creatures would have astronomers who'd be curious about their star, right? So they send out a laser signal that matches the star's pulsations. When you look at the star, you see their signal. What's more logical?" "All right," I groused. "You've had your joke...." "Tell you what," he insisted. "Let's put that one wavelength into an oscilloscope and see if a definite signal comes out. Maybe it'll spell out 'Take me to your leader' or something." * * * * * I ignored him and turned my attention to Army business. The meteorological equipment was functioning perfectly, but our orders read that one of us had to check it every twelve hours. So I checked and tried to keep my eyes from wandering as Rizzo tinkered with a photocell and oscilloscope. "There we are," he said, at length. "Now let's see what they're telling us." In spite of myself I looked up at the face of the oscilloscope. A steady, gradually sloping greenish line was traced across the screen. "No message," I said. Rizzo shrugged elaborately. "If you leave the 'scope on for two days, you'll find that the line makes a full swing from peak to null," I informed him. "The star pulsates every two days, bright to dim." "Let's turn up the gain," he said, and he flicked a few knobs on the front of the 'scope. The line didn't change at all. "What's the sweep speed?" I asked. "One nanosecond per centimeter." That meant that each centimeter-wide square on the screen's face represented one billionth of a second. There are as many nanoseconds in one second as there are seconds in thirty-two years. "Well, if you don't get a signal at that sensitivity, there just isn't any signal there," I said. Rizzo nodded. He seemed slightly disappointed that his joke was at an end. I turned back to the meteorological instruments, but I couldn't concentrate on them. Somehow I felt disappointed, too. Subconsciously, I suppose, I had been hoping that Rizzo actually would detect a signal from the star. _Fool!_ I told myself. But what could explain that bright emission line? I glanced up at the oscilloscope again. And suddenly the smooth steady line broke into a jagged series of millions of peaks and nulls! I stared at it. Rizzo was back on his bunk again, reading one of his magazines. I tried to call him, but the words froze in my throat. Without taking my eyes from the flickering 'scope, I reached out and touched his arm. He looked up. "Holy Mother of God," Rizzo whispered.