When I was young, there was no television. This was difficult to explain to my children. “Oh no, Dad,” they would say, “There was always TV.” They can’t understand what people did at night in that incomprehensible time when lives were not illuminated by television.

But I remember. My world at night was filled with the magic sounds of radio. I would lie in bed in the darkness, watching the dancing glows of the filaments in my bedside radio. I imagined sometimes that there were little people encased in those tubes, and their voices were those I heard. Now in the modern daylight of television it is hard to explain the reality of radio in that long lost time. I rode with the Lone Ranger. I sent away for the secret decoder ring from Captain Midnight so I could unscramble the coded messages about the next episode. I dreamed that I was Lamont Cranston. (“Who knows what evil lurks in the heart of man? The Shadow knows.”) The pictures that I saw were those drawn in my mind, and perhaps they were more real than the ever-changing, evanescent images from the ubiquitous cathode ray tubes of today.

I wanted to create this miracle of radio myself. I built crystal radios with cat whiskers that touched delicately upon little cubes of quartz, and listened acutely through earphones as I moved a steel pointer across a coil wound on a cardboard tube. Sadly, I never heard a peep. So I studied a book entitled, “Boys’ First Book of Radio” and dog-eared a precious copy of the Amateur Radio Handbook. From them I learned about superheterodyne receivers. I designed and built one, and experienced an unforgettable thrill when I turned the switch and music came from the speaker. That radio made an engineer of me.

One of the most memorable moments of my life was when I first saw television. I crept silently upon a neighbor’s porch with two friends, standing precariously on a snowy woodpile. Peering awkwardly through the window I could see the family in their living room, their faces lit dimly by a strange flickering blue light emanating from a large wooden box containing a small round picture tube with a large magnifying glass suspended in front. I could see a person on the screen mouthing unheard words, someone I came to know later as Milton Berle in a show entitled “Texaco Theatre.”

Flash forward a mere 20 years or so. I sit comfortably in my own living room watching a large screen color television as I see a man descend the steps from a strange vehicle that has landed on the moon. The whole world watches with me, united around uncounted millions of television sets. Which was the greater miracle – that man had walked on the moon, or that the world had been able to tune in to see the event live from outer space? It was a momentous event for mankind, one in which there was a great triumph of technology and a unique shared spirit of achievement. If only there could be more such uplifting and coalescing experiences!

That magic of radio lives with me today, but now I see it though the eyes of an experienced engineer. I look out the window at the clear blue sky and think of all the radio waves crossing that seemingly empty space. If those waves had visible color, the sky would be as bright as a laser light show. But it wasn’t all that long ago when there were no waves at all. I remember the feeling I had when I visited Marconi’s home outside Bologna, Italy, with his daughter, Gioia, who had become a good friend. I looked out the window where he had sent the first radio pulse, and wondered what he must have felt like when the iron filings in the glass tube of the coherer detector across the hill jumped at the recognition of his pulse.

Somewhere out there, 100 light-years distant, infinitesimally small, that first pulse is still traveling among nearby stars. It whispers that earth is alive. Its creator, Marconi, must have believed that the heavens had been opened to unlimited communication. As an engineer in the late 20th century, however, I came to realize the limitations of that ether. In a short century, we had used it up. We moved from the broadcast world that I had known as a child to the world of cellular telephony, where everyone has his personal transmitter. The precious spectrum that had seemed free and infinite in Marconi’s day had been sold in tiny slivers for billions of dollars.

Today, once again, we use Marconi’s word, wireless, to describe cellular radio. There has been a renaissance in thinking about the capabilities of that empty sky. New methods of transmission, of processing signals, and of sharing the spectrum have cascaded out of the universities and research laboratories. The last century saw radio emerge, blossom, and ultimately devour all the capacity that nature had given us. The next century may see us reclaim the vastness of Marconi’s dream with these new technologies.

I still dream of radio. My dreams now are filled with equations, rather than little people encased in glass tubes. It amazes me that after a century of exploration, so much remains to be done. The magic still lives.