What Do Light Bulbs and Vacuum Tubes Have to Do With Computers?

In the 21^st century, it is all too easy to take today’s powerful microcomputers for granted, and as artificial intelligence continues to make inroads, the assumption is that massive amounts of data can be crunched in fractions of seconds. But computers weren’t always that way, according to a video on the YouTube channel Veritasium, titled, "Why the First Computers Were Made Out of Light Bulbs."

In fact, the video traces the development of early computers to the invention of the light bulb at the outset of the 20^th century.  According to the video, scientists noted that the filament inside the bulb would emit electrons which would collect on the bulb’s inside surface and eventually discolor the bulb. This phenomenon was called thermionic emission. Later on, the addition of filaments inside the bulb led to the development of the practical vacuum tube devices with triodes.

As it turned out, vacuum tubes were instrumental in the development of the first computers, after scientists discovered the use of mechanical relays to make primitive calculators would not suffice for developing larger computers that used Boolean logic operations. Quieter, more reliable electronic-based switches were needed, which vacuum tube triodes were able to provide, according to the video.

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The video noted the first electronic programmable computer, called Eniac, came online in 1945. Eniac required a whole room, weighed 30 tons and used 175 kW of power. In fact, the computer had its own generator to supply power. The video noted that Eniac could perform 500 operations per second─a snail’s pace by today’s standards─but powerful enough to be useful in helping develop the atomic bomb.  

But eventually, computers comprising vacuum tubes turned out to be noisy, bulky, power-hungry, and unreliable. Luckily, the development of the transistor a few years later would lead to the powerful computers we rely on today.

You can view the video here.