I visit Walmart about once a month. It's off my beaten path, but carries a few items that are so inexpensive it's worth stopping by to stock up. The "site-to-store" free-shipping is hard to resist too. The SKUs and the shelf layout hardly change, which makes the shopping quick and easy. That also makes the changes stand out.

The last time I went a few days ago, one thing stood out: no tube televisions.

Over the past several years, the shelf-space for tube televisions had shrunk to a single side wall. Then half of that. Prices plummeted. At the end, Walmart was obviously shedding inventory. And where Walmart plants its giant retail feet, there for good or ill can be found the smack dab median of American consumer supply and demand.

The television tube is dead. Long live the television set!

Fanatics still buy turntables and tube amplifiers. But the television cathode ray tube is a bulky kludge that has little to recommend over its technological replacements. Like the internal combustion engine, the real miracle of this Rube Goldberg contraption is not that it can be made so inexpensively, but that it works at all.

The CRT is the last true vacuum tube--a filament, cathode, grid and anode sealed inside of glass and depleted of air--found in consumer electronics. For decades after the introduction of the transistor, a television set had two vacuum tubes: the CRT and the high-voltage rectifier that charges the anode. The latter was long ago replaced by silicon devices.


While the typical "radio tube" has a few hundred volts at the anode, the CRT requires tens of thousands. It's a cliche that the computing power of a Cray supercomputer can be packed into a cell phone. Less appreciated is that for half a century, a large proportion of the world's population had a small linear accelerator sitting in a corner of their living rooms.

It's also become a cliche to remark about how complex the technological world is becoming. But as materials science and manufacturing improves, and Moore's and Shannon's laws reach their limits (plus the very non-theoretical problem of heat dissipation), the macro can only grow to the extent that the micro gets simpler.

The junction transistor (1947) is a simpler device than a vacuum tube (though the underlying physics is a bear). The field-effect transistor--most common today--is simpler than the junction transistor (and more analogous to a vacuum tube). It was theoretically described in 1925, but the necessary silicon purities weren't possible until 1952.

Philo Farnsworth's scanning electron beam television was the best version possible with 1920's technology. The plasma television is a lot simpler. It was conceptualized in 1936, but the electronics and manufacturing techniques would take 30 years to catch up. And another 30 years to make economical as a CRT replacement.

An all-electric car is mechanically much more simple than the internal combustion engine. But as is often the case, we're better at improving old technology than making new technology affordable. The laws of thermodynamics--the enormous amount of energy stored in a gallon of gasoline--is the higher hurdle here.

With consumer electronics, when all that has to be moved are electrons and photons (and a finger to operate the remote), Moore's law rules the roost. Smaller, cheaper, faster keeps getting smaller, cheaper and faster. The CD wiped out a century of technology in a decade. The DVD took out VHS even faster. I now have a tiny Nokia and no landline.

And yet we still dial phone numbers. Will we still watch the tube after the tube is gone? I will for the time being. My boxy old JVC is good enough. Though if I ever move, it won't come with. When I was at Walmart, I easily lifted a flat screen the same size. The last time I moved that JVC around, I nearly put my middle-aged back out.

Besides, winter's coming. It's the closest thing I've got to a fireplace: big, warm, and impersonally friendly.

Labels: computers, pop culture, technology, television