Seventeenth-century French philosopher Rene Descartes spent most of his time searching for a single, certain truth. At the very least, Descartes wanted to prove for certain that nothing was certain - but he couldn't even prove that. In the 18 superscript th century Ben Franklin put the notion to rest for a while, asserting that nothing in the world was certain, except death and taxes.

Then, in the early 20 superscript th century, Albert Einstein theorized that the speed of light was the only certainty in the universe. But even Einsteins can be wrong sometimes. Subsequent scientists, including Hubble, of telescope fame, disputed Einstein, postulating that the universe's continual expanding and contracting prevented a constant speed of light.

At the cusp of the 21 superscript st century, we've come to depend on high-speed, electronic-driven machines. We'd like our appliances to run all the time without fail, but we know they won't. For one thing, computers need a constant supply of clean power that never deviates or diminishes. For another thing, uninterrupted power or not, machines break and computers crash.

Nothing's 100% fail-safe in this world. So long as human touch is a factor, mistakes will be made and machines will malfunction - eventually. So why do Internet providers, facility managers and power-protection equipment manufacturers insist upon using buzzwords like 24/7 and even 24/365? Sure, power-all-the-time is an admirable goal. And, sure, things keep getting better all the time, but technology always stops short of perfection. AT&T, IBM, Hewlett Packard and others, claim Five Nines - or 99.999% reliability - for their newest computer networks. But that near-perfect rate of success hasn't been proven over time.

Engineers know that machines fail less frequently if they're backed with standards of operations, maintenance and redundancy. In some businesses a single second of computer downtime adds up to big money - even millions - so owners heap backup-power redundancy upon redundancy to safeguard their systems, hoping their computers never blink.

Manufacturers of fuel-cells, said to be the most promising technology for uninterrupted-power, also claim Five Nines of power reliability - or 3.4 defects per million. But even if certain high-priced facilities ultimately achieve a 99.999% power supply, the rest of us will have to settle for less for our homes and businesses. Utility power, particularly in an era of deregulation, will never be perfectly clean and constant.

Outside the realm of electrical power delivery, most machines don't even aspire to deliver perfection. The most dependable mass-market car, the Toyota Camry, doesn't come close to approaching 99.999%. Television sets cost less now than they did 10 years ago, but manufacturers don't build them to last like they did 10 years ago. Now they count on consumers to discard the big old sets - when a loose weld or solder blows the picture tube - and buy up to better technology every four years or so.

Computer hardware works reliably, like solid-state TVs used to. But how about computer software? Microsoft Windows, the Gremlin of reliability, pokes along, stalls, backfires, circles and crashes without warning. (Apologies to the now-defunct AMC Corp. - but why name a car "Gremlin?" You may as well have called it "Lemon.") Windows is a great technology that's forever changed our lives, but it always seems to let us down in the crunch. Working with Windows is sort of like watching old-time TV sets. If fiddling with knobs and adjusting the antenna didn't produce a picture, you'd call a TV repairman. If fiddling around with Windows gets you nowhere, you end up calling your company's computer-help line or toll-free number for help.

Maybe it was the telephone that spoiled us into thinking we could hope for near perfection. Phones have long worked dependably - instantly, efficiently, almost magically. Even during power outages phones will work for hours because they need such a low amount of voltage to transmit and receive.

But I've strayed from the primary topic. Should we believe in the fail-safe 7/24, all-the-power-all-the-time dream? Nah, even God once took a full day off to rest. Total reliability is an impossible dream - but a good goal to strive for. How about a slightly less than immortal 99.999%? You can talk about your five nines - but I'll sooner believe a cat really has nine lives.