Hacker News Reader

> (much how the expected lifespan of an incandescent bulb is independent of its previous usage)

Either I'm reading this sentence incorrectly or there is something else I don't understand. How can that statement be true?

View on HN

It's possible if you have a completely flat failure rate. For every time unit spend it has x% failure rate. An example is a piece of rock on the side of the road. Everyday it has a small chance to be smashed by a car. But that chance doesn't increase or decrease over time. Unless external factors change

Whether it's true for light bulbs I don't know.

I guess the bulb does not degrade over time, it just break at some point when some random events occur.

I don't think that's true, the filament evaporates (sublimes?, sublimates?) from the heat and eventually it is too thin to support itself and breaks. That's how I always understood the main failure mode of incadescent bulbs and that's why the above statement confuses me

Reply on news.ycombinator.com