Shoes Wearing out all at once?

I though I would relate an unusual experience i just had. it made me wonder-what if material things (like cars, appliances, etc.) all had a finite life-and at that point, they would just suddenly fail? Anyway: i had a pair of inexpensive shoes 9rubber soles, leather uppers). i rotate wearing my shoes, because i suffer from excessive swaeting of the feet. So typically, i will wear a pair for a day, then move on; and wear the original pair a week later. One day, I put these shoes on…and notices i was leaving bits of rubber on the carpet. on returning home that evening, major chunks of the soles were missing. the next time i wore them, the soles simply disintegrated! It was as if i had reached the lifespan, and the things just fell apart! Have you ever noticed this? Years ago, my Dad had a Chevrolet car-he had it for 14 years-and then it fell apart-within weeks he had engine problems, brakes, electrical, etc.
Just wondering if it is possible (statistically) for everyhting in a product to reach its lifespan at the same time-and fail!

Yes, it is possible (statistically). Statistics also say a coin flip can result in heads 10 times in a row. In the case of the 14 year old Chevy, there is a non-zero chance than many parts will fail simultaneously. Your selective memory only notices the times that something unusually like this happens.

In the case of the shoe sole, I suspect that either the chemical bonds holding the sole together degrades over time (such that the entire sole became chemically unstable) or it was recently exposed to something that sped up the degradation.

Alcohol can act as a solvent on cheap, rubber-like plastics. As can motor oils.

Likely, you stepped in some goo.

The sole of a shoe is different than a car. The sole of the shoe is made of one substance. I would expect that if it degrades, it would degrade fairly uniformly since the degradation is either chemical instability or something like the goo mentioned above. A car is a bazillion mechanical parts and there’s no particular reason that everything should fail at once, although the engineering specs for all those parts may dictate a similar service life by design. But for every car like your dad’s Chevy, there’s another one that racks up 150,000 miles.

Reading the thread title, I thought you were saying that all of your shoes decided to fail simultaneously. That would be a big coincidence.

Not necessarily.

I have found a office show that I like, and usually buy 2 or 3 pairs at once. Then I rotate them, using a different pair each day, and letting each one rest a day or two before wearing it again. Given that pattern of use, all the pairs get approximately the same amount of wear, and they often start to wear out at about the same time.

Not a coincidence, but a natural result of my pattern of usage.

I vaguely remember from my Ceramic Engineering degree (vaguely mainly due to it being 20 years ago and pursuing an IT career instead of materials science) that Weibull statistics can be used to estimate expected lifespan of materials. Prof speculated that Fiat motor company employed many skilled Weibullists as his wife’s car suffered a similar fate to ralph124c’s father’s Chevy.

The Deacon’s Masterpiece (AKA, the Wonderful One-Hoss Shay)

You might have accidentally stepped in some solvent as well. Not sure what eats rubber – maybe gasoline or acetone?