Not gonna lie. I thought this was a reference to how long you can leave food on the ground before picking it up and eating it.

No worries It's natural to confuse cache misses with missed catches.

I know you're kidding, but can anyone explain why people believe the 5 second rule?

The instant food falls to the ground it's going to pick up any dust / mites / microbes, so it will be no less and no more infected after 5 seconds. It's perplexing to me, what mental model explains how the food is cleaner during the first 4 seconds on the ground?

Edit: the Wikipedia article is pretty clear that any bacteria attach basically immediately (each of the cases when tested showed no difference after 5 seconds).

I believe in a indefinite period of time rule. The food might pickup dust / mites / microbes, so what? There are dust/mites/microbes everytime you breath. You probably swallow other people's shit particles several times a day. It's OK, you have an immune system that can deal with it. If you do (very very rarely) get an infection we live in magical times where an antibiotic pill will clear it right up. You could lick the floor at the sports stadium bathroom and you'll be OK. People need to stop it with the cooties crap.

The wikipedia article claims most people who invoke the rule use it in jest, but there is research that indicates different surfaces allow for different speeds of bacterial spread: https://en.wikipedia.org/wiki/Five-second_rule

Time for some true confessions. My mental risk model tells me I'm not more likely to get sick if the food touches some surface. I'm a pessimist so I generally assume all those bacteria are already on the food and/or in my body. I don't know if my risk model matches reality or not.

That's the five second rule.

https://en.m.wikipedia.org/wiki/Five-second_rule

But it would have made an interesting article if someone discovered you could often leave food on the ground for multiple minutes without issue, and named the article after their new "five minute rule" ;P.

Evidently your floors are cleaner than mine.

If you are interested, read all 3 papers on this.

Jim Gray pubished the first paper, 5 minute rule in 1985 (http://www.hpl.hp.com/techreports/tandem/TR-86.1.pdf)

In 1997, he (along with Goetz Graefe) published the followup - The Five-Minute Rule Ten Years Later (http://research.microsoft.com/en-us/um/people/gray/5_min_rul...)

Goetz Graefe published the 2nd followup in 2008 - The Five-minute Rule: 20 Years Later (https://queue.acm.org/detail.cfm?id=1413264)

The note at the bottom about web pages is interesting. I always wish browsers followed that behavior so the "Work Offline" button would actually work when I got on a plane. I'd be happy to sacrifice 10GB+ of my SSD for the browser to permanently cache (at least for the life of the Cache-Control header).

I wonder how performant a proxy like Squid would be to run locally with a disk cache.