I heard somewhere that honey is the only food (or even thing?) that never perishes. Apparently honey found in Egyptian tombs was still edible… Is this true??
Yes, according to the honey association.
There are a couple of beekeeper Dopers who should be along shortly to confirm or deny.
But WhyNot, the question is Why?
I couldn’t resist. 
What’s in honey that makes it last forever?
Wouldn’t 2000+ year old honey have most likely have turned into a sugar like solid. This might be a factor in honey preserving itself.
Seems like I’ve also heard that popcorn (unpopped of course) can also be stored indefinitely. Anyone care to comment?
Fructose and glucose. A sufficiently concentrated solution of these compounds is “inedible” to bacteria. If you dilute honey with water it will become inedible in a matter of days.
While it may be perfectly edible, honey does alter over time. I remember my grandmother used to have a many-years-old jar of honey in her larder, which had separated out with a crusty layer of sugar crystals and a watery runny layer. Edible, yes. Appealing, no.
The key here is water activity, which is defined as the partial pressure of water vapor over your substance divided by the pressure over pure water. Microbes (bacteria, fungi, yeasts) require a water activity of at least about 0.6. Honey has so much sugar in it that it binds to all the water, making it unavailable for metabolism. There are a few unusually tough strains of yeasts that can grow in honey, but generally it’s not a good growth medium.
You surrender too quickly, Colophon. Just submerge that honey jar in some warm water for about ten minutes, then stir. Ta-da! Good as new. (About ten seconds in a microwave will do it, too. I knowed dem t’ings was good fer somet’in’.)
That is not very true at all unless you administer some life-saving techniques to the kernels. Popcorn depends on hot water (steam) to pop and its internal reserves of water needed to do that deplete over a few years. If you have old popcorn kernels, you might be able to pop it by soaking it in water for a few minutes before you try to pop it and there is a good chance that many will pop. However, I seriously doubt that popcorn several decades old is going to pop into anything resembling popcorn even if you soak it in water first.
What about sugar? Does that deteriorate/ decay over time?
Tupelo honey does not granulate. And it is incredibly sweet.
There is only one place on Earth where it is produced commercially - Wewahitchka, Florida (just east of Panama City). Known around here as simply “Wewa”. The movie Ulee’s Gold was filmed there.
If exposed to the elements, yes.
Just visited the unearthed paddle boat Arabia in Kansas City. Largest collection of pre-civil war artifacts in the US because the boat went down with all its cargo, including several jars of pickles. The excavators said the pickles were still sweet. So, 140 years for cucumbers.
My impression is that all syrups are self-preserving. I never refrigerate molasses, or sorghum syrup or honey or even pancake syrup. No need to, because of the high sugar content. The stuff keeps indefinitely, in my experience. (Pancake syrup might be a little iffy, as it seems watered down.)
Neither does fireweed honey. Or it takes a very long time to do so. Light and sweet…yummmm.
Gee, I like granulated honey. Purposefully set it aside for a few months…
How 'bout Ketchup? Seems to have an infinite life-span alstoo.
I dunno about “infinite” with ketchup. Put it this way: If you offer me a taste of 1000-year-old ketchup from some forgotten tomb, I think I’ll pass. 