It seems to me that people are far too casual about one of the greatest personal threats, that of suddenly being translated into another world, era, or alternate history. This happens all the time. You walk around the horses in a little town near Berlin, in 1809, and you disappear (with a popping sound). You get hit by lightning, and suddenly you find yourself in Ostrogothic Italy or medieval Iceland. Some bruiser hits you on the head with a crowbar, and you wake up in Arthur’s England. While investigating reports of strange gases in an abandoned coal mine in Pennsylvania, you fall into a kind of suspended animation for 492 years, waking to find America under the iron heel of the Air Lords of Han. While chasing down an armed perp (again in Pennsylvania), you’re accidentally swept up into someone’s sideways-in-time vehicle and land in a Keystone State full of pagan Aryans in desperate need of a new source of gunpowder.
Sometimes you don’t go alone. You and your posse might be losing to Commies in Angola when you’re providentially scooped up by a flying saucer in search of mercenaries. Your Yankee island, coofs and all, may suddenly slide back to the Bronze Age. You look out the window of Flight 33 and see brontosaurs, which can’t be good.
I don’t believe anybody can prevent these sudden translations, but we can do a better job of readying ourselves. It should be possible to develop a small kit that materially improves your chances in such circumstances – whether your goal is mere survival, introducing/saving/restarting civilization, or becoming King and/or Warlord. More than a bug-out bag.
Looks to me as if you might want to use a kind of flow chart: figure out key survival facts first, and only later pursue more general investigations. Immediately check for predators, volcanism, and hostile humans. If there are no immediate threats, you probably want to check where – or when – you are.
The flora and fauna tell you a lot: if you see mammoths, you’re either in the past (but not terribly far back) or you’re in a future rife with genetic engineering. If you see several identifiable species, you can intersect their ranges to home in on your location.
If you see a hummingbird you’re in the Americas: if you also see eastern hemlock you’re almost certainly east of the Mississippi river. Eucalyptus is strong sign of Australian location. And so on.
A clear night sky is damned informative. If you’re not too far in the past or future, the stars can give you a rough date and latitude. They could also tell you if you’re in some other local solar system: you should carry maps giving you key altered constellations (both hemispheres) for the 20 closest solar systems. For example, if Orion looks like this, you’re in the Alpha Centauri system:
The Moon is a giveaway: you’d know that you were on Earth even if the constellations were time-distorted beyond recognition. Luna can give you some temporal info as well: if you don’t see Tycho, you’re more than 100 million years into the past. If it’s green, you’re definitely in the future.
Knowing some very old-fashioned astronomy can be very useful when you’re on the verge of being burnt at the stake. Learn about the Saros cycle – predict eclipses and amaze your enemies.
We can learn from what has been found useful in past incidents of this kind. Having some real silver money in your pocket is good – it might let you pay for your lodgings for a week or so, while you scope out the situation and prepare to build the world’s first still. . If you want to introduce agriculture, carry seeds. Cortez got wheat farming in Mexico started with three kernels found in a sack of rice from Spain – I would suggest teff, since you can hold enough in your hand to to a sow a field.
If you must carry a gun, bring silver bullets.
I’d include two extra pairs of glasses, so that you can break one pair and still have fun reading up a storm, after the big nuclear war.
You’d want to be inoculated against smallpox, and bubonic plague, and maybe some other things. Bring some antibiotics - stuff that doesn’t require refrigeration
Maps with locations of easily exploited, highly valuable minerals, like the beach diamonds of Namibia would be good to have. Generally, you would make maps from thin oiled silk, like flyer’s escape maps in World War Two. Durable, solar-powered digital devices might be better: in a few gigs you could easily store all the best parts of western civ, including the 1911 Britannica. You might also want to home-brew a dosimeter out of a solar-powered digital camera and a plastic scintillator, so you can avoid the worst-hit spots from the ancient nuclear wars…
Of course you may land somewhere where high tech does not work. Bring a grimoire or two in microfiche: you can find nonelectric handheld microfiche viewers.
These notes are just a beginning. Suggestions are welcome.