One day every human on earth capable of understanding a language gets has the same thought in their respective language repeated 3 times over the next three hours:

"In order to reduce human impact on nature and let ecosystems recover, starting from 30 days from now (equals the first of April), all of humanity will be sent 75 years into the future. From then on, this jump will occur every 25 years."

And sure enough, on the specified day, every human, as well as every foreign substance or object that is currently within that human (eg air in the lungs and food in the digestive system) gets transported onto the exact location on earth 75 years in the future, replacing any material that has since moved into that spot in that year without preserving any velocity while leaving a person shaped vacuum in their time of origin.

While this means you aren't going to instantly die on arrival as you are now part of a tree or whatever, it doesn't necessarily save you from death moments later. For example, if a skyscraper you were in at the time of the jump had collapsed in the meantime, and you were in the top floor at the time you'd now plummet to your death, while your buddy Mark who was in the ground floor, is getting crushed or suffocated by rubble at the same time.

I assume that in the time of the first jump, there would be a considerable death toll. While people might be awaiting the day anxiously, and many might make some preparations, I can't imagine most people being able to just "take the day off". Bills need paying after all, or they simply expect it to be an elaborate hoax of sorts. For simplicity, let's just assume that in the wider area the story takes place, the split is 15% completely convinced that the jump will happen and will do everything they can to prepare, 50% unsure or have to many other things going on to commit all their time into preparing and the remaining 35% assuming it is a hoax and ignoring the warning.

So, who would die? Initially, pretty much everyone in aerial or nautical transportation. It's raining men. People in dangerous environments that require special equipment. Your clothes and tools didn't get transported and even if you are lucky enough that they are still sitting on the ground after 75 years, they are still 75 years old, rotten and probably damaged because parts of them were replaced by you. People in unfortunate surroundings. See the collapsed building example, or maybe you are now stuck in the chassis of a truck that was driving behind you 75 years in the past. Next up, starvation. There hasn't been any food produced for quite a while, so famine is going to be an issue very soon, especially in cities. Sure, there will still be preserves around, but no crops have been sown and depending on where you are in the world there won't be much to forage at this time of the year. With starvation comes competition for resources which also will likely produce it's fair share of casualties.

Anyway, aside from these unfortunate souls, there will still be a large number of people that are still alive and kicking after the jump, regardless whether they prepped, took the day off or just got lucky.

The protagonist is a single guy in his early twenties, living in a city of around 500k inhabitants and who takes the warning seriously enough to want to at least make some preparations. He is willing and able to spend between 1.500€ to 2.500€ or its local equivalent to prepare.

I have already created this list of no-brainers:

  • Avoid being in the "who would die category"
  • Make likeminded friends (Living becomes much easier if you have someone to watch your back and share labour)
  • Create a supply-stash (Drinking water, preserved food, clothes, whatever useful equipment and material I can afford) and store it somewhere that will still be safe and accessible in almost a century, easier said then done)
  • Find a safe location and meet up there with my friends the day before the jump. (Might need to do overtime to get the day off)
  • Get an easy to use weapon or learn how to trap animals

Some additional thoughts:

One thing I am unsure of is the danger of unsupervised infrastructure like oil rigs and nuclear power plants, simply because i am less than a novice in these areas of expertise. Will things like oil spills and nuclear meltdowns render large swathes of land and sea uninhabitable? No clue.

The story is planned to take place in Northern Germany or Denmark, but if you have some interesting ideas for your own country, feel free to add them.

For every jump following the first, preparation time is 25 years.

Many items will likely to be sold out as soon as they are replaced in the stores and get really expensive (tp, canned food, charcoal, etc) .

It might be a good idea to leave the city some time earlier and set up shop close to sources of food and water that will still be around in 75 years such as a river/an orchard/a forest

Some infrastructure will likely be salvageable even if it is just a bike

Perhaps it would be possible to break into a poultry farm and release the birds shortly before the time jump occurs, giving their descendants a chance to be around to eat later.

It is unknown (and for this question unimportant) who or what causes the jumps and if they will ever stop occuring and there is no way of knowing no matter hard people try to find out.

Not really related to the question, but I assume the less "civilized" a people is, the more likely you'd be to just be able to carry on as normal.

So, how should I best use the 30 days I have left to make sure I will survive the first, as well as (if possible) ease the following jumps (when im in my forties/seventies)

  • $\begingroup$ Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on Worldbuilding Meta, or in Worldbuilding Chat. Comments continuing discussion may be removed. $\endgroup$
    – L.Dutch
    Aug 16, 2023 at 17:09
  • $\begingroup$ You might enjoy en.wikipedia.org/wiki/The_Peace_War, which deals with such a mechanism. $\endgroup$
    – ceejayoz
    Aug 16, 2023 at 18:04
  • $\begingroup$ Your question provides a lot of details about how this works, and some of the existing answers rely on your protagonist knowing those details; but your telepathic message doesn't provide those details. Can you clarify your expectations on this point? $\endgroup$
    – ruakh
    Aug 17, 2023 at 0:10
  • 1
    $\begingroup$ The percentage of people believing this to be a hoax will probably be quite high given the "first of April" in the announcement :p $\endgroup$ Aug 17, 2023 at 5:53
  • $\begingroup$ I have no idea what majority of people would do, but the civilization itself will definitely prepare to mitigate the damage of future jumps (so only the first one will be an issue). Afterwards it is gonna be the research into time physics (we would know that time travel IS possible). Then fast expansion and finally finding and purging those filthy xenos that almost destroyed our species! $\endgroup$
    – Negdo
    Aug 17, 2023 at 7:47

19 Answers 19


It really sounds like a fun story.

If I knew and believed a 75-year time jump was to happen, I would make sure to have like-minded acquaintances in a country with enough rivers and fertile lands and I'd go there for when the time comes.

I'd help them weld shut doors and windows from the inside of whatever place we believe is best to seek shelter from wildlife. Naturally I'd like to have the necessary tools to remove welding.

I would bring all kinds of canned foods, seeds, bottled water, or honey and I'd toss out any short-lived foods like fruits and meats.

I would wear or bring linen clothes, as they're supposedly more lasting than other materials.

I'd disconnect any electrical device, remove batteries and store them safely. I'd bring a flashlight, for the miraculous case that any battery is still usable.

Just in case, I'd bring paper maps, a compass, a mechanical watch, a radio and my paper documents.

If there was time, I'd help build metal coffins with holes for breathing that can only be opened from the inside, and each one of us would use one of these, holding our properties with us.

Lastly, I wouldn't waste time trying to convince family and friends to come along; I would know this is a critical situation and, as such, I would pretty much prefer staying alive myself. If they want to come along, that's great, otherwise, I'm leaving.

  • 10
    $\begingroup$ Instead of the flashlight, pack a dyno torch. Grandpa's one from WWII still works here :) $\endgroup$ Aug 15, 2023 at 11:03
  • 6
    $\begingroup$ "...in a country with enough rivers..." This could also be an interesting small plot point. Rivers move over time, so they likely wouldn't be where they were hoped to be. It'd probably not hurt the protagonist too much (75 years isn't that long), but it'd be a great reminder of what time does, even to nature. Everything changes. $\endgroup$
    – Cort Ammon
    Aug 15, 2023 at 14:42
  • 4
    $\begingroup$ don't forget weapon, your biggest risk is all the people who did not prepare and now face starvation wanting your stuff. you also forgot the single biggest part of survival, a way to make fire. sealed matches and ferro rods. Fire is tool number 1! $\endgroup$
    – John
    Aug 15, 2023 at 16:44
  • 2
    $\begingroup$ While a good answer, this misses implications of a continental drift. Having been time travelled in exact place relative to Earth is not the same as being in exact place relative to your house, let alone a steel coffin. Imagine that after the time travel you've appeared with your face within the thick of a concrete wall. There goes one unlucky protagonist. $\endgroup$
    – Vesper
    Aug 16, 2023 at 4:54
  • 2
    $\begingroup$ I don't think there is any canned food that will last 75 years. I even wouldn't trust bottles of water actually. $\endgroup$
    – Ivo
    Aug 16, 2023 at 11:31

An amusing question. Many thoughts. Excuse me if I ramble.

First thing would be to get out of cities. As you note, anyone in the upper floor of a building might find the building has collapsed and he promptly plummets to his death. If he's on the ground floor he materializes inside a pile or rubble and suffocates.

Even someone standing in an open field ... what if the ground level has changed in 75 years? If ground level has fallen, then when he materializes he falls. Maybe not enough to be instantly killed, but possibly enough to break bones. Or if ground level has risen, he materializes with his legs embedded in the ground. Can he dig himself out?

Or if a tree has grown on the spot or a boulder has rolled there, he materializes inside a solid object and either instantly suffocates or finds himself trapped, unable to move, until he starves.

This sounds like a pretty horrifying scenario to me, actually.

Even if he survives the initial appearance ... No one has been farming for 75 years. There is naturally-growing food that one could forage. Those skilled in hunting could kill and eat animals. But there would be nowhere near enough food for the world population. Billions would starve. Maybe, possibly, this could be staved off if people planned ahead and stored non-perishable food in safe places, or were lucky enough to find stocks of canned goods etc that had survived. Is there enough non-perishable food in the world to keep people alive until farming could be restarted? Farmers could presumably plants crops and have a first harvest within a year, but they wouldn't have tractors and fertilizer and all the tools that make modern high yields possible.

I'd guess most buildings and machinery would be almost useless after 75 years of neglect. A building can easily last more than 75 years -- my house is 110 years old and there are plenty of buildings in Europe that have been in use for centuries -- but how long would they last without constant maintenance? Maybe some of the better made buildings would still be usable. Machinery would probably mostly be too rusted, etc, to be usable.

So technology and infrastructure would have to be rebuilt, not exactly from scratch, but from a very low baseline.

When all the people disappear, there will be disasters. Motor vehicles and airplanes will crash. There will be fires and explosions at factories and power plants. (I'd guess that nuclear plants will be the least of your problems as they tend to have elaborate safety systems and will automatically shut down. But maybe a few around the world, those systems will fail and there will be meltdowns and releases of radioactive material.) Though I'd guess that by the time everyone reappears 75 years later, the scars from all this will have long since healed. There will be some changes to the landscape where, for example, a dam broke and flooded the area downstream. Which brings us back to, some people may appear to find themselves underwater and promptly drown.

If I believed the warning, I think I wouldn't worry about missing some time from work to prepare. There the question becomes how credible the warning is. If you dismiss it as a hallucination or a hoax, presumably you'll do nothing. If you absolutely believe it, you can spend every day until D-Day preparing. If you think it's possible but are not absolutely convinced, you might take time off work to prepare but not devote your life to it.

In that way this would be a lot like the year 2000 scare. For those not old enough to remember that, many were predicting that there would be all sorts of disasters on January 1, 2000 because of computer systems failing. A fair number thought civilization would collapse. I recall a co-worker of mine was stockpiling food and medicine, he was absolutely convinced civilization was going to collapse. (One day at work Harper explained everything he was doing to prepare for this imminent collapse. Someone then turned to me and asked me what I was doing to prepare. I said that I had bought a gun, and if anything happened, I was going to go to Harper's house, shoot him, and take all his supplies. :-)

So what to do to maximize your chances?

First and foremost, get out of the city. Go to the country, as far from other people as possible.

Bring a small group of friends who agree to help each other. If, whether because of the sudden transport or just some random accident afterward, one of you breaks a leg or whatever, you will then have others around to help you out until you recover. And in return you can help them out when they get sick or injured.

Make a stash of non-perishable food and medicine. Get guns and ammo and prepare it in ways that it will last 75 years, like oiling it well and wrapping it carefully. Also some knives and swords so when the ammo runs out, you still have weapons. Also other basic tools, like wrenches and screwdrivers and hammers. Obviously power tools will be useless. Store it all in the same place where you're going to be when D-Day comes.

If you are not a farmer, take a crash course in farming, so after your appearance you can immediately begin growing food. Primitive farming, by the way. No use learning how to drive a combine, they'll all be rusted piles of junk. Even if you could fix one up, where would you get fuel for it?

Oh, another thought: In your stash, include books. Especially how-to books. In the short term you'll need to know how to farm and hunt and build shelters. Longer term, as you rebuild technology, you'll want to know how to make electrical generators and install wiring. Etc. Even if you don't live long enough for some technology to come back, think about your grandchildren.

  • 3
    $\begingroup$ My house is also around 100 years old, but it wouldn't be standing if unmaintained for 75 years. These old houses still need the roof redone every 20 years or so and repairs after storms to keep them water tight. $\endgroup$
    – Separatrix
    Aug 15, 2023 at 12:31
  • $\begingroup$ @Separatrix Yes. I once visited an old prison that was being turned in to a museum. The place was badly run down and needed a lot of work. I asked if it was like this when it was in use as a prison, and the tour guide said no. The place had been abandoned for several decades and had deteriorated badly in that time. My house is in good condition despite being 100+ years old because I keep it at a relatively constant temperature, if a pipe starts to leak I fix it, etc. $\endgroup$
    – Jay
    Aug 15, 2023 at 18:35
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    $\begingroup$ Afterthought on books: The famous writer G K Chesterton was once asked, if you were stranded on a desert island and could only bring one book, what would it be? Chesterton was well known for being a devout Christian, so the reporter probably expected him to say "the Bible". Chesterton replied, "Bartlett's Guide to Boat Building". $\endgroup$
    – Jay
    Aug 15, 2023 at 18:43
  • $\begingroup$ If a dam breaks, the water would flood the area but then it would flow downstream without forming extra dams, whcih is required to have reappeared people to drown. The river flow would just get normalized to as if there was no dam in the first place. You might want to write that hazard off. $\endgroup$
    – Vesper
    Aug 16, 2023 at 4:48
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    $\begingroup$ Even "non-perishable" food will mostly be gone after that long. The freeze dried and stored in sealed oxygen free containers stuff that's popular among preppers ages out at around 25 to 30 years if stored in a cool dry place (heat will age much it faster, and damp would rust metal cans). That's not a hard cutoff, but after 2.5-3x that most of the nutrients will have broken down and be gone. $\endgroup$ Aug 17, 2023 at 16:38

Get a government job

Ideally in something critical, like disaster preparation. This might take longer than 30 days.

Realistically, the only entities capable of weathering something like this will be government scale. They're the only ones who could set things up so that they have fuel reserves that won't leak, possibly even have power from something like a thorium reactor or something relatively safe. They'll be better armed and organized than the other groups, and have nearly limitless resources to make those preparations with.

They'll also have studies of the most inactive spots to go stand in when it happens - I'd personally start with potential (but empty) nuclear waste sites - they'll be in very, very stable areas, there's unlikely to be major seismic upheaval.

Apocalypse fiction tends into prepper fantasy - how I personally can save myself, and possibly my loved ones - but humans are social, and there's a lot of strength in numbers. Even if government just becomes another gang after this, they'd be a gang with a massive resource advantage on everyone else.

  • $\begingroup$ Your resource advantage would be pretty small, even if you'd harness an entire perpetual freeze storage's worth of food for your gang. You would just not be able to reach it, as everything electric would be long gone with no means of starting it up. Everything fuel would also decompose, leaving you with cars with no fuel (even if conserved). Guns? Maybe. With them you'll achieve local supremacy, but with no source of even the simplest gunpowder they would go out of power pretty quick. The you'll be left with axes at best, and a constant need for food and warmth. $\endgroup$
    – Vesper
    Aug 16, 2023 at 4:44
  • $\begingroup$ I guess what I figure a government backed survival plan would include is: Some means of generating power, like a hydro-electric dam, shut off and specifically protected, with replacement parts submerged in oil, etc, that it can be simply restarted. Preserved food, possibly stored somewhere naturally cold, like a mountain, with maps of the location. Weapons, some means of storing oil well past its usable date, or, again, some sort of fuel generating system, again with parts protected in some intense way, or made out of extremely corrosion resistant materials $\endgroup$
    – lupe
    Aug 16, 2023 at 10:13
  • $\begingroup$ Personally, if I'm preparing for something like this, I can't, say, store a few hundred solar panels in a sealed, inert atmosphere, safely underground under a few metres of concrete. But, for a government, this won't scratch the sides of a military budget. $\endgroup$
    – lupe
    Aug 16, 2023 at 10:15
  • $\begingroup$ there's an interesting thing here on 100 year old permafrost food: arctic.ru/infographics/20170221/558250.html So that seems doable, but it's not exactly something you'd want to do without a major group, as you'd want to leave a bunch of caches. $\endgroup$
    – lupe
    Aug 16, 2023 at 10:22
  • $\begingroup$ I actually doubt if a government can seal off a hydro power plant within a month with enough quality for it to stay conserve for 75 years and still be able to be started within a reasonable time with bare hands worth of workforce. But such a plan looks plausible, at least that would allow that govt to survive The Jump once. There will be no spare parts left for the second time travel. But, generating power at a plant is not as easy, they are running at some 12 kV raw voltage with local power conversion into global grid running at 110 to 1200 kV (Russia/USSR), using this power directly (cont) $\endgroup$
    – Vesper
    Aug 16, 2023 at 12:04

Rather silly, but fun. Now I can't stop thinking about it.

You don't die on arrival because you are now part of a tree, but what if a tree has grown where you were standing? By my reading of this, when you appear, you fit exactly into a you-shaped hole made in the tree. You are unlikely to be completely swallowed by an even a 75-year old tree, but you may be trapped. Or maybe the top half of the tree falls on you. Outdoors might not be safe.

I would stay in my house. That would probably be standing if I cut down any trees that are too close (75 years of root damage could do a lot). My tools, clothes, and my bicycle would still be there. They might be in good condition if I stored them carefully. Take the wheels off the car, and put it on blocks. Take the battery out. You might get it going again.

Plant carrots, leeks, and potatoes for future Aprils. Plant fruit trees for later.

  • $\begingroup$ I think you overestimate how solid a house would remain after 75 years of no maintenance. Some buildings might survive, but a regular house probably wouldn't (or at least would be extremely unsafe to be in or around). Things like roofs need regular maintenance (it might survive a few decades without maintenance, but 75 years is a long time). Pipes will start to leak, storms will do damage that doesn't get repaired etc (every bit of small damage will start adding up over time). $\endgroup$
    – Dnomyar96
    Aug 17, 2023 at 9:51
  • $\begingroup$ @Dnomyar96 well, a brick-walled house with a stone/brick roof could well last 75 years without maintenance. I've been in a village that has its church bombed in WWII and heglected since then, it has breaches in the roof but is otherwise stable. That church has its inner decorations gone of course, yet its walls, columns and roof are still very much solid (2002, hadn't been there since). So a good-quality building can stand for 75 years without maintenance. $\endgroup$
    – Vesper
    Aug 18, 2023 at 8:04

A cave

The Dead Sea scrolls - paper - remained untouched for over a thousand years by simply being stuck in clay jars in a cave.

Find an extremely desolate cave that is ridiculously difficult to access and ridiculously far from civilization. This is a big rock, this earth thing; there are billions of these.

Assuming the government makes zero preparations for this, then stockpile a week’s worth of rations and some weapons. Your choice is to become a hunter/gatherer, or to find another community. You will NOT have a working vehicle, so you are where you are.

Make your cave as far away from infrastructure as possible (power plants, cities, etc.) These will likely be hazardous crumbling hulks.

Make your cave stable

Be as far away from a tectonic zone as possible. The possibility of vulcanisâmes or earthquakes in 75 years needs to be mitigated.

Become an entrepreneur.

Welcome to the new world. You own whatever market you master as soon as you land. Whatever skills you brought will be valuable in the first community you find. Have lots of these. Even the stupid stuff, like basket weaving will be valuable to reclaim the world. First one with the know-how wins!

Government assist

Realistically the government knows this is happening and some nations will be looking for you. All you will need is a flare, or whatever non-electronic device they provide. Someone will be coming for you.

Interesting story, but I prefer having a why in my sci-fi. Social thought experiments and other “what-if”s are entertaining but I don’t see much value in them when they pose impossible scenarios.

  • $\begingroup$ I was scrolling down to find this. Absolutely, yes. Find a structure that has already been standing for hundreds or thousands of years, and chances are it'll be fine in another 75. $\endgroup$
    – Tom
    Aug 14, 2023 at 22:45
  • $\begingroup$ You could hit the nice small problem known as continental drift. Your equipment would survive in such a cave, but you would get warped into the cave wall and get surrounded by rock. So, while the cave as an idea is good, you should meet your warp outside. And don't expect government assist, there will be no energy to spend on searching for survivors. $\endgroup$
    – Vesper
    Aug 16, 2023 at 4:38

Location, Location, Location

You want a spot not on a flood plain (not even a 100 year flood plain), away from hurricanes, tornadoes and earthquake zones. You'll want to make at least the core fireproof. Ideally you'd want huge fire breaks around a grove of robust fruit trees, but reforestation is likely to overrun it in the 75 year gap.

Build with Concrete

A concrete structure could plausibly survive intact for 75 years untended. You'll want a large concrete base around it to prevent vegetation from overrunning it and making it crumble (or a tree growing tall and falling down on it).

Sealing the place up so wildlife doesn't get in is another challenge, but not sealing it so well that you can't get out after 75 years of neglect. You don't want to arrive in a bear or wolf den, and even a bat cave wouldn't be pleasant.

Stockpile of Resources

There are certain things that can reliably last for 75 years. Many canned goods, lots of raw materials, some weapons and ammunition well stored in oil, even machinery.

Volatile organic materials like tires won't survive, but you could probably come up with alternatives. Diesel engines have a wider set of fuels they can burn than traditional ICEs, so you could probably come up with shelf-stable fuels that could last the 75 years with a bit of post-treatment (and even containers that could survive the 75 years).

The collapse of the industrial state will be hard and harsh. While a percentage of people will die on reappearance, far more will die in the decade of hell that follows. With humans gone, the biomass of mammals will probably fall to pre-human levels rapidly; while animals and feral ones will grow by a factor of 5, while our agricultural feed stock will shrink.

So at the moment humans return, human biomass will be upwards of 2/3 of all mammals on the planet, instead of the current under 1/3.

Our massive fields of grain won't exist, and reforestation will have swallowed much of the non-steppe parts of the world. Without working it, farmland doesn't stay farmland.

Surviving that first jump post-landing hellscape is going to be a matter of luck against the raw chaos and brutality of the first decade. Humans will remain your largest threat, so success in the first jump will depend on joining up with a powerful post-jump political organization and surviving against other humans.

The second jump

For long-term survival, you need to have a play to survive multiple jumps. You'll want to have relatively modern technology mothballed and recovered each jump, and be able to re-advance technology and not just scavenge off the remnants of the golden age of mankind.

Human civilization lives off energy. Be it grain, cattle, wind, water, fossil, solar or nuclear energy -- the ability to control more energy than a human can as a hunter-gatherer is pretty key. With the massive population collapse of the first jump, the raw materials stored in the ancient cities are going to be a source of wealth (why mine raw ores, when there is a pile of slightly rusted metals in cities), with the exception of processed energy (like oil).

Even if you are extremely dirty, the carbon pollution produced by a 25/100 year tiny human civilization won't cause significantly more global warming.

So, coal fired power plants might be a good plan. Northern Germany has some coal reserves which could make it a good spot.


Rent supplies, rent a location. You won't be able to make a custom fort, but you can probably rent a decent one from someone.


If you have a car, sell it and buy or rent an ancient Diesel car. Electronics is far less likely to survive than mechanics are. This can drop your budget, because if the world doesn't end you can swap back.


You'll want engineers, mechanics, farmers, outdoors, medical people, etc to be in on it. Have a party. Treat it as a laugh. Curate your list of people.


The vat of machine oil with metalic tools and materials is really useful if the vat lasts. Wrap a disassembled generator in oil-soaked cloth (hydrophobic), lift it off the ground on concrete blocks, fill it full of rat poison. Have replacement parts in a vat. Know where nearby gas stations are.


The population collapse after the jump will be intense. The place you describe -- northern Germany/Denmark -- is probably going to be a death zone, with 99.9% of the population dead. The only way you'll survive there is luck.


The oceans is one of the few spots where food will get easier to harvest. 75 years without humans means oceans will recover. So figure out a way to make a boat survive and learn how to repair and eat fish. This also provides a defence against other land-bound humans.

A protected hull, a diesel engine, a sail, a supply of patches, lubricants, lines and sail cloth, plus fishing supplies. Add in a fortified and hidden base to return to and eat, and a harbor.


There are going to be many millions of people with the same ideas and solving the same problems. Work out what materials can survive for the gap from them.

  • $\begingroup$ I would agree with the majority of your answer, up to energy problems, yet the other needs like clothing, medicines, simple tools, fire and actual food supply until the next harvest season (provided there would be something to harvest) are listed on a too bright side IMHO, the problems would be WAY WORSE. $\endgroup$
    – Vesper
    Aug 15, 2023 at 17:36
  • $\begingroup$ @Vesper Are you talking about the first one? 99.9% death rate in central Europe might be conservative, I'll admit. With 99.9% of people die, lack of medicine isn't what kills most people (most people are dying of starvation, or, well, cannibalism). There will be lots of burnable stuff and half-usable shelters for the 0.1%. $\endgroup$
    – Yakk
    Aug 15, 2023 at 17:52
  • $\begingroup$ yes the first one. With 99.9% people being corpses, even half-eaten by the survivors, the diseases would proliferate, rodents would arrive carrying plague for example, good riddance. 75 years are pretty enough for the plague to get uncovered or transferred by rodents from where it still lives in animal hosts. And this is only one, albeit most known lethal, disease. Pneumonia, dysenthery, smallpox, all this stuff would feed on people, vaccination won't help in the long run, I really doubt that there would be someone left in a formerly crowded area to be warped the second time. $\endgroup$
    – Vesper
    Aug 16, 2023 at 4:34

The whole universe is moving, my dear Assume that you vanish, and reappear 75 years later... will be... in space! Earth itself might be about at the same spot relative to the sun if our time-travel machine calculate 75 years exactly. But even so, you have to take in consideration the precession of the axis, you will be never in the same spot of where you vanished. Even though, sun its travelling "up" around the center of the galaxy at 250 km/s (about 600 billions km in 75 years). In addition, The Milky Way as a whole is moving at a velocity of approximately 600 km per second (372 miles per second) with respect to extragalactic frames of reference, which is about 1,5 trillions km in 75 years. So, in my opinion everyone in this scenario will reappear somewhere in the space, but still inside the Oort cloud making billions people, billions of comets.

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    $\begingroup$ I think the idea/spirit of the question is that whoever is doing the teleporting has taken this into account and will place everyone back at the same spot relative to our planet. $\endgroup$
    – Vilx-
    Aug 15, 2023 at 0:54
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    $\begingroup$ Other than hand waving this, you could also say everyone reappears at the same positions relative to the time travelling device which is and stays on earth during those 75 years (essentially a storage device then). This way there is no need to calculate any extra-galactic frames of reference :-) $\endgroup$
    – 11684
    Aug 15, 2023 at 8:00
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    $\begingroup$ @Vilx- even assuming that, things like continental drift do cause meaningful changes. IIRC Australia drifts something like 5 feet in 20 years, and other places have a change of height, so "the same spot relative to our planet" won't be the same as "the same spot relative to your house". $\endgroup$
    – Peteris
    Aug 15, 2023 at 9:58
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    $\begingroup$ @Peteris Yeah. And that's what this question is about. 🙂 $\endgroup$
    – Vilx-
    Aug 15, 2023 at 10:43
  • 6
    $\begingroup$ This answer is forgetting that there is no preferred frame of reference in the first place: the Milky Way isn't moving from the Milky Way's frame of reference, the Sun isn't moving from the Sun's frame of reference, the Earth isn't moving from the Earth's frame of reference, and each of these frames is exactly as valid as any other. Whoever constructs the teleporter wouldn't just need to remember to take this into account. It would be a fundamental necessity, since you would need to choose a specific frame of reference in the first place for teleportation through time to make any sense. $\endgroup$
    – Idran
    Aug 15, 2023 at 13:51

Back to basics what do you need to survive. Prepare for many jumps because everything becomes much harder to get after the first.

tools, fire, food, water, shelter, defense, social.

Tools You want hand tools, basic logging, farming, carpentry, sewing, cooking, and metal working tools at a minimum. on the upside hand tools last a long time with only minimal preparation. cover things in enamel paint and bury them in upside down plastic buckets or drums, they can now survive multiple jumps. stone cellars work almost as well. The cooking tools are the exception, no paint, use food safe oils and pack in cat litter, glass stainless steel and cast iron for preference. Hand tools for almost anything will be beneficial prepare anything you can get.

Fire The importance of fire cannot be overstated, if nothing else survives and you have this you have a decent chance. fire provided heat, cooking, safe water, sterilize medical supplies and even safety in the form of light. You want as many ways of making fire as you can get, sealed matches, ferro rods, lens, fire pistons, even old lighters if you have sealed fuel cans.

Does your house have a fireplace and/or cast iron stove if no then these are big priorities for you, you need a safe way to heat your home and cook your food. You can store some fuel, charcoal can be buried in the same way as the tools and survive just fine, you can even pack away heavy oil fuels by burial in sealed containers but it has a higher failure risk.

Food Only a few foods can be stored for that long, dry sealed grains, honey and thats about it, don't count on stored food. store vitamin suppliments and ways to get food. Farming tools, hunting/trapping equipment, fishing gear. Again favor hand tools and pack in paint or oil. Some seeds will survive if stored properly so store some high yield things like potato seeds or grain seeds. Plant some fruit trees if you have farm land available. If you have farm land get it ready for powerless irrigation, which means you have a lot of trenches to dig.

For hunting you want crossbows pack the unstrung with with as many bolts as you can get your hands on. You can pack some firearms but go with black powder firearms, most bullets will not survive the first jump much less subsequent ones. black powder can if properly stored, especially is stored without being mixed. If you want to get ambitious you can try to store chemical equipment to make your own primers or powder provided you can find the raw material. Bullet molds and lead are cheap and can be stored for centuries.

Water Trying to store water is pointless, instead dig a good well and have the tools to maintain it, set it up so it can be sealed. If you can dig more than one. Invest in purifying equipment; a still, pots for boiling store like cooking equipment. A stockpile of iodine powder and bleach are good ideas these can be stores in sealed containers on this time frame and can be used to purify water.

Shelter You don't have a lot of time to do much about this, so hope you live in a stone or brick home with ceramic or slate roofing. You just need to prepare it to survive for 75 year without maintenance. first reinforce your roof, use hurricane brackets, construction adhesive on tiles and flashing, seal like your life depends on it. Buy extra windows and roofing and store them. board up your windows. Small animals are going to get in, you can't stop that in your time frame, so your goal is to keep out weather and large animals. As a back up have some oilcloth, rope, and tarps so you can patch things when you get back, in a pinch you can use these to make a tent. Since you write the story a concrete roof or underground hillside home is even better but a lot rarer.

Clothing is easy, most clothing in a sealed container will last hundreds of years, cover in paper and put in a vacuum bag then seal clothes in a 5 gallon bucket and bury it and have clothing for the rest of your life, choose canvas ovr leather for shoes. If you have time store thread and make your own cloth, thread can be stored for centuries. Water proof clothes but rubber needs special care, it needs to be sealed in an airtight container to prevent degradation, covered in light oil before packing of an even better chance of lasting. Also store lots of dry glue in metal containers, modern shoes are mostly held together with glue.

Defense When everyone gets back people will be starving, which means violence on a large scale. You will need to defend yourselves. Melee weapons are a good idea, many many tools double as weapons. crossbows and bows will be a big help, many guns will survive the first few jumps but ammunition will get scarce quickly, black powder will last a lot longer so if you want a firearm go with black powder. for defense a percussion revolver will be your best bet as it will still likely work and give you multiple shots. But your best defense is friends and anonymity. Solo defense is always a loosing battle and people can't bother you if they don't know your there so in the beginning you don't want to use fire unless you have to as smoke is visible for a long distance.

Social On your own your doomed, humans can barely feed themselves long-term by themselves, we need a social group for support. Diversity in labor and skills is your best advantage. What does your main character have offer, they had better have something, some knowledge or skill that is rare and makes cooperation worth it. They know chemistry or have medical skills, what makes them not just dumb labor in this world, otherwise their story is very boring. If you can collect a few people with useful skills that is even better, make a community we have a lot of questions about that. Do keep in mind that medical technology will be nearly nonexistent if if knowledge survives. So be ready to have a lot of kids because most are going to die in childhood, for modern people this will have a huge impact on their psychology.

Misc. Buy books, print the internet, and look up archival storage techniques. Knowledge and entertainment will be very valuable in the new world. How to make antibiotics, engineering, history, most of science is still useful. Humans are very quickly going to be limited to preindustrial technology by food scarcity, but the science and engineering knowledge can still vastly improve what can be done with that level of technology.


How do you, specifically, survive? Stand on a mountain, above the tree line. Unless there's a major earthquake, you should be fine. The rate of growth of the Rocky Mountains isn't enough to take the soles off of your shoes.

Of course, by your description, everyone will show up naked. Getting down off of the mountain might be complicated, but most of the stuff in your backpack should be ok.

Nakedness will kill many. They'll destroy their clothing, piled up on their shoes, on arrival. Cannibalism would overwhelm the cities in about two days. Fuel in fuel tanks would have oxidized into jelly. We wouldn't quite be pre-industrial, but we would be entirely without perishable resources.

It's a fun thought. The next time around, people will accumulate on monolithic pads of stone.


No problem - just use caves, mines, or any other underground structure

Your question says that we know the day this will happen. So most of the scenarios in the answers above simply aren't going to happen to anyone except the terminally stupid or foolhardy. (And yes, terminally so.) No "raining men", collapsing skyscrapers, or any of that nonsense.

To be certain of surviving this, you just need to be somewhere which doesn't change for 75 years. For most of the world, that rules out above-ground locations. Weather happens, things erode, structures collapse, and so on. Which leads us to the natural conclusion - go underground.

In the UK we have many Victorian-era tunnels which have survived with little or no maintenance. The London Underground is a good example - for sure the lines need servicing regularly, but the tunnels themselves don't need shoring up or anything. There are tunnels down there which are now unused by trains but are still used for filming, especially historical filming, because they're unchanged from 1945 or 1960 or whenever they stopped being used. Unless you're in an earthquake zone, every underground structure will stay intact for 75 years, no problems. Hell, you can probably reckon on 750 years, never mind 75 - there are church cellars and castle dungeons around Europe which are that old.

You don't need people to be comfortable here. Remember, it's pack yourselves in or die. The packing-in process will naturally take some time to complete, of course. All the portaloos in the country will be requisitioned and moved down there, and water can be piped in. Bring your own food, but you're not going to die of hunger in a few days anyway so that's not so bad. Your government will allocate people to their nearest tunnels, caves or mines, and plan the order of evacuation to stagger arrival times. Unpacking can be less organised, because so long as you can avoid stampedes (men with guns are good here!) then it doesn't have to be perfectly orderly.

Or go somewhere which won't change significantly in 75 years

Most flatlands are pretty unchanging over time. The American Midwest, the English Fens, Ukraine, the Gobi Desert, central Australia, much of Africa, the Argentinian pampas - all of these are places where (barring human activity) you can overlay the maps from 75 years ago and now and see basically no changes to the terrain. So long as you're not too close to a river, you'll survive the Blip. Mind you, you do also need to not be too far away from a river as well, because you need to be able to eat and drink afterwards!

And stock up on tins and dehydrated food

Tinned food does come with a shelf life, but that's generally pretty arbitrary. In practise, tins without damage can survive almost indefinitely, and if the contents have been properly prepared then they won't go off.

Dehydrated food is also good, because if it stays dehydrated then it can't go off because no bugs will eat it. And Tupperware boxes don't biodegrade - just keep them out of the sun (they do break down with UV) and you'll be fine.

And then people starve because of no supply chains or mechanised farming

So you can survive the Blip just fine. What you can't survive is the years that follow. All transportation requires key elements made of synthetic rubber (especially seals) and these will be completely degraded in 75 years. Meantime all petroleum products - oils and fuels - will also be completely degraded. Your car won't work, and there isn't the infrastructure to ever get oil production back online again, because the same problem has also bitten all the extraction plants and refineries. And without mechanised farming and artificial fertilisers and pesticides you can't get enough yield to feed all the people, and you can't transport the food to them anyway.

  • $\begingroup$ What if your cave floods? What if there is a cave-in blocking your path to the exit? $\endgroup$
    – kaya3
    Aug 15, 2023 at 22:25
  • $\begingroup$ @kaya3 Like I said, that really isn't a high probability thing. Minus humans, caves stay intact for a very long time. Damage to the exits, potentially - but even there, reinforcing an entrance to last 75 years isn't hard. $\endgroup$
    – Graham
    Aug 15, 2023 at 23:51
  • $\begingroup$ Caves are also natural habitats for bears and similar predators. You don't want to end up in a bear den after you warp. ARGHHH FRESH MEAT! $\endgroup$
    – Vesper
    Aug 16, 2023 at 4:26
  • $\begingroup$ @Vesper Not generally that deep in though. Predators don't go far past the cave mouth, because they can't see. And it wouldn't be hard to put a layer of bricks over the entrance, to be demolished when you come out. $\endgroup$
    – Graham
    Aug 16, 2023 at 6:51
  • $\begingroup$ Well, for this you would also need to have some light, finding a working light source in a pitch black cave could prove difficult. Also snakes. Also continental drift thus errors in placement past warp, you could end up in a wall if the place you're in had drifted far enough. Also bears at entrance - in case you would end up having your guns wet and failing to shoot, it would be a probable combat without retreat, quite a bad situation to plan for. $\endgroup$
    – Vesper
    Aug 16, 2023 at 7:47

Look to the past, not the future.

If you pick a place that hasn't changed in the last few centuries, you've got a good chance it won't change in the next 75. That means a good distance from most things man-made, though a couple of castle ruins or old churches may work in a pinch - shame Northern Germany / Denmark doesn't have too many castles.

Caves are great, just make sure the entrance has a good chance to not be buried in a landslide, and bring tools inside just in case.

Same for your stockpile. Old simple solid tools will be useful. Clothes can easily survive if packed properly, etc. A bike and similar mechanical things should be fine if stored in a dry place. Look around which kind of stuff is from your grandparents time and still good.

As another comment pointed out: Prepare to become a farmer.

And yes, social contacts will be valuable. If 90% of the preppers and 50% of the non-preppers survive, your 500k city will still be 280k strong.



We actually have dedicated hardware for this. Bunkers are meant to exist for long times. Though not all, many have options for long time storage, as well as sealing people in safely. Even bunkers that have been made in relatively open fashion to shoot from, like shoreline defence, has great potential.

You then store a years (or even multiple years) supply of food in storage that can survive for many years.

You can add many comfort items like clothing and bed linen in airtight storages as well, so you have something when you wake up.

Some hand cranked lights would be nice, but in general you can go out during the day any way.

To further add to the survivability, you can store things like solar panels or even more simple oil for power when you wake up. With the right equipment yhey should still function well enough.

Germany and Denmark

Thanks to world wars theres plenty of bunkers around. I'm not saying it is enough for everyone, but they are more prevalent than mines or other underground structures. They can even be in the middle of a city, unassuming to many. Think of old telecommunication buildings for example. They were build to withstand direct hits from bombardments. You can also consider fortifications like the WW2 anti aircraft towers that were made a few of in Germany, of which the surviving ones can house a few hundred people. Not all have to be underground.

As there isn't enough long lasting food to survive a few weeks for 10% of the peopleall other methods seem moot. Sure you have an ok chance to be in a good apartment when you just sit in your bedroom. Bonus points for higher up in an apartment building as they are less accessible to creatures. But if you truly want to ensure your own survival, existing bunkers, or newly made in your back garden, seems to be your best bet. With all the chaos in the world currently there are actually people buying houses with bunkers or loose bunkers for the purpose of survival in case of catastrophes.

  • $\begingroup$ Cold would be the problem, in either country. First of April could still be snowy, and bunkers were not designed to have a place for open fire, especially underground ones. $\endgroup$
    – Vesper
    Aug 16, 2023 at 4:28
  • $\begingroup$ @Vesper why would you want open fires? Electric heating would suffice. $\endgroup$
    – Trioxidane
    Aug 16, 2023 at 6:26
  • $\begingroup$ Electric heating? Where you would draw electricity from? A diesel generator? Would it still have fuel that would burn after 75 years of neglect? Solar panels? You would have to mount them (back) first, also microelectronics might deteriorate due to mere molecular drift in silicon. Wind turbine? Hmm, maybe, but wind isn't constant, also I'd assume the bunker would be overgrown thus low wind would be available. External power sources would be long gone. $\endgroup$
    – Vesper
    Aug 16, 2023 at 7:50

Contrary to most other answerers, I think the safest place for immediate survival would be the ground floor of a modern brick house at most two storeys tall and with no basement, in a country with a mild climate, no significant earthquakes, not near the sea or a river.

Houses are designed to not require routine maintenance in order to stay standing, and recently-built modern houses should not have any structural problems. The main structure of the house, built of bricks, is already designed to withstand whatever severity of earthquakes are plausible to occur in that area over a timespan of at least a hundred years, and subsidence should not be an issue either.

The worst case scenario is high winds breaking the windows or roof tiles, letting the weather in, possibly allowing the timber joists to rot and give way; this is rather unlikely in a place with no monsoon season, but even if it does happen the structural part of the house (made of bricks) will still be standing, and the debris which falls to the ground floor will not be so much that you wouldn't be able to climb out.

Since (as I claim) it is rather easy for a large number of people to find places that are safe for the jump itself, and doesn't require much planning or investment, it doesn't really matter if a significant number of people aren't convinced it will definitely happen. Even most doubters would take the basic precaution of being at home and on the ground floor with the doors and windows closed when the jump is supposed to happen, just in case it does.

Another option (again considering just immediate survival) which I haven't seen considered yet is to be swimming in the sea when the jump happens. If you're a hundred metres out or so, then there's no chance your location becomes a land mass due to erosion, and so there are only really two things that can go wrong: either the sea level 75 years later is significantly higher and you arrive underwater, or it is significantly lower and you arrive in mid-air (and are underwater soon afterwards).

The change in sea level will mainly be due to the tide, and is unlikely to be more than a few metres; if you're a skilled swimmer, you should survive the jump, and then be able to swim back to land. You start off at a disadvantage (exhausted from swimming and your clothes are wet), but you'll live, for now.

The question of who survives beyond that, and how, has been covered at great length elsewhere ─ it's basically "all modern technology vanishes, what happens?", similar to here, here, here or other existing Q&As ─ so I've chosen to only address the novel part, which is surviving the immediate jump.


I would suggest maybe escaping to the isle of the North Atlantic - the Faeroes, Shetlands, Orkneys, etc.

The climate is extreme (cold, wind, rain), but that also means that the growth of trees and other destructive plants and animals is suppressed. There are prehistoric buildings on Shetland which are in a remarkable state of preservation.

You are surrounded by the seas, which after seventy-five years of recovery I expect should provide enough fish for survival.

They are also close enough to the coast of Northern Europe that once you've survived the first few years of craziness in splendid isolation, you can explore down the coast and see if there is a more friendly environment - maybe head down to Bordeaux and restart the wine industry.


The first jump.
People will starve. Buildings will fall (>proof needed< the ancient greeks and romans building do still stand). People will learn, die and survive.
For one person the obvious survival helpers:

  • Stockpiled food.
  • Luck that you don't spawn in a tree (maybe being a smartass, calculating where a river should be in 75 years, you try to respawn in that river, cause the possibilities of trees are in fact lower. Beaches kinda move much actually, maybe some more meters back?)
  • Likeminded people for survival (if they don't backstab you, just saying)
    Watch out though. The civilization can (will?) collapse only after you are transported into the future (the civ has actually a good chance of surviving >proof needed<), meaning stuff will happen, cause "lets save that unprepared guy", and "he's a friend"
  • Survival training prep. Farm prep or just someone who is a farmer in your group (And Seeds) or good hunting skills.
  • a good burial for tools, food and more WITH a good marker, to find it after 75 years

The interesting part comes from thinking about what a civilization could do, instead of a single human. But that wasn't what you asked for. But that will be the solution the world (and hopefully the protagonist too) will want achieve in 25 years / 50 years. Also humanity achieves pretty much in 25 years. Whole digitalization happened within it ... kinda ... ok cut me some slack, we are working on it


Fascinating question, and it would be a great story to consider what goes on in the world for the 30 days following the "announcement," whether the jump actually happens or not.

Pick a number for what fraction of the population believes the message. One third, one tenth, whatever. That's an immense number of people regardless, and for those next 30 days, the internet will turn into this thread, on serious steroids, with lots of suppliers getting really rich selling everything suggested here, and more, to those who are now "preppers" with a slightly different flavor and far greater urgency.

For example, glass jars and canning supplies, will probably become backlogged and unavailable at 10X normal prices within days, if not hours, of the announcement. Honey will fly off the shelves, along with salt, bleach, ammunition, and air-tight metal containers of all shapes and sizes. How-to videos for preparing firearms for long-term storage will be all the rage. The best methods of storing everything from clothing to school books to medical supplies will be discussed widely -- including a few "miracle cures" and "one weird trick" methods that probably won't work but sound convincing enough that the gullible may make the purveyors of these tricks rich.

Experts will pop up who can predict how far your continent will drift in 75 years so that you have the best chance to avoid showing up trapped inside of a wall or a tree or cliff or whatever. Groups will spring up for mutual support purposes (how reliable such instant friends will be after the event, may be rather variable). Whatever important records (deeds for property ownership, for example) will be printed & sealed so that they can be found & referenced in the future.

People will have all sorts of ideas -- some obvious, some outlandish, and everything in between -- of what would be good to seal up in various forms of containers to have around, clean & ready to go... cooking pots, plates & silverware, mechanical alarm clocks, scissors, reading glasses, tents (with plenty of spare tent stakes), backpacks, crutches, etc etc etc. Not just for your own use, but to trade later. Would gold coins & jewelry be valuable in 75 years? Not immediately, but after a while, maybe. And that means that some people will be burying caches of gold as well, to go dig up in what seems like 30 or 40 days to them, but 75 years to the world they'll be digging in.

Stones like gravestones may become a lively industry for those 30 days -- engrave "Property of John Smith" onto four large granite stones, to be placed at each corner of ones property, for instance -- it's not quite the same as a deed & a survey, but it's close enough to probably work in a world suddenly with scant records.

All of this attention, even by a small fraction of "everybody," will produce both a lot of ideas, but also a lot of shortages. Think you've found the perfect spot to be on April 1? You may find you have lots of company there! You've decided on the kit that you need, with three copies of everything (spare parts) and tools to repair it all? Great, but unless your idea is truly original, many others will be buying and ordering the same things, so you may or may not get it all assembled and sealed up in time. So the prepping process will be complicated by an immense number of other preppers.

Thus, a key to survival may be less in having good ideas, than in evaluating the myriad of ideas bouncing all over the internet, wisely picking the strategies that one can actually implement in the time remaining, given the competition for such resources, and then executing your plan well, avoiding whatever the most common & most serious misjudgments are.

And then getting lucky... not showing up naked in a tree or rusting car (that you didn't know was parking just the exact distance and bearing that the continent would shift), nor being in the place with a freak snowstorm or (chilling) thunderstorm or flood or drought at the particular hour on April 1 of the year X+75.


Edited for plan

What is listed below still stands, with another actual addition - the ground is not static, and on a scale of 75Y jump its vertical movement due to tectonics, and soil buildup due to nature's activity could be significant to plain trap prople, no matter how prepared, in the soil, rock and concrete. So not even stone plates are safe. Thankfully the strongest observed ground level change is anthropogenic and is downward, so the hardest initial problem could be surviving the drop. Even the caves are not safe, although one could bring in a pile of hay, grass or foliage to mitigate the risk of being trapped in the raised floor.

The plan

First things first. Order a solid titanium shovel, it will be THE HOLY GRAIL past jump. Order/buy a ceramics-coated pot, a set of vacuum-packed clothing, 2-3 boxes of needles plus synthetic threads, the basic tourist survival kit, a set of simplest medicaments (glass-stored iodine solution as an example), the hardest tent to make a house, a snare, several sheets of fabric, preferably also vacuum-packed, a bottle of conservation grease and a steel shovel small enough to fit in your mouth. Ending up naked and bare-handed is enough to die off natural causes too fast to bother. It'll be the best if the shovel would have a detachable handle that would fit in your butt, as there is no other place to store stuff within one's body, you would need an immediate tool to get yourself off tricky situations. Note, NO friends, as friends would get jealous too fast and likely undermine your efforts to stay alive with a simple deathmatch. But if there would be a girl that would share your hero's ideas of living in complete wilderness, have her prepared the same way as him.

Next, learn to forage and hunt, best if you'd do that the harder way, by travelling one way away from civilization with all that you've prepared to somewhere where there is fresh water and a place where you are sure there would be no growing trees within 75 years onward, in order to not getting trapped within a growing tree. The best place would likely be around this planet's Zimbabwe, after all you as a story-setter are able to engineer a proper place with a sizable rock near a water source. Of course, amp your immunity before travel, as tropical diseases would be the things you'd face right away. Try to establish contacts with the closest tribe if there's any, probably exchange some stuff for stone spearheads and tools, or knowledge on how to make some of these yourself. Learn to use spear and knife, learn to fish in streams with either spear or stored fish hook, learn to make fire without anything fancier than a piece of stone. Learning would be the hardest preparation part, but if there would be a book with all this knowledge listed, best buy one and also vacuum-pack it together with the rest of your equipment.

Day X preparation

Use one sheet of fabric to get greased in conservant, stuff all your clothing into its plastic package to have a use for that, then wrap everything prepared, including the compacted tent but excluding the big shovel and the emergency shovel, in that piece of fabric, position it about two meters in front of you. Position the big shovel as a landmark over that compound, it would also serve as a weight to lessen the chance of wind or animals tearing up your stash. Use another sheet as a cover under yourself to minimize chances of a tree growing on your very place. If there is a stone protruding out of the ground, use that as a target, yet gather a bit of foliage to not sit on the cold, as well as raise your poor body off its surface to lessen the chance of getting buried at time travel. Stuff the emergency shovel into your mouth and butt - you're to survive mind you! No sentiments against "it's dirty" or "painful". Use a condom if it would prove hurting. If you have a girl with you, convince her to put the shovel handle into her there, as that place is the largest to hold such long but not too wide objects, also wrapped in a condom. Stand on prepared space, hugging if there's one to hug, or maybe face outwards to account for immediate danger.

After the warp

Provided you did not get rocked or treed and also not in the immediate vicinity of predators, unpack and assemble your emergency shovel that would NOT suffer the 75-year exposure to environment and be ready to do hard work. Then dig out your stash. Set up the tent, no matter how worn it is, unpack clothes, check what has survived the hasty storage, employ the shovels (the titanium one should also be in your possession by now), set up fire, check if any canned food you have left survived, if none, go for forage and hunt, use the nearest tree's bark as makeshift shoes. Set up a fireplace, use the pot to gather, boil and store water, start life as savages.

Consider everyone else dead. If you have established a relation with a nearby tribe, check if they survived and did not end up hostile, if yes, trade needles for homage. Savages are less trained in the art of deception, this and general honesty in your own actions would definitely earn you some safety in the immediate future. Use whatever survived to help the tribe, earn their respect, make children, transfer gathered knowledge, hunt and forage with everyone, wrap in furs, learn from their chieftain or shaman, write the story.

Second warp

Most likely the only equipment left from the dead civilization would be the pot and the titanium shovel. Build up a mound of stones no less than a meter high over a former fireplace, put the pot over the shovel bottom up, place the shovel into the mound with the pot visible. Stuff the stone and bone tools nearby, best if soaped or coated in whatever preserving substance the tribe can get, most likely salt and fur, to maximize chances of bone to remain functional. If any glass survived, use that as containers for salt or whatever other consumables the tribe would try to save for the warp. Before the mound, create a big bonfire out of your huts to solidify the ground, and spread people all over the burned patch, best if each human would stand on a separate rock the size of a pumpkin.

Subsequent warps

Nothing different, except for the shovel and pot, which would likely still wear out from extensive use. Replace with clay pots. If, however, those aliens won't stop their warping, your tribe is locked up in a 25-year cycle of losing everything, as 75 years of natural wear-and-tear is enough to wither even titanium, let alone crude iron that it would be able to melt with wood. Maybe though the mound would evolve into a carved stone sealable structure like a Dolmen or a sarcophagus, that would be able to hold stuff designed to survive the warp in at least dry sheltered environment. The tribe may expand outwards, potentially making roads with salted ground to not have them overgrown in their absence, yet humanity won't be able to progress beyond Iron Age, as stone will be the best material to store information, and having to start agriculture or animal herding from scratch won't add anything to ability to progress.

Frame challenge - preserved for reference

As you know probably, the universe is ever-moving. Earth flies around the Sun, the Sun flies around the center of Milky Way, that itself is attracted to (yet not too hard) Virgo supercluster, and that set of matter is also attracted somewhere bigger that we might not even know. So, when your spacetime coordinates shift by "(0,0,0,75Y)" all of a sudden, where would you end? About 100% is that you would end in empty space.

Considering those aliens that move humans in spacetime have actually calibrated their foom-stuff to use a coordinate system that's aligned with Earth's surface (which is the hardest among possible coordinate systems, as Earth rotates, revolves and is involved in the entire solar system's other movement, solar-centered system would have one less movement to calculate, etc), they should be able to actually disperse humanity across habitable planets in the 75 light year radius from the Sun with the same machinery. And just say "hey it's just Earth's biosphere had mutated over time", or plain leave the time traveller without enough data. I consider the latter effect to be quite a lot better for planetary ecology together with humanity, so they should have considered that possibility at least.

Provided they did overcome this set of complications, the actual outcome would be this:

The humanity would have been set back in time tech wise, down to no less than Iron Age, and die of hunger and diseases

PS: this sounds like one good serious clean-up to set up grounds for Civilization 7: Real Life... And note that this would be the result of a single time travel, the subsequent actions would likely not be needed as humanity would definitely get reduced to five figures worldwide.

  1. Make sure there is a governing system, even a monarchy or dictatorship is better than nothing, otherwise everyone will be a bully and everyone will be a cannibal,under such circumstances everyone will have to take extreme measures even if not in a mean way, being a cannible will somtimes be defensive; even a dictator put some order enough to stop the worst of mankind. 2.there has to be a set of laws 3.community servants; civil workers, such as in charge of getting food
  2. democracy is for an advanced cvilazation, with a democratic culture
  3. find out what is the culture of the time,who knows maybe slavery will be in favour just this time Black is master and white is slave and the "N" word is so holy that a white man that dares say it is lashed. There will be a new philosophy backed by super ai to prove that is the right way to think. White man will be building new ai based on cosmological DNA to argue that they have to be freed.
  4. police and judicial system to enforce the law

Disclaimer: Yours is a really, really, really, really long question and I frankly didn't read it word for word. That was rude of me. Sorry. I'm about to give you a really, really, really, really long answer, so I won't be offended if you don't read all of it. But, if I say something below that doesn't make sense because you said something above that I was too lazy to take the time to read. I really do apologize. Anyway, my basic reaction to what I read was...

You're screwed!

But that's not necessarily a bad thing because, you, dear friend, have solved the mysteries of time travel! (And can set the rules of time travel for your world.)

Solution #1

Said another way, you've already overcome the basic problem of "where to put people" because you've overcome the problem of spatial translocation. The Sun moves. The solar system moves. The Earth moves. You're not just moving people through time — you're moving them through space — and you've figured that out.

What this means is that you can plop people down on the planet exactly where you want them in the future.

Whatever organization it is that's solving humanity's problems by moving everyone 75 years into the future, that organization has a prep-crew that's been lavishly provided for who will stay on the Earth for that 75 year period with just one purpose: To make sure the landing zone is completely clear and ready to receive humanity. The organization has meticulously determined the rather large acreage they need and where it must be to have the smallest footprint of damage during the long wait.

Let's say it's New Jersey.

No offense to anyone living in New Jersey! But poor old New Jersey has been the butt of jokes like this since the dawn of time. Or at least since Futurama first aired. We love the people! But it's time for New Jersey to pony up to help the human race once again.

So your team is working to clear a huge space and keep it level. Let's even make it out of concrete. Yes, we're trying to help poor old Earth, but you're about to drop eight billion people on her again and believe me, that little pad of concrete (no matter how large) will be the least of Earth's problems. Now, you could cover the state of New Jersey with concrete and receive all 8 billion people at once. But that might be an indignity that's too much even for New Jersey and keeping a slab of concrete that big perfectly flat (ignoring the curve of the Earth, which your transporter can handle), would be a pain in the neck.

So, let's just say it's four square miles of lovely, flat concrete that's prepared just six months ahead of the first returnees.

And then you're time travel experts are wise enough to drop only as many people on that four square mile pad as can comfortably fit. Let's be generous and say that each individual needs 16 square feet (children won't need it, a few of my friends might test that size...). That means you can drop about 7 million people at a time onto the pad. Give your team a week to clean them up and send them on their way. And you spend the next 22 years plopping people down on that concrete slab. Honestly, it doesn't matter how long it takes, right?

This is important, since time travel over any appreciable length of time requires spatial travel as well, that means you have teleporters. That's just time travel where the time dial is set to zero. And you'll need them.

So, your team takes a week to shuffle 7 million people into transporters that can move them to other locations on the planet, which are either prepared or can be known to be safe destinations because your team was there the whole time to figure that out.


Solution #2

People die.

It's an immutable law of the universe (insofar as we know today). So you follow @RichardKirk's idea of having everybody be at home, sitting on the floor when the time travel occurs, and ship them forward.

Some people will die. Earthquakes will have moved things around. As will hurricanes, tsunami, and a host of other issues. Wildfires will have burned some land to the ground. Trees don't just grow, they fall down, as do rocks. A meteor could hit the Earth changing a LOT of things.

My point?

According to your premise, you're trying to save the Earth. What's a few less people with that goal? A necessary consequence of saving the planet is that some people will die. The casualties are expected losses. You're beaming a plan into people's heads, beam the platitude that they might be making a sacrifice for a notable goal as well.

Of course, that might cause riots, but no fewer than the riots on the other end of transport when people find their loved ones dead in the middle of a tree.

And one problem to resolve... or ignore... I prefer ignore.

We're ignoring the idea that teleportation of any kind requires a precision that is really hard to keep within the bounds of suspension of disbelief — which is why so many writers simply don't talk about it. Those transporter pads in Star Trek were brilliant because the pad was part of the emitter/receiver system that could rationalize why your feet weren't a few angstroms into the pad, which would mean you had to peel them off the surface like a cellophane wrapper.

The concrete pad in solution #1 serves the same basic purpose. If we patiently explain that it's as precise as a Hubble Telescope mirror, it justifies a successful transport where people walk away without concern.

If we transport people 75 years into the future in any other way, it's not just trees that are your problem, it's grass and soft dirt, and blown dust, and carpet, and who knows what else that makes the surface the transported people are landing on unstable. Yes, you could transport them an inch above the proverbial surface to account for that. You'll scare the beejeebers out of people as they recover from that unexpected one inch drop, but it would help.

But in the end your biggest problem is the atmosphere. Atmosphere moves around us as we move, not through us. Teleporting your travelers into the future means they're arriving "within" the atmosphere. Everybody dies from the bends or worse.

So, in the final analysis, don't stress too much about avoiding trees. It's a cool aspect to give your story a bit of flavor — but there are much worse things than trees to worry about and you're not going to solve them without some kind of Star Trek transporter beam that forces everything that's in the way, out of the way.

Which brings me to solution #3

Your time travel technology swaps the volume of space from the future with the volume of space in the past.

If you can move a human, you can move a can of soup. If you can move a can of soup, you can move a cylindrical space around a human. And by moving the volume of space from the future to the past, you minimize the risk (and solve the atmosphere problem).

You'll still have a few deaths. Earthquakes can move a lot of dirt, which means someone appears in a lovely cylindrical space inside a hill. They're dead in minutes. Some appear in the space once occupied by the trunk of a tree. They die when the rest of it falls on them.

But you've minimized the number of deaths.

It's important to realize that all these issues are not intrinsically bad. You don't want a perfect transport system. Perfection is boring in stories. You want opportunities to explore human emotions. Yes, the fact of transport causes some human emotion, but then there's all the emotions due to the imperfections of transport vs. the good of saving the planet. At least for a while. 8 billion people will screw it up awfully quickly.


While the idea is fun to play with, keep in mind that you have some serious impracticalities. At the top of my list is the number of people you'd need to leave behind to keep the infrastructure happy, like dams. And we're not just talking about people at the dams, but people transporting raw and processed material to the dams, and people creating the processed material, and gathering the raw resources, and feeding all those people, and making them liquor to keep them happy, and the police for when the liquor is over applied, and the millions and millions of people you'd need to keep things running and ready for 8 billion returnees.

Or you just let all that infrastructure rot. Power stations are unusable. Dams break. Roads go bad. 8 billion people show up to the biggest clean-up project in human history and the very first thing they're going to want is several million bulldozers running on diesel.

Be careful what you ask for. A story about a quick-fix for the Earth's problems — if they really exist (it's harder than you think to kill the planet) — has serious implications in reality that will often be worse than the problem you're trying to fix.

Or you can ignore all of that and tell a fun story. If your readers don't like what you have to say... screw them.

  • 2
    $\begingroup$ Downvote rationale: Not reading the question was a brave gamble that didn't pay off. Admitting it in the first paragraph doesn't absolve of responsibility to read any question before answering it. Most of the answer isn't relevant (the situation's described as a snugly-fitting case #3, and nobody's left behind). More importantly, it answers a question that may've been interesting (how to impose population-wide time-travel), but not the question asked (how a single person could best prep for such a scenario). $\endgroup$ Aug 15, 2023 at 0:18
  • 1
    $\begingroup$ @DewiMorgan You win some you lose some. Thanks for the feedback. $\endgroup$
    – JBH
    Aug 15, 2023 at 1:28

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