Despite the generally frivolous answers, this is an interesting question and one I often wonder about. What turns out to take up all the time if we want to reproduce where we are now? Presumably the optimal plan is to spend practically all your effort on machine tools.
It would be interesting to be able to figure out what would be the best benchmark of progress. Would it be the precision with which you could machine metal? That might do up to about 1900.
It might turn out that most of the time was spent on something nontechnical, like moving stuff from place to place before you'd developed fast ways of doing that. So maybe in practice the most important benchmark would be how fast you could move stuff.
Reproducing where we are now would in some ways be harder than getting here was. E.g. the most accessible coal and mineral deposits used to be sitting right on the surface, but now those are gone.
You wouldn't need coal. If you can make a fire, charcoal is easily produced from wood.
Making forges and blast furnaces isn't too difficult. To build one, pile up dirt or clay walls to form a bathtub like structure. Make sure you have holes at the base so air from your bellows can make it though. Construct a fire in the tub and pile on alternating layers of charcoal and iron ore. Keep pumping on the bellows for the next few days until the the charcoal burns up. Your iron ore should now have turned into pieces of high carbon steel, perfect for making any tool from ploughs to blades.
You might be able to find iron ore as dark colored sand in stream beds. I don't know where you would find copper or zinc.
Once you have steel, everything follows. If society knows about existence of a technology, reproducing it shouldn't be difficult. The hardest part about progress is inventing brand new things.
If you are interested in learning how to make machine tools from very simple materials, look up the Gingery series on making a complete metalshop from scrap:
I've built the gingery furnace, an poured aluminum twice. It's hot and scary. I've made arrowheads out of old glass bottles using a broken antler.
I think you're underestimating how spectacularly hard it is to make anything without tools. Go into the woods naked, and show me how to make a bellows.
I'm pretty sure i could do it, if i could keep my glasses, and my shoes and a knife and a bunch of food. I think i could run down a deer, if all the other people i'd be in competition with didn't kill me after i was 10 miles into the run.
I don't think steel matters very much. Sanitation, clean water, lots of food.
"If society knows about existence of a technology, reproducing it shouldn't be difficult. The hardest part about progress is inventing brand new things."
I disagree. Once upon a time, people drove cars on the moon. Should be a n easy thing to reproduce eh? heck, we've got 40 years of technology on them. The hardest part about progress is convincing other people to do what you want them to do.
The gingery books are FANTASTIC. i'd highly recommend them to ... everyone.
I guess I meant that coming up with new ideas is hard. Invention is hard.
In the hypothetical case that everything is gone tomorrow, the ideas still exist. All we need to do is implement them.
I'll explain it in CS terms. What would happen if all copies of the quicksort algorithm were destroyed overnight? Someone would spend a few hours and write another one because he/she knows about the algorithm. It would take about an hour.
Consider the further case that no one on earth knew that the quicksort algorithm even existed. How long would it take to be duplicated? Months? Years?
How did someone get the idea to smelt metal? It took thousands of years. Now that we know that smelting exists, all that is left is finding a way to do it. Many people in modern society will have the knowledge to rebuild technology. I would argue that expanding technology is much harder than rebuilding technology.
As to pouring molten metal, sure it is scary at first, just like driving a car. After much practice, like most things, it ceases being scary.
> I'll explain it in CS terms. What would happen if all copies of the quicksort algorithm were destroyed overnight? Someone would spend a few hours and write another one because he/she knows about the algorithm. It would take about an hour.
That's like saying you just woke up in a Blacksmith's shop, with the anvil and fire ready. That's the last mile, which isn't the hard part. Compare it to destroying all traces of CPUs and computer hardware/software. Okay, now go fabricate a processor.
What I mean to say is that once you know about an invention, reproducing it is much less difficult than actually inventing it. Do you disagree?
In high school, I was obsessed with metalworking and built several forges. I played around with melting metal and forging blades. I created charcoal. I read everything I could get my hands on about blacksmithing. I read a lot of fiction books about rebuilding post-apocalyptic societies.
I understand where you are going. If we lost it all tomorrow, it would be quite hard to reproduce tools, machinery, high precision equipment, etc. to get back to where we are. For new inventions, you need both to do all the building of the machinery that builds that machine that will build the new invention, but you also need the novel new idea that is the invention to be made. 2 hard (and quite different) problems to solve, instead of just the first (which, as mentioned, is ridiculously hard in and of itself).
i'm also interested in how-to-make-stuff-from-chemistry series (candle, soap, pulp, paper, ink, oil, nylon, plastic, etc) preferrably from the same author(s)
not necessarily from scratch (burn tree to get ash etc)
One of the hardest intermediate steps would be developing a sufficiently large cooperative social unit. Right now I'm typing this on a computer that was made by people I've never met in a number of different countries that I've never visited; structures like international trade agreements and currency exchange mechanisms make it possible for us to have a mutually beneficial economic relationship. (Size of cooperative unit makes a pretty good benchmark of progress, extending past 1900 to the present.)
If technology disappeared, our social and economic organizations would suddenly extend no further than the tribal level, i.e. the number of people we could have cooperative relationships with would be limited to the people we saw in person on a daily basis.
Even assuming we still had the necessary schematics to understand what we were trying to build, it would take a long time for us to get sufficiently well-organized to manufacture it in quantity. Of course, it's possible that in this starting-over scenario, technological progress would outpace the rebuilding of social organization, to the point where we'd have all the same electronic goods, for instance, but each region would make its own. Or maybe we'd have to duplicate the transportation-technology revolution of the early and mid-20th century before we could get anywhere with the communications-technology revolution of the last 20+ years.
>One of the hardest intermediate steps would be developing a sufficiently large cooperative social unit.
Churches would probably be the nucleus for these. There are already numerous churches that are beyond tribal size, and they are of course geographically localized.
It's funny to see this discussion popping up here, I've been thinking about this quite a lot. I've never really made any progress: coming up with good answers requires a lot of cross-discipline knowledge that I just can't bother to track down in my spare time. Geology, chemistry, materials engineering, mechanics/industrial design etc, etc. It stands to reason that all the science and engineering disciplines would be involved.
Machine tools are the foundation of just about everything, but there's a lot more to do once you can produce and shape metal. Chemical production is a big task once you have the handling of basic materials out of the way, and energy is important right from the start (electricity!). You'd have to have easy access to clean, and hot water to maintain good hygiene and a decent standard of living, which is important for morale. Which questions do we consider - just the technology part, or the kinds of social precautions you would have to take? A struggle for resources causes all sorts of difficulties. How would the economy work? There's no way to maintain governments like those we have today when there are no means for fast communication.
What is the easiest way to bootstrap technology from scratch? It would probably be a lot easier in temperate climates where food is abundant; in many parts of the world too much effort would have to be spent on just staying alive. The focus would have to be on tools right from the start: gather resources to build stuff and then use your new gear to build more stuff. Even if everybody knew exactly where we were going, it would take decades at the minimum. There is just so much to do, and so much of our technology depend on things we have developed already.
We could write books about this stuff. You could probably dedicate whole academic careers to the question, especially if you really want to try out the practical aspect. I'm disappointed about most of the posts on this story, there is so much interesting stuff to explore here.
>What is the easiest way to bootstrap technology from scratch? It would probably be a lot easier in temperate climates where food is abundant; in many parts of the world too much effort would have to be spent on just staying alive.
If technology ceased to exist today, there would certainly be a massive die-off. Farmers would not have the ability, and possibly not the motivation to feed all of the newly-useless urban dwellers. Even if it would be possible for low-tech farming to feed everybody, it would be impossible to retool and retrain millions of people in time to plant this year. California would get it the worst. How would they even get across the desert and mountains to places where food is grown without irrigation?
Speaking of writing books about stuff, communication equipment would be probably of an equal or even higher priority to sanitation since efficient information transfer will greatly speed up the re-engineering effort. Furthermore it wouldn't be terribly difficult to do early on. You don't need too much metallurgy to cast type, and the rest of a basic letterpress could be made of wood. Paper isn't too hard to make. Neither are batteries, so as soon as you can produce wire efficiently you can set up a telegraph. Telephone, radio, typewriters, Linotypes, and lithography would all require more mechanical sophistication, so they can wait a bit.
If we can head towards magnets and wire, we could be on for an early boost from electricity and radio as an alterative to the entire postal service (much much easier than rebuilding all the roads and railway).
How much useful electricity can you get from a donkey walking round in a circle driving a generator instead of milling flour?
Cut ahead a few years, we can avoid the effort of roads entirely if we brush the ground flat and pick hovercraft and hot air balloons for longer distance matter movement.
If the population would remain the same, then all the effort will have to go into feeding it. And most likely will fail.
The next hurdle is organizational. You have to get the engineers together and working.
Once you cleared both, I'd guess not so long. Furnaces aren't really high tech, if you don't go for volume. Simple machine tools could probably be made out of wood, with only the essential parts of metal and using alternative power (animal, water, wind...).
In the end it'd still be a matter of administration (market?). If you get a group of knowledgeable people do one thing only (a furnace, a machine shop, an assembly line) it wouldn't take more then 1-2 years per step and many can be done in parallel.
"Reproducing where we are now would in some ways be harder than getting here was.."
Opposing factor to speed up these sorts of setbacks is that much of the experimentation/testing would already be done. We'd know the fuel efficiency of coal for example. We'd know not to bother with methods that have failed.
I'm more curious what technologies we'd realize never needed to exist. Would electric cars be the route we choose? Would open source operating systems be 100% adopted...etc
I assume every artifact made by man disappears instantly? No books, no canned food, no clothes. Everyone i know would die in a week. My grandma grew up very poor in the dustbowl. She would have a chance, but it's cold at night.
So, you're left with people who can recreate their tools in a few days, and don't really need what they have. the !Kung in africa? There's probably 20,000 people in the world like that. Expansion around the globe would likely happen as fast as the first time. 100k years?
I think teching back up would take a lot longer. The easy to get natural resources are gone. 100k years aren't really enough for plants to turn back into oil. Maybe really big earthquakes would bring metals to the surface. Once upon a time there were black puddles of oil on the ground. Now, we have to pump saltwater into deep reserves to get the oil out. I suppose there's plenty of easy to reach coal. I don't know much about copper mines, they always look very deep to me. perhaps there is a lot of easy to get surface copper, just not in high enough concentrations to make it worthwhile to mine.
I don't think 20,000 is a reasonable bound; here in the tropics (Puerto Rico in my case) it doesn't get cold at night; you'd have a lot of starvation and the society would be feudal pretty quick, but I'll bet you'd end up with more than 20,000 people on this island alone. Now multiply by the rest of the tropics.
But the likelihood of our returning to a technological civilization after that? No. I'm betting we never would, for two reasons.
First: all the data's gone. It's just skills in people's heads, and most of the people with skills will be dead in a few months. And the ones that don't die right off the bat will be too busy not starving, and making sure their kids don't starve, to write anything down, on non-existent paper with non-existent pencils, until they themselves die of old age at 55. No medicine. No antibiotics. Plenty of privation and overwork, though. (And even if some overachiever does write stuff down -- how long does that survive? And how does it get distributed beyond his own little village of 100 people? Answer: it doesn't. And all the resources he knows how to use are no longer available from Edmund Scientific.)
OK? So there's no skills, really fast. But there are legends of the fast-burning city civilization that let us all down. Humanity will never try it again; I just don't believe it. We're barely trying it now -- how many people really still believe in technological progress these days? I mean, in terms not of making a buck, but of inevitable progress towards a better life? Damned few. And that's before it all goes away and 99% of the people in the world die as a result.
> Once upon a time there were black puddles of oil on the ground. Now, we have to pump saltwater into deep reserves to get the oil out.
Hmm. I know where to find some of said black puddles.
While there are reasons why they're not being exploited today, I guess that makes me pretty valuable when all the tech goes away, at least until someone figures out that we need metal to deal with said "puddles".
Just out of curiosity, what part of the world are these puddles in? Assuming that all technology won't be disappearing anytime soon, it's probably safe to share ;)
(1) I doubt that ANWR has ground-level oil because I think that the Inuit would have exploited it.
(2) The Inuit know, or at least knew, how to survive in that area without significant tech. If "all the tech disappears" happens in winter and they wake up naked and outside (with no inside available), they don't wake up. If it's summer, they can cope.
We have a few trees left. We can always burn those puppies up. (Actually, if you've ever been to the Azore islands of Portugal, this is exactly what happened. You'll be hard pressed to find many trees on several islands.)
Long enough that most of humanity would die very quickly. Without tools to grow food to satisfy our current population, we couldn't make enough. Couple that with lack of heating for cold regions, general lack of knowledge of survival skills, and the realization that we must first get metal before we can even create decent tools... I'd say we'd be goners.
Don't forget to stir in another factor: Localized conflicts would soon break out over scarce food and other resources, It's an interesting question whether the people most likely to prevail in such conflicts (and thus most likely to avoid near-term starvation) would be those possessing the skills to recreate even rudimentary technologies.
Also, we've used up a good deal of what got us started the first time. Unless the metal ores were returned to their starting places in the ground when the technology disappeared, the quantities reachable and usable without high technology simply aren't there anymore--a chicken and egg problem. We'd also have far less runway to wean ourselves off fossil fuels this time; coal would be useful, but whale oil would be a more workable solution than petroleum. So even if when technology disappeared we lost the need for food and water, we still might never make it back.
Sure a lot of humanity would be wiped out. But the strong will survive. The resourceful ones would be left standing in the end. People in cold regions would work there way to warmer ones or stay warm with fire and making clothing. I'm not sure the scope of the original question. Whether we are starting from pre-language times or we wake up tomorrow as is with no technology. But assuming we aren't starting from scratch and still have basic communication and enough skills to irrigate and hunt we could survive.
do we still have the knowledge but have no material technological items? do we still have the stuff but no knowledge? are we being impeded by some sort of magical force? are there dragons?
Even with everyone alive today, the world's premier superpower (the USA) has recently let on that it can no longer make components of its current nuclear missile fleet.
What I mean is, with everyone who is alive today, the resources of the larger economies providing large military funding backing a program that's both important to national defence and the safety of highly dangerous weapons, with lots of smart people working on it, ways of doing things are still lost.
It's a near certainty that the current ways of manufacturing steel are not what the ancients used, and even if you studied the best available guide to the ways the ancients used there would be implied and secret knowledge you wouldn't have, terms and names you wouldn't understand (or worse, seemed OK but were actually wrong). So much of what we "know" simply isn't there.
Medicine? What do I know of medicine outside drug brand names? I "know" activated charcoal can help people who have ingested poisonous substances. But I don't have any understanding of how activated charcoal differs from any other kind, what it looks like, how to make it, how to administer it, or how to make or find normal charcoal or how to store it or if there are alternative poisonous kinds.
Iron? Know what Iron Ore looks like or where it's likely to be found or how to refine it without using things you can buy at a shop? Not me.
But there's a deeper problem than that lurking. Ok, we carved stone, put likely iron ore into our clay furnace, pumped by sewn leather bellows and got a rod of metal. Still, we have shelter, and we don't need girders, I-beams, railways, canons, ironclad ships... what are we going to do with iron exactly, anyway? What did people use iron for?
Not only am I lacking knowledge of how to make things and what they were used for, but we're lacking an entire civilization within which to make use of things.
When the OP asks what it would take to recreate where we are now, what does that mean? Fabric dye wouldn't be high on my list of things to work on, nor would post-it-note glue or felt, leatherette sofas or shampoo which smells of flowers and has sea cucumber in it, asbestos, pewter, even cardboard is only useful because people post things to me in it - I don't do anything with it. With no postal system and not many things, what would we want with cardboard?
In fact, the core of what I probably want to recreate is some way for other people to do things I don't want to do, in exchange for me doing things I do want to do that other people will pay me for. And by the time I've tought myself to become a blacksmith or soap maker or wheelright or glassblower or died trying, then recreating where we are now no longer matters quite so much.
i don't know much about anything, but i do know how to make basic concrete, i do know how to make basic alloys and i do know about things like penicillin and other natural drugs.
i don't need anything fancy to make use of this knowledge. i could build a house, farm some crops, and stay kind of healthy with this knowledge. could make this happen in a very short period of time if the knowledge is retained. its just a matter of reogranizing to build back up the structures of society if we still had our knowledge.
it would take much longer to relearn, because you would have to relearn the knowledge and then rediscover how to structure society. if we had residual buildings and computers, they'd be useless as they went into disrepair due to our lack of knowledge.
At first i would be concerned with not freezing to death and finding food, I'll leave technological advancement for the better days.
You see, we started to develop technologies only after we had people who could afford not to have to kill their own food, so they had some free time to make now tools or have new ideas. cave men weren't stupid, they just didn't have any spare time to waste.
HA! I love this thought. I hope we can assume that knowledge is infinitely accessible. If not, it may turn out more like "idiocracy" in that initially we build things that suck.
Well I suppose the bigger question is, does everything the technology created go away too?
Technology built everything, but do all our houses disappear or just all the wiring and plumbing and crap? Because if the house goes, then surely so should all the people who were brought about by technology.
Realistically there would be approximately (assuming the max for 10,000 years ago) about 10 million people on the planet. If so, with the distribution spread throughout the world then I think if humanity were born with our present knowledge I think we would do rather well, presuming we were swapped out with the Cro-Magnon. I bet about 50% of the people would probably die off within the first decade just through lack of knowledge (again presuming even IQ and knowledge distribution), but if people managed to start bringing back technology I think we could advance things pretty quick.
I mean one person with the knowledge of how to make steel and devoted their life to teaching everyone how to make advanced tools, well we'd have skipped 9,800 years in the space of maybe 50.
So I suppose it's all in how it would happen and then a large handful of random chance and human nature. I mean if the one guy who remembered how to build a blast forge, also knew how to make gun powder (I know the principle on how to build both) decided to instead of helping the world decided to build a machine gun and build his own country then it could all end when someone usurped him without the knowledge to build tools or weapons.
We still have the knowledge, so assuming that knowledge is utilized i guess you could answer that question by simply reverse engineering the amount of time it took to obtain the knowledge of achieving a significant process and then determine from that point how long did it take to implement the solution. Since you would be implementing the solution only you would then need to know how many key solutions are you re building and you could figure this question out quite easily.
Seems to me that there are two ways it could go, depending on how you take the question.
If when all the tech disappears the resources reappear, I'd say it doesn't take too long at all. Maybe ten years, maybe a hundred, maybe a thousand, but nothing more than that. This is a sort of "If people with modern knowledge fall back in time" scenario.
On the other hand, if the resources aren't available, ie all the iron that's been mined over the last hundred years is simply gone then we'd be pretty boned, and would probably go extinct. This is more of a post-apocalyptic scenario, except you can't even mine the I-beams out of old skyscrapers, but all the cheaply accessible metal's been mined anyways so your civilization simply can't advance past the bronze age (or wherever you manage to scrape it up to). We'd be like the australian aborigines, who lived for (if wikipedia is to be believed) an astronomical 40000 years on the continent without developing anything more sophisticated than the boomerang.
Are you asking this question in reference to last night's Battlestar Galactica finale? It was somewhat surprising to see everyone give up technology so easily and start anew with just clothing, some food, and their own language. But I guess being cooped up in those ships for that long and seeing how the abuse of technology led them to such events could have that effect.
To answer your question, it's hard to guess. Without medical or agricultural technology, I think most of our current population would die out. The rest would war over the remnants of societal structure. Technical progress, as we see it, would take a long time to begin -- primarily dependent on stability. There are too many unpredictable events that would alter the length of time before returning to stability and our current standards.
I have not seen that episode. Thank you very much for telling me how it ends. I guess that will teach me the dangers of not seeing everything the second it airs. A couple of comments like that, and I can throw away my PVR completely, and save a lot of money.
To keep on topic, I think that many would die due to lack of food and medical technology, but it wouldn't take long to reach the technology level of 1900. The difference between then and now, is that we know it is possible. How much time was wasted because people didn't think something was possible?
The BSG folks were dumb. Everything in nature is trying to kill you all the time. You can use a wrench to hit things long after there are no more nuts to be tightened. Apollo will run out of bullets and the natives will spear him, or the lions will eat him.
funny thing was just the other day I was showing my children how to make fire with two sticks. Didn't work. Father failure, though they did understand the idea of friction and the result: heat. Now, my second attempt is using a boot lace with bow (from curved stick) to turn a wood axle with a top brace. Makes smoke, but no fire yet. Somehow, this was much easier when I was younger. However, my point is the basic skills are just as important as the knowledge.
I would say three to five years. In my opinion, technological tools are overrated. Most things can be built by hand using common materials.
Actually, it would be a very cool project! Take a bunch of hackers. Set up an isolated camp for them in a remote area. There will be no technology there, but there will be plenty of edible plants, fresh water, and some medical supplies. The hackers will be supplied with a sample of every raw material that Earth has to offer. And when I say raw, I mean, for example, iron ore. Have video cameras all around the place to make sure they are not bringing technology from anywhere. Measure how long it takes them to build, say a computer. I think it will be less than a year. (The reason I answered 3-5 years to the main question is because in the situation you described most humans will be busy fighting each other, and hackers will have less time to devote to rebuilding technology.)
I think you would see a large drop in population before we were able to rebuild. Population growth only occurs when the technology can support it.
If we were starting over without any of the knowledge we have now, then it seems reasonable to assume that it would take roughly the same amount of time.
If we had history to look back on, then maybe we would be looking at a few hundred years instead of a few thousand.
I think the more interesting question is, if we had the knowledge of our past history to look back on, what would we do differently? Would we be more green from the start, for instance? A lot of the problems with adapting to green tech today isn't that the technology is necessarily so knew and unknown, it's that well-established infrastructures and systems are in place that are implemented on vastly different technologies and the cost/logistics of replacing them is prohibitive.
If we woke up and all the technology was gone, would we want to get back to where we are now...a second time around would be a good chance to fix/improve stuff.
You'd hopefully get pretty far while current experts are still alive. Otherwise, you'd better at least have a plan for getting printing and libraries up and running pretty darn quickly so they can leave instructions for the next generation...
However, I find this kind of question fascinating. This question is posited in the book Marrow, and it takes a very advanced society about 5000 years to get back to where they were.
I think the situation right away would work more or less like this. Within the first few weeks to months, nasty. We're literally talking about BILLIONS of people that will starve to death within a matter of several months.
Based on your scenario, we're not looking at instantly restored nature. Vast areas of the world would suddenly be large, vacant, barren land where the cities were. Places that were verdant farm land before being paved over by roads, cities, and suburbs are likely to be nutrient starved and unfarmable for many years.
You would immediately have millions of people moving out into surviving "wilderness" areas. Trees burning, wild animals being hunted for food. I'm mainly thinking of the U.S., but the ideas apply to most other industrialized countries. "Third world" and agrarian societies might actually fair better. We're talking about the utter decimation of many remaining "protected" species. Suddenly removing everything humans have built, at this point in history, would seriously fuck what's left of nature on the land. On the other hand, humans would no longer have immediate access to the deep ocean. Given the results of ocean recovery in protected areas in recent years, its encouraging to think that many threatened and endangered species and ecosystems would immediately start recovering.
The next important thing to take into account is culture and religion. There will likely be surviving populations worldwide that represent the varieties of cultures and religions that we already have. In small pockets, you might find members of the intelligentsia trying to recreate primitive paper as soon as possible, to re-record as much general knowledge as they can. In other parts of the world, particularly the Muslim populations, there will be a religious fervor and general destruction of any remaining advanced knowledge. This will also happen in much of America, due to our retarded Evangelican populations. We might actually find more preservation efforts in Europe and Japan, due to their longer-term cultural histories mixed with being extremely modern. I can't say about China, but they have a long history and might also work to preserve knowledge.
People are adaptable, and anything short of a global disaster that fucks the basic life processes of the world, people will survive. It would likely take several hundred years at a minimum, and at most several thousand, before we saw some resemblance of modern technology re-emerging.
However, the only cultural artifacts that people would have is what was created from the morning after, onward. There would be no Pyramids, Stonehenge, Jerusalem, Aztec ruins, or anything. No cave paintings, primitive burials, etc. By saying "all technology", this means that all physical remains of our progress would need to disappear too. We would only be left with our memories. In every graveyard around the world, all caskets would disappear. All pacemakers and artificial joints would be gone from the skeletons. They would also be gone from the living.
After a couple of generations without any physical remnants of our civilization's evolution, with no pre-history, our descendants would be completely cut off from their past. They would of course be able to re-learn about evolution over the billions of years of life because fossils won't go anywhere. They could relearn about our own evolution, but only from the biology side of things.
I would imagine that future historians would eventually realize their legends of an ancient global civilization might have some credence, even though there is no physical evidence. There would be the tell-tale signs, the footprint, that our technology had even though the tech itself is gone. There would be the atmospheric carbon levels, the concentrations of uranium where reactors and weapons were, and hundreds of other alterations to the physical world that we've made.
So the question is whether the humanity will be able to stabilize before current generation (with the knowledge of technology) will die (including because of age)
I prefer http://en.wikipedia.org/wiki/Robinson_Crusoe - Crusoe built all sorts of things to make his life easier from wood. Tom Hanks just spoke to a volleyball the entire time.
All technology? I guess we're back at the bottom of the Civilization advances tree, eh? Do you want triremes, maths, militia or granaries?
England has ~65 millions of people. Take away all manmade technology (including buildings, tarmac, concrete) and any city would be many square miles of bare earth collapsing into holes where sewers and tunnels and underground trains once were.
Within a day or two it would be many square miles of human waste, corpses, mud if it rained, and people making their way to the nearest rivers.
Within a couple of weeks, significant fractions of people have starved or died of lack of medical treatment, fighting, illness from river water contaminated with sewage and corpses, etc.
OK, you can drink from the river you may not get ill for a while. What can you eat but other people? City areas -> wastelands.
Out in the country, farmers with easily harvested crops in season are the best off, until they get looted. With no food stores or shops, animals and current crops will be eaten quickly and that's pretty much that. Good luck surviving on hedgerow food and hunting with no experience and everyone else trying to as well.
Some strong willed resourceful people in remote niches will survive (nobody could travel to them very quickly). After a few years we'll see who. Small farms, maybe some farm animals, fast growing trees coming into usable sizes. Levers, (wooden) wheels, barrows, hammers hoes, heaters, cookers, flint/stone axes, they'll be around.
Maybe in short order some beach sand melting -> glass jars, glasses. The people who survive are the people who currently live with reduced technology and will be busy staying alive.
What then? I don't know. A few decades to a population big enough and connected enough for mass trade, I suppose. By then a similar sort of grind up through metalwork, blacksmithing, banking, debt, economic collapse...
What technology could we skip to that would hasten us through such developments? I say at least two hundred years.
The last time a similar topic came up at HN, it was the "what if you time travelled back to the past" question.
I didn't think of it in time for that thread, but I wanted to turn the question around: Looking back through history, if we wanted to spot a technologically advanced person appearing in the past and trying to create 'future' technology, what markers should we look for? (and ... has this happened?).
It would be interesting to be able to figure out what would be the best benchmark of progress. Would it be the precision with which you could machine metal? That might do up to about 1900.
It might turn out that most of the time was spent on something nontechnical, like moving stuff from place to place before you'd developed fast ways of doing that. So maybe in practice the most important benchmark would be how fast you could move stuff.
Reproducing where we are now would in some ways be harder than getting here was. E.g. the most accessible coal and mineral deposits used to be sitting right on the surface, but now those are gone.