Portals to Parallel Earths

In this setting events diverge when massive breakthroughs in physics are made. The breakthroughs effectively prove the many worlds interpretation, but more drastically they allow portals to be opened to parallel universes. Other advances are made because of this knowledge but none remotely as significant as the portals that can be made. Events in this setting diverged very recently so other than the things caused by the portals and breakthroughs in a certain area of physics, things are pretty much the exact same as our world.

Portal Specifics.

Where the portals go: New portals connect to the equivalent positions in the parallel universe. New portals connect to worlds exactly the same as our own, however the instant the tunnel between them is opened symmetry breaks and random quantum events cause them to start diverging.

It is of note that the parallel universe you just reached through a new portal, will have equivalent portals in their universe that lead to parallel versions every universe that your portal leads to. This means in addition to the portals that exist in a given universe every universe connected to also has portals connecting to parallel universes themselves. Thus the number of connected universes is actually infinite.

Once a portal has been made to a another universe, the worlds are permanently linked. Future portals can be opened to that specific universe if you have the energy readouts from any machine that has opened a portal there before. If you can't obtain energy readouts from a machine you can obtain them by using specialized equipment on any area that the portal was near because of subatomic portals that occasionally still open leaking barely detectable energy, this detection equipment costs around a hundred thousand USD.

Portals connect to the exact position in the other world. Portals can be moved but both sides of the portal are physically connected and can't be moved apart. Opening a portal between two preexisting worlds is impossible if there isn't a portal machine at the same location in both worlds. The portals can be made as small as 2 meters in diameter starting out at about 130 thousand USD, the price of a portal goes up almost linearly with the diameter of the portal, not with the surface area. The technology used will obviously remain unspecified, but it involves the use of small particle accelerators, as thus the machine and created portal tend to be circular.

Note: While portals may cost upwards of 130 thousand USD the power requirements to open a portal and keep it open aren't very high, as thus you can pay to open a portal and pay a flat fee for however long you want to keep it open. Given the cost of opening a portal for a few minutes anyone can afford to do it.

In this setting the oldest portals were opened by researchers a few years ago, as thus no worlds have had longer than that to diverge. The older worlds usually have diverged somewhat since opening. There are thousands of portals, just from the early scientific testing of this technology, and most of their energy signatures are easily available online, which means nearly anyone can travel to them. It is of note that some people may find due to the events diverging over a few years, that their double in a world is actually quite different, due to the effect of a random event in the time since they diverged.

Economics: Given most of the worlds are so similar and the fact portals open to the same position in both worlds, it is obvious that most economic trade is pointless, because the worlds aren't sufficiently different. However, the one main commercial use for this technology (other than selling machines and portals) is taking advantage of having duplicate selves to perform larger amounts of mental work. For instance, scientists in different worlds may coordinate to run different calculations on supercomputers and then share their results allowing them to perform that calculation much faster. Entertainment may also become more competitive, worlds may decide to create different media, so that they can make material different than that of another world, afterward the different media will be shared between worlds.

For tasks where the final result is information (which can have different worlds do different parts of the same calculation, or work on different things, then share the information) the production of that sort of information will become dirt cheap and there will be a far larger amount of this information. One example of an area where improvement should be expected to increase is animation. With thousands of cheap portals, a company can choose to do animation that would otherwise be slow with many, many portals each connected world can choose to only do a tiny amount of the total work and at the end they share their work with each other and each profit off the end result. The improvement made in animation is analogous to the improvements made in any mental task.

Portals can never be made such that you can generate energy or decrease total entropy: The portals connect to the same point in both worlds so you can't use them to decrease travel time. The portals are supposed to be made using potential future technology and as such, aren't magic and are constrained by realism. Of course once we learn more about physics it seems unlikely we will find out we live in a world where this technology is remotely possible, but it still can't be completely ruled out.

The Actual Question:

With all of that in mind, what would be the large scale global economic effects of this technology? On the personal level the biggest effect will likely be using the portals to meet your doubles, but on the larger levels the main use of this is to perform utterly massive amounts of mental work and calculations quickly. What would be the effects of this technology be on the global level, how would this affect economies and governments?

How would the fact that calculations and mental work could be done in massive amounts, in incredibly short times affect the economy. I think it's a given that many jobs will be cut. After all why have thousands of people do a job if literally one person can do it by collaborating with their doubles, provided they know how to do the entirety of the task.

  • $\begingroup$ This question concerns the economic effects of this technology future, future aspects of this setting will be in future questions $\endgroup$ Dec 8, 2015 at 1:00
  • $\begingroup$ When you say "130 grand", are you meaning 130,000 USD? "Grand" may not mean the same thing to everyone and there are several different countries represented on WB. $\endgroup$
    – Frostfyre
    Dec 8, 2015 at 1:16
  • $\begingroup$ I mean U.S. currency $\endgroup$ Dec 8, 2015 at 1:18
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    $\begingroup$ Agrajag... you put a bounty on a question that's obviously too broad for today's rules? Don't you realize that answering about the effects on a global economy requires writing a textbook for a decent answer? (Please tell me you've taken any college economics course....) $\endgroup$
    – JBH
    Apr 7, 2019 at 22:39
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    $\begingroup$ Good grief! I'm not reading all that! can you not compress it into something a bit more succinct? ~ & why the bounty when you already had at least 3 detailed answers? $\endgroup$
    – Pelinore
    Apr 10, 2019 at 1:01

11 Answers 11


I think that your statement

Given most of the worlds are so similar and the fact portals open to the same position in both worlds, it is obvious that most economic trade is pointless, because the worlds aren't sufficiently different.

is incorrect.

Consider two countries, on earth, with almost identical populations, economies, and infrastructures in which each has factories producing very similar goods. If there was free trade between the countries then the development of even a small manufacturing advantage in some product would mean that the factory with the advantage would eventually out-trade its opponent - so the symmetry in production would soon be broken.

If there were many (or infinite) connected worlds then a similar process would develop. Say you manufacture pencil sharpeners - and via minor 'divergences' in production methods (or just dumb luck), you win a contract delivering sharpeners to a next world. Now you can bump up production and by economy of scale you can undersell all the connected world's pencil sharpener manufacturers. With an almost infinite market, you can set up mega factories making billions of sharpeners.

Other worlds will grab the toupee market, the jam market, or the sports-car market. I predict that within a few decades this effect would lead to massive specialization where each planet would produce and export only a few products and import other goods from connected planets.

  • 1
    $\begingroup$ Of course with extreme specialization there is a significant risk if, for some political or technical reason, the portals suddenly close for an unspecified but significant time-period. A population trapped in pencil-sharpener world, with no access to jam, toupees and sports-cars (etc.), might find cause to revolt. Is it even possible to beat pencil-sharpeners into swords? $\endgroup$
    – Penguino
    Apr 9, 2019 at 20:32

The types of uses of this technology fall into 3 classes:

1) Parallelization of Tasks

As people have pointed out earlier, while you can't do everything in parallel, there are a lot of cases where doubling your workers and resources more than doubles your production, thereby allowing you and your parallel-universe-twin to split the resulting value and still come out ahead. An example of this would be a car company copying their prototype division and making 16 models in parallel. After testing, one of the models proves to be the best, that model is shared, and 15 out of those 16 copy-companies benefit from improvements to their design without any additional expenditure of resources (even the last one doesn't LOSE anything by participating in this and then closing the portals again).

Parallelization could work well on smaller scales as well. Many simulations are massively parallelizable, and so supercomputers could be built which reap huge power boosts by splitting their computations between dozens or millions of universes, then sharing the results at the end. Two interesting sub-implications of this:

  • It is currently impossible to accurately simulate chaotic systems, such as weather, over long time intervals. However, an absurdly large collection of networked supercomputers could possibly manage it with some clever approximations ("absurdly large" as in one node per atom in the sky). This can be achieved by opening portals with low de-sync times so that it produces a hall-of-mirrors effect and spawns crazy-large numbers of universes very rapidly. Therefore, it wouldn't be too far-fetched to imagine that in this world, governments using parallel universe computing can figure out where to place proverbial butterflies so that their wing-flaps will change the winds and prevent billions of dollars in hurricane damage, for instance.
  • Graphics processing in personal computers is highly parallelized. I'm not sure what the physical limitations on portals are in this universe, but they may eventually be miniaturized into nano-portals that can be built into graphics chips. This would add improvements to graphics that's actually ridiculous, since it would scale as the exponent of the exponent of how many of them you could fit on a chip. Photorealistic graphics would be commonplace just a year or two after this extension of the technology hit the market. And that's not to mention other fields in CS that would love to have that kind of parallel scaling, like AI. I would be shocked if AI didn't make massive leaps forward in the years after this portal technology appeared.

2) Multiplication of Uniqueness

If someone or something is one-of-a-kind, no matter how much you pay, you could never get more of them. Unless you had portals. For unique people, this includes uses like

  • Gathering 8 each of the world's top scientists to solve a crisis
  • Televising, live in 4 universes, the match of the century: 3 Lebron Jameses vs. 3 Michael Jordans in 3x3 basketball
  • Hearing the world's best violinist self-perform a quartet

It also includes more clinical pursuits, like copying the same person 16 times and testing different medical treatments on them. The huge differences between the metabolisms of individual people would be a huge hurdle for medical science to suddenly overcome. Psychology and sociology can similarly tease out effects much more accurately - we'd be a lot more sure about whether subtle subconscious cues can change opinions if we could literally see the difference between the presence or absence of that cue in a single person.

Other unique things we could replicate:

  • We could run twice as many experiments at the Large Hadron Collider if we doubled the universe and coordinated which experiments to do in each, then compared notes at the end.
  • We might be able to save endangered species if we could double their numbers in captivity and gather them all in one place (though obviously, this wouldn't help their gene pool at all).
  • If you're strapped for cash, crash at your parallel universe self's place for a week and put your place up on Airbnb (there could be severe market implications if it becomes too easy to do this).

3) Specialization and Trade

As mentioned previously, two identical people or companies or countries in identical universes could specialize in different skills or products. Due to accumulation of knowledge and economies of scale, you could reap a larger-than-linear benefit for a linear increase in resources.

How this applies to trade between countries is straightforward and has already been elaborated upon in other posts, but a related thing I want to draw attention to is personal specialization. It's generally much easier to learn from a tutor than to learn from a book, for instance. So just have 2 copies of yourself learn different skills and teach them to each other. I could imagine this revolutionizing education.

So on the whole, people would have better computers, see more economic output in most industries, receive more effective treatments, etc. Basically, the pace of innovation would increase dramatically across the board.

  • $\begingroup$ Hi, welcome to Worldbuilding.SE! If you havent yet, please take the time to read our tour page. $\endgroup$ Apr 8, 2019 at 0:28
  • $\begingroup$ "If you're strapped for cash, crash at your parallel universe self's place for a week and put your place up on Airbnb (there could be severe market implications if it becomes too easy to do this)." You should elaborate on this, because if I'm at all representative a massive number of people would try to save money by having their duplicates as roommates (commuting to another world should be fairly affordable), which would have interesting effects on housing. $\endgroup$ Apr 8, 2019 at 23:54
  • $\begingroup$ Thinking about it more carefully, I don't see it being incredibly disruptive. The supply of apartments on Airbnb would increase and the demand for multiple-person housing (to be rented out by copies of one person) would also increase. Those prices would drop and rise, respectively, and the markets would just find a new equilibrium. I don't think either case would make such a big dent that the markets would collapse or anything. $\endgroup$ Apr 9, 2019 at 15:26
  • $\begingroup$ Re "roommates" - I imagine the only people who would derive substantial economic value from doing that are the rather small number of people who would, ahem, enjoy the company of their duplicates enough to share a 1 BR instead of splitting a 2 BR. The rest would just end up paying a little bit less to share a 2 BR instead of renting a 1 BR on their own (after allowing for the markets to rebalance), and when you factor in the reduction in privacy, I'm not sure it's worth it for most people. $\endgroup$
    – Kevin
    Aug 15, 2019 at 1:10
  • $\begingroup$ Re parallelization: It might be beneficial to drop a mention of Amdahl's law, because there actually are limits to how much good parallel processing can do in many practical applications. $\endgroup$
    – Kevin
    Aug 15, 2019 at 1:18

This is less useful than you think.

You're describing parallelization of tasks to make everyone more efficient. However, most normal tasks (especially mental ones) are not that easily parallelized. If you were familiar with Gantt charts you'd know why this entire exercise will be fruitless.

For the case of your example, animation rendering, it's just not worth it. An animation company is not going to spend several hundred thousand dollars just so it can try to coordinate computer resources with its duplicate company. The rendering time is not the bottleneck and if they're going to spend that kind of cash they could simply buy more servers or rent server time.

For mental tasks it's even worse. A human working on a problem is a very linear task. Think about any problem you've solved and I doubt you could have just as easily started anywhere in the problem and then combined the finished result. Think about splitting up to write your question, could you have jumped in at any paragraph and submitted it to your other selves to form the complete question? Highly unlikely.

How about a larger task? Consider a company working on producing a more efficient and less expensive portal. There are a few phases to go through to get it done. For instance:

  1. Design
  2. Simulation
  3. Prototyping
  4. Testing
  5. Manufacturing

Those phases of the project can not be split up between identical companies across worlds. There is nothing to simulate until the design is complete, you can't test something that isn't built, and you can't start manufacturing until testing shows the device will work. Again, useless. As often cited, nine women can't make a baby in one month.

The only benefit is going to come down to one world entity convincing another to give up some resources. Someone is going to get a better deal eventually and be in a better position to continue getting better deals. The worlds will continue to diverge and disparity will increase.

  • 2
    $\begingroup$ This answer pretty neatly sums up my own thoughts on this question. +1 to my potential inter-dimensional double! $\endgroup$ Dec 8, 2015 at 6:59
  • $\begingroup$ @type_outcast I already have an identical twin, my intra-dimensional double. While it's super awesome to have someone who thinks the same things given the same input, it's not enough to complete a project in half the time. $\endgroup$
    – Samuel
    Dec 8, 2015 at 7:03
  • $\begingroup$ Yeah I suppose you're right that for most mental tasks, the increase in speed wouldn''t be linear, as people would collaborate to get each consecutive task done but the tasks still need to be done in order. Since a good deal of tasks can't receive a linear increase by having more people working on it, it might make more sense to have groups work on different tasks then share the end product. $\endgroup$ Dec 8, 2015 at 22:11
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    $\begingroup$ I'm sure twins can work through a problem together better than two "singlets", so there can be some productivity boost. Also, nine women can't make a baby in one month, to debunk another parallelization myth. $\endgroup$
    – House
    Dec 9, 2015 at 23:00
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    $\begingroup$ Breaking a large project into smaller parts may not be a win, but it's easy to imagine a media company like Disney opening a 2-meter portal to another world, and coordinating production of the next two Pixar projects by letting one world do one movie and the other do the other, while both versions of Disney hold exclusive distribution rights in their respective worlds. It's a no-brainer to get the revenues from two movies while only paying to produce one of them. The talent that gets a piece of the pie would be better-compensated, however. $\endgroup$ Feb 8, 2016 at 16:19

Economics of scale, but not only for intangible goods

  • new interdimensional gate 130k dollar
  • new microchip factory - ~2 bln dollar
  • new Boeign 737 - quote price ~100 mln dollar (presumably a bit cheaper after discounts)
  • high speed railway ~$25–39 million per km

In price ranges involved those gates are dirt cheap. Yes, someone may point out that in few years one would not remodel the whole infrastructure... Sort of true... Just all future investment would include it.

In case of air traffic it would be immediate revolution. Building a few dozen gates would mean that there would be enough air traffic. In our world there is not enough traffic between city A and B to keep regular flights. But if one can gather all passengers from cities A[1-10] willing to go to B[1-10] you can stuff whole biggest Airbus. Perfect, new route. Even for already profitable routes you can push passengers through gates and increase utilisation. Bad weather in one of the worlds? No longer an issue.

Using google route finder to get in to interdimensional travel would be fine. Oh, by occasion, tourist often wouldn't even have to get to the right world. Seeing parallel Paris, as long as credit cards are accepted, should also be fine.

In RL world high speed railway often ends as flop because of lack of passengers. Retouring people from a dozen of worlds should suddenly solve this issue.


Well, the exact magnitude of the economic impact would depend on the scale on which these portals would be built, and who would have access to them. The implications of these things are incredibly complex.

Parallel worlds are mostly very similar to ours. That means that the military could potentially test out political and military scenarios in one of these parallel worlds, in order to determine their actions' impact on the economy/politics.

They could easily open a portal, drop a tactical nuke - or some other devastating weapon - on a city/fort/military facility, then send special forces teams to extract gold/information/weapon designs/etc.

The scenarios are literally endless. The government wouldn't care, as it would be the United States in the other universe who would pay the price for their actions. In the mean time, they now have solid intel, or incredibly valuable information, etc. which is completely applicable in their own universe.

Alternatively, imagine the two countries from parallel universes cooperating. The US military sending massive waves of troops/planes/ships through the portal to help the other US absolutely obliterate their enemies, and then having them return the favor. The first country to think of that one may very well rule the world (both of them)

And now, you see how dangerous this tech is. Depending on how it's used, and by whom the world as we know it may very well cease to exist.

And so, I don't think that I can answer your question in exactly the way you've asked. All I can say is that the impact on the economy is going to be huge, however you have not provided all the data to determine whether in a positive or a negative way.

  • $\begingroup$ Ok I think you misunderstand the question somewhat. If you opened a new portal events would diverge at that moment, if you dropped a nuke it would hit the nuke coming from the other side of the portal... Not to mention the older worlds that won't be synchronized are well known so you can't hide it if you nuke them. $\endgroup$ Dec 8, 2015 at 5:36
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    $\begingroup$ @VakusDrake I think AndreiROM understood that. "open a portal, drop a tactical nuke" would obviously need some (peaceful) delay in between. Your point about hiding your intentions/actions is indeed a problem your story will need to address, but I think it would be a mistake to downvote this answer, as it brings up a number of scenarios that (possibly with a little work) seem quite plausible. A lot of people and governments would see their doubles not as allies, but potential competition, especially those with a suspicious nature. "I know how that guy thinks, and where he hides the money..." $\endgroup$ Dec 8, 2015 at 7:07
  • $\begingroup$ @type_outcast - thank you for your support, that last line of yours is exactly what I had in mind. $\endgroup$
    – AndreiROM
    Dec 8, 2015 at 14:11
  • $\begingroup$ Another implication of this strategy may be that militarily defeating a government completely might be impossible. Since any government or terrorist group being defeated could just open a bunch of portals and have them and their duplicates from many worlds all travel to a single world where they will have be much stronger due to their combined forces (leaving them absent from the rest of the worlds). Though if the worlds they fled from or were attacking found the traces of their former portals they might team up against them. $\endgroup$ Apr 8, 2019 at 16:52
  • $\begingroup$ Keep in mind that permanently leaving your home universe behind is a very serious choice. Your job, your friends and extended family, all the connections you built up in your life are basically gone, since the "you" in the world you're hiding out in wouldn't let you take their place and access their versions of those things. I think a choice like that would be out of the question for any organization that built roots of any kind. Only the most desperate militias that already severed their ties would resort to it. $\endgroup$ Apr 8, 2019 at 21:04

Genocide is profitable

So you have an identical worlds with identical resources populated by identical people. Now if you had an identical world with identical resources, that would be much more useful. All you need to do is get rid of those pesky people besides who would miss one planet of people in an infinite multiverse.

Only catch with this thinking is if another universe has the same idea so you really need to guard against someone opening a portal to your universe and doing it to you.

Sure this is as ethically as black as it can get but there are corporations and governments in the world who would do this in a heartbeat.

Just think of the oil, gold, mineral resources you could get, not to mention the perfect prison planet, toxic waste dump, ethically abhorrent research lab or environmentally damaging manufacturing plant.

An empty world has infinite value once you get rid of a few pesky native. It's morally abhorrent but there are people in the world who would use it this way.

  • $\begingroup$ How would people get away with this though? After the worlds are going to think to guard against this sort of thing and if you say dump toxic waste through a portal (which would require someone build/place a portal on the other side) then people can just get the readings from the contaminated area and figure out which world it came from and likely contact other governments in your world (as well as send missiles through the portal if you try to do this again). $\endgroup$ Apr 8, 2019 at 16:42
  • $\begingroup$ I'd imagine you'd dump an engineered virus through the portal and close it and wait. As for getting away with it, who'd know? Easy to pick one randomly from a infinite universe that nobody would ever find. $\endgroup$
    – Thorne
    Apr 9, 2019 at 0:06
  • $\begingroup$ You need someone in the other world to open the portal for you. If you open a new portal that means copies of you with your exact same plans on the other side. If you use a world that's been diverged for longer that means getting a compatriote in the other world to open up a portal for you. Making an engineered pathogen with current tech also has the issue that organizations like the CDC in developed countries will pretty good at combating this sort of thing and wiping out a world just isn't going to happen. $\endgroup$ Apr 9, 2019 at 2:39
  • $\begingroup$ Additionally even if you do wipe out a world in order to take their resources, you will need to employ so a lot of people to exploit that world. So you can't really hope to keep what you did secret which means probable sanctions or worse from other nations in your world. $\endgroup$ Apr 9, 2019 at 2:41
  • $\begingroup$ 'Ours is the only reality of consequence'? $\endgroup$
    – Jontia
    Mar 29, 2023 at 22:26

Who are you ... but actually

Do you and you twins from different worlds trust each other or commit massive identify theft? Then ask the question again for companies and countries.

We could see large scale power blocks as people ally with their twins to do great or terrible things. Who would you trust more than your exact clone, but who knows better how to fool you? It would seem the wining strategy for each cooperating collective of twins is to diversify their choices as much as possible to increase the chance that any one has huge success. This would tend to drive divergent evolution of worlds even faster.

We could see huge economies of scale in tec and research as the research from one world can be shared with the others for free, and some planning keeps us from duplicating research.

There also would be so much more knowledge available because we could to completely controlled experiments, on whole cities and planets.


What I found interesting about this question is that the number of connected worlds grows exponentially. The first world A, comes A = A when the first portal is created, and after they diverged AB = AC with the identical time lines A and divergent time lines B and C. With second gate AB=AC becomes AC=AB = AB=AC, which then diverges to ACD=ABE = ABF=ACG. And so on.

This has two interesting things about it. First, the growth is exponential. The amount of worlds is 2N, if N is the number of gates. Second, it is actually the number of unique time lines that doubles. At first sight it would seem that only the world with the new portal gets a diverging copy but actually all the connected worlds do.

So it could be argued that this is not really a portal. It is a world doubler. And a dirt cheap one at that.

The economic effect of this would probably be stability.

Let us assume a small event such an officer handling the Russian nuclear weapons drinking way too much and setting out to prove that he can indeed circumvent all the security measures and launch all out nuclear assault without anyone being able to stop or abort it.

Normally this would be fairly disastrous. Even if you are not in where the Russian nukes fall, it seems unlikely the Russian would be able to convince the US and China that it was just too much vodka causing all those nukes and there is no need to counter-attack. Honest! So lots of pretty fireworks. And fallout and nuclear winter and all that.

But if we assume the world had the portal tech and a modest number of gates, say 8, less than half percent of people would be directly affected. Maybe, probably, the nukes would break the gates and the world would be cut to segments that cannot get reconnected.

But even that is unlikely to be significant. One world just is not that important here. And even if it was the segments would continue to grow exponentially. And given how cheap the portals are 8 really is unrealistically low. It is more likely every world would have hundreds of portals. So even a nuclear apocalypse would be too small to make much of a difference to the whole.

And if we assume more realistic numbers of gates some of them would survive even the nukes. And survivors near a gate could just go into another world where everything is just fine. And there they could spread to an infinite number of worlds, so the number of refugees per world would be pretty low.

So the portals would give us an exponential amount of redundancy and mass to absorb any negative events.

It would also give us an exponential amount of information. Since every time line is actually truly unique we are not just doubling same old information, we are doubling the new information. Naturally much of that will be duplicated and redundant. But even if we assume that people make no effort to avoid duplicated effort, exponential growth is really scary.

Assuming one percent chance of new idea being non-dupe, which is probably unrealistically low, the amount of available ideas would still be multiplied if the number of gates is as large as we'd expect given the low prices. And honestly I do not think the universe is deterministic enough to keep that uniqueness down to single digit percentages. Certainly under the premise of this question it could not be, otherwise the worlds would not diverge and the portal would be an expensive vanity mirror not a dirt cheap world duplicator.

And naturally people would actually take efforts not to duplicate work. Why should everyone make this experiment when we know the result in one world will be valid in all? And that the rapid growth of the network pretty much guarantees somebody will be making the duplicate test anyway, so there is no reason to duplicate work on purpose.

I think this is about what can be deduced here. There are lots of interesting questions about how people and governments would react to all of this. With lots of options.

For example, world growing at an exponential rate would be very difficult for everyone to comprehend, this might lead to rise of populism and anti-elitism as people look for safety in the simplified and familiar. People might turn to religion or away from it. People might go for aggressive economic strategies to get maximum benefit from the opportunities or conservative ones because there is no longer real need to compete with exponential growth.

And eventually how various people solve these questions is what would determine the specific changes. And every world would be unique and divergent.

Note that even if a world stops making gates or goes all out to make as many gates as it can, all worlds get duplicated equally with every gate. Even if you destroy all your gates, there would still be lots of shards with worlds that differ from you in only not actually pulling the trigger.

But I feel those are about actually building the world and no longer about answering this question.

  • $\begingroup$ I like your naming convention for the universes. And yes, your point about exponentially increasing information is entirely valid I think. On the basis of that alone, I think we'll see huge leaps forward in technology, assuming we have a good way to aggregate that information and allow the best ideas to become known to all worlds. Connecting worlds to each other via the internet (with some kind of web standard that differentiates parallel sites and users from each other) could be relatively effective at this. $\endgroup$ Apr 14, 2019 at 8:34

Cold War dynamics and heavy regulation of incoming portals

I will focus on effects on governments because I think it is the most important question by far. In my view, a zero-sum-game dynamics would quickly unravel unless you have a cheap way to block incoming portals to your own universe.

John von Neummann, a pioneer in game theory, came up with the Cold War strategy of Mutually Assured Destruction (MAD), a strategy in which

each side has enough nuclear weaponry to destroy the other side and that either side, if attacked for any reason by the other, would retaliate with equal or greater force. The expected result is an immediate, irreversible escalation of hostilities resulting in both combatants' mutual, total, and assured destruction.


neither side has any incentive to initiate a conflict or to disarm.

The problem is that in your framework there are infinite sides in conflict, not only two!!

In this game, every universe has a huge incentive to form a coalition and attack another universe whose resources would become available to the members of the coalition. But people in the other universes know this (there is a Jon von Neumann in each universe!). Therefore, each universe will try to:

  1. Prevent others from attacking.
  2. Form a coalition and attack first.

This is a highly unstable situation and no universe can be sure there are no plots against it. If universe A and B start a plot against C, A cannot be sure that B and C are not planning a plot against A. The same goes for B, and so on. Since the number of universes is infinite, the number of possible coalitions is infinite and the situation becomes rapidly unmanageable. If your coalition strikes first you might get an actual chance of a) making a profit out of it and b) survive. This movie, in which people meet their other-selves, is an example of the kind of things that could happen when parallel universes are available to humans.

The good news is that every universe knows this too!! So the one strategy that leads to increased stability is to devote resources to monitor incoming portals and develop defensive systems against them, just like countries do today in their borders.

In addition, portals would have to be heavily regulated not only due to military strategy but also to prevent trafficking, smuggling, etc. You can hide drugs in the alternative universe in your basement and viceversa ad infinitum. Moreover, if you kill someone in the alternative universe, are you a criminal in your own universe? What if John from universe A kills Sam from universe B and John from B kills Sam from A? What if you kidnap people from the other universe?

  • $\begingroup$ You seem to be making 2 points here, and I have issues with both. First, that nations would test weapons, viruses, etc. on each other. If you mean that they would open portals and do this to the nation on the other side, why would they risk it, when their odds of being attacked by an equally-strong enemy are near-50%? No weapons test is worth that. If you mean that this would occur once the portals are open for a while and the power balance is no longer 50-50, well, I'd expect this to be rare for the same reasons that powerful countries in the real world don't do weapons tests on weak ones. $\endgroup$ Apr 13, 2019 at 15:33
  • $\begingroup$ The other point is this "infinite-sided conflict." It's an easy line to miss in the original question, but opening a portal requires a willing participant in both universes to establish the connection. So there are at most a number of enemies equal to the number of people in your nation willing to open a gate to allow the enemy through. I'd consider this kind of danger minimal-to-nonexistent since, as I stated before, countries don't start ruinous wars with each other without good reason. $\endgroup$ Apr 13, 2019 at 15:39
  • $\begingroup$ Hi @GiladM. Thanks for your comments! First, are you sure corporations and countries do not test their weapons on weaker enemies? For example, what would prevent Russia, China or the US to test their weapons in the Middle East or Africa? I'm not saying I have proofs but I'm saying I do not see any credible reason to prevent them from doing it. After all, the weapon trade represents 40 billion USD for the US alone $\endgroup$ Apr 13, 2019 at 23:37
  • $\begingroup$ Well, ongoing conflicts certainly do provide a means for testing new weapons. The US extensively innovates in its current wars in the middle east, for instance. However, this is an internationally-tolerated way to test weapons on people (for better or worse). What you're talking about - opening portals and testing weapons on the other side with no provocation - would bring about international condemnation that just isn't worth it. Especially when testing them on ISIS carries no such drawbacks while actively furthering existing military objectives. $\endgroup$ Apr 14, 2019 at 9:17
  • $\begingroup$ I thought about your points and I realized weapon testing is not necessary for my argument, i.e. governments would have to regulate incoming portals heavily or risk elimination. $\endgroup$ Apr 15, 2019 at 17:09

Looking into the logic of the question as asked, and looking at the salient comments to it - I see only one outcome.

The first time that one opens a portal to another parallel world - according to the rule that until a portal is opened, there is no divergence, thus, when a portal is opened to a world, the equivalent person on that world is opening a portal to a world on which the equivalent person is opening a portal rinse & repeat.

When the first portal opens - an infinite number of worlds springs into being - according to your specification in the question apparently you have the address to all of these? How big is your address book? On your hard drive?

What you have is an infinite number of universes, with an infinitley massive hard drive.

In each.

Each and every universe collapses upon its'self from within it's Hubble horizon creating a supermassive blackhole billions of times larger than any seen since the last civilisation tried this.

Noone makes any profit, except the hyper-dimensional gameplayers who made bets on whether they could trick you into doing this in the first place.

  • $\begingroup$ I never said that they had the readings for every parallel world indirectly connected to their own (of which there are an infinite number) just every world they have portals to directly, of which there are only a finite number. $\endgroup$ Apr 8, 2019 at 16:34
  • $\begingroup$ Not to mention that there isn't any infinite doubling effect when you activate the first portal (though there is one if you activate a second portal while your copy in the first parallel universe is still duplicating your actions). A new portal is just a single connection, constructed at both ends by 2 copies of you. There's only one of it that corresponds to both universes, so it doesn't copy itself the way it does for every other object on either side. $\endgroup$ Apr 8, 2019 at 17:05

No one is taking this to the logical, horrific end

The first nation that discovered the tech would basically have to conquer the world. Some other answers are postulating that different Universes would compete with each other. Why? The mirror USAs or Mexicos or Germanys would have way more in common with each other than the other nations of 'their' worlds. So I think something much worse would happen. Here's an example.

North Korea gets the tech. Kim Jong Un decides he wants to ally with his counterpart. They open a portal to another, virgin world. Suddenly, they have two North Korean armies. Each North Korea secretly built a single medium range nuke missile, and has a single sub to deploy it. They each have ten transport ships, and a couple million conscripts. Then they open another portal. It's only $130,000 American, so doable. Now they have doubled. Then they do it again. Another doubling. And again. And again. And again. It takes a week, they ally, hash out an order to conquering their home dimensions one after another. Each Kim Jong Un gets their earth. All of a sudden 16, 32, 64, 128, however many subs that original Earth doesn't know about, because their Norks only built one - launch their nukes at US navy assets. 150 million Nork conscripts sail for the west coast. There simply aren't that many assets to stop them. The Nork Portals are on a different 'tree' of dimensional portals, so no one can warn them. Any portals you open have already suffered this Alpha Strike scenario, so you can't do to them what they did to you.

Now imagine the preceding scenario, except it's Russia. Iran. China.

America - presuming they are first in discovering this - or the EU would have literally no choice except preemptively taking over the planet and reducing everyone else to the point where they couldn't even attempt such an alpha strike exploitation of the technology.

  • 1
    $\begingroup$ 2 points I want to make here. First, the whole point of mutually-assured destruction is that it doesn't matter if NK has a million nukes - if they use them, it only takes 1 US nuke to destroy them in return. Second, say world 1's NK multiplies its army with the intent of conquering worlds one by one. Once they've conquered the US (assuming no nukes were fired somehow), how exactly do they plan on keeping the world from retaliating after their army leaves to help NK 2? These sorts of plans seem good on paper but fall apart because they don't actually increase your resources in the long term. $\endgroup$ Apr 14, 2019 at 8:50
  • $\begingroup$ I'm not saying North Korea would conquer the world. Their logistics would fail them. They would just wreck the world for little actual cost to themselves. But when you include the possibility of Russia doing this? $\endgroup$
    – Marbrand
    Apr 17, 2019 at 4:04
  • $\begingroup$ I don't understand how you're arriving at "little cost to themselves." No matter which country attempts this, it's an absurdly risky plan with no actual chance of gaining the average participant anything. In the short term, someone crazy with no long-term plan can cause a lot of damage and then self-destruct, and in that sense this is a potentially dangerous technology. But no nation that understood the technology would attempt anything like this. Maybe I'm just misunderstanding your suggestion. There's a chat for this question now, so if you want, we can go over it there. $\endgroup$ Apr 17, 2019 at 13:01

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