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Set in the distant future humanity has successfully developed working time machines which can allow user to go back in time, but no further back than the year 1900 A.D. Nowadays companies are making models that can send batches of people and non-animated objects into the past. However, the time rift becomes exponentially unstable around the year 1899 and earlier. This prevents time travel to times earlier than the year AD 1900. If it wasn't an engineering challenge, what could be the reason for the restriction?

Note: please use magic sparingly and there is no grandfather paradox because new timelines fork every time a time rift occurs.

Edit: the time machine when activated will fall through a temporal rift and reappear in the past timeline, any attempt to change history will cause that timeline to split.

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    $\begingroup$ I'm voting to close this as POB. Without knowing the mechanics of how time travel works in your world, literally any coherent answer is equally valid. Can you edit in a description of your time travel mechanics? $\endgroup$ – sphennings Mar 5 at 1:01
  • $\begingroup$ @VLAZ: Yes, that's question have many answers I'm looking for. $\endgroup$ – user6760 Mar 5 at 8:53

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Y1900 problem. Time machine software has a bug that prevents it from correctly handling years before 1900. Despite all efforts, people still think it's a hardware issue.

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    $\begingroup$ I believe Excel uses that date as the Epoc date. Bug could exists because of the use of an unsigned variable. $\endgroup$ – Michael Kutz Mar 5 at 1:57
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    $\begingroup$ Often times people rule out obvious explanations. $\endgroup$ – Galactic Mar 5 at 2:01
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    $\begingroup$ @MichaelKutz a time machine built with excel macros. That'd be hilarious $\endgroup$ – Pierre Arlaud Mar 5 at 8:48
  • $\begingroup$ It would be really funny if this was as a result to a fix for the Y2K problem. Some legacy system somewhere has been patched and accepts dates after 2000 but the patch was sloppy, so it doesn't accept dates before 1900. Perhaps it was changed from two only accepting a two digit number x and calculating 1900 + x to the x being more than two digits, so you can do x = 120 for the year 2020. However, that still only allows positive numbers, you can't have x = -150 for year 1750. $\endgroup$ – VLAZ Mar 5 at 8:59
  • $\begingroup$ @MichaelKutz There are other options that I think are more likely. C/C++, Lisp, even Mathematica. But I appreciate the joke reveal potential of the time machine being powered by Microsoft Excel. $\endgroup$ – John Dvorak Mar 5 at 9:40
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This is a bit strange, but maybe time starts in the year 1900.

For some reason, the universe began in the year 1900, and everything that appeared to happen before that actually didn't. Since you can't time travel to where there was no time, you hit a barrier at the year 1900.

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  • $\begingroup$ Excellent! I was thinking this same thing! Maybe when they finally force a jump to 1891 things are very, very different than expected, $\endgroup$ – Willk Mar 5 at 1:25
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    $\begingroup$ Take a look at the Church of Last Thursday last-thursday.org $\endgroup$ – Suppen Mar 5 at 9:27
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    $\begingroup$ the Matrix began in the year 1900 - Fixed That For Ya! :-) $\endgroup$ – fr13d Mar 5 at 9:43
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It uses a nickel-iron signature as a lock-on to stabilize

Time machines don't really exist, handwavium all around to justify them. The real question here is just how to justify picking any given year and using it as a backstop for the time machine. So I did some digging, and the nickel-iron battery was invented in 1899 by Waldemar Jugner, later improved by Thomas Edison in 1901. So all you need to do is conjure a suitable technobabble. Here, I'll take a crack at it.

Time Travel

When Professor Sylvester McMonkey McBean invented his fantastic time machine, he quickly discovered a pressing concern. You see, the fourth dimensional wormhole caused by the newly discovered Sneetch Effect requires the presence of nickel(III) oxide-hydroxide on both ends of the wormhole to stabilize, or else it is subject to Yertle Syndrome, and no one wishes for it to be subject to Yertle Syndrome. Fortunately, as this is a time machine rather than a space machine, so long as the when has the presence of enough nickel(III) oxide-hydroxide, it matters not where the where is. Unfortunately, nickel(III) oxide-hydroxide was only used in batteries starting in 1899, and there just wasn't enough until the early 1900.

Time travelers are recommended to, at all costs, never travel before 1899 and the presence of sufficient nickel(III) oxide-hydroxide, because then you will be subject to Yertle Syndrome, which had no known cures.

-excerpt from 'A Beginner's Guide to Time Travel'

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    $\begingroup$ Damn, you just typed faster than I did... :) $\endgroup$ – Tim B II Mar 5 at 0:58
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    $\begingroup$ @TimBII Rush to your time machine and fix that. $\endgroup$ – Victor Stafusa Mar 5 at 4:14
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Time Machines are Electrical in Nature, and timelines can't be breached by technology exotic to the time.

It IS possible for a time machine to go back in time, but there is a catch; the time machine cannot carry materials or devices that could not have existed in that time. So, for example, your time travellers can't wear polyester clothing if they want to travel any further back than 1941. It causes a vibration in the machine that tears it to pieces if it contains a molecular substance in a form that does not exist anywhere on the planet (time machines are at least a little localised in that regard) outside the machine at the same time.

So, why does that block ALL time machines from going back further than 1900? Well, the first form of rechargeable battery was a Nickel Zinc battery and it was invented in 1900 by Thomas Edison. He got the patent on it a year later, in 1901. Prior to that, even if the substances existed (which they would have) they would not have existed in the same form of configuration, making the flight of the time machine unstable at best.

So your time machines have to use their battery store to go back, then find a way to recharge in the local timeline so that they can come back. They all use Nickel Zinc batteries simply because that way they can go as far back as 1900, but no further. This effect also acts as a physical barrier to major changes in technology in the time line as it stops you taking (say) LED TV screens to 1910 (or any date before 1962) and expecting them to proliferate. You can take back information, but you CAN'T take back actual materials.

Ironically, this effect could actually explain why our technological development has accelerated in the last 100 years or so; we take back ideas to explain how to do things better and what practical uses technology may have, but we still have to invent it on our own before we can take back a better example of it. That means that as we discover new things, our ability to improve on them and make them better accelerates, but not the rate of discovery itself.

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    $\begingroup$ "molecular substance in a form that does not exist anywhere on the planet" - great idea, but how picky is it? If it considers the entire DNA at once, it limits time travel way more than intended, and if it considers the entire rubber thread woven into your headband a single molecule (as it should), plenty of travelers are in for a nasty surprise. As for batteries - if you allow copper/zinc/brine batteries (have fun powering anything with them though), that lets you go all the way to 1780s. $\endgroup$ – John Dvorak Mar 5 at 9:57
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    $\begingroup$ I'm picturing the hilarious notion of a time machine being built around a massive array of potato-batteries because that's the only way to travel far enough in time for the operator's goals. $\endgroup$ – Ruadhan Mar 5 at 11:13
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    $\begingroup$ @Ruadhan on the upside, I think I have a new idea how to get Matt Damon off Mars. $\endgroup$ – John Dvorak Mar 5 at 11:14
  • $\begingroup$ If it worked for Hanville Svetz, it'll work for us. $\endgroup$ – Ruadhan Mar 5 at 11:17
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They don't know

In theory they should be able to but anyone who tries fails to return. Automated testing time machines also fail to return. There is no sign of them ever arriving. The scientific community is stumped.

The first time machine went back to the year 1900AD

Since then, no machine has been able to go back earlier. Scientists suspect the universe forked off into two universes at this point for the first time and time machines can no longer go back any further.

A Temporal Ban

A very far distant time travel policing agency blocked off any earlier for "public safety" reasons. In reality, a cabal made up of the heads of the world's major religions sealed off earlier times to prevent the public from discovering that all the religions are fictional.

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    $\begingroup$ The ban was created by humans in the distant future, that's why nobody knows about it, not even the heads of the world's major religions. They simply hijack any time machine that goes before 1900. One time engineer working in deep secrecy manages to acquire some samples of the Earth's mantle from 1890 but is unable to convince anyone when they came from. (so he is not detected by the time police) $\endgroup$ – user253751 Mar 5 at 12:21
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Nuclear class explosions cause ripples\markings in space time that the time machine uses for targeting. The Tunguska event is the oldest explosion we know enough about to target.

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The classical answer is that time machines cannot go back any further in time than when they were started, but this leads to the interesting question as to why the time machine you built in 2500 AD can go back to 1900 at all.

The most plausible method of time travel using physics as we understand it is "frame dragging" using enormous masses (i.e. stellar masses) moving at relativistic speeds, such as the "T" machine.

enter image description here

Frame Dragging using a T machine

Since this is rather speculative, there are a few handwaves possible for you as the author:

  1. The T machine is pointing light cones at "other whens", but due to the limited size and power can only point the light cone to an alternate history 1900. This isn't real time travel the way we think of it, but for story purposes it can do
  2. The T machine built on Earth or in the Solar System is interacting with another T machine built by alien technologies and activated in 1900 in our frame of reference
  3. Avoiding the aliens, there is a natural T machine created by the rotation of a neutron star, which also corresponds to 1900 in our frame of reference. We did not see a Supernova because it is actually ancient, it is just passing through space close enough to interact with the human T machine. If this isn't understood, time travelers will be stranded once the neutron star passes out of range.

Since time travel is already a very questionable proposition with our understanding of physics, the addition of a few extra handwaves should not cause much of a problem.

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  • $\begingroup$ "the addition of a few extra handwaves should not cause much of a problem" - like the small inconvenient issue of having the device and everything near it collapsing into a black hole. $\endgroup$ – Victor Stafusa Mar 5 at 3:12
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Your time machine creates, in effect, a bridge between times. It needs something to support it on the other end to move large objects like humans across the "bridge". What it needs is an electrical generator, or preferably mains power, to hook into to stabilize the bridge. Therefore, you can't (practically) travel back into time before electrical power was available. In theory you could, if you had a truly absurd amount of power in the present, but the engineering requirements make it infeasible.

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Microsoft Excel

The calculations needed to perform a time jump are all handled inside a big monstruous .xlsx file with a bunch of Microsoft Excel formulas. The reason it was done in Excel is because it has the wonderful power of holding in a lot of data in its spreadsheets and do a lot wonders of calculations. All time machines comes with Microsoft Windows and Microsoft Excel installed.

Someone tried to make engineers and physicists learn actual programming. The result was that some of them were able to learn VBA and used it to write macros in Microsoft Excel. After that, they considered that they already know enough of programming and have no spare time with playing with those boring If...End If and For...Next toys any further because they already have too much actual hard work to do with physics and engineering.

Engineers and physicists are people that never even heard about the existence of a RDBMS. If they ever hear someday about the existence of a thing called RDBMS, then they will never have a clue about what it is or what it is the purpose. If in some full moon night at Friday 13th, they get it, then they would never be willing to learn it because knowing Microsoft Excel is already enough. If they learn about RDBMS, they will always keep still using Excel because they'll never be able to decode that strange alien language called SQL. If they eventually learn SQL, they will try to use SQL with Microsoft Access as a thing to input data into Excel spreadsheets and never feel any need to go any further with this. If they eventually realize what is the purpose of a RDBMS, how to use proper SQL and how to correctly wire it to a software system and what is the benefits of that design, then they immediately suffer a simultaneous hearth attack and stroke and die.

Someone proposes the idea of calling some actual software developers to give a look onto that. After seeing a lot of incomprehensible gibberish in a big mess of Excel formulas salted and peppered with some VBA macros, all of them quickly resigned their jobs and went work in some other jobs which was paying much higher salaries for actual programming in Java, C#, Pyhton, PHP, Node.JS or anything else, as long as it has nothing to do with Excel nor VBA.

So, the sad conclusion is that it is impossible to create a time machine without using Microsoft Excel.

Dates in Microsoft Excel starts at January 1st, 1900. Negative dates are used as a hack to travel to the future instead of going to the past. This could perhaps be changed, but nobody know for certain where in the sea of Excel formulas and VBA macros that sort of thing is handled.

Someone also had the idea of going to February 29, 1900. That person landed here.

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The time machine was invented in 1900

The time machine can only transport a person to the past of the machine itself. Much like how a train can only get you as far as the tracks go, some iteration of the machine was first constructed in the year of your epoch date. It would have been an early version, probably not functional at all, but the core remains there and it serves as a "rail" on which your time machine can transport people.

Going further in the past means going to a point in time before that device existed, meaning there is no place to "land" in time. You either cannot do it, or you end up in deep space or in the planet's core or at some other incredibly inconvenient location.

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Using too much power could damage the machine

With the current V1 Delorian time machine, the further back in time you go, the more power/fuel is required.

1.21 gigawatts will take you back 350 years or so (which right now is around 1900).

Using more power than that could risk burning out the flux capacitor, making it a one way trip if you go back any further.

You'll be stuck in 1885 for quite some time...

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    $\begingroup$ This is similar to my own idea so I'll add it as a comment. Maybe the distance (in time) you can travel is some kind of logarithmic function of the energy input. That is, it's simply not possible (even in the year 2456, or whenever) to supply enough energy to go any further back than a few hundred years. $\endgroup$ – K. Morgan Mar 5 at 11:53
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Carrington Event

If you are a little flexible about the year you could make a connection to the massive solar flare known as the Carrington Event which happened in 1859.

https://en.wikipedia.org/wiki/Solar_storm_of_1859

Perhaps in the story, that event wasn't really a solar flare, but an electromagnetic time disruption caused by an early botched attempt at time travel.

This attempt left the timeline damaged in some way (residual harmonic temporal fluctuations) preventing travel to around that time zone or before.

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For years the scientists and technicians could not determine why they could not go back beyond the year 1900 - it just seemed like they had hit a "hard block". But obviously the time machine didn't know nor care what year we decided to call it, so there must be something else, something in the timeline that was preventing passage past that date. Gradually, all their formulaes and theories seemed to coalesce around a central fact: Something (or someone) was preventing them from crossing this boundary - there was no other physical or other barrier that could be determined. Upon further investigation, it was postulated that possibly members from a future time-line had put up a hard barrier at just that date. But why? For years historians and others tried to delve into exactly why this hard barrier existed. Gradually, all the science and mathematical formulas pointed to one fact- on Sep 8, 1900, in Galveston, Texas, a hurricane killed between 6000 and 12,000 people. This was the central reason that the block existed. But they still did not know why - was it because someone in the future time-line had came back, altered history to ensure someone born in the late 1800s, living in Texas, did not live to do what they would have done? Or was it because they had already tried to save the thousands of lives and discovered that someone they had saved had turned out to be a monster? And if so, what kind of a monster could justify condemning all the others in that devastating hurricane to death? Or was it another reason? There was only one way to figure this out - try to communicate with those that had put this hard block in place.

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Time machines use the position of some exotic particles which were first fabricated in 1900 as a map of time

Basically in 1900 somebody fabricated some sort of exotic mater/particle/material which later formed a basis for time machines to orientated them self's in time and land at the correct point. And since the particles didn't exist before 1900 no time machine can map the time prior to 1900 and can't pinpoint a target to land at. Similar to KeizerHarms solution of the time machine being inveted in 1900

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  • $\begingroup$ Welcome pizamotas, please take the tour and at your leisure read-up in the help center about how we work. I enjoyed your first post, +1.(From review). $\endgroup$ – Tantalus' touch. Mar 5 at 10:40
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The machine uses electrical fields to pinpoint points in time and before 1900 there just wasn't enough electrical generation/use. you can see here approximately how much power was use in 1900 which is roughly 12.1 PetaWatt hours or 43.56 Exajoules

note: as a bonus, if you need excuses to go further back but only to specific dates you can say there was a some sort of mega thunderstorm/volcanic eruption that lets you lock onto that point in time

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Fuel

If the time machine uses some kind of resource to operate. There should be a theoretical limit of how much fuel you can carry, thus making limits of such an advance. Also, if you travel to a year before the time machine was born, you can't re-fuel, because no one can make more at that time.

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  • $\begingroup$ That makes the issue no longer about the year 1900 but instead about the current year - N where N is the furthest you can go due to fuel restrictions. $\endgroup$ – Thymine Mar 5 at 9:42
  • $\begingroup$ @Thymine Yes, but we can say "the farthest anyone ever travelled is 1900" and it does not really needs more explaining. $\endgroup$ – szab.kel Mar 5 at 10:21
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The time machine uses a worm-hole (or something similar) as a bridge - one end of this is in 1900... it just happens to be when it popped into existence. However, scientists are looking for other "bridges"...

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One of the first prototypes was sent back to 1899 to a cave just recently discorvered. The plan was to send it back and reclaiming it there to get testdata of long time travels.

The thing is, the experiment failed causing an explosion in the fabrics of time itself - not noticeable for humans, but impossible to traverse in future timetravels.

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Related to the ideas mentioning Microsoft Excel is the problem of February 29th, 1900. This day did not exist, but one of the calculations involved in the calibration of the time machine assumed that 1900 was a leap year. These equations are so difficult and the only person who was able to solve them has died, so they nobody has been able to correct them. Because of this inconsistency, any attempt to return to February 28th, 1900 results in different components of the time machine working inconsistently (with some parts correctly aiming for one day before March 1st and others, which relied on this calculation, incorrectly aiming for two days before), with a similar effect for any earlier date. In fact, if the equations assume that every year that is divisible by 100 is a leap year, the discrepancy increases to two days for dates before March 1st, 1800, three days before March 1st, 1700, four days before March 1st, 1500 (1600 was indeed a leap year) and so on.

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Stealing directly from the Ars Paradoxica podcast.

All time travel is actually time travel to 1900. But some people get off the bus early. Time travel works by unmoring yourself from the present time, and then you are naturally sucked backwards in time to 1900.

Some event in 1900 created some kind of time-attactor that does this. A special point in space-time that just sucks things towards it. Maybe it is the only one that ever has happenned. Maybe it is one of many and you get sucked towards the nearest (or nearest in the past?) or maybe with many you can do some kind of leaverage/manvovering to navigate fairly freely but 1900 is the first so can't get beyond it, because it sucks towards it.

There have been several options already posted for what that event could have been, or what it was misinterpretted as.

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