# A Nonlethal Time Dilation Field

I want a way to enclose an area (building-sized and on Earth, let's say) in a field that warps spacetime so that time appears to pass 100x slower within it. You don't need to explain how the field got there or what effect could produce it, only lay out a consistent framework that it operates under. (i.e. I don't need explanations for what kinds of relativistic effects would result in a field like that - just assume it works by magic). It doesn't need to conserve energy or momentum (I suspect it'll be nearly guaranteed NOT to conserve them, since the barrier breaks Lorentz invariance). It just has to have 3 features:

1. Within the barrier, it feels just like being in normal space, except that if you emerge from the field after (what feels like) an hour, it will have been more than 4 days.
2. People can pass through the barrier without protective gear and without being crushed by their own skeletons, burned by a shell of captured photons, ripped apart by expanding space, etc.
3. Conditions inside the field are hospitable to humans as well (i.e. I'd rather toxic levels of CO2 didn't build up inside the field). This is what dooms the naive answer of just setting time to pass 100x slower in the field with no other changes.

Anything that fulfills those conditions is fair game - I just want to know if it's possible. The edge of the field can taper gradually if you want, with the speed of time smoothly changing from 1x to 100x normal. You can make it so that space inside the region becomes physically larger, as do the people who enter it, if that helps. Not saying it will, just that enlarging things 100x might offset the pressure at the barrier, though I personally haven't been quite able to get it to work.

• The field is open to the air, which means that if the rate of time is just strictly different inside, atoms outside the field will be moving 100x faster, so they enter the field 100 times more often than they leave. By this logic, the air inside the field should be at lethal pressures, regardless of whether or not the barrier is a smooth gradient.
• How does light interact with the barrier? Assume that, other than any spacetime-warping effects, it's transparent. My first instinct is that, since much more light enters the field per second than leaves it, the outside seems bright to the people inside and everything inside appears dim to those outside. Not too problematic, but I can imagine fixes to the previous bullet point causing issues here.
• We need to find the limiting factor for what about being in a time gradient would kill a person first. Certainly, blood pressure differences could cause issues, but I imagine the brain's sensitivity to timing differences would kill at much gentler gradients. Hard to put numbers to that, though.

Creative answers are welcome! Maybe the whole inside area is spinning! You know, interesting angles like that, except that they actually solve the problems instead of making things worse.

• You're going to need some kind of gradient for the interface between the special area and normal space. Any kind of instantaneous transition between the two areas will not end well (think nuclear weapon but much, much worse). – Gryphon Apr 18 at 17:33
• Can you say Tidal Stress? Fred can’t any more. Poor Fred. – Joe Bloggs Apr 18 at 17:35
• "This is what dooms the naive answer of just setting time to pass 100x slower in the field with no other changes." Could you clarify what aspect of just setting the time to travel slower makes the field inhospitable to humans? – David Coffron Apr 18 at 17:42
• Because the people passing through the field are not 2-dimensional, they die pretty quickly (disclaimer: that's my answer to a similar question). – JBH Apr 18 at 19:34
• Could someone help me phrase this question so that people don't keep posting answers about relativity? I already wrote in bold that I don't need explanations, and laid out the actual issues. I'm not sure how to be clearer about it. – Gilad M Apr 19 at 11:27

Stargate to a world near a black hole.

That's how they did it on Stargate SG1. I cannot find a video which shows the excellent opening of episode 2-15 but you can watch the whole thing here for \$1.99. https://www.youtube.com/watch?v=4n2xxesfLDw

In short - team SG10 is exploring a planet when the binary star of that planet condenses into a black hole. The team sees bad stuff going down in the sky and starts running to the stargate, which for those unfamiliar with the show is a technologically enhanced wormhole. They are transmitting through the gate and their transmissions get slower, and slower. As time slows for SG10, they will never reach the gate to escape. I like to think they never realize this.

The rest of this episode deals with the ramifications of being connected to a spot near a black hole via a Stargate wormhole. The ability to connect to a black hole via Stargate is revisited in a later (so awesome!) episode.

For your purposes: slow land is an area near enough to a black hole that time is slow. Alternatively it could be a destination that is moving extremely fast as compared to the starting destination. The transition from normal time land to slow land must be some Stargate-like tech enhanced spacewarp thru special space that matches velocity etc.

checking...hard science tag? No! It's all good.

• I mainly avoided the hard science tag because I thought that people would try to explain with hard science how this field was supposed to be made, citing relativity and such. But I guess in your case it had the opposite effect :P Like I mentioned in other comments, I'm not concerned with the causes of the field, only that it doesn't kill people moving through it and that it can exist stably on Earth. – Gilad M Apr 19 at 15:08

## Entering the field

So you're worried about timing differences hurting or killing people. A solution is that the time gradient will always be constant on a solid object. So if your person's center of mass is halfway across the boundary layer, they run at 1/10 speed1 as seen by the outside world. Every bit of them. You can take electronics inside and they won't fail from transistors running at different speeds.

It will help for people to not notice if the boundary layer is very thick. (If you have a difference of 1% per meter, then the boundary layer should be ~463 meters thick.) People noticing something is off might violate requirement #1 (Seems like ordinary space) but the boundary layer being incredibly thick is not a requirement for this solution to keep someone alive.

This would cause interesting effects for mechanical devices made up many different solid parts moving across the boundary layer.

## Air problems

The pressure buildup inside the zone will require a separate system to fix. Making the air exempt from the time dilation will result in people being squished, while including it, as you already realized, is that people die under 100 atmospheres of pressure.

On the harder side of ideas, the area inside the time dilation zone is a pressure chamber. When the hatch is open, it can pump out the excess air.

On the softer side of things, consider something like Red Tornado's aerokinetic core, from Justice League Unlimited and Young Justice. The aerokinetic core is what allows Red Tornado, a robot, to create tornadoes and wind. A similar system of mechanical aerokinesis would allow an effective pressure gradient to be kept across the boundary layer.

1: I'd actually assume that a time dilation's boundary layer would have an exponential curve, so to square the rate the boundary layer doubles in thickness.

• The idea of solid objects all being at the time rate of their center-of-mass is interesting, but I'm not sure it really holds up. For instance, if you took a long, rigid bar and put it halfway through the barrier, then the end inside would only move at 1/10 speed, but people inside at 1/100 speed or outside at normal speed could still interact with it, and it's unclear how that would work. Also, how did you do your 230 m calculation? I got ln(0.01)/ln(0.99) = 458 m. – Gilad M Apr 20 at 10:31
• I mean, it's not like repulsion would break. If it was spinning like an axle, they would observe it as rotating at different rates. (2 rpm vs 200 rpm) Except if they were able to measure the forces inside the rod, which would show a third rate (20 rpm) – ltmauve Apr 20 at 15:27
• I did 1/log(1.01), which is actually incorrect, it should be 2/log(1.01) since log(100) = 2 – ltmauve Apr 20 at 15:29
• I also said 100atm in my initial answer, but then changed my mind to 10,000atm (1gigapascal). I'm still not 100% sure though, so I figure I'd see what you think. My current line of reasoning is that velocity is 1% less, but temperature is related to kinetic energy, and kinetic energy is related to velocity^2. Therefore, temperature is effectively a factor of (1/100)^2 lower, and since PV=nRT, the pressure is (1/100)^2 lower too. Therefore the pressure inside would have to grow to 10,000 ATM to equalize. Thoughts? – conman Apr 21 at 3:01
• I mean, it still has the same energy and temperature, but it's effectively lowering n by decreasing the number of particles that can head out per time. When the air molecules collide, they run at approximately the same time so the temperature/energy difference doesn't matter. – ltmauve Apr 21 at 3:55

On the atmospheric point, unless I'm missing something, CO2 isn't going to enter the time dilation zone at any different rate than any other component of the atmosphere? So CO2 poisoning shouldn't be a problem, but runaway pressure build-up could still be, but you could remedy this with just a big air pump shifting the surplus air back out of the dilation zone. This would take a lot of energy to power, but luckily you could generate a lot of that power by setting up a ring of wind turbines around the circumference of the dilation zone to take advantage of the super-sped-up air (these would also have the advantage of slowing that air down somewhat).

• Yeah, I agree that air pressure in general is an issue, but what I meant is that so is CO2 poisoning specifically if people are living inside the field. The wind turbine idea is a good one, though - if you somehow have an energy-conservation-breaking field, why not get free energy from it? – Gilad M Apr 20 at 18:55

The only solution is handwaving. There is no realistic way for this to not be lethal. Fortunately, things like this show up all the time in tv/movies/books, so you don't even have to explain it. Just do it and treat it like it is perfectly natural. As for why this isn't possible, it boils down to the fact that a 100x time dilation is actually quite large, and this impacts everything. For reference, to experience a 100x time dilation due to special relativity, you would have to travel at roughly 99.995% of the speed of light. By comparison, a baseball traveling at 0.9c is a city-ending event. This is a crazy high time dilation factor. Here's what it does:

1. Air Pressure: It's not just about CO2. Air on one side of your barrier will enter faster than air on the other side of your boundary. If the boundary were to suddenly turn "on", the air on the inside would effectively act as if it had a fraction of the pressure. You would end up with a gigantic vacuum sucking air into the time dilation zone until the "pressure" on both sides equalized. I'm not 100% certain on how the math would apply, but let's assume the ideal gas law applies and that air inside the barrier is effectively traveling at 1% of the speed of air outside. Temperature is proportional to kinetic energy and kinetic energy is proportional to velocity^2. Therefore air with 1% of the speed has 0.01% of the temperature and 0.01% of the pressure (PV=nRT). Naively, this means that the pressure inside your dome is effectively 1/10000 of that outside. Therefore our gigantic vacuum will continue until that large pressure difference equalizes, with some very large change in density or temperature inside the bubble. In the end though, the bubble must have an air pressure of 10000ATM (1 gigapascal) to equalize, which is unbelievably high. For reference, the compressive strength of concrete is measured in megapascals. The pressure in the core of the earth is around 360 gigapascals.
2. Light Intensity: Light of course has the same problem, although this may be survivable for the people inside. Inside your time bubble time travels at 100th the rate. That means the light is travelling 100 times slower. As with air, this creates a problem at the boundary: light enters much faster than it leaves. In fact, when the field first turns "on" it may appear to turn black for a brief moment as light which enters cannot immediately bounce back out for you to see it. Presumably, things inside the barrier would initially appear 100 times dimmer. The eye is a logarithmic detector, so this difference won't be as apparent as you might think, but it would be quite obvious. It would be about the difference between a bright star at night and the dimmest you can see. However, this effect would be temporary (I think). The "energy density" of light inside the zone would always be 100 times higher than outside, but once light has had a chance to make it to the center and bounce back out, it will become visible at normal "brightness" (for the same reason that your vacuum stops once the pressure on both sides equalizes).
3. Light Frequency: Of course it isn't just the intensity of light that will change - also its frequency. This is more or less the same as what happens with the doppler effect. Light entering the bubble would be "blueshifted" by a factor of 100, turning visible light into high energy ultraviolet light. Conversely light leaving the bubble would be redshifted, moving visible light into the near infrared. This means that if you were inside looking out you would see not visible light but infrared (you'd be able to see everyone glowing!), and if you were outside looking in you wouldn't be able to see any light sources inside. Technically you'd be able to see any ultraviolet light sources, but we don't actually use a lot of those, so you won't see anything unless it is illuminated from light first coming from the outside.
4. Impulses: Force exchange from the outside to inside of the barrier becomes interesting. I assume energy is still conserved. If you imagine being inside the barrier and hitting an object just outside the barrier with a hammer, the amount of energy you impart will presumably remain the same. However, from the perspective of the thing outside, that energy is imparted over a time period 100 times smaller. Same energy, less time = larger impulse, more force. I'm guessing wildly here, but this might mean (for instance) if the field is in the middle of a high rise, people walking inside the bubble may end up cracking and breaking the floor just outside of the bubble without meaning too. I'm not sure what other impacts this might have.

The unfortunate part is that a gradient doesn't help any of this. A gradient might turn your vacuum down to a small wind, but in the end the atmosphere inside won't stabilize until the pressure at the center is 10000x higher than outside. I just don't think there is anyway to cancel out all the effects of such an extreme time dilation without completely violating the laws of physics. At that point in time, the answer is really just "magic", so just own it and come up with your own fun explanation.

Again though, I don't personally think it's a big deal, even as someone with degrees in physics who excessively criticizes movies/books for bad physics. This time dilation zone works and doesn't kill people inside because you say that it doesn't (or more specifically, you don't say anything and people in it don't die). See this clip, especially starting at 1:10.

• All good points. (Though I think energy isn't conserved across the barrier. The easiest way to think about it is that the impulse has to be mediated by electric fields, since that's what's doing the interacting when objects hit each other. These are transmitted at the speed of light, which slows across the barrier, causing the impulse momentum to slow as well.) I was hoping there would be a clever way to manipulate spacetime to solve the issue of gas and light entering the field, but it's proving harder to fix than I thought. – Gilad M Apr 21 at 0:38
• @GiladM I updated my answer because I realize I got my math wrong (it's worse now) and also forgot some more fun effects! Really though, I'm not trying to be a downer. I'm more physicist that creative writer, so "can't be done without magic" is more a representation of my own biases than an accurate assessment of the situation. – conman Apr 21 at 2:44
• No, this is great! This is exactly the kind of thinking that led me to post this question in the first place: the realization that without handwaving, this sort of field would have huge pressure issues, among other things (I'm also a physicist BTW). Also, I think that if light at 1/100th normal frequency was interpreted by an eye-brain system that experienced time at 1/100th normal, it would probably look the same. So light from outside wouldn't look infrared... maybe. To be honest, these sorts of double-negative analyses are the hardest for me to be sure about. – Gilad M Apr 21 at 14:19

I see that @Willk has already meantioned a black hole, which is what i was thinking of.

To a distant observer, clocks near a black hole would appear to tick more slowly than those further away from the black hole.[78] Due to this effect, known as gravitational time dilation, an object falling into a black hole appears to slow as it approaches the event horizon, taking an infinite time to reach it.[79] At the same time, all processes on this object slow down, from the view point of a fixed outside observer, causing any light emitted by the object to appear redder and dimmer, an effect known as gravitational redshift.[80] Eventually, the falling object fades away until it can no longer be seen. Typically this process happens very rapidly with an object disappearing from view within less than a second.[81]

We know that it is impossible for life to exist within a black hole, however its your story, so you could possible have something like a very small, spontaneous black hole forming on a planet, and if someone enters it, there is the time gradient like above, and because its your story, life is possible but we dont know because the time difference makes it that anyone who enters and then leaves, even a couple of minutes later, are a few days ahead of an observers timeframe. Dont know if that helps or would fit in for you? hope the link works

• The question wasn't about what would cause such an effect, but what the effect might look like such that it doesn't kill everyone inside. – conman Apr 19 at 17:33

Well according to Einstein's Theory of Relativity (Time Dilation-- a video on it is linked below), time is relative, but the faster something moves the less time it takes (i.e. Walking a mile will take 30 minutes, running a mile takes 15). So this field of time could make people/life move exponentially faster which would make time inside the field feel short and the time outside long. And because it is its own field, this transition could potentially feel normal to those inside it.

Video on Einstein's Theory of Relativity

There is one other scientific possibility. Passage of time on Earth is mostly dictated by the sun (i.e. One revolution= 1 year, 12 months in a year, 1 turn of earth= 1 day, 24 hours a day, 60 minutes an hour, 60 seconds a minute). So if our planet's time is based on the sun in our solar system, that can easily be done with other solar systems (considering there are at least 200 billion stars in our galaxy alone). Yet that is from Earth. If we colonized Pluto, one year on Pluto would be 248 Earth years.

So if you have a star in a solar system that is used for relativity, you could create a sort of planet-to-planet time field. So four days on one planet could equal an hour on another planet.

Though travel through this planetary time relativity field would require high-tech space traveling technology.

But if it didn't need to be explained...bubbles and trees seemingly came to mind. I don't know why. But maybe you just have this weird flat plain made of trees made of bubbles. Bubbles that last super long and don't pop very often (unless touched), which became the deciding factor of time. So when the bubbles pop an hour has passed or something (and the bubbles just regenerate themselves).

• That's... not really what I'm talking about. Like I said, I'm not looking for mechanisms that would allow time to slow down, but rather how I could imagine a fictitious, unexplained time dilation field in such a way that it doesn't kill everyone inside. I appreciate the comment, though! Hope you're enjoying what you've seen of the site so far. – Gilad M Apr 18 at 22:17

Most answers focused on air pressure. The reasoning looks like speed should be increased -> molecules of air should move faster -> air pressure is different -> air would leak from field border. But I suppose it's incorrect in many ways.

## Air pressure difference is not necessary.

Not only air molecules would move faster. Anything and anybody. What about human speed? Is people moving 100x faster too?
Also, in general relativity theory time could be slow down not because of fast moving but because of high gravity. In that case air pressure inside should be increased.
Since barrier breaks Lorentz invariance we could easily say it breaks continuity of speed (or continuity of gravity). Just because speed is component of momentum which you suppose don't conserve.

## (Magic) Gateways

What if border consist of many something like airlock gateways?
Each gateway isn't so big, just 1m size. It could be constructed by magic handwaving technology from fields, not from steel. So when human travel through the border it passes dozens small gateways. Probably he even doesn't noticed that gateways.
If human traffic is low then remember animals, birds and insects would traveling through similar gateways. So we could say there is enough air traffic between inside and outside areas to allow CO2 to be ventilated.

## Building ventilation system

If we talk about building size let's see how same problem are solving in buildings. Most of them have ventilation system (with propellers or just passive one). Let's say that inputs and outputs of this system are passes through barrier. Somehow.

Your field has a gel like skin that prevents anything from traveling through it without effort. How it would work is any object attempting to travel through would push a bubble out and when the entire object is over the threshold of the field the field reforms behind them and the bubble they pushed out pops effectively instantly making them a part of the new time on whichever side they are on.

For most other effects (eg the sunlight is entering the field 100x slower than normal making the light from outside seem dim) The gel compensates for as much as you want, increasing the intensity of light, being selectively air permeable to let gas exchange with the outside at what would seem to be a normal rate from inside, correcting gravity because I'm not sure how time dilation effects that.

One interesting side effect of this is from the view of people in the bubble anyone pushing in would enter almost instantly, where as people exiting could be watched pushing through for hours by people outside (and maybe pushed back inside).

• Hm, interesting idea. If the barrier itself had some resistance to gas pressure on the outside surface but allowed larger objects through it, that could resolve the pressure imbalance and CO2 issues. Though your concept of a bubble inside the field doesn't seem too consistent to me. Like, does every air molecule get its own bubble? And is the vacuum between bubbles moving at normal time, and if not, why? I think it might be conceptually simpler to run with your idea of the field barrier itself deflecting air and light without adding this bubble mechanic. – Gilad M Apr 21 at 14:26

It takes a long time to enter or exit the field

This particularly dense area of spacetime offers a resistance to anything entering or exiting. The border is only a metre or so thick. But walking through it is like pushing against cornstarch slime (time gel). The barrier is not made up of solid matter but some sort of handwavey space-time gradient. You cannot force your way through. You just have to move really slowly over the course of about ten minutes until you get past the barrier.

This makes it safe for people to cross over since the worst that can happen is you get tired pushing and have to rest halfway through the barrier, then proceed more slowly.

Fast-moving objects have problems though. A missile fired through the barrier would be torn up as the gradient suddenly slows it down. Fast-moving light and air particles have difficulty passing through but statistically some proportion of them still make it.

By some miraculous coincidence this proportion is about 98%. This just about cancels out the fact that there is 100 times as much light/air trying to enter as leave.

Visually I expect most of the light to be refracted and/or reflected off the barrier. So from the outside it looks like an extremely foggy mirror.