# When universes collide, how much of an emergency is it?

The world of Pandemonium is a world in another universe where humans may exist, that is gravitationally connected to Earth in our universe. Over the course of history since the big bang, these universes have periodically collided, transferring organised matter from one to the other, including humans. Now these two universes are about to collide again, in present day Earth and Pandemonium.

To explain what the collision is like, to use a two-dimensional analogy, think of each universe as being like a sheet of wrinkled crepe paper, and when they collide, it is as if the two sheets of paper were laid on top of each-other. At the places where the two sheets touch, matter may cross from one universe to the other.

In essence, when the universes collide, wormholes will appear throughout the parts of the two universes that are in contact with each other, ranging in size from a few metres to a few hundred metres across. Individual wormholes may occur as close to each other as several hundred metres apart, but most will be at least several kilometres apart, and some wormholes may be up to fifty kilometres away from any others. At or below ground level or within a few hundred metres of the ground, the average distance between any two wormholes may be around 5 kilometres, but rapidly increasing in distance as altitude increases to several thousand kilometres between wormholes at the Kármán line, tens of thousands of kilometres apart in interplanetary space, and hundreds of thousands of kilometres or more apart in interstellar space.

Wormholes are readily visible due to the optical distortion effects around their fringe and visibility of the space in the universe on the other side.

The wormholes will have a slight repulsive effect that means that unless an object is moving with sufficient energy in the right direction, more or less directly toward the centre of the wormhole, it will tend to be pushed away from the wormhole. Matter that passes through the wormholes will tend to do so in its entirety, unless the matter in question is a body of liquid or gas bigger than a wormhole. For a solid object to be torn apart in a wormhole would require a collision with the wormhole at least energetic enough to tear apart the object regardless of what it collided with, and a wormhole of insufficient size to allow the object to pass through in its entirety. When the wormholes appear, they won't generally cause significant damage to static infrastructure. On a human scale, if a person was to deliberately try to force themselves through a too-small wormhole, they might suffer bruising as if they had tried to force themselves through a too-small opening in a solid object. The more likely outcome if a person wasn't trying to get to the centre of the wormhole is that they would be harmlessly diverted to one side.

Because the two universes have been colliding at decreasing intervals and for increasing amounts of time across their existence, and they are gravitationally connected, wormholes will open between roughly equivalent places, underground to underground, ground to ground, air to air, space to space and so on. There may be some slow atmospheric or hydrological exchange where there are significant pressure differentials.

Because of the laws of relativity, the wormholes between these two universes occur relative to significant objects within them, i.e. stars and planets. This means that the movement of these objects will carry the nearby wormholes along with them. Since Pandemonium and Earth are 'co-located' and are in effect moving along the same orbits at the same speed and the same rotation, the wormholes will be stationary relative to both of those worlds.

At the 'moment' when the wormholes appear, they will all appear at a small size and increase in size rapidly over the course of a few minutes, and after that, they will fluctuate slowly and more or less simultaneously in size to about +/- 20% of their initial inflated size over the course of around a month following a sinusoidal pattern.

Given that background, I now come to my question:

Given that these wormholes will appear all across the world more or less simultaneously, including in our cities, how much of a disaster will their appearance cause?

I'm not concerned with the political situation, only the emergency services situation. As I haven't written about the society on the Pandemonium side, responses need only consider the Earth side.

• I'm afraid this question is incoherent, because I believe neither space nor time exist outside a universe. This means there is no physical framework that governs the interactions of these two universes. It would be impossible to describe e.g. the periodicity of the collisions you talk about, because that project requires both distance and time -- measures that have no meaning because there is no space "between" universes in which they could have meaning. This also means that relativity does not apply to or between universes as objects. Relativity is a law within a universe.
– Tom
Commented Aug 25, 2023 at 3:29
• @Tom, I've explained how this situation works. If the fact that it's "two universes colliding" means that you can't answer it because of your beliefs, so be it. However, if there's something you can't understand, please say so, and I'll try to clarify it. Commented Aug 25, 2023 at 3:46
• Let's say the wormholes are open for a month, then they close, then in two years they open again. When they open again will they be in the same locations, or is the placement of individual wormholes semirandomized? Semirandomized would be significantly worse for immediate disaster response and long-term "disaster containment" Commented Aug 25, 2023 at 14:31
• If a wormhole starts out just next to a permeant standing object like a tree or a wall, will its growth be contained by the object, will it slowly push the solid thing aside like tree roots slowly lifting a sidewalk, or will the wormhole itself be pushed aside to accommodate the physical object. Commented Aug 25, 2023 at 14:56
• Wrong tag, not science-based in any way. The wormholes have whatever properties the author decides them to have. How bad it is for the people entirely depends on this decision. The same for people's reaction on it. The author seems to ask to write a story, not resolve any particular problem or inconsistency. Commented Aug 25, 2023 at 15:58

## The biggest hazard will be logisitics

In the olden days of nomadic life, these wormholes would not have been a problem. If anything, they would open up new opportunities to explore new hunting grounds and the like.

However, in modern times we have roads and train tracks all over the place that risk a wormhole opening up in one. A wormhole could not only make a road inaccessible, but chances are, there is not a road on the other side; so, you could be driving down the Interstate only to be confronted by a hole in space that spits your 70mph car out into the middle of tropical rainforest. Many highways and train tracks will be cut off, and this will significantly impact our logistics. Entire towns could be cut off from civilization. People could find themselves have to drive several extra hours to get to work or deliver goods as longer routes must be taken and the remaining roads become congested.

While you've done a lot to minimize the ecological and physical hazards of the wormholes, the economic impact would be very noticeable. Prices will quickly rise, available goods and services will be reduced, and many companies will be forced to close causing increased unemployment.

Wormholes will also force many people out of thier homes if for example thier kitchen is suddenly a portal into the middle of a Pandemonian highway. I don't think your insurance would cover that; so, society would have to scramble to figure out how to deal with this sort of thing too.

If you want to make wormholes less harmful to your society, the best thing you can do is make them movable. You mentioned that they have a slight repulsive force, but if they also have a limited inertia of thier own, then perhaps a bulldozer could, if moving slowly enough, push problem wormholes out of the way of important places. In this case the damage would be roughly equivalent to a hurricane or a blizzard: it would be inconvenient for a few days while the work crews do thier thing, but society could easily suck it up as all the wormholes are safely contained, and then go back to business as usual.

## But After the Bust, there may be a Boom

While the short term effect on our economy would be bad, the long term effects could be great. Humans of Earth have invented all sorts of cool new things since the last convergence that the Pandemonians might really want to trade for... and all those wormholes mean lots of potential trade routes to get to them. Selling things like Cellphones, Waterbeds, and Mocha Frappuccinos to these new untapped markets could cause an economic explosion leading to many good years ahead for the people of Earth, and maybe Pandemonium too.

• You beat me to it! The one thing you didn't mention that I would have is the fear/displacement factor: Most humans are going to want to get as far away as possible from the most "active" wormholes, because the beings on the other side are devil-shaped. There might be a big exodus away from cities on Earth that have a "matching" city on Pandemonium, and conversely, the FBI-or-equivalent might set up a huge base near a place that's a boring field on Earth but a regional landmark on Pandemonium. Commented Aug 25, 2023 at 16:58
• @MediocreFantasy The OP wrote: "I'm not concerned with the political situation, only the emergency services situation. As I haven't written about the society on the Pandemonium side, responses need only consider the Earth side." So, I wrote my answer under the assumption that Pandemonium is essentially just another Earth with other people living there. Unless actual hostile encounters happen on the norm, I'd imagine the portals would be treated more like immigration checkpoints than full fledged military camps. Commented Aug 25, 2023 at 18:41

I will draw the equivalence between universes collision and galaxies collision.

Both are mostly made of empty space, with grains of matter here and there. When two galaxies collide, the chance that two of these grains of matter crash into each other is very slim. What is more likely to happen is an extended gravitational perturbation of their orbits.

I expect something similar to happen when two universes collide.

On the good side, it means that practically no planet or star has to make an awkward phone call to their insurance company explaining how they tailgated an unidentified planet that appeared in their Hill's sphere.

On the bad side, it means that many families will be torn apart, with planets being flung away from their stars, stars from their galaxies, and so on.

To answer your question, it will be a long-term emergency, not a short-term one. This means that you will have time for negationist movements to arise and claim that stars have always moved around and that there is no evidence that universes are colliding.

• If you read the question, the gravitational effects have always been there, and pretty much galaxy-wide, matter will intersect with the matter on the other side through the wormholes. Commented Aug 25, 2023 at 6:22

So let me take this at face value, the wormholes dont suck anything in or push anything out, they dont pose a threat to buildings, or people since it will push them away without harm.

The anwser is, it depends on what you want it to happen.

Building on gases and liquids being able to partially go from side to side, on earth nothing interesting or significant would happen at all.

But outside a wormhole might connect a star to an empty region of space thus getting the gas to the other side and making the start smaller/die.

But since you say that a underground wormhole connect to the same place underground on the other universe (Assuming that means the exact same spot) nothing at all would happen. In the worst case scenarios some car crashes or small stuff would happen WHEN they show up, afterwards its status quo

• All the stars and planets in the two universes are in the same places, at least where the contact takes place. I was concerned more with people crashing vehicles into wormholes, seeing people who have crossed over and look like devils and don't speak any language that anyone has heard before, or the occasional new river coming out of a wormhole. Commented Aug 25, 2023 at 14:52
• Thats the small stuff i was talking about, no world ending even would happen, small stuff like you said would happen but the it wouldnt be an emergency, a big scare ? for sure Commented Aug 25, 2023 at 15:26