# Teleportation rules that don't cause Infinite Energy

High-Magic world. What sort of rules could be put in place to nip the pesky infinite energy teleportation problem from happening? Currently the rules I have are:

• Large mana use / long cooldown
• Short distance only (under 5 miles)
• Can only be done from a higher elevation to a lower elevation
• Pressures must be within certain range between source and destination
• (Possibly unneccessary) Only between pre-constructed fixed points (Anchors, basically)

Are there better ways to word these? (For example, should I say from a lesser gravity well to a higher gravity well, instead of elevation?) Would this prevent infinite energy problems?

Edit: When I say the infinite energy problem, I mean the problem of infinite potential energy through teleporting objects.

• Can you say more about the pesky infinite energy teleportation problem? My google did not turn up what that is. – Willk Apr 17 '18 at 13:42
• Please define your "better". Also, what is mana in your world? And why can't you just say that teleportation uses exactly the amount of energy teleported object would gain? And radiates excess energy as heat if object would lose it? If you don't want it to break conservation of energy, simply state it can't? – Mołot Apr 17 '18 at 13:43
• Can only be done from a higher elevation to a lower elevation => So you want to avoid potential energy that com from gravity. OK, so I teleport an air-filled balloon under the ocean. It have also some kind of potential energy, as it will go up until it reach the surface, creating energy from nowhere. – Kepotx Apr 17 '18 at 13:50
• Give it an energy cost greater than would be gained by (ab)using it. – Separatrix Apr 17 '18 at 13:56
• I'd say go with cort suggestion and make mana another form of energy or make the spell casting consume work (in that case the range problem is probably self handled by a nice mage ice statue after a long rang teleport) – Sefa Apr 17 '18 at 14:26

Larry Niven wrote an essay on the consequences of various rules for teleportation. I think it would be worthwhile to read it. The title is something along the lines of The Theory and Practice of Teleportation, I think I first read it in "All the Myriad Ways." Edit: He explores limiting teleportation to short range, long range, cheap to use or expensive to use, both scientifically and briefly the consequences on society. Most germane, I recall he discusses the problem of energy gain or loss. A solution I recall was storage of the excess or deficit energy (as I recall, using it to move water in & out of storage tanks). This could be adapted to magic, possibly with the teleport spell freezing up if the magic storage capacity was full or empty.

• Welcome to WorldBuilding.SE! Answers that reference existing material are fine, as long as they summarise the content from that material, and are able to stand alone as answers in their own right. Currently, I don't believe your answer fits that criteria. Could you add in a summary of Niven's rules, and how they would help the OP with his problem? – F1Krazy Apr 17 '18 at 15:00
• Here is a link to the article: e-reading.club/chapter.php/75689/7/… – AndyD273 Apr 17 '18 at 15:21

The teleportation spell converts "mana" energy into the potential, kinetic and compression energy needed for the teleported mass to achieve equilibrium with the target destination. If the target requires LESS energy, the remainder is converted to wild mana, heat or radiation that is released at either or both ends.

In this scenario, mana is some kind of low-entropy energy that allows mages to manipulate other systems. The entropy is what makes the spell irreversible. Mages can't recharge their powers by teleporting down a few floors, as the energy returned is more chaotic (or in scientific terms: KABOOM!).

Teleportation to unknown or far away destinations would be quite hazardous in this system, as it might take all of your mana (and leave you stranded halfway) or cause a giant explosion. For short range travel, mages would likely establish a list of favorite destinations and memorize the energy requirements from a range of altitudes and distances. Included in those budgets would be the mana cost of protection against the waste heat.

For longer range travel, specially prepared teleport rooms would be necessary, equipped with either a mana focus or energy dissipation mechanisms, depending on the destination. Personal protection for the travelers is also recommended.

A downside of this would be the potential for destruction by suicide attack.

To avoid infinite-range-catapult magic, add the condition that momentum changes cost energy too. Unlike energy, changing it is always a cost. On an earth-like world (i.e. a spinning globe) that means momentum differences increase with distance because the angle changes. Teleporting to the opposite side of the planet would mean reversing the momentum completely, costing a prohibitive amount of mana. And no, you don't get hypersonic rocks that way, as the teleport won't work unless the object ends up "at rest" relative to the destination. Something about reintegration failing when moving too fast.

• That seems like in this system there is no reason to not be waging war by teleporting rocks. – SpaceMouse Apr 17 '18 at 14:13
• @SpaceMouse Teleporting them high up costs a lot of mana, not much better than the classic Fireball. Teleporting them down costs a lot of mages as they suffer the backlash. – Cyrus Apr 17 '18 at 14:22
• @Cyrus You could make a nice plot device out of a spell variation (or artefact or whatever) that causes the excess energy to only be released on one side. – cube Apr 17 '18 at 14:34
• @Cyrus you misunderstand; you build a road up a mountain. And proceed to teleport rocks from the top of the mountain down to a city you want to attack. It might not work: at 4km of delta-altitude, the rock is 100x less explosive than TNT. Might just warm the rock up. However, you could just teleport the rocks 4 km above the target city and drop them for 0 mana. – Yakk Apr 17 '18 at 15:08
• That is true. It doesn't provide for infinite energy though, as the potential energy has been added through carrying those rocks all the way up the mountain. Disallowing rock-dropping warfare is not part of the question actually, but I will address it. – Cyrus Apr 17 '18 at 15:16

Infinite energy is only an issue if your system does not address it.

The most obvious solution is to make "mana" be a form of energy, and casting a spell obeys the conservation of energy rules just like every other physical interaction. Problem solved.

If your mana must not be equatable to energy, for some reason, then you must either deal with infinite energy or ensure the spellcasting itself does not do any work (in the physics sense). One approach for this would be to create a portal which one can be "pushed through," doing all of the work required to maintain conservation of energy as the object passes through the portal. Or perhaps teleportation only supports movement to places with lower potential energy.

If that too is impossible, you have a connundrum. If your teleportation must be able to do things which cause work, but you need mana to not be a form of energy, then you're between a rock and a hard place.

One solution that I've played with is to make casting not be a guaranteed thing. Make it so that the mere act of casting fundamentally changes the teleportation spell itself whenever cast. Casting the teleportation spell in energy-creating situations might destabilize the spell, making it less castable. You can devise the mathematics behind it any way you please, but the general pattern would be "if you abuse it, you lose it." You make it so that there's only a finite amount of energy that can be created with teleportation spells at all before the fabric of spellcasting itself shifts such that teleportation can no longer occur. If you like your spellcasting abilities, you better not abuse them (and you better convince all those who share the spells with you to not abuse them either!)

• I guess I'm more specifically trying to figure out how to solve the conservation of energy rules with moving things from one place to another. Are the rules I put forward good enough? Is there any way to abuse this system? Or can it just be hand waived as "it can't create more potential energy"? – SpaceMouse Apr 17 '18 at 14:15
• Whether your rules are "good enough" depends on the context. If you're writing a "friendly" book where nobody tries to do anything tricksy, then you could be fine with just stating "magic can't create more potential energy." If you were writing rules for a game to be played by a bunch of min-maxing rules-lawering munchkins, then your rules wont even come close. For example, the first thing I'd be doing is exploiting magnetism. When you patch that, I'll move to electrostatics. In that kind of an environment, it's better to explicitly include conservation in the spells – Cort Ammon Apr 18 '18 at 4:17

Just do a matter for matter swap instead of teleportation. You teleport a certain mass somewhere you replace it with an equivelent mass. This means you have to be careful how you teleport, as your mass in air would leave a big vacuüm and a nasty hit as the air rushes in. So you would have to partially teleport people into the ground so they can dig themselves out, or you allow the equivelent mass to be nearby but not necessarily on the location of the teleported thing.

Perhaps easier would be to have masses ready at the teleportation site. For example, each teleport site has a bunch of big rocks and sand on the edges. Each time you teleport, a part of the rocks and sand similar to your weight is teleported to your starting teleportpad in exchange for your mass. You can even have an economy on getting rocks and some types of sand to the teleporter to keep it running if it has to accept more teleports than it has to send, while a teleport that sends a lot of people needs to constantly haul Stones and sand away to prevent it being burried.

• Or, for an interesting variation. Have statues of people which you can swap with (presumably hollowed out to fit the mass-profile of a person) One imagines a scenario under which a target statue would be carefully prepared beforehand by filling it with sand to particular weights. With some form of magical focus which the teleporting individual can use as a target for the spell. – Ruadhan Apr 17 '18 at 14:42

I would add another component: teleported objects should arrive at their destination with zero velocity, related to the ground they will be landing on.

This is assumed in most magical systems, such as teleportation in DC or Marvel comics, or in RPG's like Dungeons & Dragons. However, this is taken into account in games such as Portal and in worlds such as the Discworld. Teleportation is usually lethal in the latter due to that.

This will prevent abuse of thermo's second where something would shoot out of the lower gate (due to momentum) just to fall back up inside the upper gate.

If teleportation does not involve gates/portals, though, then you should already be fine.

You might get some good ideas by reading Vernor Vinge's The Witling. It's nominally SF, but its set on a world where the aliens can teleport, but only as long as the teleport obeys physical laws.

Vinge is a very good writer and also thought through the implications of non-law-breaking teleportation very carefully. In fact, much of the tension in the story arises from teleportation's non-violation of the laws of conservation of energy and momentum.

So the aliens can teleport between hemispheres, but if they jump too far nearby, they hit the ground (or fly off into the sky) due to the relative velocity difference of their starting point and ending point. They are an old civilization and have chains of artificial lakes all over the planet and jump (in a boat) from one to another, letting the water cushion and dissipate their relative velocities.

They can jump uphill and downhiil because they exchange equal masses to keep the potential energy due to gravity constant -- failing to do this can hurt them badly.

They kill with their minds, teleporting a bit of their opponent's body or brain. (They can shield themselves from the effect.)

Again, read the book. Vinge has done a lot of thinking about what a society of teleports would be like.

• This answer would be improved by describing the laws. – Yakk Apr 17 '18 at 15:09