Mark Atwood asks:
Do stargates conserve kinetic and/or gravitational potential energy? If I put half a pair on a planetary surface and the other a few lightsecs away, do I get to jump into steller orbit without paying for the climb out of the gravity well? If the other half is in orbit around said planet, do I get to jump into planetary orbit without having both pay for the climb out of the well and paying for accelerating to orbital velocity.
The numbers get even bigger, if not as immediately apparent, if one half is orbiting insystem 1 AU from the star, and the other half is outsystem in the inner oort of that same star.
And even bigger when one half is a few hundred ly coreward of the other. The gravity well of a galaxy is surprisingly steep, even this far out, when measured over ly distances.
And then there is conservation of the momentum vectors. Depending on what is conserved and how, putting a hole pair in opposite or right angle orbits around something could do… interesting things. Or else demonstrating some conservation laws between momentum and/or energy and/or hidden variables that we dont have or know in the current real world.
There is both a theoretical and a practical answer to that.
The theoretical answer to that is that they do, because, well, conservation of energy and conservation of momentum are the law, belike. Which can occasionally be bent, but never broken.
So in theory, a stargate jump, in conserving those things, will leave you in a great many awkward situations. If, for example, you were to gate from a planetary surface into orbit, you would absolutely not have orbital velocity, and as such would plummet rapidly to your doom. (Or, if you gated to an internal destination in orbit, slamming into the habitat hull at orbital velocity and being reduced to – extremely destructive – squishy pulp.) In a regular interstellar jump, you will arrive with the exact kinetic energy and momentum relative to the destination system that you had before you left (notwithstanding relevant GPE corrections, which are where it gets complex, although since most gates are at roughly similar depths in stellar gravity wells to a certain extent GPE can be traded for GPE); which is to say, with that of the origin system relative to the destination system included; which is in turn to say, going UNGODLY FAST in a VERY INCONVENIENT DIRECTION.
This is inconvenient, to say the least.
As such, the stargate system goes to a great deal of trouble to ensure that this is prevented from happening. With selective distortions of the shape of the wormhole’s space-time, it’s easy enough to correct this “intrinsic problem”, but conservation won’t be denied and the energy/momentum has to go somewhere. Fortunately, the exigencies of stargate construction mean that it has an entangled kernel, a nice high-mass (relatively, compared to anything likely to be jumped) Kerr-Newman black hole, right there. So in practice, while energy and momentum are conserved, the transaction it’s conserved within includes the gate singularities acting as a K-sink; excess (or deficient) energy/momentum is dumped into (taken from) the spin, etc., of the kernel to keep the books balanced.
(There are limits on how far this can go, in each direction – so there are occasional issues when a lot more traffic is going one way than the other. Most commonly, this is solved by having the stargate pair dial up its internal link when there’s no ship in transit and use it to swap spin between each end. Ultimately, if that won’t solve the problem, there are internal mechanisms that can be used to spin the kernel up or down, but those are energy-expensive, so they try not to use them much. Either way, unbalanced gates have occasional, periodic downtime while they recharge their K-sinks.)
…there are, of course, various clever tricks you can play with this kinetic compensation system, up to and including disabling it entirely, if you have the privileged-access codes for your blue box, but Ring Dynamics don’t give those out to just anybody.