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submitted 8 months ago by [email protected] to c/[email protected]

In Portal, using the portal gun to get to the moon is the obvious space travel usage, but I think people are overlooking how it'd let you trivially break the rocket equation.

Hell, you could build a >1g torchship using nothing but the ocean.

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[-] [email protected] 1 points 8 months ago

I'd do the math on how much thrust you'd get out of sticking one portal at the bottom of the Mariana Trench and the other in a ship, but I think it'd maybe be slightly tricky because you've got yourself an inertialess thruster right there, which is slightly illegal according to physics.

The Einstein cops are gonna show up and impound your spaceship

[-] [email protected] 1 points 8 months ago

And that's just thinking about a static arrangement of portals. You could also use a dynamic arrangement where you use gravity to accelerate mass to arbitrarily high speeds and then fling it out the back

[-] [email protected] 1 points 8 months ago

If you could make portals bigger you could also have a fun setup where you build your spaceship and then just let gravity accelerate it though a portal-loop.
You get going as fast as you want, then just swap the portals so you're now aimed at Mars.

[-] [email protected] 1 points 8 months ago

@[email protected] I get the feeling it would be amazing for some fraction of a second before either:
Relativity smacked you in the face
Friction did it's thing
Physics gets angry and stops the earths rotation around the sun
Or
The people running this simulated universe turn it off and patch that bug before starting over.

[-] [email protected] 1 points 8 months ago

@[email protected] thread a rope with a weight through two vertical portals so the rope is pulled through infinitely as the weight drops.

Now you have infinite rotational energy to run a generator and the thermodynamics police are definitely going to break down your door

[-] [email protected] 1 points 8 months ago

Anyway the lazy, boring way to use a portal and pretend you aren't violating a bunch of physical laws is to just use it for fuel transport.
You have a bunch of fuel on the ground, a tiny tank on your rocket, and you keep topping off the rocket's tank by piping in the fuel.

[-] [email protected] 1 points 8 months ago

BTW, as a variant on the kzinti lesson, the portals are extremely dangerous as a weapon, because of how good they are as a weapon.

Ignoring the obvious ways to fight with them like opening a portal on the enemy's hull, shoving out a nuke and then closing the portal...

You could also just have a rock that you're letting accelerate to arbitrary speeds in a vacuum. That's free unbounded kinetic energy, the only limitation being the "charge" time.

[-] [email protected] 1 points 8 months ago

@[email protected] there are no unarmed spaceships

[-] [email protected] 1 points 8 months ago

@[email protected] I recall Peter F. Hamilton doing just that in one of his books. The nuke part at least. Not sure about the space rock yeeting.

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[-] [email protected] 1 points 8 months ago

@[email protected] The Pierson's Puppeteers did this to fuel probes in Ringworld. The only difference was their technology required a physical teleportation device to be placed at the destination instead of just opening a portal anywhere, & transmission was limited to the speed of light.

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[-] [email protected] 1 points 8 months ago

@[email protected] This is (spoilers!) one of the weaponizations of space magic in The Paranoid Mage indeed.

[-] [email protected] 1 points 8 months ago

@[email protected]

I think - I am a physicist but not a rocket engineer - that a portal wouldn't propel anything.

Putting a portal on the underside of the spaceship and another in the deep ocean just makes the two of those places adjacent. The water would spray into space (and probably immediately freeze) but the reaction force wouldn't be on the ship: there's no water pushing back against it, after all. If there's any reaction force it would be against the ocean.

[-] [email protected] 1 points 8 months ago

@[email protected] That raises a question: Are portals subject to reaction forces? If not, a deflector would still be required and solid 'fuel' may be less usable.

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this post was submitted on 16 Jan 2024
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