# Feasibility of a black-and-white FTL drive?

I have an idea for a faster-than-light spacecraft that I would like to run by the expert minds in this community for a plausibility check. Basically the interstellar ship itself is of unspecified dimensions (you can decide that bit) and its means of traveling to other star systems is this: it generates a small black hole and keeps it suspended a set distance in front of the ship (along the vessel's central axis) and it also generates a small white hole at the opposite end of the ship along the same axis. My working idea is that the ship gets propelled through space away from the white whole and towards the black hole simultaneously. Feel free to poke the idea full of holes (hehe) as I know it's kinda kookoo.

Not going to work.

1. You can’t lift yourself off the ground by pulling your own pants higher. The black hole pull runs into the same problem. Gravity pulls two things together... it doesn’t chain them along.

2. The white hole would just push you into the black hole faster because you’re closer to the white hole than the black hole is.

3. Gravity cannot accelerate anything to faster-than-light speeds. It’s a fundamental force and so bound by the speed limit of physics.

Only two known ways to move: push off against something or have something faster than you ram into you (really the same thing from different perspectives). And both ways are bound by C. The only known way to move faster than light is taking advantage of inflation of space itself, which is why you hear stories about warp drives. There are hypothetical designs out in the world, but nothing looks promising at this time.

The trick here is "generates".

Let us consider just one hole, to keep it simple. The ship generates a black hole in front of it and falls towards that hole.

There does not seem much prospect of bolting some sort of rig onto a real, wild black hole to hang it in front of you, like a carrot hung in front of a donkey. The event horizon and all. But your system does not require that. It generates the black hole out of... whatever.

Gravity works because matter changes the topography of space. If your generator could change the topography of space to mimic a black hole absent any matter, it would be the functional equivalent of a black hole. And you would not need to deal with the immense pesky amount of matter that comprises a black hole and which has a lot of inertia. It is hard to move truly massive thing.

Your black hole generator is a space warper and the warped space you are falling into has no mass, and so can ride along in front of you.

@Ryan_L is right: this is similar to an Alcubierre drive. There is a lot about those on this stack. Here is my take, including diagram I stole from someone showing humps of space.

Using magnetic fields to prevent a weaponized warp drive?

The first issue I see up front is how do you keep the black and white holes suspended "a set distance" from the front and back of the ship? You'll need some force to accelerate the holes, which doesn't seem to come from anywhere, since you're using the holes to accelerate the ship in the first place.

This would be like bolting a rig to the top of your car that has a strong attractive magnet at the front and a repellent one at the back. Sure, there will be some attraction/repulsion between the car and the magnets, but the apparatus as a whole won't go anywhere - you'd need an external force to constantly reposition the magnets in order to make the car move.

On a somewhat more fundamental level, the speed of light is the theoretical upper speed limit of our universe. You can't accelerate beyond c by just doing "more" acceleration - as you approach c, it takes progressively more and more energy to accelerate, to the point where accelerating to c would require an infinite amount of energy. Relativistic effects dominate when you approach c, you can't just keep your foot on the accelerator and cruise past it like you can when accelerating a car past 100mph. Any method that uses any form of conventional acceleration will never get you to c, much less beyond it.

Let me see if I got this right.

You want to conjure an object, have it contain enough mass and gravity to collapse on itself without dissipating, motivate it to move at FTL speed, drag your vessel along with it, then create an new repelling object, motivate that object to follow you at equal speeds, close enough to push you towards the dragging object, all the while keeping these objects perfectly aligned to make sure you are absolutely centered between them, then poof-begone these objects, while you remain, having arrived at your destination, while hopefully not having messed up the destination by moving a black hole and a white hole into their neighborhood at FTL speed?

I actually think it would be more feasible to invent warp-speed.