B Can Curved Spacetime Enable Faster-Than-Light Travel?

[Marcarious Thomas]

Based on the current understanding of general relativity, it is possible that curving spacetime in the back of a spacecraft would allow for faster-than-light travel. In general relativity, the curvature of spacetime is determined by the universe's distribution of matter and energy. If a propulsion system could create a very dense region of matter at the back of a spacecraft, wouldn't it possibly curve spacetime in a way that allows the spacecraft to travel through space faster than the speed of light, essentially "surfing" on a wave of distorted spacetime. This type of propulsion has some advantages over the Alcubierre drive in terms of energy requirements and does not involve the same degree of manipulation of the surrounding universe. What are your thoughts?

 

[mfb]

A dense region of matter at the back pulls the spacecraft backwards. It doesn't allow faster-than-light travel in any way.

 

[Vanadium 50]

I'm not getting the proposal.

You have a mass that curves spacetime - produces a gravitational force in older language, and that causes the spaceship to accelerate towards the mass. The spaceship then pushes the mass forward so it can keep accelerating forever.

I don't think that's going to work.

 

[Hornbein]

 

[PeterDonis]

Based on the current understanding of general relativity, it is possible that curving spacetime in the back of a spacecraft would allow for faster-than-light travel.

You speak as though there is a known solution of the Einstein Field Equation that has these properties. Can you give a reference?

If you are not aware of such a solution, then your post is personal speculation, which is off limits here at PF.

 

[Dale]

wouldn't it possibly curve spacetime in a way that allows the spacecraft to travel through space faster than the speed of light, essentially "surfing" on a wave of distorted spacetime. This type of propulsion has some advantages over the Alcubierre drive in terms of energy requirements

I also don’t think there is a known solution of the EFE with these properties. I also think a reference is in order.

 

[PeroK]

Based on the current understanding of general relativity, it is possible that curving spacetime in the back of a spacecraft would allow for faster-than-light travel. In general relativity, the curvature of spacetime is determined by the universe's distribution of matter and energy. If a propulsion system could create a very dense region of matter at the back of a spacecraft, wouldn't it possibly curve spacetime in a way that allows the spacecraft to travel through space faster than the speed of light, essentially "surfing" on a wave of distorted spacetime. This type of propulsion has some advantages over the Alcubierre drive in terms of energy requirements and does not involve the same degree of manipulation of the surrounding universe. What are your thoughts?

You could start your investigations here:

 

[nicm05]

Would it be possible to create more density in the rear of the craft while also lessening density in the front? Creating a push/pull propulsion system much like a water pump? Redistribution of mass would be important but is it achievable in space?

 

[Ibix]

Would it be possible to create more density in the rear of the craft while also lessening density in the front? Creating a push/pull propulsion system much like a water pump? Redistribution of mass would be important but is it achievable in space?

No. That's just moving stuff around your center of mass, which doesn't move. Unless you start throwing stuff out into space, of course, but that is just a rocket.

 

[nicm05]

No. That's just moving stuff around your center of mass, which doesn't move. Unless you start throwing stuff out into space, of course, but that is just a rocket.

What is being done with light and its momentum to use as propulsion? Everything I’ve read is older and the thread has died off

 

[Ibix]

What is being done with light and its momentum to use as propulsion? Everything I’ve read is older and the thread has died off

As a rocket it's very mass efficient but extremely low acceleration. Solar sails have been deployed, though.

 

[Alien101]

Based on the current understanding of general relativity, it is possible that curving spacetime in the back of a spacecraft would allow for faster-than-light travel. In general relativity, the curvature of spacetime is determined by the universe's distribution of matter and energy. If a propulsion system could create a very dense region of matter at the back of a spacecraft, wouldn't it possibly curve spacetime in a way that allows the spacecraft to travel through space faster than the speed of light, essentially "surfing" on a wave of distorted spacetime. This type of propulsion has some advantages over the Alcubierre drive in terms of energy requirements and does not involve the same degree of manipulation of the surrounding universe. What are your thoughts?

The core problem is no matter how you curve spacetime, you cannot make anything travel faster than light locally.Einstein's theory has a built-in speed limit that applies to all matter and energy moving through spacetime, regardless of curvature.

What Actually Happens? When you create dense matter behind a spacecraft, you're essentially creating a gravitational field. This does curve spacetime, but the spacecraft still follows geodesics (the straightest possible paths through curved spacetime). Locally, it never exceeds the speed of light, you've basically built a very inefficient gravitational slingshot.

 

[physics2222]

Not sure but I think the OP is referring to generating negative curvature behind the craft to push it. This would need some negative energy density. At least this is similar to the "Alcubierre drive."