“First, you get the money, then you get the power, and then you get the women.” Tony Montana Scarface.
For Warp drive. First, we get the math, then we get the physics and then we get the warp drive.
We not have all of the math and the physics but there has been progress on getting a better mathematical understanding of the physics of warping space and understanding how to possibly create warp drives.
There has been progress made on the math and physics of the warping space. In 1994, Miguel Alcubierre found a way to make them work in General Relativity. It is called the Alcubierre Drive. The idea was you contract space-time in front of you and expand it behind you, which moves you forward. There were still huge problems and it has barely moved from hand waving concept to mathematical hand waving. The amount of energy needed was like converting the mass of Jupiter into negative energy and concepts did not actually describe acceleration.
There have been experiments and efforts to try to make warping space into engineerable problems. However, new work mathematically defines mechanism for acceleration.
Problems with Alcubierre Drive: it requires negative energy (which we have never made and do not know for sure if it exists). Second, it requires a huge amount of that. Third, the energy is not conserved. Instead, what you actually do when you write down the Alcubierre space-time, is that you just assume you have something that accelerates it beyond the speed of light barrier. That it’s beyond the barrier is why you need negative energies. And that it accelerates is why you need to feed energy into the system. Please check the info below the video for a technical comment about just what I mean by “energy conservation” here.
The new paper is titled “Introducing Physical Warp Drives” and was written by Alexey Bobrick and Gianni Martire.
Bobrick and Martire describe the geometry of a general warp-drive space time. The warp-drive geometry is basically a bubble. It has an inside region, which they call the “passenger area”. In the passenger area, space-time is flat, so there are no gravitational forces. Then the warp drive has a wall of some sort of material that surrounds the passenger area. And then it has an outside region. This outside region has the gravitational field of the warp-drive itself, but the gravitational field falls off and in the far distance one has normal, flat space-time. This is important so you can embed this solution into our actual universe.
What makes this fairly general construction a warp drive is that the passage of time inside of the passenger area can be different from that outside of it. That’s what you need if you have normal objects, like your warp drive passengers, and want to move them faster than the speed of light. You cannot break the speed of light barrier for the passengers themselves relative to space-time. So instead, you keep them moving normally in the bubble, but then you move the bubble itself superluminally.
As I explained earlier, the relevant question is then, what does the wall of the passenger area have to be made of? Is this a physically possible distribution of mass and energy? Bobrick and Martire explain that if you want superluminal motion, you need negative energy densities. If you want acceleration, you need to feed energy and momentum into the system. And the only reason the Alcubierre Drive moves faster than the speed of light is that one simply assumed it does.
The new paper advances toward understanding how to improve the math. There are still gaps to getting the first warping of space.
SOURCES – backreaction – Sabine Hossenfelder
Written By Brian Wang, Nextbigfuture.com