At first I thought he would be a quack, but his technical credential look legit. http://www.icarusinterstellar.org/team/harold-white/
I just wish he would explain a little better why this was an allowable violation of relativity.
I just wish he would explain a little better why this was an allowable violation of relativity.
The vast practical difficulties are in addition to the enormous theoretical challenges. I would absolutely love it if something like the Alcubierre drive could be made real, but there are multiple steps between here and there that would each deserve a Nobel prize. If I were White, I'd be talking about how I'd solved all of those problems (or any of them!) before jumping straight to trying to generate a warp bubble in the lab.
Why not try to generate a bubble, if it works great, otherwise try formalize it in greater detail. If warp bubbles are possible than it may be that they are already being created through random chance at the micro-level in the natural world.
Missing the part from the paragraph about having no idea how to generate that condition, although if it existed in the past it would presumably be "sorta stable" in fact it would never be able to shut off as presently understood.
A good analogy would be trying to talk to the original Lada Ada about silicon based computers without the folks of that era knowing enough solid state physics to contemplate whats going on in a simple transistor. "So if you could magically understand how to create a transistor, which won't happen for a century, then logically it follows that such and such array of those magic devices would make a great full adder circuit to add binary numbers"
Your link mentions that negative energy density has been observed at very small scale as a result of the Casimir effect. It's difficult to see how that could be scaled up, but I suspect that's what White is using here.
(wikipedia)
The thought experiment: imagine a billiard table with a wormhole which curves around and goes three seconds into the past. Roll a billiard ball into the wormhole such that it will emerge three seconds earlier and knock itself off the path, so it doesn't enter the wormhole.
Instead, the ball emerges along a slightly different path, striking itself merely a glancing blow that allows it to enter the wormhole.
And why did it emerge with an altered path? Because it was struck a glancing blow.
I can only imagine this kind of thing happening in a reversible, constant entropy system and a system without intentional processes.
For example, imagine a programmable drone. It is programmed to enter the singularity if and only if nothing seems to emerge and to then avoid collision with anything once it emerges - and transmit a signal announcing it's emergence to boot. Maybe you could do setup a fancy scenario for not winding up with two (or no) drones at the "end". But things not longer seem very plausible.
And you could probably arrange for a thing to carry entropy backwards if you had a varying entropy a system. But that's left as an "exercise for the reader".
Why does it do that? I get why the principle demands that it does and I get why it's a stable solution once it's been made to happen, but how did it actually make the jump from "straight on" to "at an angle"? Presumably not every self-consistent causal loop materializes itself out of thin air just because it would work if it did.
Edit: possibly lame example, but in Terminator 2, we find out that terminators were a secret government project that went awry. Where did they get the technology? Well, a terminator from the future came back and died in Terminator 1 and the parts it left behind allowed engineers to get a head start on building one. So there's a similarly self-consistent causal loop. But it doesn't really answer the question of how there came to be terminators.
The wiki entry I linked is intriguing. It says in some cases there are an infinite number of consistent solutions. They found they could analyze those cases with quantum mechanics, doing a sum-over-histories that only includes the consistent solutions. That gave a probability for each particular outcome.
So maybe that's fundamentally how causation actually works in the universe, and in the absence of time loops it reduces to normal causality. Now I can't help speculate whether actual quantum mechanics involves time loops somehow. (And in fact, Cramer's transactional interpretation does involve waves travelling backwards in time.)
Another way to look at it, maybe, and take with a grain of salt because I came up with it myself: Imagine there isn't just one timeline. In the paradox the universe runs an infinite loop, the ball first going into the wormhole, then not, then it does, then it doesn't. But given quantum mechanics, the position and momentum of the ball is uncertain. Given a very large number of trials, it's eventually going to shift significantly. At some point, it hits on a consistent solution, and the looping finally stops.
But, hey, I'd love to be wrong.
Are we sure space is perfectly elastic? What if space is infinitely plastic? Then when you turn the drive off, for all observable data you would be sitting in normal space just short of your destination.
Any object with mass warps spacetime towards itself. This doesn't cause an infinite buildup of 'spacetime' on the object's surface.
There are concerns with built up energy in front of the spaceship but not being sent back to your origin.