Alcubierre Drive and Time Travel

[Lorizael]

Yeah, our resident physicists aren't really in attendance anymore, but I'm gonna give this a whirl anyway.

So the general refrain is that any kind of FTL allows for time travel, which leads to causality violations (or perhaps it's the other way around!?), making baby Jean-Claude Van Damme cry. I'm not disputing this, but I do have a question. How would an Alcubierre drive (or some other space-warping type of FTL) enable time travel? That is, what is the precise series of events that leads from turning on the Alcubierre drive to killing your own grandfather?

Diagrams are encouraged. Videos with hand puppets are greatly encouraged.

Thanks.

[rah]

You really need to start school

[Lorizael]

I looked, but Maryland doesn't seem to offer a course in warp drive mechanics.

[AAAAAAAAH!]

1. Super fast travel allows us to reach the planet of immortal mountain wizards
2. Immortal mountain wizards teach us the black arts of time travel
3. We get revenge on our grandfathers for taking all the social security money

[Ben Kenobi]

So the general refrain is that any kind of FTL allows for time travel, which leads to causality violations (or perhaps it's the other way around!?), making baby Jean-Claude Van Damme cry. I'm not disputing this, but I do have a question. How would an Alcubierre drive (or some other space-warping type of FTL) enable time travel? That is, what is the precise series of events that leads from turning on the Alcubierre drive to killing your own grandfather?

Basically... You see time as something indistinct from space. Our normal experience leads us to conclude they have nothing in common. The problem is this.

Time really isn't distinct from space. This is something Einstein uncovered. You can test this out here on earth with a very accurate clock - clocks on a higher floor, over time, will lose time compared with clocks on a regular floor.

Extending this - in a sense everyone is already time travelling, it's just on a scale that we don't notice it. Things that we see are technically not as they are, because it takes time for us to see them. All motion, in a technical sense is time travelling.

What does this have to do with space curvature? Well - to take another step out - time is a part of space. This is very hard for us to understand. If you can curve space, you'll curve time as well, and distort it. We see this on very, very large scales, and it's hard for us to perceive it on smaller scales.

A space warping device would permit "time travel", in the sense that it would allow us to cut the distance between point a and point b.

The really wild thing is, - what if everything in space-time is actually accessible? Then, warping space time would allow us to travel to any point in four dimensions. In theory - it should work, but how one would go about curving space to this extent and whether all points on space time is accessible is something we don't know.

[Lorizael]

BK, remember how I've been studying physics for the last two years? I don't need a primer on relativity. I just need to know what you need to do with an Alcubierre drive in order to create a closed timelike curve. Pretty sure I said that in the OP.

[rah]

We are talking about BK here so you must lower your standards considerably or just ignore him.

[Ben Kenobi]

BK, remember how I've been studying physics for the last two years? I don't need a primer on relativity. I just need to know what you need to do with an Alcubierre drive in order to create a closed timelike curve. Pretty sure I said that in the OP.

What it does is create discontinuities in space time. You have a segment of flat spacetime surrounded by a bubble of negative mass. The bubble transports the object in flat spacetime, and permits it to achieve an acceleration without a moment of inertia associated with the acceleration.

Read up on Lorentz contraction and time dilation if you're not already familiar with it.

But, you weren't really interested in an answer, you were just being a dick.

[Ben Kenobi]

We are talking about BK here so you must lower your standards considerably or just ignore him.

Wow, great answer, rah. I'm sure that's a helpful post.

[rah]

Thanks, I had to make up for your post. (which Lori deemed useless)

[Ben Kenobi]

Thanks, I had to make up for your post. (which Lori deemed useless)

Meh, I'm a teacher. Unless otherwise specified I always assume that the person in question knows nothing. Also - Lori needs to work on General Relativity, which my post attempts to explain by starting with special relativity.

If he wants the equations and ****, then he needs to specify.

[OneFootInTheGrave]

Physics subforum

Actually makes sports into Physics and bring sports threads back here.

[Lorizael]

What it does is create discontinuities in space time. You have a segment of flat spacetime surrounded by a bubble of negative mass. The bubble transports the object in flat spacetime, and permits it to achieve an acceleration without a moment of inertia associated with the acceleration.

No. Alcubierre drives expand spacetime behind them and contract it in front of them, allowing the drive to take a ride with superluminally-traveling space, while still moving less than the speed of light from its own reference frame.

Read up on Lorentz contraction and time dilation if you're not already familiar with it.

I spent the last two semesters doing problem sets on Lorentz contraction and time dilation. I have no reason to read up on them.

But, you weren't really interested in an answer, you were just being a dick.

Yes, you caught me, BK. I created this thread hoping you would come along and give a dumb answer, allowing me to hurl abuse at you. You didn't disappoint.

[OneFootInTheGrave]

Is there any other reason why people post here?

[Lorizael]

Ugh, what am I doing? I really have to stop hitting View Post on BK's inanities. Okay, here we go: I will not view another BK post for the next six months (unless moderation duties require me to).