I did read that some scientists think that bringing a ship powered by an Alcubierre drive out of warp would kill all of the life in the star system you were arriving in. So it might be a one way trip.
What I want to know is how this works with the Causality Principle. No, the ship doesn't move FTL, it warps space around it... but theoretically you could travel to a star 50 light years away, see what's going on, FTL back and beat the light from the star, thus violating causality. Would love to know if that therefore invalidates the causality principle or how it all works together.
Might punt it over to StarTalk Radio and hope NdGT answers it.
The warp drive works by cheating the laws of physics without actually breaking them and travelling faster then light. It treats space like a ship sitting on a tablecloth, space in front of the ship is compressed dragging it forwards whilst space behind the ship is expanded, pushing it along. As you do this tug and push motion, the ship inches along from one point of the cloth to another. The ship itself exists in a "warp bubble" of unaffected space that doesn't move to prevent A) The crew being slammed against the bulkheads and turned into a bloodied paste along the walls at the sudden excessive G-Forces of conventional FTL speeds and B) Debris is warped around the bubble preventing even a small speck of dust from impacting the ship's hull releasing vast amounts of energy and causing a catastrophic impact. Also, because the space around the ship is moving but the ship itself isn't, it is therefore not breaking the fundamental speed limit of the universe because it isn't actually moving and thus complies with the laws of physics.
Of course no-one has actually built a warp drive yet and there are still problems like radiation shielding, power supply (that could make the latter problem worse) impulse drives for low speed manoeuvres and finding ways to make sure the crew don't kill each other once they realise how isolated they are to overcome. Along with would it actually work in the first place.
We talk about these laws like they are government laws, and how to evade (or avoid) them. According to Albert, it just cannot be done rather than we need to cheat them.
I'm not saying all of this isn't possible still!
What you could do with that information, I don't know, but it would violate the principle AFAIK.
EDIT: similar to discussions of instantaneous communications: http://www.askamathematician.com/201...ate-causality/
Last edited by sonofsanta; 12th June 2014 at 09:54 AM.
This post is a better exploration of the issue, actually (just reading through it now): Q: Hyperspace, warp drives, and faster than light travel: why not? | Ask a Mathematician / Ask a Physicist
In short: FTL travel gets complicated because of frames, lightlike, timelike and spacelike separation, and allows you to travel back in time which is really messy and shouldn't be able to happen (by going somewhere FTL then coming back again FTL, you skip back in time).
Most of this is over my head, mind you. I know enough to ask the question and not enough to understand any answer
Say you’ve got the Enterprise (NCC-1701) and it works just like you’d expect: it cruises around at sub-light speeds until it engages its warp drive, which allows it to move at FTL speeds. It moves from one star system to another, then eventually disengages the drive and “drops out of warp”, no harm no foul. However! When viewed from a different frame, the same situation can be very strange.
The engage and disengage events are spacelike separated, so they don’t actually have an order. From (any one of) the proper frames, the disengage event can happen first (right half of the image above). When that’s the case you find that:
-First there’s one ship, traveling slower than light.
-Then suddenly, and without cause of any kind, two new copies of the ship appear at a place some distance away. One is traveling faster than light, and the other is traveling slower. This event corresponds with the drive being shut down.
-The FTL version travels backward until it contacts the original ship, at which point they both disappear at the moment that the original engages its drive.
Now, sure, ships coming into existence and popping out again may seem bad enough, but the big problem is that FTL travel opens the door to backward time travel (forward is fine: you’re doing it now).
By taking a couple spacelike paths that end earlier than they started you can zig-zag back in time and find yourself in the same place you started, but earlier than the time when you originally left.
Last edited by sonofsanta; 12th June 2014 at 10:11 AM.
As for the HS2 garbage only reason that's happening/not happening is we don't blooming need it. Government should have stuck the billions into building a huge FTTP program to every home in the UK and then once up and running privatise it to recoup as much of the money as possible. We'd then have been the world leaders in connectivity and we wouldn't need HS2 ripping up the countryside and devaluing peoples homes etc because it would make home working much more feasible. In fact you could have diversified call centres with people logging in from home to take calls reducing companies overheads and making it much easier for people with disabilities to work.
But what the hell do I know i'm just a schmuck that pays their taxes...
Last edited by Bananas; 12th June 2014 at 11:12 AM.
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