The Alcubierre drive and Gravitational waves (Not a disscussion of them)

[SurrealShock]

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Edited April 25 by SurrealShock

[K^2]

11 hours ago, magnemoe said:

How hard would it be to make an slower than light Alcubierre drive? 
Would you escape many of the impossible requirements for the FTL one? 

Sub-light Alcubierre is just as bad as an FTL one. But that has to do with certain features of Alcubierre metric that aren't necessarily general to all Warp Drives.

In theory, if your drive is not capable of exceeding light speed, then energy conditions are not violated. So as far as we know, that means negative energy densities are not strictly required. But all that says is that there may be a configuration that allows for sub-light warp. I am not aware of any known configurations that would satisfy that, and I don't know if anyone is even seriously looking for one.

If we do find a configuration that works, and if it happens to have similar energy requirements to Alcubierre, which scale with the speed of the bubble, then a 0.1c warp ship could actually be feasible based on technology we either have or can conceive of. This really isn't saying much, but we're really early in our attempts to understand warp drives and whether or not they are feasible.

[PB666]

12 hours ago, magnemoe said:

How hard would it be to make an slower than light Alcubierre drive? 
Would you escape many of the impossible requirements for the FTL one? 

Slower than light warp drive, easy, just fly strait into earth, Earth warps space you need a differential between whats in front of you and whats behind, ta-dah

If everyone who wanted warp drive just did that simple test, the warp problem would be solved, or at least we would not be hearing about it.

[magnemoe]

2 hours ago, K^2 said:

Sub-light Alcubierre is just as bad as an FTL one. But that has to do with certain features of Alcubierre metric that aren't necessarily general to all Warp Drives.

In theory, if your drive is not capable of exceeding light speed, then energy conditions are not violated. So as far as we know, that means negative energy densities are not strictly required. But all that says is that there may be a configuration that allows for sub-light warp. I am not aware of any known configurations that would satisfy that, and I don't know if anyone is even seriously looking for one.

If we do find a configuration that works, and if it happens to have similar energy requirements to Alcubierre, which scale with the speed of the bubble, then a 0.1c warp ship could actually be feasible based on technology we either have or can conceive of. This really isn't saying much, but we're really early in our attempts to understand warp drives and whether or not they are feasible.

Ok, it was an earlier discussion here about it  about the sub light one did not require negative energy. 

[Spaceception]

18 hours ago, SurrealShock said:

We all know how reliable physical time warp is with large ships in KSP. (Sarcasm) Just imagine if we messed with the laws of physics in the real world. 

We'll open up a dimension to the Kerbals, which I wouldn't mind, they could take us to the Stars

[rtxoff]

We don't need an Alcubierre drive to reach relativistic speeds. There are a few already known technologies to do that.

[magnemoe]

6 hours ago, gpisic said:

We don't need an Alcubierre drive to reach relativistic speeds. There are a few already known technologies to do that.

Antimatter or laser pumped solar sails to be accurate. 
Yes particle accelerators do this but only for atoms, fusion and other engines are unpractical past 0.05-0.1c 

[kerbiloid]

On 16.12.2015 at 2:49 PM, SomeGuy123 said:

Why is it impossible?  Remember the Von Neumann thread?  Assume Von Neumann machines are possible, for the sake of argument.  

Well, if true FTL travel is possible and there's no upper limit (standard for sci fi, it varies from mere hyperdrives to engines that can cross between galaxies in a few hours), you could build a von neumann machine that ate the universe in a few years.  Since the universe appears to be uneaten, but von neumann appear to be possible, the most likely explanation is that either

        1.  FTL travel that doesn't involve at least a slower than light startup phase is impossible.  For example, it would be possible still if it involved wormholes but you can only move a wormhole mouth slower than light.

       2.  It caps out with a hard cap relatively close to the speed of light, with infinite energy needed to go faster.  (10x faster or something, this was how it was limited in Star Trek though warp 9 was absurdly quick)

"Since the universe appears to be uneaten".
Does it? Or the whole Universe already does appear to be a von Neumann machine? (And a BigBang was it's splash screen on startup after eating all pre-Universe)?

Btw about "no information/no energy can be transferred with velocity > 1 c".
Imagine there is another part of the Universe far far away, > 13 billions l.y., i.e. unaccessible for us due to the lightspeed limit.

Do you have any information about it? No.
Can you deliver some information from there to here? No - until its light/gravity/other 1c waves reach us.

What do you know about it? Nothing except "it can be or can not be".
So, you already know that a bit question is defined for that sub-Universe.
I.e. you by default have one bit of information about it: "its appearance can be a binary question about its existence".

So, "bit" idea is defined for it.
So, "coordinates" idea is defined for it.
So, binary linear algebra is defined for it.
So, you can develop mathematical basis for it.

So, you can get much information about the beyond-lightspeed region much faster than a lightwave can reach it.

As delta-information = minus delta-entropy (by definition), that means you can transfer not only information, but to match entropy state of both sub-Universes beyond the lightspeed.
As you are an observer, and just have determined the current state of that sub-Universe, this means you have effected its state due to Indeterminancy Principle.

Conclusion. Universe is von Neuman machine, mathematicians are magicians, lightspeed limit is just a postulate defining the range of applicability of the relativistic theory, but not a Total Cutoff.

[fredinno]

On 2/13/2016 at 10:17 AM, Spaceception said:

Actually, a special type of 'road' is needed because it uses superconductors and magnets to work.

But lets get back on track now.

Exactly, that's what I meant.

19 hours ago, Spaceception said:

We'll open up a dimension to the Kerbals, which I wouldn't mind, they could take us to the Stars

The Kerbal's can't go to the stars, their Universe is a single star system.

[Spaceception]

5 hours ago, fredinno said:

Exactly, that's what I meant.

The Kerbal's can't go to the stars, their Universe is a single star system.

Not if you get mods!

[Nothalogh]

On 12/16/2015 at 1:57 AM, Bill Phil said:

It's probably possible, but impractical for small vessels. And it may very well cause an Event Horizon like scenario. So... Do you really want it?

My favorite movie 

[magnemoe]

14 hours ago, fredinno said:

The Kerbal's can't go to the stars, their Universe is a single star system.

Such an horrible fate for an species who invented the asparagus staged orion nuclear pulse rocket.