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Re: starship-design: FTL

Steve VanDevender wrote:

> Even Alcubierre presented his idea in the context of general relativity,
> and I don't think even he claimed you can have FTL without causality
> violation.

It was indicated in many places, including his paper. Like you said, the
Lorentz contraction causes this, and alcubierre FTL eliminates this
since you are not travelling FTL, rather sitting stationary in a bubble
of warped spacetime that is moving FTL (which isn't forbode)

> Despite what you want to think, this simply says that FTL travel is not
> accepted in the context of current physics.  _Every_ FTL method that's
> been tossed around in the physics community depends on purely
> hypothetical, unobserved, unconstructable phenomena.

Thanks for saying current physics. It shows that some scientists are
willing to accept the possiblility that what is now considered
impossible may someday be possible. 

> The reason that you are an amateur, Kyle, is that you don't even
> understand the physical laws that you want to break.  I won't claim to
> fully understand relativity, but I've at least tried to learn about it.

I've tried on many occasions to ask questions, but all I get from people
are nasty comments. I am reading all I can on the subject.
>  > Why is this a
>  > drawback? Because negative energy density is forbidden by the Weak,
>  > Strong, and Dominant energy states of general relativity. Sorry guys,
>  > but physics failed again. Negative energy density is as real and true as
>  > any other type of energy density. It HAS BEEN PROVEN.
> Where has it been proven?  Show me a region of negative energy density
> sufficient to satisfy Alcubierre's requirements.

Casimir cavities. We don't yet have technology necessary to build such a
device. I don't think that it will be possible by 2050 anymore. Unless
we make contact with a civilization that is already travelling FTL...

>  > Unidirectional inertia is not impossible, we just don't know how to do
>  > it yet. What do you think an alcubierre drive is? I'd be very careful
>  > about calling scientists with odd or unproven ideas ignorant, as the
>  > Wright brothers were treated the same. And flight was physically
>  > impossible for humans! FTL is not impossible. I don't wish to argue, but
>  > merely have an exchange of ideas. I thought that was what science was
>  > about. Apparently not anymore.
> The Wright brothers knew that things could fly because people had seen
> things fly ever since there were people.  At the time machine-powered
> flight was considered impossible merely because of engineering
> limitations, which the Wright brothers overcame.  Flying faster than the
> speed of sound was exactly the same situation -- obviously not
> physically impossible (people had already made things other than manned
> aircraft travel faster than sound) but beyond what most considered the
> engineering capabilities of the time.
> The reason FTL is considered impossible is that it's not allowed by the
> laws of physics, and is therefore not an engineering limitation.
> Breaking the "light barrier" is nowhere near the same kind of problem as
> breaking the sound barrier.

>From what I understand, you can't 'break' the speed of light, but jump
past it theoretically.

> Science is about _critical_ exchange of ideas, not just accepting any
> random thoguhts that people have, ignorant or not.  Float a wrong idea,
> and everyone who thinks about it will tell you it's wrong, and why.
> Many more wrong ideas get sent around than right ideas, which is part of
> the process.  If your idea really is right, it will stand up to critical
> analysis and experimental verification.

Alcubierre's idea stood up to critical analysis. One day I'm confident
it will be tested experimentally. Unfortunately, I probably won't live
to see FTL come about. But perhaps I can still make some form of
contribution to science.

Kyle Mcallister