
Warp Drive May Be More Feasible Than Thought, Scientists Say - mtgx
http://news.yahoo.com/warp-drive-may-more-feasible-thought-scientists-161301109.html
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nostromo
This appears to be the original paper:
[http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2011001...](http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110015936_2011016932.pdf)
and follow up: [http://www.icarusinterstellar.org/daydreaming-beyond-the-
sol...](http://www.icarusinterstellar.org/daydreaming-beyond-the-solar-system-
with-warp-field-mechanics/)

~~~
mvzink
Another reminder of the internet's awesomeness: browse through the comments on
the followup to see the original author answering reader questions.

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nessus42
You can't have faster than light travel without violations of causality. And
while the equations of General Relatively allow for universes where causality
is routinely violated, the probability that we are in such a universe seems
vanishingly small. E.g., just because you can violate causality does not mean
that you can go back in time and kill your grandfather. If you were to try,
something _would_ stop you, as a universe in which you kill your own
grandfather is _not_ consistent with General Relativity.

A universe that gives you the means to go back in time and try to kill your
grandfather, but then somehow always thwarts you, would be a very strange
universe indeed.

Edit: To whoever down-voted me, have _you_ taken any classes on General
Relativity? I have.

In any case this is from Wikipedia:

 _Causality is not required by special or general relativity[citation needed],
but is nonetheless generally considered a basic property of the universe that
cannot be sensibly dispensed with. Because of this, most physicists[who?]
expect that quantum gravity effects will preclude this option.[citation
needed] An alternative is to conjecture that, while time travel is possible,
it never leads to paradoxes; this is the Novikov self-consistency principle._

The "Novikov self-consistency principle" is the the one that states that you
could try to create a time paradox, but that you would never be able to
succeed. I.e., the universe would be a very strange place!

~~~
jxcole
A lot of people responding to this thread do not understand relativity. The OP
is correct, the fundamental problem is causality, relativity and FTL do not
mix. The common way of saying it is that you can have two of the three: FTL,
causality, or relativity. You cannot have all three. Here is a very nice
explanation of why:

[http://thebestforumever.com/community/threads/tachyon-
pistol...](http://thebestforumever.com/community/threads/tachyon-pistol-duel-
thought-experiment.47326/)

Also, I've never understood how the Novikov self-consistency principle would
work in reality. Causality violations can be a lot simpler than killing your
grandfather. Say, for example, you set up a pool table with a pool ball and
hit it through a time machine such that it went back in time and hit itself,
making it miss the time machine? Would the pool ball be suddenly acted on by
some invisible force? Would it explode? Would the universe just end? The whole
scenario seems so implausible that addressing this theoretical concern is a
lot more relevant than worrying about the energy levels required to manipulate
space time.

~~~
bluekeybox
The link had a really interesting but unsatisfactory explanation, IMO. The way
I am understanding it is as follows: Man A and Man B are traveling (with
combined speed of 0.866c) away from each other. Because of time dilation, to A
it appears that B's clock is twice slower (1/sqrt(1 - 0.866^2) == 2). Then A
shoots from some sort of weird space gun whose bullet is instantaneous. The
bullet passes B at 4 seconds (relative to B). B notices that and shoots back,
and B's bullet, due to equivalent effect hits A at 6 seconds causing a dead
grandfather paradox.

However what I don't understand is this -- to say that the bullet shot by A
passes B at 4 seconds presumes that we are talking about A's frame of
reference (because it is from A's point of view that B is 4 seconds "behind"
-- and likewise A is 4 seconds behind from B's perspective). However, what if,
from B's frame of reference, A's bullet actually passes B at 0 seconds?

~~~
bluekeybox
For anyone reading this, the referenced explanation finally did make sense
after I drew a Minkowski diagram of the two duelists. I guess this means that
I finally understood special relativity... Brief summary: FTL would indeed
violate causality, unless a special frame of reference is proposed (this
violates special relativity) or a specific new property of Universe is
established such that it would prevent certain events from occurring (aka
Novikov conjecture) -- and we don't have evidence for any of the two being
true.

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CWIZO
As much as it pains me to say this, but I think we have to invent some more
advanced weapons before we start poking our heads out of our galaxy. Don't get
me wrong, this is fantastic and I'm all tingly from excitement (this is the
first time I've read about warp drives in the context of real science) ... but
like I said, taking a stroll trough the galaxy with our bombs and finding a
hostile alien world. Well we'd be screwed.

Just food for though here; this is from the Halo universe, where the timeline
goes something like this: humans invent "warp drives", they colonize other
worlds, soon this colonies start to rebel which leads to a massive space civil
war. Later the aliens arrive and set to destroy all of humanity. Now, if it
waren't for the civil war, humans would have no experience in space combat,
and they wouldn't have developed more advance weapons which would later
allowed them to defeat the alien threat.

~~~
Ygg2
Seeing how if we use our warp drives to 'colonize' space, other creatures
would have far more to fear from us than we from them (think Independence day
with roles reversed). If a space faring species encounters non-space faring
species, the one with warp is probably (not necessary) in the better position.
Even without the weapons, FTL drive implies a magnitudes greater technology
than anything a non-FTL race would have. In fact atm we might be the most
dangerous creature out there, so in future (if we get that far) I probably see
human species branching out into several subspecies and then waging endless
war against each other.

Halo is a work of fiction, not a real life based drama. We'll probably be
lucky if we find anything more interesting than a microbe. First encounter
will probably be more like Solaris than Halo. We'll most likely find an
organism that we can't even perceive as one.

So no, we don't need guns in space. Best weapon in space is Newton's second
law (i.e. Kinetic bombardment). Cheap and easy to set up, hard to defend if
your target is in a gravitation well.

~~~
nullc
> If a space faring species encounters non-space faring species, the one with
> warp is probably (not necessary) in the better position.

I read a fun science fiction novella once about a interstellar space faring
species that invented their warpdrive whatchamacallit before their industrial
revolution, no electricity, machines, etc. Flying medieval space galleons. And
they were going about successfully conquering a bunch of similar or more
primitive species. Then they encountered 20th century earth...

Wish I could remember the darn name.

~~~
jloughry
'The Road Not Taken' by Harry Turtledove.

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outworlder
> An Alcubierre warp drive would involve a football-shape spacecraft attached
> to a large ring encircling it.

Obligatory Star Trek reference.

This seems close enough: [http://www.ex-astris-scientia.org/schematics/surak-
timur-niv...](http://www.ex-astris-scientia.org/schematics/surak-timur-
nivar.jpg)

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olalonde
If this is really possible, it should increase the probability of having been
contacted by advanced extraterrestrial civilizations. Maybe we're really alone
after all :( <http://en.wikipedia.org/wiki/Fermi_paradox>

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johnnymonster
How about we first build a space ship that travels anywhere near the speed of
light?

~~~
goldfeld
I assume travelling near speed of light with conventional physics is
impossible, since the ship's mass would crush itself as it increased
infinitely.

Warp drives, on the other hand, seem to work by moving space-time, not the
ship. So in theory the ship is left intact, without the people inside feeling
any acceleration whatsoever.

~~~
palmtree3000
I'm fairly certain that wouldn't be an issue. Relativity means that any (let's
say non-accelerating, to keep us within the context of special relativity)
reference frame is just as good as another. In the spacecraft's reference
frame, it's chilling out, and a bunch of stars off a ways are moving really
fast, but they don't really affect it.

It is an interesting problem though; I'm not really sure why it can't crush
itself...

~~~
spullara
Aside from the light from stars directly in front of them that becomes hard
gamma rays at high speeds.

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gotrythis
I skimmed through the responses, which seemed to be all about the execution,
with little or no discussion or debate questioning if this is a good thing or
not.

Even more than the idea excites me, I hope this fails miserably. We're at the
Avatar stage of our evolution, not Star Trek.

I think this says it best: (no affiliation)
[http://www.facebook.com/ResurrectingtheGoddess/posts/3960760...](http://www.facebook.com/ResurrectingtheGoddess/posts/396076033792108)

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dholowiski
Exotic matter = Magic?

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jayfuerstenberg
At this point I'd settle for impulse and artificial gravity. That should be
most of what is needed to get people to Mars and the moon.

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Rickasaurus
Why, I always get my science from Yahoo news.

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jstalin
Engage.

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cryptoz
> The only problem is, previous studies estimated the warp drive would require
> a minimum amount of energy about equal to the mass-energy of the planet
> Jupiter.

Uh, no. The "only problem" is that the concept relies on exotic matter, a
hypothetical matter with 0 evidence for its existence (so far). See
<http://en.wikipedia.org/wiki/Exotic_matter>

~~~
randallsquared
Well, the Casimir effect generates a tiny amount of negative energy, does it
not? Maybe that's how they think they can test it in the lab.

~~~
jerf
There are places in physics where "negative mass" can briefly appear, but as I
understand it, the quantity of such negative mass times the duration of the
negative mass is a constant... and a very, _very_ small constant to boot. It's
a balancing term in QM interactions, not something you're ever going to hold
in your hands.

As I like to say, assume one impossibility in physics, and it's not surprising
that you get other impossibilities as a result. Unfortunately, in practical
terms, requiring Jupiter sized amounts of stable negative mass and requiring
"Voyager" sized amounts of stable negative mass do not appear to be
appreciably different in difficulty, both being totally impossible.

I'd also point out that this article isn't even remotely unique. People have
been tweaking the Alcubierre equations ever since they came out. Nobody has
yet squeezed the "impossible" out of it, but each and every one of them has
been accompanied by, well, basically this exact article. I support people
trying to tweak them as a scientific Hail Mary, but I wish credulous science
writers would stop writing these stories as if moving from "impossible" to
"impossible" was some sort of huge step forward in practical terms.

~~~
lukevdp
I agree entirely. The journalist in this article is giving the impression that
this idea is more widely accepted than it actually is. It paints a picture of
scientists agreeing on this when in reality it's a person or small group of
people saying this.

At the same time, this kind of research is cool, and is an important part of
science. It's just misrepresented by publications.

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powertower
I don't understand how the warp-bubble would itself travel through space-time
faster than C (it's effects are inside of it), only that the space-craft
traveling through that warp-bubble would. But the space-craft is stationary /
in the center of it?

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heyrhett
Warp speed is only 1/10th the speed of light.

As far as some news about faster than light travel, refer to:
<http://xkcd.com/955/>

~~~
ChuckMcM
Well if you read the paper the effective speed is 10c, not .1c. They postulate
'boosting' the effective speed by contorting space-time around the craft, see
this quote in the paper:

 _"assume the spacecraft heads out towards Alpha Centauri and has a
conventional propulsion system capable of reaching 0.1c. The spacecraft
initiates a boost field with a value of 100 which acts on the initial velocity
resulting in an apparent speed of 10c. The spacecraft will make it to Alpha
Centauri in 0.43 years as measured by an earth observer and an observer in the
flat space-time volume encapsulated by the warp bubble. "_

~~~
rickmode
So if I understand right, the warping does not affect the "internal" speed of
the spaceship in relation of the universe outside of the warp bubble.

Maybe someone much better with maths and physics can answer this: will the
0.1c speed have a noticable relativistic age-slowing effect for the travelers
compared to their Earth-bound friends?

~~~
ChuckMcM
1.005 seconds vs the observer at rest [1] So 157 days on the ship (.43 years)
would be 158 days back at home.

[1] <http://www.wolframalpha.com/input/?i=time+dialation+at+.1c>

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acqq
Infinite Improbability Drive

[http://hitchhikers.wikia.com/wiki/Infinite_Improbability_Dri...](http://hitchhikers.wikia.com/wiki/Infinite_Improbability_Drive)

