Talk:Alcubierre drive/Archive 3

message: This is nonsense. Mass bends spacetime. Object would still be subject to relativistic effects. (unsigned 210.55.240.194)
:Providing more information than just disputing it is preferable. -- Cat chi? 15:38, 20 Mar 2005 (UTC)
replies: text: From the article conventional relativistic effects such as time dilation do not apply in the way they would in the case of a ship moving at high velocity through flat spacetime. From Alcubierre's paper Since coordinate time is also equal to the proper time of distant observers in the flat region, we conclude that the spaceship suffers no time dilation as it moves. This may be wrong, but it is what Alcubierre's theory says so the article is not wrong to state it.  If citeable sources have made this criticism then they can be mentioned. SpinningSpark 16:14, 8 June 2008 (UTC)
thread_title:  Cite your sources! 

message: I might be completely missing the point of the Alcubierre Drive, but what exactly does the second image  represent ? There are no labels or information telling us anything. Does it represent the distance that the space is contracted behind and in front of the ship, or something else ? There should at least be a descriptive caption (or an explanation in the text referring to this image). I await elucidation. :) Mpatel
:What second image?  I only see one image.  That image alleges to illustrate a characteristic effect of the Alcubierre style warp drives: the expansion tensor of the canonical ADM congruence, which is a timelike geodesic congruence, shows contraction ahead of the bubble and expansion behind.  This is not what causes the bubble to move (no cause or method for creating or controlling it is apparent), but only a description of how the bubble effects this particular family of nonspinning inertial observers.  Jose Notario has introduced another kind of warp drive spacetime which supresses this expansion/contraction effect.
---CH
:The second image (or diagram to be correct), in the 'maths of the Alc. drive' section, shows a 3D picture of a :sort of crest and trough of a wave - I assume it depicts some sort of contraction/expansion effect, but I'm not :sure.
:I think both topics, (Alcubierre Drive and metric) should be merged.--Mpatel 09:07, 24 Jun 2005 (UTC)
thread_title:  what does the second image mean? 

message: Hi all, I have just corrected a misconception and clarified the present status of 'Warp Drives' in the article on the Alcubierre metric.  Unfortunately, at present this article suffers from the same problems I pointed out for the earlier version of the Alcubierre metric article.  In addition, I think that the two articles on the same topic is redundant, so the two should be merged.  
Possibly instead of explaining the original warp drive in great detail, a slighly simpler version should be used?  (After all, the original paper is on-line.)  Some years ago, inspired by Broeck's paper, I did some work on simple eigenthing objections, similar to some which have now appeared in print, and wrestled with the energy requirement problem.  In fact, I wrote a long unpublished paper on the simpler versions I have in mind.  
Someone should add something about the Notario variant, which is expansionless and therefore significantly different from the Alcubierre drive and minor variants such as the one I considered.
And, the merged articles should be retitled warp drive spacetimes, since this term is now fairly standard in the small but slowly growing literature on warp drives.
---Chris Hillman
: The merger sounds like a good idea. ---Mpatel 09:07, 24 Jun 2005 (UTC)
thread_title:  Proposal to Merge This with Another Article 

message: ... (myself and Mpatel, both of whom voted to merge), but this message has been up for quite a while, so I'll announce that I intend to carry out the merger as soon as I get a chance.---CH  (talk) 01:39, 22 August 2005 (UTC)
thread_title:  Only two people voted so far... 

message: Wasn't such an idea used in Captain Future? I saw it in French and they were talking of vitesse|mode ondulatoire (undulating/waving speed|mode) —Reply to David Latapie 15:07, 16 October 2005 (UTC)
thread_title:  Captain Future? 

message: This sounds similar to the Soliton Wave technology described in episode 110, "New Ground", of Star Trek: Next Generation. --tvleavitt 06:42, 13 May 2006 (UTC)
thread_title:  Soliton Wave 

message: Fanboy mode on... Alcubierre may not be mentioned explicitly, but the Next Generation Technical Manual has an image of a warpfield which clearly shows a two-lobed structure, one ahead of the ship and one behind.  (Note that this isn't a fan drawing, it's a color-inverted scan from the official book.)  It looks an awful lot like the graph of the Alcubierre metric.  The notion that relativistic effects do not affect warp travel was also mentioned, if memory serves.  Obviously the two aren't exactly the same, but the shape of the drawing and the constant talk in the series about various types of "warp bubbles" seems to me a pretty clear reference.  Worth a mention, at least?
:Actually from the look of that diagram it would seem as if there are multiple warp bubbles surrounding the ship, has it been considered that to achieve a usable Alcubierre drive without the requirement of a couble solar masses to power it would be the 'multiplicitive' effect of several of the effects stacked within one another, interesting (who knew science fiction would lead to such thoughts). --Chase-san (talk) 20:46, 7 January 2008 (UTC)
thread_title:  Star Trek 

message: I merged in what I could from Spacewarp. Its going to need further refinement. Cwolfsheep 02:40, 24 July 2006 (UTC)
thread_title:  Merged in Spacewarp 

message: I'm not proud of this merge, but I disbursed the content as evenly as possible. Someone's going to need to check the math sections: they appear to be the same thing, but they're different formulas. I also tried moving the talk page from the metric article, but not sure if I did it right. Cwolfsheep 03:01, 24 July 2006 (UTC)
thread_title:  Merged in Alcubierre metric 

message: In the movie the spice, Melange, has the property of bending space-time in a similar manner to the Alcubierre drive. Dessydes 14:49, 21 August 2006 (UTC)
replies: text:  The Guild only uses spice for its Precog effects, the folding is a Holtzman effect.  I don't recall the movie munging this, but I'd have to watch it again.  The Alcubierre drive is a warp drive, Dune uses a fold drive (see Holtzman Drive) ---XanMat 20:06, 20 October 2006 (UTC)
thread_title:  Fiction: [[Dune (film)|Dune]] 

message: The one thing I think that is both missing from, and of interest to those viewing this article is the (theoretical) values for various energy requirements, travel times and/or relative speeds.  Not being a theoretical physicist, I am yet very interested in the field, particularly new developments.  Hence, I would be interested to see any statistics relating to the energy requirements (both from the original Alcubierre metric AND from Loup, Waite and Halerewicz' Reduced total energy requirements for a modified Alcubierre warp drive spacetime mathematics.  
If possible, maybe an addition could be made to the original article outlining these three statistics for easily recognised distances, for example:  
From Sol to Earth, Jupiter, Pluto, the Alpha Centauri system, Rigel, Betelgeuse, and the Milky Way's centre, as well as including other recognisable distances, such as: crossing Milky Way's diameter and from the Milky Way to Andromeda (M31).
Where the variation of energy usage may increase/decrease the values for effective travel time and effective speed, this additional data could be included, also.
This data (I feel) would be of great interest to those of us unable to sift through the mathematics and the background physics necessary to fully comprehend the complexity of the Alcubierre metric. Twphillips 12:15, 13 January 2007 (UTC)
thread_title:  Energy Requirements and Effective Travel Times / Speeds 

message: I see this article is tagged "may be confusing or unclear for some readers". There are at least 2 classes of potential reader: those with no mathematical understanding of general relativity (including me) and those with at least some. So I suggest the article should have 4 major sections (including table of contents):
* Introduction. Something like "In 1994 Alcubierre proposed a hypothetical models of: a space ship drive capable of 'faster than light' travel; a model of space-time (the Alcubierre Metric) which described the 'warp field' which the drive would use. The intro should use pop-science terminology to avoid frightening off the non-specialist reader.
* Table of contents. This will reassure more mathematically-inclined readers that the article also contains material that meets their level of interest.
* "Popular"-level explanation. The second paragraph of the current article describes the basic idea in terms which are just about simple enough. This should be followed by explanations of the difficulties: is it possible at all (exotic matter?)?; is it economically feasible, even after the later refinements (how much exotic matter?)?; how to get it started and does this require slower-than-light space travel?; the difficulty of flying blind because the warp bubble is causally disconnected from the rest of space-time; etc. The "popular" section would also contain the Trekkie stuff ("The Alcubierre drive and science fiction" and "Warp fields")
* Mathematical exposition, covering much the same ground but more technically.
Of course a competent physicist would have to check the "popular" section to ensure that it contained no gross blunders or misrepresentations beyond those inherent in trying to describe a very mathematical subject in ordinary language.
It might even be a good idea to split the article into a popular and a technical article, with the popular article titled "Alcubierre drive" and linking to an article titled "Alcubierre drive (technical analysis)". This would give Wikipedia the option to freeze the popular article after 
sign-off by a competent physicist and leave the technical article open for editing to take account of new technical publications.
Such a division might also help to get rid of the "requires authentication or verification by an expert" and "missing citations and/or footnotes" tags.Philcha 23:00, 16 February 2007 (UTC)
replies: text: Perhaps a brief popular-level section might be a good idea (not a real article; there already exist articles with  the Trekkie stuff, Warp drive for one). But it is rather hard to write such a section without over-simplifications and misleading notions like the (non-existing) 'warp field' which would put off any serious reader. --Seador 13:55, 17 February 2007 (UTC)
replies: text: I'd put "warp field" in quotes to show that it's just a label, not an accurate description. Or can you suggest another term which is more correct but still brief and easily understood by non-specialists? And similar replacements for any other terms you're concerned about in my proposal?Philcha 16:30, 6 April 2007 (UTC)

text: "Warp field" is not a misnomer, but a misconception. That's why I wouldn't use it at all. As for a popular intro, it seems that the first paragraph (that above the Contents) is precisely what you proposed?--Seador 13:20, 7 April 2007 (UTC)
thread_title:  Possible re-structuring? 

message: I would delete that section, because 1) it seems to be more appropriate in Warp drive. 2) The passages like "they allow the transport of physical objects or the transmission of information faster than the speed of light, which is currently understood to be impossible under most circumstances in the real universe", or "While there are natural phenomena that might be likened to warp fields, such as the area of distorted spacetime thought to exist around a black hole, no feasible method of artificially generating one has yet been proposed" look terribly strange amid the discussion of the Alcubierre bubble, which is exactly a means of transportation of physical objects or the transmission of information faster than the speed of light and which is an area of distorted spacetime (though not around a black hole). --Seador 01:30, 21 February 2007 (UTC)
thread_title:  Warp fields 

message: "Sergei Krasnikov is a theoretical physicist at the Central Astronomical Observatory at Pulkovo in St. Petersburg, Russia. He identified what he saw as a critical flaw in Miguel Alcubierre's space warp proposal for space travel: if the space warp moves faster than the velocity of light, it cannot be controlled from inside. Krasnikov's analysis shows that at superluminal speeds the interior of the bubble is causally isolated from its surface and exterior. Photons cannot pass from the inside to the outside. Therefore, there would be no way of controlling the space warp—of stopping, starting or steering."
If you were to set up a track, of sorts, a series of devices strategically placed throughout space that could sustain and move the warp  bubble onward through space, which would allow an object to be steered through space at superluminal speeds to an intentional destination. This would mean we would first need to have reached the destination using conventional methods to deploy such devices, but at least it would make the trip much faster for future travelers. --Steakpirate 04:52, 27 April 2007 (UTC)
replies: text: Question: Does this kind critics forbid to use a method of jumping into the blind, that is to use a hypothetical device together with a hypothetical ship in such away to load a hypothetical device (what ever this means) and jump a few light years with superluminal speed and repeat this procedure at least to reach the destination. Ok this looks like the triple jump known in track and field athletics but it allows to reach the destination. --werner 12:01, 27 April 2007 (UTC)

text: If the warp bubble is generated from a device internal to the bubble, then stopping and starting is not a problem despite Krasnikov's objections.  Steering might also be possible, except that you can't see to steer.  But so what?  Space is mostly empty space.  If you know the meta-velocity of your bubble (the rate at which it propagates itself through space, you can't exactly call it a real velocity), whether that's 50c, 500c or whatever, you just (a) point the ship in the desired direction and (b) turn the warp drive on for the required travel time, then off. (If there's something in the way, you'll have to make a couple of "jumps" at angles.)  To get even more hypothetical, while photon interaction with outside may be disallowed, the gravitational space curvature near massy objects may have influence on the warp bubble that the warp generator can detect.  This of course is highly speculative. -- AJWM 04:59, 11 May 2007 (UTC)
replies: text:  As far as I understand the quotation, the point is: the warp bubble cannot be generated from a device internal to the bubble (that is unless one uses tachyons). --Seador 13:06, 11 May 2007 (UTC)
thread_title: Response to a Warp Bubble Criticism (About controlling the direction/movement of a warp bubble)

message: I have removed the last item because 1) Coule just retold Krasnikov's result and 2) it is, in fact, what is already said in the first item. Kidburla, if you feel that the idea should also be expressed in terms of tachyonic matter, maybe you'd better expand that item? --Seador 12:40, 2 May 2007 (UTC)
thread_title:  Tachyons 

message: I would like to question the purpose of this part of the entry.
"Because nothing can travel faster than the speed of light, it has been stated that bending spacetime itself would cause an object to travel faster than light; this idea has been utilized in the Warp Drive concept in science fiction, but also is the Alcubierre drive theory. The following formula, based on general relativity, permits the travel of an object faster than light provided that spacetime is curved[1]:
    G\mu\,v+8\pi\,GT\mu\,v
If spacetime is warped in this way, then technically the object(s) are not moving faster than light, instead, the space around them shifts so that that object(s) arrives at its destination faster than light would in normal space. Space would be collapsing at one end of the "bubble" and expanding at the other end."
This seems to me to be a case of someone blindly quoting something they do not understand and have no idea what it means. My main problem is,  G\mu\,v+8\pi\,GT\mu\,v
this does not mean anything. One can only assume that he means the Einstein Field Equations which are, 
G_{\mu \nu}=\frac{8 G \pi}{c^4} T_{\mu \nu}
I am really not sure about what this person is getting at. First off the Field Equations always assume that space is curved, otherwise we can use simple old Newtonian Physics(or SR if we are traveling sufficiently fast) to describe the interactions. Also if my memory serves me right(and since I am currently a few hundred miles away from my copy of Misner Thorne and Wheeler's Gravitation it will be a few days before I can look it up), you can travel faster than the speed of light in an inertial reference frame, ie that matter can only travel less than or equal to the speed of light is constraint of SR that gets broken under GR. So this seems of little importance to the topic. Since the rest of this section simply says that normally we take the Strss-Energy Tensor and try to find the Curvature Tensor, but with this instance there was a proposed Metric and the Curvature Tensor was Created, I suggest that the portion that was quoted be deleted.Jetherrie 04:40, 12 May 2007 (UTC)
replies: text: Done --Seador 18:57, 12 May 2007 (UTC)
thread_title:  Usage of the Field of Equations in Physics of the Alcubierre drive

message: I just reverted two changes by Harold f, and wanted to explain why. First, he changed
:The ship would ride this wave inside a region known as a warp bubble of flat space.
to
:The ship would ride this wave inside a region known as a warp bubble which itself moves faster than light through flat space.
But the intent of the original sentence was that the space inside the bubble is flat. I think it's clear from context that the space outside is flat and that the warp bubble effectively moves faster than light. Secondly, he changed the sentence
:Thus, the Alcubierre drive does not contradict the conventional claim that relativity forbids a slower-than-light object to accelerate to faster-than-light speeds
by adding "provided that the warp bubble itself is not considered an object". But this condition is unnecessary, since what's being referred to here is the prohibition on local superluminal travel (i.e. with respect to the local metric), and the warp bubble doesn't violate this in point of fact. -- BenRG 11:05, 19 August 2007 (UTC)
thread_title:  Reverted changes - explanation. 

message: I object to the removal of the page.  There are a number of references at the bottom of the page, and though the page needs work, it is an important article in discussing the attempts of science to explain the theorhetical world of faster than light travel.  This article should not be removed, rather improved over time.  - Eisenmond  —Preceding unsigned comment added by 192.91.171.36 (talk) 21:22, 13 November 2007 (UTC)
replies: text: It is not a question of whether or not the article is interesting, but whether it is verifiable by using reliable sources.  In order to show that it is, and that it isn't original research, inline citations are the way to "show your work" so to speak.  Full information and suggestions for citing information can be found at WP:REF.  The easiest method (for me) is:
 Blah, blah, statement of fact.insert citation here
and then, at the end of the page, add the following section
 ==References==
 
which will cause the footnotes to be listed there.  Hope this helps.  Pastordavid 15:43, 14 November 2007 (UTC)
thread_title:  Removal of the page 

message: Hope this helps. SpinningSpark 21:24, 4 January 2008 (UTC)
replies: text:  Aha... Thanks --Seador (talk) 23:33, 4 January 2008 (UTC)
thread_title: References

message: I've come across this article a few days ago, and reading the talk page I get the idea that the article has been proposed for removal. I sincerely object to the proposal for removal, as it did indeed seem a very good article by now - citing a lot of references, while explaining clearly the idea behind it. Also, I did not find any part of the article ambiguous or unclear, in my opinion the authors have done a really wonderful job of making the concept understandable in layman's terms. I really found this article useful. I hope this post helps in preserving this article for the future. Thanks, Hirak 99 (talk) 16:46, 10 January 2008 (UTC)
thread_title:  Objection to removal of this article 

message: Could the author explain:
# "González-Díaz proposed considering closed, time-like curves. This refinement allows for multiply-connected spaces"
What exactly does this mean? Did he propose to consider time machines? Together with the bubbles? Instead of them? How can consideration of time machines allow  for multiply-connected spaces?
# "closing the geodesic incompleteness and satisfying quantum instability requirements."
What is meant by "closing the geodesic incompleteness"? What are the "quantum instability requirements" and why would one wish to satisfy them? --Seador (talk) 01:07, 14 January 2008 (UTC)
thread_title:  González-Díaz' paper 

message: What would happen if a spaceship travelling with an Alcubierre drive ran into some object?  Would it shatter to pieces like you'd expect a really-really-fast impact to or would something more exotic happen?  What if instead of a physical object, the spaceship collided with another warp bubble?  -- Milo  —Preceding unsigned comment added by 81.171.2.42 (talk) 19:52, 26 February 2008 (UTC)
replies: text: You should ask this question at the Science Desk.  This page is for discussing how to improve the article, not to discuss the subject itself. SpinningSpark 00:14, 27 February 2008 (UTC)
thread_title:  Collisions 

message: I'm sorry but the following quote (and section of the article) makes very little sense to me, even when I try to put it into context in terms of this article.
"The pilot inside the bubble is causally disconnected with its walls. Therefore the bubble cannot be used for the first faster-than-light trip to a distant star. In other words, to travel to Vega (which is 26 light-years from the Earth) one first has to arrange everything so that the bubble moving toward Vega with a superluminal velocity would appear and these arrangements will always take more than 26 years (Krasnikov, 1998)."
Am I just, for some reason, incapable of understanding this and it's written correctly or am I right and there's something wrong with it. I've reread it several times and it still makes very little sense to me. Rajrajmarley (talk) 03:50, 3 March 2008 (UTC)
replies: text: What is clear from Krasnikovs' 1998 paper, but is not clear in the article, is that there is a requirement for ". . . placing in advance some devices along the pilot’s way . . ." (page 10).  The trip to place these devices must, of course, be at sub-light speed since the Alcubierre drive is not yet constructed.  Maybe this is Rajrajmarleys' difficulty.  Can I suggest this as a useful addition to the article? SpinningSpark 12:29, 8 March 2008 (UTC)
replies: text:  What you are saying sounds absolutely correct. If you think that (important!) point is not clear enough in the article, please do clarify it Seador (talk) 23:53, 8 March 2008 (UTC)

text: Thank you SpinningSpark, I think that was all the clarification I needed, I really couldn't figure out exactly what that section was talking about, I think the language of the quote is a bit to abstract/artistic for my taste. Rajrajmarley (talk) 07:21, 2 June 2008 (UTC)
thread_title:  Needs Clarification 

message: Currently, this article states, "The Alcubierre Drive vessel is not able to go dashing around the galaxy at will. It is only able to travel routes which, like a railroad, have first been equipped with the necessary infrastructure." This is very definite statement about a theory that is far from definite. Do all versions of this theory require a road? If not, qualifiers are needed, such as "in some versions of this theory, an Alcubierre Drive vessel must travel routes . . . ." Either way, more citations are needed. 98.209.154.40 (talk) 06:36, 11 June 2008 (UTC)
replies: text: Sorry, I was the one responsible for that colourful phrase.  In my defence, I wrote it in response to complaints that the original text was not understandable, however I do not believe I actually changed any of the original meaning.  It comes from Krasnikov (the meaning, not my strange way of phrasing it) and the relevant paper is already referenced at the end of the section.  I will fix this to make clear that it is Krasnikov and that also he proposes this after eliminating the possibility of using tachyons. SpinningSpark 08:11, 11 June 2008 (UTC)
replies: text: It was also discussed in detail in Ref. [7]. Seador (talk) 12:33, 11 June 2008 (UTC)
thread_title:  Claims about the drive needing a road 

message: The Star Trek diagram in this article has been bothering me for some time and I wanted to test what others think of it.  The image licence claims that it was created by the uploader and appears to have been made by plonking a starship image on an Albubierre field diagram.  If it is self-created and not based on anything in the Star Trek fictional universe then it is WP:OR and should be removed.  The text of this section also seems to indicate that the scriptwriters have not strongly aligned themselves with Alcubierre.  Retaining this diagram gives the false impression of the opposite.  On the other hand, if it is based on something in the Star Trek technical manuals then a reference should be provided to indicate its in-universe provenance. SpinningSpark 18:39, 29 November 2008 (UTC)
thread_title:  Star Trek graphic