Talk:Krasnikov tube

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Contents 1 2 Krasnikov Tubes 2 Time travel via Krasnikov tubes 3 Potential copyright violation 4 Response to Warp Bubble Criticism 5 2 tubes

[edit] 2 Krasnikov Tubes

I do not get what it is that violates causality in this example. Astronaughts go into one tube, and appear nearly instantaneuously on the other side. Then they go to the other and go back to earth. Its instantaneous but I see no causality violations.

Instantaneous travel produces causality violations in relativity. There's an explanation in the WP article on special relativity.--76.93.42.50 (talk) 19:49, 7 May 2008 (UTC)

[edit] Time travel via Krasnikov tubes

What prevents time travel or round-trip FTL in the situation where you have two parallel tubes pointing in opposite directions? --Christopher Thomas 20:03, 20 Jun 2005 (UTC)

The events are always timelike ordered. Although the proof isn't quite explicit yet for two parellel tubes. --Son Goku 07:59, 22 June 2005 (UCT)

It would be handy if the constraints that force this to be the case were made clear in the article. At present, the justification seems to assume that only one tube exists. As long as the tubes remain in place over time, it's difficult to see how you'd prevent time travel with two that ran in opposite directions with the description that's currently present. --Christopher Thomas 15:10, 22 Jun 2005 (UTC)

Adjustments have been made. Is the article clear enough or still too technical for the average reader?--Son Goku 22:55, 22 June 2005 (UCT)

The "causality violations" section makes things much clearer, thanks. The only extra information that would be handy would be a "references" section with links to the papers by Krasnikov, Everett, and Roman. --Christopher Thomas 22:25, 22 Jun 2005 (UTC)

[edit] Potential copyright violation

I note that large parts of this article are rather similar to this article: http://www.npl.washington.edu/AV/altvw86.html which was "Published in the September-1997 issue of Analog Science Fiction & Fact Magazine". Is it republished with permission of the author? —The preceding unsigned comment was added by 137.222.10.57 (talk • contribs) .

[edit] Response to Warp Bubble Criticism

"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 moved 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)

The trouble that would arise is, what if the bubble's direction was even just slightly off? Even if it were only off by a tenth of a degree, the ship would end up something like 71 billion kilometers off course over the distance from Earth to Alpha Centauri. Would it be possible to steer the bubble from an outside device? Even if it were so, you'd need quite a few of these devices along the "road" to your destination (or perhaps a large number of these devices orbitting the destination star at a distance of, say, 100 billion kilometers to catch arriving ships). And what if something went wrong and the bubble were veered off the road completely? It would end up flying through space forever, uncontrolled. Nik42 18:10, 12 May 2007 (UTC)

[edit] 2 tubes

the math on the trip to daneb doesnt seem to work out. the wikipedia page on that star says its 3000 light years away, if the ship created a 2nd tube on the way back, wouldnt it take 6000 years? not 3200 some odd? Narmical 20:29, 24 May 2007 (UTC)