# Alcubierre drive - theory changes/breakthrough? **URL:** \ **Category:** Factual Questions\ **Created:** [December 3, 2013, 5:13pm UTC](https://boards.straightdope.com/t/alcubierre-drive-theory-changes-breakthrough/675384 "2013-12-03T17:13:01Z")\ **Posts on this page:** 1\ **Showing post:** 18
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [December 4, 2013, 6:54am UTC](https://boards.straightdope.com/t/alcubierre-drive-theory-changes-breakthrough/675384/18 "2013-12-04T06:54:20Z")
From [another thread](http://boards.straightdope.com/sdmb/showthread.php?p=15473197#post15473197) on the subject (I only considered information transfer, but you can replace this with any mode of transmission you want; additionally, I’ve covered only the limiting case of instantaneous transmission, but basically the same story works for all speeds greater than c): > [@Q about "warp" drives](https://boards.straightdope.com/t/q-about-warp-drives/634206/5): > > Special relativity: Say two spaceships meet each other at time t[sub]0[/sub]. They travel at a relative speed of 0.87c. On both spaceships, there’s an instantaneous transmitter, i.e. a device that transmits information at ‘infinite’ speed (this works for any speed greater than c, but the math gets more complicated for finite speeds). Now, say, a minute after the meeting, people on ship A notice that ship B’s back light is broken, so they instantaneously send a message to ship B informing them of their gross violation of intergalactic traffic codes, which as everybody knows are enforced with extreme rigidity. However, since ship B moves at a speed of 0.87c relatively to ship A, it is subject to time dilation, and thus, only thirty seconds have elapsed since the two ships met. > > So far, so good. The engineer on ship B, being of the swift sort, fixes the back light, mumbles something about how he cannae change th’ laws o’ physics, Captain, and then sends back a thanks, at about 45 seconds after the ships met. However, again, since ship A is moving at 0.87c relatively to ship B, it is subject to time dilation; thus, if 45 seconds have elapsed on ship B, only 22.5 seconds have elapsed on ship A. Thus, the thank you arrives on ship A 22.5 seconds after the ships have met, and thus, 37.5 seconds before ship A ever sent its message to ship B, which of course, seeing as how the problem’s already fixed, they now don’t have to. > > Or, with more detail, see the story [here](http://www.theculture.org/rich/sharpblue/archives/000089.html). --- _[View the full topic](https://boards.straightdope.com/t/alcubierre-drive-theory-changes-breakthrough/675384)._