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<blockquote data-quote="freyar" data-source="post: 6638088" data-attributes="member: 40227">Fair enough.&nbsp; Please note, I've not seen the movie, so I'm just going on hearsay there.&nbsp; However, the rest of the point is that Morris &amp; Thorne have argued that, if you want to engineer a wormhole to have negligible time dilation and tidal forces (ie, comfortable for human travel), it has to be big.&nbsp; Like 20x as big as the solar system.I just did a literature search on the best research database for this kind of thing, looking for research papers by Kip Thorne about wormholes.&nbsp; I don't find any evidence for such work between 1993 and 2015 (the 2015 papers were about visualization for Interstellar).&nbsp; A number of other authors have worked on wormholes, of course, and I'm skimming through some of that literature for curiosity's sake.I think I must not have explained properly.&nbsp; Morris &amp; Thorne weren't looking at wormholes without exotic matter.&nbsp; They just didn't want exotic matter filling up the entire universe, so they wanted spacetimes that have a wormhole created by exotic matter surrounded by space with normal matter (including people, space stations, etc), like where we live.&nbsp; To do that, they found a &quot;comfortably traversable&quot; wormhole needed to be very large.&nbsp; Smaller than that would have large tidal forces and at least noticeable time dilation.&nbsp; Keep in mind that Morris &amp; Thorne were specifically trying to make wormhole spacetimes with small amounts of time dilation and were willing to postulate any characteristic of matter necessary.Side point: Gauss-Bonnet gravity need not be associated with brane-world models.&nbsp; The point is that the Gauss-Bonnet term doesn't change the Einstein equations in 4D; they only do that in 5D and above.&nbsp; That's interesting for brane-worlds as well as other extra dimensional models.&nbsp; Also as a side note, I've written a paper using 5D GB gravity myself.In technical terms, the wormhole solutions written down connect two distinct asymptotic regions.&nbsp; In plain English, the two ends of the wormhole are connected to two distinct universes, or maybe more precisely two regions of space that don't connect to each other except through the wormhole.&nbsp; In principle, I don't think there's a reason you couldn't make a wormhole connecting two parts of the same universe, but I haven't yet seen a metric that does that.&nbsp; It's not what people typically study when the look at wormholes.And how to make them flat enough to traverse was the point of the Morris-Thorne paper.&nbsp; Key point --- you have to make them big to avoid either tidal forces, time dilation, or both.</blockquote>

[QUOTE="freyar, post: 6638088, member: 40227"] Fair enough. Please note, I've not seen the movie, so I'm just going on hearsay there. However, the rest of the point is that Morris & Thorne have argued that, if you want to engineer a wormhole to have negligible time dilation and tidal forces (ie, comfortable for human travel), it has to be big. Like 20x as big as the solar system. I just did a literature search on the best research database for this kind of thing, looking for research papers by Kip Thorne about wormholes. I don't find any evidence for such work between 1993 and 2015 (the 2015 papers were about visualization for [I]Interstellar[/I]). A number of other authors have worked on wormholes, of course, and I'm skimming through some of that literature for curiosity's sake. I think I must not have explained properly. Morris & Thorne weren't looking at wormholes without exotic matter. They just didn't want exotic matter filling up the entire universe, so they wanted spacetimes that have a wormhole created by exotic matter surrounded by space with normal matter (including people, space stations, etc), like where we live. To do that, they found a "comfortably traversable" wormhole needed to be very large. Smaller than that would have large tidal forces and at least noticeable time dilation. Keep in mind that Morris & Thorne were specifically trying to make wormhole spacetimes with small amounts of time dilation and were willing to postulate any characteristic of matter necessary. Side point: Gauss-Bonnet gravity need not be associated with brane-world models. The point is that the Gauss-Bonnet term doesn't change the Einstein equations in 4D; they only do that in 5D and above. That's interesting for brane-worlds as well as other extra dimensional models. Also as a side note, I've written a paper using 5D GB gravity myself. In technical terms, the wormhole solutions written down connect two distinct asymptotic regions. In plain English, the two ends of the wormhole are connected to two distinct universes, or maybe more precisely two regions of space that don't connect to each other except through the wormhole. In principle, I don't think there's a reason you couldn't make a wormhole connecting two parts of the same universe, but I haven't yet seen a metric that does that. It's not what people typically study when the look at wormholes. And how to make them flat enough to traverse was the point of the Morris-Thorne paper. Key point --- you have to make them big to avoid either tidal forces, time dilation, or both. [/QUOTE]

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