<story><title>Faster Than the Speed of Light?</title><url>http://www.nytimes.com/2013/07/23/science/faster-than-the-speed-of-light.html?hp</url></story><parent_chain><item><author>lisper</author><text>The right way to think of this: the speed of light is not a speed limit, it&amp;#x27;s a speed &lt;i&gt;reference&lt;/i&gt;.  Everything is always moving at the speed of light through spacetime.  When you &amp;quot;move&amp;quot; through space, you&amp;#x27;re not changing the magnitude of your velocity vector, only its direction.  So the more you move through space, the less you move through time.&lt;p&gt;If you could move through space at the speed of light your velocity through time would be zero and you would appear (to yourself) to be moving infinitely fast, or equivalently, to be everywhere at once, or (again equivalently) that the universe had no spatial extent in your direction of travel due to an infinitely large Lorenz contraction.</text></item></parent_chain><comment><author>calhoun137</author><text>This explanation is wrong, and is not what the article is talking about at all.  This article is about creating a warp bubble using negative energy, which changes the distance between two points.  You can think about it sort of like creating a kink in a piece of metal with a piece of dust inside of it, the kink then propagates through the metal by distorting the geometry of the larger object in such a way that the distance traveled by the piece of dust is less than the original distance between the start and end point of the kink.  The reason this works has nothing to do with special relativity, it comes from the fact that if you plug negative energy into the equations of general relativity, you get warp bubble solutions which travels between two points faster than light could travel between the two points if there was no warp bubble.&lt;p&gt;A few years ago I actually read through most of the original paper[1], and worked out a lot of the equations.&lt;p&gt;Although I don&amp;#x27;t see it mentioned in the article, and I&amp;#x27;m speculating here, the reason the approach described in the article might work out for photons is that negative energy has been discovered at the quantum scale in something called the Casimir effect[2].  The Casimir effect happens when you have two conducting plates which are placed very very very close to each other, then in the space between the plates, something which behaves exactly like negative energy exists[3], and it causes an attractive force to be exerted between the two plates.&lt;p&gt;A natural thing to try would be to harness this type of negative energy to create a tiny warp bubble, and try somehow to stick a quantum particle like a photon in it.&lt;p&gt;[1] &lt;a href=&quot;http://arxiv.org/abs/grqc/0009013&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;arxiv.org&amp;#x2F;abs&amp;#x2F;grqc&amp;#x2F;0009013&lt;/a&gt;&lt;p&gt;[2] &lt;a href=&quot;http://en.wikipedia.org/wiki/Casimir_effect&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Casimir_effect&lt;/a&gt;&lt;p&gt;[3] &lt;a href=&quot;http://physics.stackexchange.com/questions/47922/can-negative-energy-be-created-by-the-casimir-effect&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;physics.stackexchange.com&amp;#x2F;questions&amp;#x2F;47922&amp;#x2F;can-negativ...&lt;/a&gt;</text></comment>
<story><title>Faster Than the Speed of Light?</title><url>http://www.nytimes.com/2013/07/23/science/faster-than-the-speed-of-light.html?hp</url></story><parent_chain><item><author>lisper</author><text>The right way to think of this: the speed of light is not a speed limit, it&amp;#x27;s a speed &lt;i&gt;reference&lt;/i&gt;.  Everything is always moving at the speed of light through spacetime.  When you &amp;quot;move&amp;quot; through space, you&amp;#x27;re not changing the magnitude of your velocity vector, only its direction.  So the more you move through space, the less you move through time.&lt;p&gt;If you could move through space at the speed of light your velocity through time would be zero and you would appear (to yourself) to be moving infinitely fast, or equivalently, to be everywhere at once, or (again equivalently) that the universe had no spatial extent in your direction of travel due to an infinitely large Lorenz contraction.</text></item></parent_chain><comment><author>TomGullen</author><text>I really really want to understand this, but I can&amp;#x27;t get past your third sentence.  No fault of your own, just me.  But if you have anything I can read that explains it better I would be grateful!</text></comment>