Is Faster-Than-Light Travel or Communication Possible?

I'm going to be the odd man out here. There are several statements made in the article that are incorrect, and then other arguments are based on them.<p>In particular, the tying together of speed and time.<p>"By 'world line' we mean a curve traced out in the four dimensions of space-time". Time is not a dimension. Time is a human concept. Clocks don't measure a physical dimension or force called time, they repeat mechanical motions at regular intervals that we label as time passing. Same for atomic clocks. We measure the spin rates of cesium atoms but that isn't any different than mechanical clocks. Time is not a force that figures into physics equations.<p>Further, time doesn't exist. Not in the classical sense. What we experience as time is the entropy of energy in the universe winding out. We remember things that happened before and imagine things in the future, but since there is no physical "time" dimension there is no traveling forward and back.<p>If you are on a ship traveling close to c, the rate of entropy in the matter and energy on your ship is lower than the outside universe. That's why time seems slower.<p>There's a classic thought experiment that you can build a time machine by putting one end of a wormhole on a ship, send it out for 20 years near c, then bring it back. At this point you would have a wormhole with ends in two different times. It doesn't work like that though. Passing through it will just put you wherever it opens to, and you'll just end up in whatever local entropy rate is going on.

Special Relativity states (and so far all evidence confirms it ) that speeds faster than "c" is impossible relative to (i.e. _through_ ) local spacetime ("aether") . The mathematical model of SR (smooth manifold with static metric (and we know that our real world doesn't have static metric, so real applications of SR approximate it by considering only sufficiently local regions of space during short periods of time)) doesn't cover and thus doesn't preclude or contradict with other types of relative "motions" (for the lack of better term) which are known to exist and have speed faster than "c" :<p>- quantum entanglement (we don't know the machinery behind it, very-very possible that the SR's smoothness of space is also only a rough approximation of the real world.) Obviously any attempts to find the "signal" between the entangled particles in the conventional sense (something traveling through smooth static spacetime) have so far been and will continue to be futile.<p>- relative motion of the parts of the (our expanding) Universe that are far enough from each other (observed, space expansion, described by General Relativity, at this scales of spacetime the SR's condition of static metric just isn't valid anymore )

I am constantly reading that information cannot travel faster than light, and I accept each of the explanations as to why the various methods for attempting to send information faster than light do not work.<p>What I do not understand is whether sending information faster than light would cause a paradox of any sort. It may be that it happens to be impossible. But is it <i>necessarily</i> impossible?

There is one sentence I have a problem with in this post: "Shadows and spotlights suffice to show that there is no logic in this suggestion, because they can certainly go FTL and still be seen." Now, I was only scanning over the article and certainly missed some explanatory section, but can someone explain to me how shadows and spotlights go faster than light?

From the article:<p>&#62;<i>Now consider the description of an EPR-entangled pair of photons:<p>(|↑↓&#62; + |↓↑&#62;)/√2<p>At first glance this looks very much like the single-photon case, except that where before we had ΨU and ΨL we now have |↑↓&#62; and |↓↑&#62;, representing respectively photon 1 being in the upper slit and photon 2 being in the lower slit and viceversa. But this distinction is crucial because it turns out that there is some notational sleight-of-hand going on here. First, |↑↓&#62; is shorthand for |↑&#62;|↓&#62;. Second, the arrow symbols have no semantic significance; they are just compact mnemonic identifiers. We could just as well have written |UL&#62; and |LU&#62; (which of course is shorthand for |U&#62;|L&#62; and |L&#62;|U&#62;) as |↑↓&#62; and |↓↑&#62;. Finally, ΨU is just another way of writing |U&#62;.<p>So if we employ alternative notation we get the following description of two entangled photons:<p>(ΨU |U&#62; + ΨL |L&#62;)/√2</i><p>As I have probably demonstrated other places, IANAQM. But I don't follow that last transformation. If |↑↓&#62; == |↑&#62;|↓&#62; == |U&#62;|L&#62; == |UL&#62; and ΨU == |U&#62;, how does (|↑↓&#62; + |↓↑&#62;)/√2 == (ΨU |U&#62; + ΨL |L&#62;)/√2 and not (ΨU |L&#62; + ΨL |U&#62;)/√2 ? Shouldn't the |U&#62; and |L&#62; be reversed?

Something I've always wondered is -- of course going back in time is a bad thing -- but is going "faster than light" necessarily going back in time? I wonder why, say, instantaneous communication across the galaxy wouldn't be possible, as long as it doesn't go back in time. (BTW: not necessarily from a physics point of view, they would say that not only can't one travel back in time, neither can you go faster than the speed of light, but I was wondering more from a paradox / time causality point of view).

Assuming that space and time collapse into/onto a one dimensional membrane, time wouldn't be of consequence. Information would remain and it would be "every where" at "every time." Question is, where are we in reference to that membrane right now?

anyone care to give a simple TL;DR for the rest of us?