The Dungeons & Dragons Antiteliphone

[mathmancer]

I will try to answer this in order.

No.

FTL Velocity is what FTL Travel means.

Alright, well it will only get more confusing if we start arguing somantics at the same time we argue physics, so I'll make another attempt to find some common language. That IS what you are objecting to with that statement right? Because if not... then you're defeating your own argument (are we arguing?)

By the transitive property, if a=b and b=c then a=c. in this instance, a would be FTL Velocity and b would be FTL Travel. By what I just quoted above, you're statement is a=b.

By what I said:

FTL Velocity: your Delta-Position is greater than C (the speed of light) at any moment (don't invoke Zenos Paradox please. The burden would be on you to show why people actually ARE in motion).

FTL Travel: You arrive at the destination BEFORE the light cone of your departure. This includes all the sci-fi tricks. Wormholes, Hyperspace travel, Alcubiera drives, Stargates (a manmade wormhole... according to the shows lore), Jump drives, Spelljammer helms, using the Astral Plane as a shortcut, using ANOTHER UNIVERSE as a shortcut, Spice Navigators from Dune who will you to the other end of the universe without moving, Warp Travel (Like in warhammer 40,000), Quantum Tunneling, Laplaces Demon, and more.

FTL Travel (b) = set C{Wormholes, Hyperspace travel, Alcubiera drives, Stargates (a manmade wormhole... according to the shows lore), Jump drives, Spelljammer helms, using the Astral Plane as a shortcut, using ANOTHER UNIVERSE as a shortcut, Spice Navigators from Dune who will you to the other end of the universe without moving, Warp Travel (Like in warhammer 40,000), Quantum Tunneling, Laplaces Demon, and more}

so by the transitive property, FTL Velocity = set C.

Which would mean that you're saying FTL Velocity = teleportation. But since that's what you're arguing against, then you clearly don't mean that when you say

No.

FTL Velocity is what FTL Travel means.

So we need to find some common language, because we ARE talking about two different things. That's what I was trying to do when I made the distinction between the terms FTL travel and FTL velocity, but I suppose I failed at that. So now I have to come up with a term or word for what I'm describing, which is just about any way of arriving at your destination sooner than what is, by the current known theory of physics, possible.

If I was to name a catagory that included teleportation, hyperspace, wormholes, and simply having an FTL Velocity, and more, but not use the name "FTL Travel" for that catagory.... well... I guess it can't be a name that describes the catagory then. Lets just call it CATAGORY DS. an item in CATAGORY DS would be a form of CATAGORY DS travel. DS is for Doc. E.E. Smith, a scifi author known for writing space opera. The methods of space travel in a space opera will always move at the speed of plot(that's a joke).

Continuing this, that means that FTL Velocity is one item in CATAGORY DS, but it is not the only one. Another item in CATAGORY DS is teleportation.

The logical statement (not the equation or phenomena those equations describe) would be:
If an item appears in CATAGORY DS, then that item breaks causality.

And it is, apparently, my burden to show that that logical statement is true (I will, keep reading).

I'm trying to clarify things, because your statement revealed that I needed to be more explicit, but I'm afraid that by being more explicit and technical I'm also being more confusing.

You and a beam of light departing from point A and you arriving at point B before the beam of light does does not mean that you have traveled back in time. When light catches up to you is utterly irrelevant.

This is, I must concede, technically correct. But only because light will travel slower within a medium. So there ARE times when you could travel slower than C, but faster than the beam of light, and you would NOT travel back in time or mess with causality. I am partially to blame here, because I was being lose with my terms earlier. I will continue to make such mistakes, even willfully, because I'm trying to explain it easily and I'm still a laymen myself.

Explain to me, entirely in non-physics terms, how going faster than C and folding space are at all the same.

They are very different methods, I will agree, but they both violate causality. I'm assuming (and I know it's bad to assume) that when you say "folding space" you're folding space in order to achieve the same end result as the teleportation spell. I also have to assume that you don't want me to simply "explain...(how those things)... are at all the same" because that's open ended enough to let me say something like "Because they're both not real!"(a joke, come on lighten up people!). So now I have a bigger assumption. I'm assuming you want me to show how moving faster than C and folding space BOTH result in causality violating time travel.

So, hoping I have guessed your INTENT correctly, here is my attempt at doing what I believe you have challenged me to do (Oh god the number of qualifiers I have to use to dance my way through every sentence is getting unbearable!) I can restrict myself to non-physics terms, but I can't explain very much that way. Here's my best attempt:

How moving faster than C and folding space BOTH result in causality violating time travel.

The principle of causality is fairly straight forward. According to causality, if there is some effect which is produced by some cause, then the cause must precede the effect. So, if for some observer (in some frame of reference) an effect truly happens before its cause occurs, then causality is violated for that observer. Now, recall our discussion in Section 1.1 concerning when occurrences happen in a frame of reference. There I took a moment to explain that when I talk about the order of events in some frame of reference, I mean their actual order, and not necessarily the order in which they are seen. One can imagine a situation whereby I could first receive light from the effect and later receive light from the cause. However, This might be because the effect is simply much closer to me than the cause (so that light takes less time to travel from the effect I observer, and I see it first). After I take into account the time it took the light to travel from each event, then I will find the order in which the events truly occurred, and this will determine whether or not there is a true violation of causality in my frame. This true violation of causality is what I will be talking about, not some trick concerning when observers see events, but a concept concerning the actual order of the events in some frame of reference.

Ok, so this explains more or less what causality is, and how, depending on where you are and what you're doing you can start to see some strange things.

Also, incidentally, I see now that I WAS confusing the concept of an "observer". I thought it all WAS a trick on observing things out of order, but Dr. Hinson just explained that Relativity goes a lot.... DEEPER than light tricks.

I refer you back to Diagram 2-9 (reproduced below as Diagram 8-1 ) so that I can demonstrate the causality problem involved with FTL travel. There you see two observers passing by one another.

Diagram 8-1
(Copy of Diagram 2-9)



The origin marks the place and time where the two observers are right next to one another. The x' and t' axes are said to represent the frame of reference of O' (I'll use Op--for O-prime--so that I can easily indicate the possessive form of O as O's and the possessive form of O' as Op's). The x and t axes are then the reference frame of the O observer. We consider the O system to be our rest system, while the Op observer passes by O at a relativistic speed. As you can see from the two coordinate systems, the two observers measure space and time in different ways. Now, consider again the event marked "*". Cover up the x and t axis and look only at the Op system. In this system, the event is above the x' axis. If the Op observer at the origin could look left and right and see all the way down his space axis instantaneously, then he would have to wait a while for the event "*" to occur. Now cover up the Op system and look only at the O system. In this system, the event is below the x axis. So to O, the event has already occurred by the time the two observers are passing one another.

Normally, this fact gives us no trouble. If you draw a light cone (as discussed in Section 2.8 ) through the origin, then the event will be outside of the light cone. As long as no signal can travel faster than the speed of light, then it will be impossible for either observer to know about or influence the event. So even though it is in one observer's past, he cannot know about it, and even though it is in the other observer's future, he cannot have an effect on it. This is how relativity saves its own self from violating causality.

However, consider the prospect of FTL travel with this diagram in mind. As O and Op pass by one another, the event "*" has not happened yet in Op's frame of reference. Thus, if he can send an FTL signal fast enough, then he should be able to send a signal (from the origin) which could effect "*". However, in O's frame, "*" has already occurred by the time O and Op pass by one another. This means that the event "Op sends out the signal which effects *" occurs after the event which it effects, "*", in O's frame. For O, The effect precedes the cause. Thus, the signal which travels FTL in Op's frame violates causality for O's frame. Similarly, since "*" has already occurred in O's frame when O and Op pass one another, then in his frame an FTL signal could be sent out from "*" which could reach O and tell him about the event as the two observer's past. However, for Op, the event "O learns about * as O and Op pass one another" comes before * itself. Thus, the signal which is FTL in O's frame violates causality in Op's frame.

In short, for any signal sent FTL in one frame of reference, another frame of reference can be found in which that signal actually traveled backwards in time, thus violating causality in that frame.

Notice that in this example I never mentioned anything about how the signal gets between the origin and *. I didn't even require that the signal be "in our universe" when it was "traveling" ( remember our definition of FTL travel). The only things I required were that (1) the signal's "sending" and "receiving" were events in our universe and (2) the space-time between the origin and "*" is flat (i.e. it is correctly described by special relativity diagrams). Some FTL ideas may invalidate the second assumption, but we will consider them a bit later. We will find, however, that violation of causality still follows from all the FTL travel concepts.

Alright, so this is where Dr. Hinson explains how regular FTL Velocity violates causality. Interestingly, he makes the same distinction I did between FTL Velocity and FTL Travel.... but I only mention that to help people understand what he's talking about.

Lastly, as Dr. Hinson promised:

9.3 "Folding" Space (Without Special Provisions)

Another concept which pops into the minds of science fiction lovers when considering FTL travel is that of "folding" space. Basically, the idea is to bring two points in space closer together in some way so that you can travel between them quickly without having to "actually" travel faster than light. Of course, by our definition of FTL travel in Section 6.1 (where the light you are "racing" against goes through normal space between the starting and ending points) this would still be considered FTL travel.

A frequently used approach for picturing this idea is to think of two dimensions of space represented by a flat sheet of paper. Then consider yourself at some point on the paper (call this point "o"). If you want to travel to some distant point ("D"), you simply fold/bend/crumple/etc the paper and place "o" and "D" close to one another. Then its just a matter of traveling the now short distance between the points.

Again, we see an FTL concept which is built in order to get around the problem of the light speed barrier. However, we will see, once again, that the second problem of FTL travel is not so easily fixed.

We begin to understand this when we consider again the sheet of paper discussed above. Every object in that two dimensional space has a place on the paper. However, because objects may be moving, their position depends on the time at which you are considering them. Basically, if you are sitting at "o", you imagine every point on that sheet of paper as representing space as it is "right now" according to your frame of reference. However, as we have discussed, what is going on "right now" at a distant location truly depends on your frame of reference. Two observers at "o" in two different frames of reference will have two different ideas of what events should be represented on the paper as going on "right now". This difference in simultaneity between different frames of reference is what allowed for the "unsolvable paradox" problem to exist in the first place. Thus, even though you "fold" the paper so that you don't "actually" travel faster than light, you don't change the fact that you are connecting two events at distant points (your departure and your arrival) which in another frame of reference occur in the opposite order. (In the other frame of reference, you aren't just bending space, you're bending space-time such that you travel backwards in time.) It is that fact which allowed the unsolvable paradoxes to be produced.

In the end, unless special provisions are present, one can use this form of FTL travel in our FTL bullet example (I refer you back to the listing of events in Section 8.3 ). Op will fold space in his frame of reference to connect the passing event with the event "*", while the third observer will fold space from his frame of reference to connect the event "he sees the victim die" with an event "O learns of the victims death before the FTL bullet is sent". Thus, you can used this method to produce an unsolvable paradox as we discussed earlier.

And that's where Dr. Hinson explains how folding space will still create gross violations of causality. And by virtue of that, Teleport, which involves NO MOTION AT ALL, still belongs to the set CATAGORY DS.

I have to apologize. I don't have a Doctorate in Physics. I can't do very much better than "That's what physicists say happens". Dr. Hinson isn't some crackpot Doctor with a shady online degree either. Dr. Hinson isn't even explaining his own theory, he's just describing the implications of theorys that were developed by Einstein and Einsteins contemporary called the theory of Special Relativity and the theory of general Relativity.

Unlike me, Dr. Hinson can do a little bit better than "Hey, that's just what Einstein says ok?", but I can't get him to re-write his webpage to fit your demand for non-physics terms, and I don't know enough about how it works to explain it in simpler terms than he does. really I don't understand it at all, I just understand the conclusions of "FTL = time travel" and "Teleport = FTL too!"

On that note, if you're smarter than I am (which is not at all unlikely), i encourage you to read Dr. Hinsons page at http://www.physicsguy.com/ftl/html/F...#sec:ftleqvofc
I also encourage you to not just take HIS word for it, and to do your own indipendant research. To get you started, check out

• Relativity of Simultaniety. That's a good term to research. Don't just settle for wikipedia's page on it either.
• Closed Timelike Curves (CTC). Also relavent, but you'll see how every one who believes these to exist are also scrambling to figure out how to preserve causality.
• If you can read German (I can't) try reading the publications of the original physicists! Einstein, Heisenberg, Godel, and a few others all wrote stuff relevant to what I'm failing to explain here.
• Also, check out http://www.projectrho.com/public_htm...asterlight.php It's about nuclear space ships, and it mostly just uses the same links that I did, but like me he's trying to relate the implications of physics to literature

This probably does a better job of showing what happens if you make a "Dungeons & Dragons Anti-Telephone" than I did any where else in this thread.

but then Fiery Diamond said

The racetrack analogy is spot on. Explain how it isn't.

Ok, this ones a little easier. The racetrack analogy goes like this (reprinted in a poor attempt to make this slightly readable)

If I have a circular racetrack that is 1.1 light-seconds long, and observe that the finish line is right there by where the starting line is, and so turn around when the starter pistol goes off and cross the finish line in a second, I didn't really travel faster than the speed of light - I just took advantage of a shorter route.

Effectively, the Astral Plane is the shorter route to everywhere.

It needs some adjustment. To fit it into the topic, you have to assume that ALL OF THE SPACE INSIDE THE LOOP MADE BY THE RACE TRACK as well as the line that segments the Finish and Starting Lines are divided by the Astral Plane.

I can't see it fitting any other way, or else you're suggesting that the destination is spatially next to the source, which would mean that light wouldn't travel on your race track (it would take the same path as the guy who turns around and walks back over the start/finish line). Since 3d space doesn't cross the finish line, we can say that the start and finish are 1.1 light seconds apart. If not, then the source and destination are only a foot step away and the whole rest of the track can be ignored. Important thing isn't how fast your moving, or what route you take. The important thing is that the start and the finish are spatialy 1.1 light seconds apart (in this analogy) within the context of the material plane, and you went from one to the other in less than 1.1 seconds.

The start and finish aren't close together physically in the material plane. An Astral Plane shortcut doesn't speed up the propagation of the very rules of the universe. As Dr. Hinson explained, it's not a trick of the light. If a permanent portal was open, and some one could shine light from the source onto the destination 1.1 light seconds away in under 1.1 seconds, that would only break down causality AND link those spots spatially.

Looking at Fiery_Diamonds version of the analogy, it's interesting that he makes all of the corrections needed to relate the analogy to a one way trip. The issue is the same though. If you get from A to B (in your analogy) by "... we cross the other dimension from A to B, we arrive faster before light along the track does." then you're just describing the space-fold scenario that Dr. Hinson addresses. There is a frame of reference where you arrive at B before you leave A, and because "now" depends on your frame of reference, and ALL frames of reference are equal, you DO arrive before you leave.

you don't change the fact that you are connecting two events at distant points (your departure and your arrival) which in another frame of reference occur in the opposite order. (In the other frame of reference, you aren't just bending space, you're bending space-time such that you travel backwards in time.)

Now, onto...

TL;DR: The OP is arguing that an event hasn't occurred from your frame of reference until you've had the chance to see it happen. This is empirically false (see: astronomy and cosmology).

That's ... not really what I was "arguing" at all. I was trying to understand Relativity of Simultaniety, not the collapse of Quantum wave functions. However, like you suggested I went back and looked at... well not astronomy... or cosmology. I looked at physics instead, and hopefully you'll agree that the second look at physics created something more relevant to the topic. In the explanation from Dr. Hinson, the CORRECT interpretation of Special Relativity agree's with the results of the "Dungeons & Dragons anti-teliphone"

I'm.... not sure what you mean by "empirically false". That seems to be the opposite of what Dr. Hinson suggests. Empirical is

based on, concerned with, or verifiable by observation or experience rather than theory or pure logic

In this situation, my understanding of the theory was wrong, but if the event ever did occur, we would observe the same thing, that is, we'd see time travel.

I really only wanted to single out the use of the word Empirical, because that's one of my pet peeves (that and the words Proof, and Logic, and Science. I have too many week spots for people to zing).

Lastly, just for giggles, here's a funny quote I like from Atomic Rockets:

About every six months or so, some science writer stumbles over a reference to "quantum entanglement" or "Bell's Inequality" or "spooky action at a distance", then immediately writes an article or blog post about OMG! Quantum Mechanics can send radio messages faster than light!

Short answer: No, it won't work.

Slightly longer answer: When you send the message, it will technically arrive faster than light. But the message will be in two parts: a scrambled sequence of numbers at the source, and a second scrambled sequence at the destination. The only way to decode the message is with both sequences. So the source has to send the first scrambled sequence to the destination over conventional just-as-fast-as-light radio. Which sort of defeats the purpose.

After receiving both parts of the message at a rate equal to the speed of light, you can find out after the fact that yes indeed there was some faster-than-light communication. Oh, my, wasn't that pointless?

Longest answer:
Back in 1930, several physicists in general and Albert Einstein in particular were quite upset when Quantum Mechanics was invented. Everything about QM was offensive to those who like their physics logical, deterministic, and non-weird. Einstein and co-authors Boris Podolsky and Nathan Rosen wrote a paper in 1935 demonstrating that Quantum Mechanics had to be utterly wrong, or at the very least quite incomplete. The paper set forth a paradox. The two solutions were [a] Quantum Mechanics is wrong or incomplete or [b] there exists bizarre spooky action at a distance which travels faster than light (actually it is instantaneous). Since [b] was obviously impossible, Einstein and his co-authors smugly sat back and waited for Quantum Mechanics to be discarded into the dust-bin of history.

Unfortunately for Einstein et al, in 1964 some clown named Dr. John Stewart Bell wrote a paper showing how to test the paradox (called "Bell's Inequality"), and to the horror of the foes of quantum mechanics it turned out that bizarre spooky action at a distance which travels faster than light actually happens.

This saved quantum mechanics from the EPR paradox, but now all the physicists had to deal with this obnoxious FTL action at a distance. As mentioned above, physicists hate FTL because it destroys causality and thus makes the entire structure of Science collapse into a flaming ruin.

As it turns out: yes, the FTL effect is real but no you can't use it for anything useful. Physicists heaved a sigh of relief (and science fiction writers became quite angry).

It's funny, and notice how it's dealing with Quantum Entanglement, which doesn't have anything to do with FTL VELOCITY as is being understood in this thread. No matter, not even a quantum particle, is traveling the intervening distance. Even in that situation, they basically have to censor effects of QE in order to preserve causality.

Red Fel, I am sorry, but this post is getting long and the conversation is moving on without me. I will respond to your post in a later post of mine.