A new model for faster-than-light travel that uses conventional physics

The issue isn't when the light arrived. The issue is that I can find a frame of reference where T2 < T1, that is, the actual events occurred in the other order. It's not when the light reached me. The problem is the time of the events themselves.

Again, though: how? Specifically: how would a third observer have any impact at all? He's an observer. Judging by that new Wikipedia article, the answer seems to be "well the observer will perceive events at different times from when they actually happened, and therefore two simultaneous lightning strikes weren't actually simultaneous because the observer didn't see them simultaneously", but I'm failing to see why we should be treating the observer's interpretation as fact: just because the observer perceived something at various times doesn't mean that's how they actually played out.

Further:

> It's no co-incidence that Alice and Bob in the Tachyonic antitelephone are moving with respect to each other, therefor with different frames of reference.

Are they, though? This seems to assume that their movement around and perception of each other is only happening through "normal" space, but the very premise of this discussion states otherwise: that they are communicating via a region of spacetime where their distance is fixed (or at least changing much more slowly than the relativistic speeds given in those Wikipedia examples). If Alice and Bob are talking to each other through a wormhole, for example, then through that wormhole they are (approximately) stationary, and therefore there'd be no significant time dilation as far as that communication is concerned.

Same deal if they're communicating via "miniature starship enterprises", as you put it. The very premise of a warp drive is to get an object from A to B without any actual movement from A to B - specifically by warping spacetime such that the distance from A grows and the distance from B shrinks. This therefore creates a pathway between A and B where they are effectively stationary relative to one another, specifically because the message is stationary relative to each of them. Therefore, messages conveyed on this pathway don't seem to leave any possibility of time dilation, and therefore no possibility of inverted causality.

Now, obviously I'm missing something here, but from what I can tell, the math checks out fine. And a lot of physicists who are not community college dropouts like I am seem to agree (or else they wouldn't be putting forward hypotheses involving warp drives and wormholes and such as a means to achieve superluminal communication without time-dilation-related effects).

Except that your notion of T1+t1 is already going to be different from any other (non-stationary) observer's, yes?

> I do a little math to calculate how long it took the light to get there (t1)

Doesn't this assume that light has a fixed speed? We know already that this ain't necessarily the case, even in a vacuum; there are plenty of things - like sufficiently strong gravity wells - that can slow down light considerably. And in the context of situations involving warp drives and wormholes and other things bending spacetime willy-nilly, that further throws a wrench in attempting to figure out how long it took light to reach you.

> and now I know what T1 is

More like you have a vague idea of what T1 should be, assuming a flat spacetime. My point is that spacetime curvature can already throw this out the window, and that it therefore doesn't seem like we should be taking that estimated departure time as fact.

That is: if how an observer is perceiving something is indeed what actually dictates reality, then I don't see how causality can actually exist in the first place, because different observers can perceive the same events in different sequences based on their relative movement. If causality is to exist at all, even under normal conditions, then it seems like it needs to be possible for observers to be wrong, no?

So maybe I need to ask this even more specifically:

> The issue is that I can find a frame of reference where T2 Okay, which frame of reference would that be? Under what conditions? By what mechanisms that would apply to literally all cases of superluminal communication (even ones explicitly formulated to avoid things like relativistic relative speeds upon which thought experiments like the tachyonic antitelephone depend)?

Which specifically describes coordinate transformations between two reference frames in motion relative to one another, right? My whole point is that in this context the reference frames are not (significantly) moving relative to one another - that relative movement is exactly what things like wormholes and warp drives are designed specifically to avoid.

So no, that doesn't clear up much at all, unfortunately.

To expand on that, because I still think we're talking past each other here:

> If causality is to exist at all, then 1) causal signals can't travel faster than the speed of light, and 2) neither can an observer.

Okay, which wormholes, warp drives, etc. seem to satisfy:

1. The causal signals - from the reference frames of the signal, sender, and recipient - are all moving such that v is less than c, because spacetime has been warped accordingly

2. In order to observe these signals, the observer would, too, have to be part of that system of warped spacetime (i.e. inside the wormhole, or in the path of our Alcubierre pigeon, or what have you). Otherwise, how would the observer actually see anything?

In any case, thanks for bearing with me here.

In my mind the "cascade of simplicity" occurred when I subconsciously realized that bullet-time mechanics could really occur is a multiplayer game. The player in bullet-time would experience higher tickrate that anyone else, meaning that anyone else would see them speeding away. There's more to make it possible in a simulation, but that's unimportant: you can reason about these scenarios. My reasoning maybe incorrect, but it does afford me the ability to approach these mind-blowing subjects.

Either way, it may be impossible for a subluminal observer to identify a superluminal apart from a warp traveller (aside from the former being outright impossible). The observation is identical, the cause is completely different.