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Old 03-03-2020, 11:49 AM   #121
Polkageist
 
Join Date: Sep 2007
Default Re: Coolant [Spaceships]

Eh, I still maintain that the correct answer to "Why aren't people smashing ships into planets when they disagree over lunch?" is "Because we're not playing genocide simulator the RPG."

Anyway, another neat toggle to reactionless-ish drives is that they have some sort of 'drag' that happens on spacetime. It would pay off the many examples in fiction of a spaceship needing to both 1) be under thrust always, and 2) have an upper speed limit.

The drive itself 'drags' on spacetime (or the ether, or the local gravity well, or whatever) such that if the ship isn't thrusting the drive and the ship it's connected to will decelerate down to a relative stop in whatever medium it's dragging against, which can conveniently be a nearby planet or something. And, because this means now that there's a drag component to moving through space, there's a top-speed of a sort that can apply to a given ship.

Endless possibilities on cool ship designs or nifty engine gadgeteering to reduce drag, or maybe mess with an opponent's ship say with an anchor-missile that when it hits a ship attaches an etheric anchor that kills a ship's velocity. Maybe even drags the engine out the back, that'd be a cool (weird, spectacular) way to disable a spaceship.
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Old 03-03-2020, 01:42 PM   #122
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Default Re: Coolant [Spaceships]

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Well, that depends on whether certain formulas are actually complete. Since the break in causality is represented by negatives or square roots of negatives occuring in the formulas, it may just be that the formulas are incomplete (lacking absolute functions). Unfortunately, this is quite difficult to test, as we will not know if formulas are incomplete unless someone actually stumbles upon FTL and, since everyone would 'know' that FTL is impossible due to the incomplete formulas, it is highly unlikely that any would receive sufficient funding to do the necessary research anyway.
The classic saying is "FTL, Causality, Special Relativity. Pick two." Relativity, as we understand it, makes FTL equivalent to time travel. It becomes possible (even with just sending FTL messages) to interfere in events you've already seen take place. One example I have seen is destroying an enemy ship before it launches the missile you just saw destroy your ally.
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Old 03-03-2020, 01:48 PM   #123
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Default Re: Coolant [Spaceships]

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Well, that depends on whether certain formulas are actually complete. Since the break in causality is represented by negatives or square roots of negatives occuring in the formulas, it may just be that the formulas are incomplete (lacking absolute functions).
Incorrect. Break in causality does not require resolving any of those negative numbers, because all that's required is a signal moving FTL, it doesn't actually matter what physics is like while moving FTL, just that it's possible and allows for a FTL message (if information content is reduced to zero by traveling FTL, the causality problem goes away but it's also rather useless).
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Old 03-03-2020, 02:39 PM   #124
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Default Re: Coolant [Spaceships]

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(if information content is reduced to zero by traveling FTL, the causality problem goes away but it's also rather useless).
Now I'm tempted to have a disintegrator weapon that is the result of experiments trying (and failing) to create FTL travel...

Now, it is possible to avoid the causality problem and maintain most of special relativity (I think) while having FTL, but it requires a "nature abhors a time machine" clause. lwcamp's Vergeworlds setting does it with artificial wormholes. Basically, any time two wormholes would interact in a manner that would violate causality, the "weaker" of the two collapses and ceases to exist the moment before that would be the case (presumably, if the two are somehow of absolutely equal "strength," which fails is random). I assume this violates some aspect of special relativity, but most of it is retained.
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Old 03-03-2020, 03:50 PM   #125
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Default Re: Coolant [Spaceships]

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Incorrect. Break in causality does not require resolving any of those negative numbers, because all that's required is a signal moving FTL, it doesn't actually matter what physics is like while moving FTL, just that it's possible and allows for a FTL message (if information content is reduced to zero by traveling FTL, the causality problem goes away but it's also rather useless).
You can't really send a signal with no information (at least not in a way that can be in any way meaningful), since merely receiving a signal or not is itself information. One beep for yes, two for no.
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Old 03-03-2020, 04:21 PM   #126
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Default Re: Coolant [Spaceships]

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You can't really send a signal with no information (at least not in a way that can be in any way meaningful), since merely receiving a signal or not is itself information. One beep for yes, two for no.
Well, you can as long as the recipient cannot determine whether the signal has been sent. The reason quantum entanglement isn't FTL communication is because you can't actually use it to communicate.
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Old 03-03-2020, 05:04 PM   #127
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Incorrect. Break in causality does not require resolving any of those negative numbers, because all that's required is a signal moving FTL, it doesn't actually matter what physics is like while moving FTL, just that it's possible and allows for a FTL message (if information content is reduced to zero by traveling FTL, the causality problem goes away but it's also rather useless).
Casualty is only violated if the message arrives before it is sent (not before the light of the location it is sent from hits the location). Light is a record of the past, not a reflection of the present.
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Old 03-03-2020, 05:13 PM   #128
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Casualty is only violated if the message arrives before it is sent (not before the light of the location it is sent from hits the location). Light is a record of the past, not a reflection of the present.
Yes, but it only has to arrive before it was sent in some frame of reference.
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Old 03-03-2020, 05:31 PM   #129
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Casualty is only violated if the message arrives before it is sent (not before the light of the location it is sent from hits the location). Light is a record of the past, not a reflection of the present.
Given the peculiarities of relativity, it's easy to experience an event before the cause occurs in your frame of reference, but as long as you are limited to the speed of light, it's a novelty - since the delay to reach the cause will always be greater than the discrepency in observed timing. Combined with the ability to escape your future light cone (i.e. FTL) it allows you to ignore causality.
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Old 03-03-2020, 05:36 PM   #130
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Default Re: Coolant [Spaceships]

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Casualty is only violated if the message arrives before it is sent (not before the light of the location it is sent from hits the location). Light is a record of the past, not a reflection of the present.
Pretty certain violating casualties is a war crime. *checks International Humanitarian Law* Yep, there it is, Rule 113.

More seriously, if you have special relativity and FTL, it's possible to set things up so that a message can arrive before it's sent. The wormholes from lwcamp's setting give a good example (or would, if that universe didn't have that pesky "nature abhors a time machine" natural law). Build two connected wormhole gates; keep one on Earth and send the other on a 0.99c ride (which you can manage fairly easily, as you can keep supplying it with reaction mass via your side of the wormhole, and have it throw its exhaust back through your wormhole) relative to Earth. This will create significant time dilation; keep it going for a while, turn it around and kill velocity, then bring it back. If the time dilation effect means the other side of the wormhole is 1 year in the future, you now have a gateway to Earth one year in the future; even if you never pass another atom through the wormhole, future-you can easily tell you via radio what stocks did well, which team won a given sporting event, etc, which is pretty much the definition of a message arriving before it was sent.

Now, I'm not certain how to get a time machine out of some FTL schemes, but it is apparently possible. For my Harpyias setting, FTL communication is only possible by carrying the message on a physical ship, which transition to hyperspace to travel FTL to eligible systems (essentially, hyperspace can only be entered or exited around stars with certain properties; our sun isn't one of them, so Earth is largely cut off from the rest of the setting). I'm not entirely clear how to build a time machine out of that premise, but I don't doubt someone could come up with such a scheme.
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