They don't even have it aboard 29th century timeships. The Aeon pootles along at warp in Future's End.
Do they even
need conventional propulsion in the 29th century? The Aeon was able to go from 29th Century to where Voyager was located in the DQ in the 24th Century. It was also able to transport Voyager from 20th Century Earth to the 24th Century DQ without problems. Janeway specifically asked if Braxton would just transport Voyager to the 24th Century AQ, and while he said he could he wouldn't due to the Temporal Prime Directive.
Also, the Aeon was basically a one-man shuttlecraft. We never really saw the capabilities of a full size starship like the USS Relativity, apart from its time abilities. The USS Relatively was able to transport people across multiple time periods and locations. If you're able to transport people to any place, any time, conventional travel becomes pretty moot.
Spock's jellyfish ship in the reboot doesn't have it (even when getting to Hobus was a priority!)
IIRC Spock's craft came from the year 2387, and "Endgame" occurred in 2378. No one is saying that the moment Voyager appears, the Feds have slipstream/transwarp drive. It could take years or even decades before they have the ability to design a ship, let alone build it.
Besides which, if you want to go by the continuity of
those movies we get into issues like Khan having tech that was able to transport him from Earth to Qu'nos, and warp travel appearing to be much faster than what we see in the "regular" universe.
The renegade Q states that it will be another century (2472) before humans will reach the Delta Quadrant, apart from Voyager.
To be specific:
Q: "What have you done now, Q? Well now, isn't this just fine? Humans aren't supposed to be in this quadrant for another hundred years!"
Quinn: "I didn't bring them here. Nothing to do with me!"
This is another instance of "humans are doing things that the Q didn't expect". Remember that Q made a similar remark in "Q-Who" when he complained that the Federation was exploring and expanding faster then the Q were anticipating. Well, Voyager was there, so clearly he was wrong. An odd thing to say given that he's supposedly omnipotent.
It's not like that means much anyways. There was several times in the show where Voyager was "supposed" to have been destroyed, but that didn't stop them from changing the timeline did it? Voyager was also "supposed" to take longer to get back to the AQ, but that didn't stop Future Janeway from altering things so they got back in 7 years. After what appearing to destroy the Borg, no less. Imagine the changes to the timeline
that caused. If they are able to alter time that radically, it's certainly possible that Voyager's return could change things and open up the DQ sooner than it "should" have.
It's not on the Defiant or mentioned in DS9's future episode (The Visitor) in the future.
Alternate timeline, plus Jake was trying to re-create the exact events which led to the accident, and having an entirely different type of propulsion system would make that rather difficult, wouldn't you think?
What is it about Trek that makes people go 'reverse engineering will totally happen?'
Because that happens
quite a bit in Star Trek. Again, the Voyager crew was able to create a working Slipstream drive within days of encountering the "USS Dauntless" and without any evidence of exotic parts and materials being used. Why do you think Utopia Plantia would fail to do any better, especially after getting all of Voyager's research and prototypes? I'll admit the second Slipstream drive they built could pose a much bigger challenge, since it was exponentially faster and was explicitly stated to require exotic materials / tech.
And usually only that the Federation will be the ones doing it.
Never said that, though the Federation might have a head start with whatever tech Voyager brought back, since it
was their ship afterall(surprise!)
Regardless, every canonical future timeline features warp as the predominant method of propelling federation starships for centuries to come.
Do we actually
see how starships usually travel in future timelines? The only instance I can think of where we saw ships in action for any significant length of time was in ENT, where we saw the final battle against the Sphere builders in the 26th century. That doesn't actually help us though because like most Star Trek battles, the battle appeared to take place in normal space.
This is getting rediculous. Demonstrate the adapatation of slipstream in the future, when we see various future episodes where it is not in evidence, using canon sources, or concede people.
There is little evidence to suggest
what forms of propulsion are being used, other than by the 29th Century Federation tech had reached the point where apparently a one man shuttle can form rifts to cross the galaxy and/or travel in time, and take other starships along with it. Also, by the 29th Century full-size starships like the USS Relativity could apparently send people across space / time to a point of their choosing. By the 31st Century it appeared as though time and space travel could be done with hand-held devices.
Just to nail the coffin lid shut on this thing.
The Federation's fastest ship went to warp, not slipstream.
If that's the Federation's fastest ship at time that's pretty damn sad seeing as it was
outrun by a freighter. Does the dialog actually state that it was the fastest ship in
Starfleet? Was its max warp ever stated on screen? My understanding was that it was the fastest ship the Vulcan Science Academy had at the time, and at least according to the movie's website and the novelization I recall it's max speed being warp 8. YMMV on whether or not you want to take the novelization or the movie website as canon, though that doesn't contradict anything we see on screen.
And again, in any event there was only 9 years between "Endgame" and when Spock's ship headed to Romulus. It's certainly possible that Starfleet hadn't been able to crack the Slipstream drive tech by that point in time, or the first vessels were only in the planning phase.
It would make sense for there to be some intermediate steps taken between the 24th-29th centuries, and using the Quantum slipstream may have been one of them. But according to you, nothing happened for 500 years, then the Feds were suddenly able to go from conventional warp travel to building starships that could cross the galaxy and/or time travel at will. Sure.
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