There is at least one effort claiming 1G acceleration out of their propellentless device.
At 1G constant acceleration, Pluto is reachable in just over 17 days.
No dark matter/energy required. With already available power sources.
And that's where one-way mission cryo-sleep comes in.
I can see a 1G being achieved with a propellent, but sustaining & actually increasing in speed seems unlikely without a propellent.
To me it sounds like science fiction, but since it is not my field I may be missing something. In other words, I am not saying it is impossible, but rather if possible, how is it possible. It doesn't seem that space objects increase their acceleration rates.
We have been taught that space is a vacuum, meaning there is no air resistance or friction to slow down or speed up objects. Which we see with comets that seem to move at a constant speed and movement that they can be predicted as to when they will once again pass by us, which indicates that there is something that makes their movement controlled by some source, wouldn't it?
“At 1G constant acceleration, Pluto is reachable in just over 17 days.”
The distance from Earth to Pluto varies. But let’s use the approximate average of 6 billion miles. It would take 11.5 days to travel half this distance with a constant 1G acceleration. Then, you would need to slow down at this rate for another 11.5 days. So, it would take roughly 23 days...
Unless you just want to flash right on by Pluto.