A lot of science fiction technology concepts like FTL travel/time travel, teleportation and mind uploading look to be completely impossible BUT there are some speculative scientists and futurists who have at least out a drawing board for how these technologies might be hypothetically achieved. The Alcubierre drive, wormholes, Tipler cylinders, etc etc

Are there any sci-fi concepts where there is actually no possible pathway in science that can even remotely begin to start to try and create it?

A time yravelling DeLorean DMC-12, as modified by Dr Emmett Brown to travel in time, would be sweet.
But I'd settle for a hoverboard, the anti-grav scooter.

1 hour ago, Maximum7 said:

BUT there are some speculative scientists and futurists who have at least out a drawing board for how these technologies might be hypothetically achieved. The Alcubierre drive, wormholes, Tipler cylinders, etc etc

These are based on things that have never been observed to exist.

Are there any sci-fi concepts where there is actually no possible pathway in science that can even remotely begin to start to try and create it?

What is “even remotely begin to start”? People begin building perpetual motion machines. But they never get them to work.

1 hour ago, Maximum7 said:

Are there any sci-fi concepts where there is actually no possible pathway in science that can even remotely begin to start to try and create

A telekinetic arm. (e.g. Larry Niven's Gil Hamilton stories)

I don't see a Ringworld as being very practical. It seems to me anything as hard as "scrith" (the base material of Ringworld) would shatter if an object hit it hard enough to knock the whole thing out of orbit. However, as others point out there are lots of stories dealing with time travel, perpetual motion, and accelerating mass beyond the speed of light, in addition to materials that don't exist.

18 hours ago, npts2020 said:

I don't see a Ringworld as being very practical. It seems to me anything as hard as "scrith" (the base material of Ringworld) would shatter if an object hit it hard enough to knock the whole thing out of orbit. However, as others point out there are lots of stories dealing with time travel, perpetual motion, and accelerating mass beyond the speed of light, in addition to materials that don't exist.

I dimly recall an interview where Niven acknowledged that the RW concept had technical problems and a Dyson Swarm or similar would be more feasible. (Dyson was one of the ones who pointed out that neither shells nor rings would work) That said, as a teen who loved the Ringworld stories, it did make for a rich and fascinating setting, so there's a part of me that wants to imagine some ingenious techno solutions could somehow save the Ringworld. Could ramjet thrusters really keep a stable configuration? Could a real scrith have the tensile strength of the strong nuclear force (needed for the rotation speed of RW to maintain ~ 1G force)? Can the absence of plate tectonics and vulcanism allow a functional carbon cycle and longterm photosynthesis in an ecosystem? These issues, and more, all need really big patches. The second book, RW Engineers, applied some duct tape, but I'd have to reread it to recall all the details.

Ringworld !?!?

I just really really want a hoverboard ...

15 minutes ago, TheVat said:

Dyson was one of the ones who pointed out that neither shells nor rings would work

Do rings obey a type of "shell theorem"?

1 hour ago, MigL said:

Ringworld !?!?

I just really really want a hoverboard ...

You know, the older I get the less attractive the idea of a hoverboard becomes. But as swansont said, obviously you can speculate about virtually anything, but that doesn't make it even slightly feasible.

Ahhh, but you could make an EM hoverboard ... old man 😁 .

( although you can only use it on Monorails )

Edited October 6Oct 6 by MigL