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)