Someone recently suggested that since people like to use mine cart tracks to create their own roller coasters, it would be a good idea to add upside-down and vertical mine cart tracks. CheesyXbox, who made the suggestion on Reditt, said that these tracks could be created by inserting a slime ball to make the mine tracks sticky, and thus, let the user stick to a vertical and upside down surface.
The topic became controversial, even though it didn't get very much views. One person agreed, one person said that underpowered rails would do the job, and someone else wrote a long reply explaining why it would not work.
Acsheu's argument was that for vertical tracks, you will need to have two rail blocks occupying the same block space, which will not and does not work. To explain what would need to happen for it to work, we would need to have more underwater content, because water takes up block space. Acsheu said that if you make a horizontal and vertical tack piece combined one look, you will basically end up with a sloped track block, but with a different look and mesh. Even though Acsheu does not believe that vertical tracks are possible, he is in the opinion that upside down tracks could work, if minecarts were attached to tracks, which they are not.