I don’t know if this was real or not. The other day I saw a video where a stick shaped like a crawling snake was placed in the water and it swam upstream. If in fact this was real are there any know technologies that use this same principle? Either in water or air?
It is not real, it is pulled along by nylon line.
I was so hoping that was real I was imagining myself making arrows shaped like snakes for my flight shooting competitions
“Upstream” has no meaning in itself: The stream is moving relative to something else. So anything that’s interacting only with the water will just stay at rest relative to the water.
If you’re interacting with something other than just the water, though, such as the air, then you can, through clever design, get effects like this. For instance, I’ve seen a device that consists of a stick with a propeller at each end, and a float near (but not quite in) the middle, which will always propel itself in the direction opposite the wind: In still air, the stick would float vertically, but the wind tips it over, and then the wind causes the propeller in the air to spin, and that causes the propeller in the water to spin, which propels it.
If you had still air but moving water, then you could probably make a variant of this device (changing the relative sizes of the propellers) that would always go upstream relative to the air.
Of course, none of this would help with an arrow, which is only interacting with the air.
Do you live anywhere near an ocean? The tides, twice a day, can and do change the flow of rivers, streams, estuaries, and yes, something placed in the water on a flood tide can easily flow back upstream.
Tidal actions can reach surprisingly far inland.