Maybe not a typical riddle, but here it is:
I can travel from there to here by disappearing, but I can also travel from here to there by appearing.
What am I?
What is that which can travel from there to here by disappearing
From our point of view, it goes from West to East by disappearing
but it has that special ability to travel from here to there appearing.
From our point of view, it goes from East to West in plain sight
It sounds like a
I can travel from there to here by disappearing, but I can also travel from there to here by appearing.
It sounds like this is describing quantum entanglement, where a particle will exist simultaneously in both locations until observed. When you observe one particle, the other paired particle's spin will be determined based on that observation. The reverse is also true.
This is my second approach. My previous answer pointed at something about we cannot say is invisible at all (as title suggests).
The better match is:
Lower air pressure or low tide.
It is invisible because:
Air is almost transparent. Although you can observe low tide living seaside but obviously you cannot see it, when you travel by ship.
It travels from there to here by disappearing:
When air/water flows towards us, the lower pressure/tide disappears.
It travels from here to there by appearing:
Opposite by analogy. :)
I highly doubt this is what you had in mind, but something that behaves like this is
A local change of a variable or a quantity in a system that tends to a global equilibrium.
In a physical system this could be e.g. pressure or temperature. If for some reason there appears a local change in, say, pressure (positive or negative), the change "travels" from here to there, i.e. the magnitude of the local difference in pressure decreases where it appeared and the magnitude of the pressure difference increases everywhere else, as the system tends to a new equilibrium.
Thinking about it the other way around,
if the "original" change suddenly disappeared (i.e. the reverse happens) the change would "travel" from there to here as the system again tends to the "original" equilibrium.
As an example:
For some reason a local pocket of overpressure appears: the system tends to a new equilibrium by distributing the pressure evenly, thus introducing overpressure (relative to the "original" state) everywhere else. Then at the same location a pocket of underpressure of equal magnitude to the earlier change is formed (meaning the overpressure "disappears" locally): the system tends to the original equilibrium by redistributing the pressure and thus the overpressure travels from everywhere else to "here".