The one wrong "assumption" that all quantum physics is based upon
There is a major hidden assumption that underpins most modern quantum mechanics.
It is an assumption in the sense that there is absolutely nothing to
scientifically or experimentally support it. It is such a basic assumption that
it is presumed to be beyond needing to be justified and most everyone fails to
realize that it is a completely unsupported assumption.
"It is assumed that space and time is infinitely divisible."
This assumption is made through the mathematics of quantum physics which "assume" that point charges are infinitely small points with no actual radius and no ponderable surface. This seems to be a relatively harmless assumption, but when taken to extremes, produces obvious absurdities.
For example, if space is infinitely divisible, an arrow should never reach it's target by Zeno's paradox. This is because the arrow has to travel half way to the target, then it has to travel half again and so on. Because space is infinitely divisble, the arrow will have to take an infinite number of such steps and this would prevent the arrow from ever hitting its target. This is obviously absurd.
This exact same problem is encounted in the calculations of quantum physics which attempt to sum up a series of ever smaller terms which end up adding up to infinity. The result of which is the calculation for a point particle as having infinite inertia. The way this is solved is through a process called Renormalization, which is basically saying something like 4*infinity divided by 2*infinity is 2. This is an ad hoc band-aid for quantum physics and still doesn't at all address why the calculations are fundamentally flawed in the first place.
The way out of these infinities is to make the opposite assumption which is:
"It is assumed that space and time come in fixed amounts."
In this case, space is not infinitely divisible. There is a "smallest" amount of space and time possible. If you are summing terms, you will eventually get to the point where you have reached your size limit and there are no other terms to add, which would avoid the infinity problems.
Space would be like a pile of sand. You could divide the pile in half again and again. But eventually you will get to a single grain which cannot be divided and you must stop. I think our intuitions tell us this is how the world works. If we accept this intuition rather than accepting the absurdity of infinite divisiblity, then we can start working on solutions which make "real" sense instead of accepting the band-aid of renormalization.