This is new for me so sorry if i am missing something, thanks for any helpful pointers.
So I was thinking about this classic equation $E=mc^2$
Then I was, why is there $c^2$. I found it is just expression of units in the equation. And from this another question popped in my mind (maybe unrelated).
I found that we do not know if speed of c is same in all directions and i started thinking, if there is any possibility if this $c^2$ can be something like $\sqrt{c^4}$ with something hidden we do not know yet.
Like if in more dimensional numbers (complex, quaternions), or some other situation when you can add some "hidden number" or be in different numeric "world" when the equation $x^2 = \sqrt{x^4}$ will be not true.
I am really interested if there is any possibility of this and I would like to study it.
If $x = i$ then
$x^2 = -1$
$x^4 = 1$
$\sqrt{x^4} = 1$
$x^2 \ne \sqrt{x^4}$
This answer assumes that the $\sqrt{}$ symbol always yields a positive number if such a number is available.