What did Schrödinger call his cat?

Question

It’s your stubborn weight that never seems to change.
And how fast you are? Going in a specific direction.
Move without any vows—it all boils down to.

So the real kid who karates,
Steal 1200 from him.
A stone which defined it, began with it.

The snakes hissing within verse,
with deer without are;
it’s time.

What did Schrödinger call his cat?

Answer 1

It’s your stubborn weight that never seems to change.
And how fast you are? Going in a specific direction.
Move without any vows—it all boils down to.

Weight that never changes is mass, and speed in a specific direction is velocity. These quantities are usually represented by $m$ and $v$, which is also what's given by the third line: "move" without any vow(el)s is $mv$. In physics, mass times velocity is momentum, usually represented by $p$, which I think is the final answer for this verse.

So the real kid who karates,
Steal 1200 from him. One German stone—
the one who A stone which defined it, began with it.

The actor who plays the Karate Kid is apparently Ralph Macchio, and 1200 in Roman numerals is MCC, so we're left with $ahio$? Also MCC equates to $mc^2$, and "One German stone" is clearly Einstein; both of these give the letter $E$, which I think is the final answer for this verse.

The snakes hissing within verse,
with an accent “The”; with deer without are;
it’s time.

Snakes hissing suggests the letter S; with "in verse" gives $S^{-1}$. (Thanks to the OP for help in chat with this one.) An accented "The" is surely "Ze", so maybe $Z$ (with the US pronunciation "zee")? OK, it was "De" or $D$, also given by removing the R from "deer". So we have $S^{-1}D=T$, time, which is also given directly by the final line.

So the solution is

PET ($P, E, T$ from the three verses)

which makes sense given the question.

Answer 2

After reading Rand al'Thor's answer and making a few minor adjustments

I get E=MCC

then continuing on i am finally left only with

C

The cats' name was

Light