# What if the laws of mathematics were different in a parallel universe? [duplicate]

Mathematics is the base of everything. What would happen if the laws of mathematics would be differend in an universe? How would the universe work, what would be the laws of physics, etc...

Examples for different laws of mathematics:

2+2=3

a/a=3

pi is 42.51243

-5 is greater than 5

etc...

• Well, 1 + 11 = 111 in unary! :-) It's not clear what you're asking. Math can be used to describe the physical universe. But math does not define the physical universe. In other words, math follows physics, not the other way around. (Even theoretical physicists look to verify their equations experimentally) Your question would be possible to answer if you put it in terms of different physical constants, or physical properties of the universe (such as, say, hyperbolic geometry, or different gravitational constant (G)). – type_outcast Jan 10 '16 at 10:52
• Also much of mathematics is provable and not arbitrary (for instance, there are proofs available that negative numbers are less than positive numbers). It is not necessary to take your teacher's word on those relations. I would go farther than type_outcast and say our math is a function of (defined by) our Universe. – Jim2B Jan 10 '16 at 17:57

Laws of mathematics are actually theorems derived from axioms according to a few simple rules of logic. The mathematics taught in school are mostly based on a few very common sets of axioms, but university-grade mathematicians are aware that different axioms lead to different theorems.

• A famous example is the difference between Euclidean and Non-Euclidean geometry.
• Another example would be arithmetic with the numbers on a clock. Two hours after 11 o'clock it is 1 o'clock, twelve hours after 11 o'clock it is 11 o'clock again.

These "different mathematics" all exist in our universe, insofar as one can talk about existence in this context. We select the right model for the purpose.

Most of your examples are not "laws" as mathematics understands them, which makes them difficult to assess.

• 2+2 = 3 means 1 = 0. If you want to do arithmetic, 0 is your only number.
• a/a = 3 means 1 = 3. That's a cyclic group.
• Pi is not an axiom.
• -5 > 5 means you simply switched the symbols > and <.