Imaginary numbers are turning true in quantum physics.

(Above) An illustration of the complex number z = x + iy on the complex plane. The real part is x, and its imaginary part is y.(Wikipedia/Complex numbers)

The mode of complex number is z = x + yi. The term yi is an imaginary part of a complex number. There are theoretically no limits in the number of those imaginary parts. And that is the description of the pure complex number. If the imaginary part is 0 the number is a so-called imaginary number. 

There are many times made mistakes with complex and imaginary numbers. An imaginary number is the square root of a negative number or zero. So imaginary number is the complex number that the real part is zero. Normally is impossible to take the square root from a negative number but if a negative number is part of the complex number there is an answer. 

The complex numbers are also imaginary numbers but sometimes the complex number whose imaginary part is zero is mentioned as imaginary numbers. And complex numbers whose imaginary part is bigger than zero (i>0) are pure complex numbers. In quantum physics that imaginary part is needed for calculating the quantum states. 

The imaginary numbers are in use because there must be an answer for the formula sqrt(-a)= i(sqrt)-a   (sqrt)=square root

There i is an imaginary unit that implements the equation i=-1^2. 

The imaginary numbers are created because they are offering the answer to the equation  x^2+a=0 if a>0

"In mathematics, a complex number is an element of a number system that contains the real numbers and a specific element denoted the i, called the imaginary unit, and satisfying the equation i2 = −1. Moreover, every complex number can be expressed in the form a + bi, where a and b are real numbers. Because no real number satisfies the above equation i was called an imaginary number by René Descartes". (Wikipedia, Complex numbers)

"For the complex number a + bi, a is called the real part, and b is called the imaginary part. The set of complex numbers is denoted by either of the symbols {\displaystyle \mathbb {C} }\mathbb {C}  or C. Despite the historical nomenclature "imaginary", complex numbers are regarded in the mathematical sciences as just as "real" as the real numbers and are fundamental in many aspects of the scientific description of the natural world" "Wikipedia ´, Complex numbers", 

Complex numbers allow solutions to all polynomial equations, even those that have no solutions in real numbers. More precisely, the fundamental theorem of algebra asserts that every non-constant polynomial equation with real or complex coefficients has a solution which is a complex number. For example, the equation {\displaystyle (x+1)^{2}=-9}{\displaystyle (x+1)^{2}=-9} has no real solution, since the square of a real number cannot be negative, but has the two nonreal complex solutions −1 + 3i and −1 − 3i.

"An imaginary number is a complex number that can be written as a real number multiplied by the imaginary unit i,[note 1] which is defined by its property i2 = −1.[1][2] The square of an imaginary number bi is −b2. For example, 5i is an imaginary number. And its square is −25. By definition, zero is considered to be both real and imaginary". (Wikipedia/ Imaginary numbers)

This is a great day for quantum physics and mathematics. The complex numbers are turning real numbers that have a purpose in the real world. Researchers need Those numbers for calculating the quantum states of the material. And at least those numbers that have the "extra" or "imaginary" part are turning to "real numbers". 

In regular mathematics, a number has a certain place in number straight. But the complex number has two places in the coordinate system. Or the complex numbers can have many places in the 3D coordinate system. The number of the positions of complex numbers depends on the number of imaginary parts of the number. 

In most examples, there is only one imaginary part in complex numbers. But nothing limits the number of those parts. The problem is that the 3D coordinate system is impossible to draw on the 2D layer. 

https://www.sciencenews.org/article/quantum-physics-imaginary-numbers-math-reality

Complex numbers. https://en.wikipedia.org/wiki/Complex_number

Imaginary numbers: https://en.wikipedia.org/wiki/Imaginary_number#:~:text=An%20imaginary%20number%20is%20a%20complex%20number%20that,is%20considered%20to%20be%20both%20real%20and%20imaginary.

Image:https://en.wikipedia.org/wiki/Complex_number

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