# Help on Quantum Mechanics

1. Sep 19, 2010

### jswu1996

Hello,

While other's on this site are probably considerably older than myself, as I am only a grade nine student, I came across a book about special and general relativity, quantum mechanics and string theory. The book is "The elegant universe" by Brian Greene. Anyways, I was very interested and a friend of mine and I had many conversations about the topics, but I was not understanding many things; quantum mechanics. For starters, what is the difference between quantum mechanics and quantum physics? What does "quantum" even mean? And eventually, how does quantum mechanics work? What does it state? What does it prove? I get so confused. Is it because of my age? Or can I only understand the theory when I begin to learn the calculations of the theory and not just the general idea of it?

James

2. Sep 19, 2010

### Kevin_Axion

Quantum Mechanics, Quantum Physics and Quantum Theory are different names for a single underlying theory obeys these criteria:

Postulate 1: State of a system A system is completely specified at any one time by a Hilbert space vector.
Postulate 2: Observables of a system A measurable quantity corresponds to an operator with eigenvectors spanning the space.
Postulate 3: Observation of a system Measuring a system applies the observable's operator to the system and the system collapses into the observed eigenvector.
Postulate 4: Probabilistic result of measurement The probability of observing an eigenvector is derived from the square of its wavefunction.
Postulate 5: Time evolution of a system The way the wavefunction evolves over time is determined by Shrodinger's equation.

(http://en.wikipedia.org/wiki/List_of_elementary_physics_formulae)

I wouldn't expect you to understand what any of these definitions mean which is in direct correlation to your immature knowledge.

I'm not sure if the book would an excellent investment since you most likely haven't had a formal Physics class. There is much information that can be used to understand these concepts online : http://en.wikipedia.org/wiki/Introduction_to_quantum_mechanics

Quantum means discrete or extremely small quantity. It's fine if you don't understand it especially if your in grade 9. In the words of Richard Feynman "I can safely say that nobody understands Quantum Mechanics."

Last edited: Sep 19, 2010
3. Sep 19, 2010

### jswu1996

whoa, was that an insult?

anyways, i think the book is pretty good

and thank you for the website and definitions

4. Sep 19, 2010

### Kevin_Axion

No, it wasn't an insult, people usually interpret immature as an inability to comprehend or fully understand, what it really means is you're knowledge comprehension of the world hasn't "ripened" enough to understand the implications. It stands the same for everyone person of your age and even mine.

5. Sep 19, 2010

### jswu1996

I see...

Thank you for the websites anyways