How quantum physics is understood?

[Akash Divakar]

How quantum physics is understood?
I am wondering what the heck is quantum physics.
I love physics in that classical way in high school, but seeing the equations of quantum physics there is fear in my mind . Is it possible for me to understand each and every concept and derive equationas I learned in classical physics?

Help me out!

 

[Alloymouse]

How quantum physics is understood?
I am wondering what the heck is quantum physics.
I love physics in that classical way in high school, but seeing the equations of quantum physics there is fear in my mind . Is it possible for me to understand each and every concept and derive equationas I learned in classical physics?

Help me out!

Hi, I am scared of complicated equations too, but I found google quite helpful, specifically sites like KhanAcademy and random channels on youtube that can explain QM in a less-mathematical way, or at least at a pace where you can digest the math.

The big thing about QM is that the way things behave are more of a chance than an absolute - you're more likely guessing than giving a "correct" or "certain" answer. Starting off with wave particle duality, Schrödinger's cat, and the quantum mechanical model of an atom can help ease you into this weird and uncertain realm of physics :)

Have fun!

 

[DrClaude]

Nothing beats a good textbook to start learning. Depending on your level, I would suggest a book like McIntyre's, which has a states-first approach (instead of starting with the wave function), which is a softer approach from the mathematical point of view. Another good choice is Susskind.

However, rederiving classical physics from QM takes a bit more knowledge, so don't expect to do that at the very beginning.

 

[Urs Schreiber]

The key idea of that relates quantum physis to classical (statistical) physics is this:

A state of a classical (statistical) system is equivalently an assignment of the corresponding expectation value $\langle A\rangle$ to each classical observale $A$. Quantum physics is the result obtained from this picture simply by allowing the algebra of observables to be non-commutative.

This perspective is sometimes called quantum probability. It seems to go back to Irving Segal back in the 40s, see Segal 65.
A good quick introduction is Gleason 09.

This is the route to enlightment in quantum physics. Every other route leads to confusion.

 

[justpassinby]

I started out learning about quantum physics by watching a few videos on YouTube. Even if you don't understand it, try to watch the whole high and then, afterwards, reflect on what you learned. Then, just research more about whatever interested you. I got very interested in the theory of relativity so I researched about it a lot on Google, YouTube, Wikipedia etc. I started learning the advanced theory of relativity (I think that's what it's called). I was also intrigued by the Schrödinger equation and, believe it or not, at 13 years of age, I actually understood the basics of the equation. It's faded by now but by just watching a few videos and researching about it, I'm sure I can get it to resurface in my head. Main point, use the internet. It's so useful and gives us opportunities we've never had before so use it to it's full potential.

 

[Urs Schreiber]

This perspective is sometimes called quantum probability. It seems to go back to Irving Segal back in the 40s, see Segal 65. A good quick introduction is Gleason 09. (Hm, that server seems to be down at the moment. But there is Google's http://webcache.googleusercontent.com/search?q=cache:OuSlqIpqnHgJ:www.math.uchicago.edu/~may/VIGRE/VIGRE2009/REUPapers/Gleason.pdf+&cd=1&hl=en&ct=clnk&gl=ae&client=firefox-b-ab).

There is also a recent texbook in this vein, freely available:

• Klaas Landsman,
  "Foundations of quantum theory – From classical concepts to Operator algebras",
  Springer Open 2017
  (pdf)

 

[vanhees71]

How quantum physics is understood?
I am wondering what the heck is quantum physics.
I love physics in that classical way in high school, but seeing the equations of quantum physics there is fear in my mind . Is it possible for me to understand each and every concept and derive equationas I learned in classical physics?

Help me out!

Don't worry about math. Math is your friend (not only in physics). I don't know, why math has such a bad reputation. My suspicion is that it's, because at high schools they call something math which is the opposite of what math really is, namely a way to think and solve problems.

Quantum theory is, of course, difficult in the beginning, but it's not for the math but because it is often appears to be contrary to "common sense" or "intuition", but that's only because we are used to the behavior of macroscopic many-body systems which behave classical (in everyday life you usually deal with matter, which you can describe with classical Newtonian mechanics), but as quantum theory teaches us this is only an emergent phenomenon which, given the atomistic structure of matter, can only be understood in terms of quantum theory.

To get unafraid about it, and unfortunately there's no other way to understand it than to use math, I recommend to have a look at

https://www.amazon.com/dp/0465062903/?tag=pfamazon01-20

 

[ZapperZ]

How quantum physics is understood?
I am wondering what the heck is quantum physics.
I love physics in that classical way in high school, but seeing the equations of quantum physics there is fear in my mind . Is it possible for me to understand each and every concept and derive equationas I learned in classical physics?

Help me out!

Help you out? In what way?

If you are going to major in physics, then I do not understand this panic attack. The curriculum will provide a sequential and systematic series of courses leading up to having you understand the subject material. There are a series of steps that you have to take to get there. After all, you didn't panic the day you were born that you couldn't run the 100 meter sprint, did you? You will learn to crawl and climb, and stand up and get your feet to work together to finally walk, and then maybe run, and so on. Similarly, you should not expect to be able to pick up a QM text and be able to not only understand the equations, but also comprehend the concepts. I mean, why should you? Do you have similar expectations when you pick up a book on heart surgery?

If you are simply trying to understand this as a hobby, and at the level of a layman, then there are many pop-science books out there to start you off. But be aware that you will only have a glimpse of what it is. You'll only see a shadow of the animal, rather than the animal itself. This is true of any subject that is meant for general audience understanding. One should not be delusional into thinking that this is all there is to it on the subject matter.

Zz.