How to become an expert in physics and from where should i start ?
Go to college with a good physics department.
They say to become an expert i should'nt start from scratch rather should i start from expert stage!
So, before becoming an expert, you must start out as an expert?
I see no problems with this logic. Carry on.
....and study physics.
This is moved to academic guidance, but the OP needs to demonstrate that this is a serious thread.
You don't. You may eventually become an expert in some small sub-field of physics afters many years of study.
Like others have said, enroll in university majoring in physics, graduate, enroll in graduate school, graduate, apply for post docs, complete them, apply for professorships or apply to industry, work. Then maybe you'll become an expert in some small area of physics.
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