Observables in Quantum Mechanics

In this video, I talk about observables in quantum mechanics. Observables are Hermitian operators whose eigenvalues are real and representation of a physical value. These eigenvalues and eigenfunctions live in Hilbert space which is a vector space itself. In the next video I'll talk about statistical interpretation of quantum wavefunctions and we'll see how we can derive physical concepts from this mathematical framework.

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In this series of videos I'm going to share some information about quantum physics based on the amazing book "Quantum Mechanics" by David J. Griffiths.

Quantum Physics playlist:

[Folorunsho]

I have a question.
At 0:58 you defined some hermitian operator acting on a ket vector and equate it to another expression where it's acting on a bra functional
How are they equal?
I thought putting it in a bra changes it completely.