What are the postulates of quantum mechanics? I need simple answer without much maths and symbols.
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Postulates of QM in simple terms without much maths and symbols. Postulate 1:- Every physical state of a system can be only given using a probability value associated with it. This is given by what is called a wave function. Postulate 2 :- Two systems will have a connection (formally called...
read more Postulates of QM in simple terms without much maths and symbols. Postulate 1:- Every physical state [e.g position] of a system [e.g electron] can be only given using a probability value associated with it. This is given by what is called a wave function. [The 5th postulate is mixed here for a clearer picture of wave function] Postulate 2 :- Two systems [eg: 2 electrons...say one in Mars the other on Earth] will have a connection (formally called quantum entanglement) even if they are not nearby. Measuring a state of an electron on mars might change the value of the electron here if we have their composite (combined) wave-function. Postulate 3 :- For every measurable quantity of a system, there is a way to modify that state [using something called operator] and get a corresponding final value [called eigen functions and values] which may either be discrete or continuous. Postulate 4 :- How a quantum state changes with time can be predicted using a very specific kind of operation [formally known as unitary operator]. Postulate 5:- Finally the most important finding. All measurements and predictions of observable quantities are only probability based and cannot be carried out with 100% accuracy. One can only expect a value for the measured quantity and not be absolutely certain about its real value. read less
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Santosh Nishad
IIT Educated and well experienced experts selecting only a few highly motivated and ambitious students
Postulate 3. In any measurement of the observable associated with operator , the only values that will ever be observed are the eigenvalues , which satisfy the eigenvalue equation If A is an operator which operates on a wavefunction f and yields the value "a" without altering the wavefunction then we...
read more Postulate 3. In any measurement of the observable associated with operator , the only values that will ever be observed are the eigenvalues , which satisfy the eigenvalue equation If A is an operator which operates on a wavefunction f and yields the value "a" without altering the wavefunction then we have A (f) = a (f) Such an equation is called an eigenvalue equation. Postulate 4 speaks about how to find the average value of an observable. This is pretty mathematical. Postulate 5 The wavefunction or state function of a system evolves in time according to the time-dependent Schrödinger equation Postulate 6 This is just Pauli 's Exclusion Principle The total wavefunction must be antisymmetric with respect to the interchange of all coordinates of one fermion with those of another. Electronic spin must be included in this set of coordinates. Hope this helps read less
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Santosh Nishad
IIT Educated and well experienced experts selecting only a few highly motivated and ambitious students
The fundamental postulates of quantum mechanics are 1. The state of a system is completely described by a wavefunction. Every wave must have something wavy about it and Erwin Schrodinger took this to his heart and described matter waves mathematically by a wave function. This is analogous to...
read more The fundamental postulates of quantum mechanics are 1. The state of a system is completely described by a wavefunction. Every wave must have something wavy about it and Erwin Schrodinger took this to his heart and described matter waves mathematically by a wave function. This is analogous to the function describing waves on a string. Once u know the wave function of a string u can find out any information about velocity, acceleration etc by taking suitable derivatives. Wave function for matter waves is used analogously. 2. To every observable in classical mechanics there corresponds a linear, Hermitian operator in quantum mechanics. Hermitian operators guarantee that whenever one does any measurement on a wavefunction using an operator, then if the operator is hermitian one will get real numbers as the observed value. Imagine u applie differential operator on a wave equation of vibrating string and got a complex number for velocity then such a velocity is not observable in our experiment. Therefore it will be nice if our differential operator was hermitian so that we get real numbers as oir expected values for measurements represented by the operator. read less
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Ishmeet Kaur
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The state of a quantum system is represented by a wave function Principle of superposition. The wave function for two independent systems is the product of the wave functions for the two systems.
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1.Associated with any particle moving in a conservative field of force is a wave function which determines everything that can be known about the system. 2. With every physical observable q there is associated an operator Q, which when operating upon the wavefunction associated with a definite value...
read more 1.Associated with any particle moving in a conservative field of force is a wave function which determines everything that can be known about the system. 2. With every physical observable q there is associated an operator Q, which when operating upon the wavefunction associated with a definite value of that observable will yield that value times the wavefunction. 3. Any operator Q associated with a physically measurable property q will be Hermitian. 4. The set of eigenfunctions of operator Q will form a complete set of linearly independent functions. 5. For a system described by a given wavefunction, the expectation value of any property q can be found by performing the expectation value integral with respect to that wavefunction. 6. The time evolution of the wavefunction is given by the time dependent Schrodinger equation. read less
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Rajagopalan Nair
Physics and Maths made easy
It is impossible to express postulates of quantum mechanics without mathematics. This is because, the state of a quantum mechanical particle and the act of making a measurement on the particle changing its state cannot be explained in terms of any visualizable pictures. All the pictures of physical processes...
read more It is impossible to express postulates of quantum mechanics without mathematics. This is because, the state of a quantum mechanical particle and the act of making a measurement on the particle changing its state cannot be explained in terms of any visualizable pictures. All the pictures of physical processes we have are in terms of waves and particles which prevail in our domain as macroscopic (compared to relatively microscopic molecules, atoms, electrons and other fundamental particles) beings and we use also macroscopic apparatus recording results in terms of macroscopic physical interactions. Werner Heisenberg realized microscopic particles involving in such physical activities where Planck's constant is not a small number (mind you, an electron used in e/m experiment by J J Thompson behaved classically) cannot have their dynamical features expressed in terms of waves and particles like pictures. If those pictures are not possible, the only way to express their behaviours in the mentioned limit is with mathematics. You may kindly refer (1) Physics and Philosophy and (2) Physical Principles of Quantum Mechanics, both by Werner Heisenberg. After that, you may also try to answer the question by Merzbacher in his book titled Quantum Mechanics which goes: 'To what velocities should an electron be slowed down to have a de Broglie wavelength 1 m? Are matter waves of such proportions a reality?' Hope what I recommend in this regard will satisfy you. read less
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The postulate that energy exists in small discrete quantity or pockets or quantum necessitated a new branch of physics called quantum mechanics. In dealing with matter, matter is made up of a number of fundamental particles. Similarly energy is also made up of a small particle called quantum. Naturally...
read more The postulate that energy exists in small discrete quantity or pockets or quantum necessitated a new branch of physics called quantum mechanics. In dealing with matter, matter is made up of a number of fundamental particles. Similarly energy is also made up of a small particle called quantum. Naturally , the mechanics that involve quantum and particles of matter cannot be the same as applied to macroscopic matter. The study of quantum and matter particles and their interaction is called quantum mechanics. read less
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Career Group Institute Chd.
Naturally , the mechanics that involve quantum and particles of matter cannot be the same as applied to macroscopic matter. The study of quantum and matter particles and their interaction is called quantum mechanics
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Pankaj Kumar
Headstart to assured 95+ score in math
Please refer NCERT texts.
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Kumar upendra Akshay
Math Educator for Std.11th ,12th , Engineering Entrance and Degree Level with 11+ Years Experience
Quantum refers to the quantity. The postulate that energy exists in small discrete quantity or pockets or quantum necessitated a new branch of physics called quantum mechanics. In dealing with matter, matter is made up of a number of fundamental particles. Similarly energy is also made up of a small...
read more Quantum refers to the quantity. The postulate that energy exists in small discrete quantity or pockets or quantum necessitated a new branch of physics called quantum mechanics. In dealing with matter, matter is made up of a number of fundamental particles. Similarly energy is also made up of a small particle called quantum. Naturally , the mechanics that involve quantum and particles of matter cannot be the same as applied to macroscopic matter. The study of quantum and matter particles and their interaction is called quantum mechanics read less
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