Question

Can you explain why Eindtein never accepted Heisenberg’s uncertainty principle ???

Answer 1

Einstein's never accepted Heisenberg's Uncertainty Principle, which states that for an arbitrary accuracy it is not possible to measure both the position(x) and the momentum(p) of a particle simultaneously .

But Einstein's said If someone measures the position of a particle, the particle is disturbed, so its momentum changes. If it's impossible to measure those two things at once, how can they be defined together?  

In 1935, Einstein explain the problems with quantum mechanics which shows that how position could indeed be measured without disturbing the particle.

Further he states that Quantum entanglement of two particles which describes by quantum wave function cannot be mathematically factorised into two separate parts, one for each particle which is the important consequence and they become connected in a "spooky" kind of way which was made clear by Einstein's arguments and the experiments that followed.

Einstein, Podolsky and Rosen (EPR ) Collectively realised that in quantum mechanics which predicted entangled states of two particles which are far apart from each other does not matter but the positions(x) and the momenta(p) for two particles are perfectly correlated.

This was important for Einstein, who believed the result of anything that was done to the first particle did not have immediate disturbance to the second particle which he called as "no-spooky-action-at-a-distance". Thus,Einstein never accepted Heisenberg's uncertainty principle as a fundamental physical law.

The Heisenberg uncertainty principle (HUP) and the Einstein theory of relativity do not merge. Or, they “merge” only when there is no relative motion between the event and the observer. In other words, the HUP holds only as the non-relativistic extreme of the relativistic uncertainty principle.

It is common misunderstanding that the HUP is relativistic “because” its derivation involves the Lorentz-invariant commutator between the momentum operator and the position operator––but the “because” neglects the relativistic correction, as required, for the wavefunction of the quantum state (in the Robertson inequality).