Jim Al-Khalili explains in a TED talk: robins may fly south in winter due to a process called 'quantum entanglement.' Image Source: Digital Photographer / Michael Williams.
Destiny and faith should be foreign concepts in the realm of science. But perhaps quantum physics will devise a formula for them. This possibility started in the 1930s, with Albert Einstein (1879-1955) and Niels Bohr (1885-1962) arguing whether or how objective reality could be measured, because observing something changes its nature into what we would call a subjective reality. Of course, the distinction between objective reality - which religious people sometimes associate with God - and subjective awareness - the world limited by our individual perceptions - is a very old problem. The 16th century French philosopher Michel de Montaigne (1533-1592) wrote: "We are, I know not how, double in ourselves, so that what we believe we disbelieve, and cannot rid ourselves of what we condemn." The central question of religion asks: how are we flawed and animal humans connected to the larger order of the universe? Science asks the same question.
Image Source: Archillect.
To determine if it was possible to measure objective reality, Einstein and Bohr proposed a thought experiment to measure one particle of light, or photon, without affecting it. To do this, they proposed to measure a second particle that was related to the first one, and infer the nature of the related, but unmeasured, first particle. Then they encountered a curious problem. Their measurement of the second particle affected the nature of the first one, but they could not determine how the impact of their actions had been transferred to the first particle, especially because that information traveled instantaneously, that is, faster than the speed of light, which violated Einstein's Theory of Relativity. The distance between the photons did not matter either. They could be close together or on opposite sides of the universe. Einstein did not like this. Wiki:
[I]f a pair of particles is generated in such a way that their total spin is known to be zero, and one particle is found to have clockwise spin on a certain axis, then the spin of the other particle, measured on the same axis, will be found to be counterclockwise; because of the nature of quantum measurement. However, this behavior gives rise to paradoxical effects: any measurement of a property of a particle can be seen as acting on that particle (e.g. by collapsing a number of superposed states); and in the case of entangled particles, such action must be on the entangled system as a whole. It thus appears that one particle of an entangled pair "knows" what measurement has been performed on the other, and with what outcome, even though there is no known means for such information to be communicated between the particles, which at the time of measurement may be separated by arbitrarily large distances. ...
The counterintuitive predictions of quantum mechanics about strongly correlated systems were first discussed by Albert Einstein in 1935, in a joint paper with Boris Podolsky and Nathan Rosen. ... They wrote: "We are thus forced to conclude that the quantum-mechanical description of physical reality given by wave functions is not complete." ...
In 2013, Chinese physicists clocked the speed of 'spooky action at a distance.' They proved the speed of information as it moves through quantum entangled states is more than four times the speed of light, or three trillion metres per second. Their research paper was published in Physical Review Letters, vol. 110, listed here.Following the EPR paper, Erwin Schrödinger wrote a letter (in German) to Einstein in which he used the word Verschränkung (translated by himself as entanglement) "to describe the correlations between two particles that interact and then separate, as in the EPR experiment." He shortly thereafter published a seminal paper defining and discussing the notion, and terming it "entanglement." In the paper he recognized the importance of the concept, and stated: "I would not call [entanglement] one but rather the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought."
Like Einstein, Schrödinger was dissatisfied with the concept of entanglement, because it seemed to violate the speed limit on the transmission of information implicit in the theory of relativity. Einstein later famously derided entanglement as "spukhafte Fernwirkung" or "spooky action at a distance."
Quantum entanglement. Image Source: Glitch.