Quantum entanglement is a quantum mechanical phenomenon in which the quantum states of two or more objects have to be described with reference to each other, even though the individual objects may be spatially separated.
I find this to be a fascinating topic. The best way to describe these two “entities” is to think of them as being part of the same function.
The strangeness of the quantum world is that these functions (often thought of as waves) exist within a domain. Within this domain, the quantum “particle” is said to existing only in terms of probability rather than in definitive terms. In the Cartesian world of modeling, we expect to see a particle exist at location x,y,z at time t. In the world of the very small, those quantum particles have a probability of existing at that location. In reality there could be multiple location at which a particle can exist (having the same probability). The quantum weirdness says that the particle exists in all of those location at the same time. In entanglement, the distant particle is a superposition of the other (I am using distance as relative to the observer). The act of observing a quantum system causes it to collapse into a finite particle/state.
Matter as Particles and Waves
Quantum Physics says that matter exists as particles and waves. A particle, much like a marble, can be observed as being in a single location (x,y,z) at a certain time (t). The de Broglie hypothesis states that all matter has a wave-like nature. At the quantum world of the very small, this can be seen through the famous “double split experiment”.
Double Split Experiment
With Quantum Physics, the mechanics of the physical word that Newtonian Physics model define are suddenly redefined.
The Newtonian model is deterministic, that is to say that everything can be determined if we understand all the variables that are in play. In a real sense, Newton’s system of equations can be used to define everything that will happen in the Universe in a predetermined sense. The very actions that we take are a result of physical systems responding to a biochemical process involving synaptic electrical network engaging biological responses (though a series of predictable pathways). In this sense, everything that we experience, do or observe is predetermined by an elaborate matrix of equations.
Quantum mechanics throws a wrench into this non-volitional cosmos by introducing a truly random nature at the very fundamental building blocks of all Creation. The attributes of these quantum elements, these tiny sub-atomic particles that make up all of matter and transfer energy, are ultimately unpredictable. The attributes of these particles are said to exist as probabilities. There is a probability that a electron surrounding the nucleus of an atom would exist at a particular orbit (atomic orbitals). The Heisenberg uncertainty principle says that even when we know one attribute of a quantum particle (e.g. the location of an electron) one of the other attributes will remain completely uncertain (e.g. the momentum).