Is the universe all about predictable matter where everything is in linked in a chain of cause and effect, one that is independent and oblivious to your observations? Or rather, as Niels Bohr posited in his famous 1927 Copenhagen Interpretation, until this universe is measured it exists as a conglomerate of infinite possible universes?
When Bohr first made his thoughts public, a lively debate ensued among the greatest physicists in the world. Albert Einstein was among the most vocal critics of the theory, but when he and his colleagues set out to disprove Bohr's impossible dictum by highlight a paradox in Bohr's hypothesis, they actually sort of confirmed it. I'm talking about 'spooky action at a distance' or quantum entanglement -- the quantum mechanical phenomenon in which the quantum states of two or more objects have to be described with reference to each other. You can only measure one tangled particle and by doing so you cause a change in the properties of the other paired particle instantaneously -- meaning it happens faster than light. Quantum entanglement isn't some mere philosophical quirk. It's real and proven, as scientists showed just last week when they teleported information over 7 kilometers.
This episode from PBS' amazing Space Time series does an amazing job explaining what the whole debate is all about and which of the two, Einstein or Bohr, got it right. More than eighty years later, the debate is still ongoing. If anything, quantum physics is weirder than ever and the true nature of the universe likely lies somewhere in between both interpretations.