Quantum objects make up classical objects. But the two behave very differently. The collapse of the wave-function prevents classical objects from doing the weird things quantum objects do; like quantum entanglement or quantum tunneling. Is the universe as a whole a quantum object or a classical one? Artyom Yurov and Valerian Yurov argue the universe is a quantum object, interacting with other quantum universes, with surprising consequences for our theories about dark matter and dark energy.

1. The Quantum Wonderland 

If scientific theories were like human beings, the anthropomorphic quantum mechanics would be a miracle worker, a brilliant wizard of engineering, capable of fabricating almost anything, be it a laser or a complex integrated circuit. At the same token, this wizard of science would probably look and act crazier than a March Hair and Mad Hatter combined. The fact of the matter is, the principles of quantum mechanics are so bizarre and unintuitive, they seem to be utterly incompatible with our inherent common sense. For example, in the quantum realm, a particle does not journey from point A to point B along some predetermined path. Instead, it appears to traverse all possible trajectories between these points – every single one! In this strange realm the items might vanish right in front of an impenetrably high barrier – only to materialize on the other side (this is called quantum tunneling). In the quantum realm the two particles, separated by miles or even light years, somehow keep in touch via the link we call quantum entanglement. And, of course, we cannot talk about the quantum Wonderland without mentioning that a quantum object might (and usually does) exist at a few different places at the same time. For example, when we think about an electron in the hydrogen atom, we are tempted to imagine it as a small satellite swiftly rotating around a heavy atomic nucleus. But this image is all wrong! Instead, we have to try and imagine an electron simultaneously existing in infinitely many places all around the nucleus. This fascinating picture is called an electron cloud, and we know for a fact that it is a correct picture. We know this because the identical objects coexisting in a few different places produce a physical phenomenon known as interference, which is physically observable in a lab. The fact of these observations proves two things at once: first, that the physicists who study quantum mechanics have not gone completely mad (their relatives might disagree on this one), and secondly, that physical machinery of our universe defeats even the most unbridled human imagination.

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With all that in mind, it is quite natural to feel relief at the thought that no matter how strange the quantum laws are, they are safely confined to the realm of atoms and molecules, and simply cannot be encountered in normal everyday life. How precious it is to be able to lay on a sofa with no worries that it might suddenly dematerialize from underneath you at the most inopportune moment… Speaking of which, why doesn’t your sofa have any inclination to suddenly tunnel over the wall of your room? And what prevents a piece of apple pie from being entangled with the rest of the pie? We know that both the pie and the sofa are formed by lots and lots of atoms interacting with each other. So why do these atoms abide by one set of laws, while the pies and the sofas obey a very different legislation?