Quantum physics is insane. It is the weirdest thing in the whole universe. It is so weird that, as one physicist put it…
“those who are not shocked when they first come across quantum theory cannot possibly have understood it.”
Niels Bohr
But what does “quantum physics” even mean? Roughly speaking, quantum means “the smallest possible unit.” That is why it has the same root word as “quantity” or “”quantify.” So, to keep things less confusing, replace the phrase “quantum particle” with “really tiny thing”. Quantum physics is the study of the tiniest things in the universe.
With that cleared up, let’s dive headfirst into even more confusion. Here are four of the most insane facts that physicists have discovered by throwing maths at each other.
1 Virtual Particles: Tiny things that pop in and out of existence at random
We like to think that “empty space” is empty. It isn’t. Empty space is full of energy. And a pair of particles will pop into existence out of that energy, quite randomly. One of those particles is made of matter, and the other is made of antimatter.
Antimatter is a confusing subject too. There are many explanations available online, but they are hard to follow. For now, all you need to know is that if they touch each other they explode and disappear.
A billionth of a second or so after they appear, virtual particles will crash into each other and cease to exist. We did say that quantum physics is insane.
Virtual particles appear to violate a big assumption from classical philosophy: everything that exists needs to have a cause. Still, that is not the only assumption that we have had to throw out the window because of quantum physics…
2 Superposition: The smaller something is, the more likely it is to be in several places at once. Yep, quantum physics is insane
Imagine a person is standing in a dark room. When you turn on the light, you see where the person is. But until you turn on the light, you don’t know where they could be.
Now let’s imagine that the person is very small. If you started flipping the light switch on and off really fast, they would usually be in the same spot each time. But sometimes they wouldn’t.
One flip of the switch could put them in the middle of the room, and another flip could put them in the corner. Before you hit the light switch, they are everywhere in the room at the same time.
Not convinced yet that quantum psychics is insane? Check this out:
Location is a set of different probabilities that all exist at the same time. Before a quantum particle is measured (and forcing it to choose a location), it is in a state of “superposition”. That is, it exists between all probable locations. The set of locations that something will probably exist in gets smaller the larger the “something” is.
3 Quantum Tunnelling: Tiny things can teleport
Let’s go back to the person in the dark room. That person can be in a different place each time you turn on the light. But if you fenced off a corner of the room, they could still appear in that corner if you flipped the switch enough times.
Although they are usually on one side of the wall, they are sometimes on the other side. From your perspective, it would look like they teleported through the wall.
Just like superposition, big things are not as likely to teleport as small things. Quantum tunnelling is when something randomly jumps from one side of a barrier to the other between measurements.
4 Quantum psychics is insane: Entanglement means tiny things can communicate faster than light
Picture two hills. Each hill has a person on it. The fastest possible way for those people to communicate is by using a flashlight. This is because light is the fastest thing in the universe.
Now imagine that the hills and the people are really small. The people shook hands before climbing the hills. For this exercise, this means something that affects one person will immediately affect the other.
If you were to walk up one hill and slap the person, the other person would immediately feel it too. This would be true even if the hills are 10 billion miles away from each other.
Albert Einstein hated the idea that information could travel instantaneously. He dismissed the notion as “spooky action at a distance”. He thought that there were hidden variables. Variables which would explain this without breaking the universe’s speed limit.
However, John Bell came up with an ingenious experiment to test “spooky action at a distance” against Einstein’s competing theory. He found that Einstein was wrong. Particles that are “entangled” can communicate faster than light.
A few different ideas have been floated to explain entanglement, including wormholes and the many-worlds interpretation of quantum physics.
It is not yet clear if either of these insane ideas is true. For now, we can sit back and take a moment to appreciate that quantum physics is insane. Including the counterintuitive ideas that quantum physics has discovered as true within the last century.
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