The Universe Doesn’t Make Sense (And That’s Kind of the Point)
I just watched Brian Cox explain quantum physics for 22 minutes and my brain feels like it got reset. Not in a bad way - more like that moment when you realize everything you thought you knew about reality was just the tutorial level.
Here’s the thing that gets me: we’re not talking about some abstract philosophy anymore. This shit is real. We’re building computers with it.
The Quantum Coin That Breaks Your Brain
Okay, so you know how a coin is either heads or tails? Simple, right?
Now forget that. Throw it out. Because quantum mechanics says a particle can be both at the same time. Not “we don’t know which one it is” - it literally IS both. An electron can be 30% spin-up and 70% spin-down. Or any other combination you want.
And here’s what fucked me up: these aren’t probabilities because we lack information. Like when someone says “there’s a 50% chance of rain tomorrow” - that’s just admitting we don’t have all the data. But in quantum mechanics, the probabilities are fundamental. The universe itself is running on probabilities at its core.
Think about that for a second. Reality itself is probabilistic. Not deterministic. The cosmos is basically running on dice rolls at the quantum level, and everything we see emerges from that.
That One Experiment That Explains Everything
Cox talks about the double slit experiment - and apparently Feynman’s explanation in his lectures is so good that physics textbooks basically just say “go read that” and call it a day.
The setup is simple: shoot electrons through two slits, watch where they land.
What should happen: the electrons go through one slit or the other, you get two clusters of hits on the detector. Basic particle behavior.
What actually happens: you get an interference pattern. Stripes. Light, dark, light, dark. The exact pattern you’d get from waves interfering with each other.
Now here’s where it gets weird - you still get that pattern when you send the electrons through one at a time. Which means each individual electron is somehow going through both slits simultaneously, interfering with itself.
Not “we don’t know which path it took” - it explored both paths. At the same time. Every possible route from point A to point B, including the one where it flies off to Andromeda and back.
And yes, physicists actually believe that now. This isn’t just math, it’s a description of reality.
Einstein’s Problem (Which Turned Out to Be Real)
Quantum entanglement bothered Einstein so much he wrote a famous paper about it in the 1930s, basically saying “this can’t be right.”
Here’s what happens: you can link two particles in a special way. Let’s say you’ve got two electrons in a state that Cox describes as “up-down plus down-up.” Now you separate them - one stays on Earth, one goes to Pluto.
When you measure the Earth electron and find it’s “up,” the Pluto electron is instantly “down.” Not because you learned new information - the system itself configures instantaneously. Faster than light could travel between them.
Einstein hated this. It seemed like magic. Like the universe was breaking its own rules.
Turns out the universe was fine with it. Experiments confirm it’s real. Someone even got a Nobel Prize for proving Einstein’s objections were wrong. Nature is just that weird.
Why This Matters (Beyond Blowing Your Mind)
Cox makes a point I think gets lost sometimes: quantum mechanics used to be this philosophical thing physicists argued about. Does it matter what it all means if we can just calculate the right answers?
Now we’re building quantum computers. And those things run entirely on these weird properties.
A quantum computer with 100 qubits can exist in 2^100 different states simultaneously. That’s more configurations than you can easily comprehend. By the time you get to 500 qubits, you need more numbers to describe the system than there are atoms in the observable universe.
These aren’t hypothetical devices. Companies are building them right now. They’re physically about the size of this room, and they’re tapping into this massive computational space that exists in the quantum realm.
For certain problems, they could do calculations that would take a classical computer longer than the age of the universe.
The Part That Actually Keeps Me Up
Cox emphasizes something important: the rules are the same everywhere. There isn’t a different physics for the quantum world and our everyday world. It’s all the same physics.
Our everyday experience - the solid desk, the definite positions of things, the apparent flow of cause and effect - emerges from this probabilistic quantum foundation. And we understand pretty well how that emergence happens.
Which means reality itself is built on something that fundamentally doesn’t match our intuitions about how the world should work.
And we’re not just philosophizing about it anymore - we’re using it. We’re building technologies that only work because of quantum superposition and entanglement. The weird shit is becoming practical shit.
I don’t know if that makes it more or less unsettling. But it’s definitely more real than I ever thought it would be.
If you want to go deeper, Cox strongly recommends the first two chapters of Feynman’s Lectures on Physics, Volume 3. Apparently it’s the definitive explanation of the double slit experiment and it’s freely available online. I might have to check that out, because this rabbit hole just keeps getting deeper.