Quantum physics is what I call a “religious science.” It's a science that puts us in direct contact with the strangeness and grandeur of the universe. It puts us directly at the boundary of what is knowable, and what is not.
It is also a “useful science.” It promises technology that will create billion-or-trillion dollar industries.
What “quantum” means
Quantum means “in parts.” When scientists started working with tiny things like electrons and photons, they witnessed unintuitive behaviors, which they called “quantum” behaviors. These behaviors did not fit into the model of the world we had come to know.
For example, our old model says that objects have well-defined properties, like position, and that we can measure that position at all times. However, we found that electrons don't act like that. They act like they are not in a set location at all. They can have far-reaching effects that prove they act more like a cloud than a particle. Scientists coined this a superposition, because it is a concept that goes beyond a “position.”
Across the next 50 years, scientists incorporated these observations into a brand new model of the universe. This model is actually more lenient, so it allows things we didn't think were possible. For example, it doesn't require electrons and photons to have a definite location, orientation, or velocity.
This new model turned out to be significantly more accurate than the old one.
Quantum has since taken over physics. At the largest physics conference in the world, the 2025 APS Global Physics Summit, over 75% of the exhibitors were related to quantum.
What quantum unlocks
Now, the fruits of 100 years of progress in quantum mechanics are coming to fruition. New quantum technologies are hitting the market that can break many assumptions we held about the world. Here are a few examples.
Microscopes
We assumed there was a limit to the smallest object we could see with normal light. Ernst Abbe coined this the diffraction limit. To see any smaller, we had to invent electron microscopes, and even these have their own limits.
We now know that this limit does not hold if we can control individual photons. The invention of entangled light photography has applications in biological imaging and more. [cite]
Computers
We assumed there was no way to factor large numbers. In fact, we built our modern cryptography on this assumption.
We now know that computers based on electron spins instead of voltages are expected to be able to factor large numbers with ease.
Manufacturing
It was thought that some kinds of molecules could never be made, since they cannot be formed by natural reactions.
However, quantum manufacturing allows us to place atoms in exactly the right locations, allowing us to create chemicals we never dreamed of!
Three foundational concepts
Quantum has just three foundational concepts:
- Measurement
- Superposition
- Entanglement
In the following guides, you'll learn about each of these fundamental concepts in depth.