Quantum physics has forced scientists to rethink what the universe is made of. What if matter and energy are only part of the answer?
For most of human history, asking what the universe is made of seemed like a question about substances.
Ancient philosophers proposed earth, water, air, and fire. Later physics replaced those ideas with atoms. Atoms were divided into electrons and nuclei, nuclei into protons and neutrons, and those particles into still more fundamental ingredients.
The natural assumption has always been that if we look deeply enough, we will eventually discover the smallest pieces of reality. But quantum physics introduced another possibility. What if the deepest description of the universe is not about things at all? What if it is about information?
Think about an ordinary computer.
A photograph, a song, a video game, and a paragraph of text seem completely different to us. Inside a computer, however, all of them can ultimately be represented using information.
The physical hardware matters, but the same information can exist on many different kinds of hardware.
A photograph can be stored on a phone, copied onto a hard drive, transmitted through a fiber-optic cable, or stored somewhere across the world.
The information survives even as its physical representation changes.
Quantum physics makes this distinction between information and physical objects much stranger.
Imagine two quantum particles that have interacted and become entangled.
Afterward, neither particle can always be described completely on its own. The most complete description belongs to the pair.
The information is stored in their relationship.
This is deeply different from the way we usually imagine reality.
We naturally think of the universe as a collection of objects, each carrying its own properties.
An electron is here.
Another electron is there.
Each object should have its own independent description.
Entanglement tells us that nature does not always work that way. Sometimes the relationship between two systems contains information that cannot be reduced to a simple list of properties belonging separately to each one.
At the quantum level, relationships may be just as fundamental as objects.
This raises a surprisingly difficult question:
What does it mean for something to be real?
Consider a quantum particle before it is measured.
Quantum mechanics does not always assign it one definite classical property waiting to be discovered. Instead, the theory describes a range of possible measurement outcomes.
When a measurement occurs, we obtain information.
But physicists have argued for nearly a century about what exactly happened.
Did the particle already possess the answer?
Did the act of measurement create a definite outcome?
Did the observer become entangled with the system?
Do all possible outcomes occur in different branches of reality?
Quantum mechanics predicts experiments extraordinarily well.
What those predictions tell us about reality itself remains much less obvious.
One of the most famous ways of expressing this puzzle came from physicist John Archibald Wheeler.
He suggested the phrase:
“It from bit.”
The idea was deliberately provocative.
An “it” is a physical thing: a particle, field, object, or event.
A “bit” represents information.
Wheeler wondered whether the physical world we observe could ultimately emerge from something more closely related to information, questions, and possible answers.
Today, quantum information science has transformed that philosophical idea into something scientists can actually investigate.
A qubit demonstrates how unusual physical information can become.
Unlike an ordinary classical bit, quantum information can exist in superpositions. Multiple qubits can become entangled. Quantum information cannot generally be copied perfectly. Measuring it can change what we are trying to observe.
These are not merely strange rules invented for quantum computers.
Quantum computers work precisely because those rules already exist in nature.
In that sense, building a quantum computer is almost like interrogating the universe about the rules it uses to store and manipulate information.
Every qubit is a small experiment about what information is physically allowed to be.
Black holes make the question even stranger.
Suppose information falls into a black hole.
According to quantum mechanics, information should not simply disappear. But classical descriptions of black holes once appeared to suggest that information entering them could become permanently inaccessible.
This became the famous black hole information paradox.
For decades, physicists including Stephen Hawking have debated what happens to that information.
The question may sound abstract, but its implications are enormous.
If information can truly be destroyed, one of the foundational principles underlying quantum physics would need to change.
If it cannot be destroyed, then our understanding of black holes and perhaps spacetime itself must somehow preserve it.
The study of black holes eventually produced an even more extraordinary idea.
Some theoretical work suggests that the amount of information associated with a region of space may be connected not to its volume, but to its boundary.
That observation helped inspire the holographic principle: the possibility that the physics inside a region could, in some sense, be described by information encoded on a lower-dimensional boundary.
Imagine describing everything happening inside a room using information written entirely on its walls.
The real proposal is far more mathematical and subtle, but the philosophical implication is remarkable.
Space itself might not be as fundamental as it appears.
Entanglement may offer another clue.
In several areas of modern theoretical physics, researchers have discovered deep connections between the structure of quantum entanglement and the geometry of spacetime.
That has inspired an extraordinary possibility:
Perhaps spacetime is not the stage on which quantum physics takes place.
Perhaps aspects of spacetime emerge from quantum relationships underneath it.
If that idea is correct, the familiar picture of reality becomes almost inverted.
Instead of objects existing at locations and then becoming entangled, patterns of quantum information might help determine what it even means for locations to exist in relation to one another.
None of this means that physicists have discovered that the universe is literally a computer.
That comparison can easily be taken too far.
Information still requires physical systems. Quantum information theory does not prove that reality is a simulation, nor does it mean that atoms are secretly made from ones and zeros.
The deeper lesson is more interesting.
Physics increasingly treats information not merely as something humans write down about physical systems, but as something constrained by the laws of physics themselves.
Nature determines whether information can be copied.
Nature determines how much information can be extracted from a quantum system.
Nature determines how information can spread.
Nature determines whether information can apparently disappear behind a black hole.
Information has become a physical concept.
This also changes the way we can think about quantum computing.
The goal of quantum computing is often described simply as building faster computers.
But there is another way to see it.
A quantum computer is a machine built specifically to manipulate information according to the deepest rules we currently know about nature.
Classical computers reduce information to ordinary bits.
Quantum computers force us to work with superposition, entanglement, measurement, uncertainty, and the limits nature places on what can be known or copied.
That makes quantum computing more than an engineering challenge.
It is one of the rare technologies whose operation forces us to confront philosophical questions about reality itself.
For centuries, physics progressed by asking:
What is everything made of?
Atoms.
Particles.
Fields.
Perhaps strings.
Those remain enormously important questions.
But quantum physics has added another:
What information can the universe contain, and what can it do with it?
Maybe information is simply another useful language for describing matter.
Or perhaps future physics will reveal that information, entanglement, space, and matter are pieces of a much deeper structure that we have not yet learned how to describe.
We do not know.
And that uncertainty is precisely what makes the question interesting.
The next revolution in physics may not come only from discovering a new particle or building a larger quantum computer.
It may come from understanding what a physical world actually is when, at its deepest level, objects can no longer be separated from the information connecting them.
Maybe the universe is made of particles and fields.
Or maybe those are what information looks like from the inside.