Information in Physics How physics gives information a very different meaning

Information is not a single idea but a concept viewed in different ways across different disciplines. Physics offers yet another perspective, treating information not as meaning or knowledge but as a description of physical reality. Seeing this distinction helps us avoid confusing very different uses of the same word.

When we talk about information in everyday life, we usually mean something that informs us. A book contains information. A conversation conveys information. A database stores information.

But in modern physics, the word often means something quite different.

One of the most famous puzzles in physics is the black hole information paradox. According to classical thinking, anything that falls into a black hole disappears forever. If that were true, the information describing the object would also be lost. Yet quantum theory strongly suggests that information cannot simply vanish.

Here, information does not mean meaning, knowledge, or a message. It refers to the complete physical description of a system, the information needed, in principle, to distinguish one physical state from another. The debate is about whether that physical information is somehow preserved, perhaps encoded on the black hole’s event horizon, rather than destroyed.

This is very different from Gregory Bateson’s idea of information as “a difference that makes a difference,” where information depends on a system noticing and responding to a distinction. It is also different from the knowledge management view, where information is something people read, share, and interpret.

It is perhaps closest to Claude Shannon’s concept of information. Shannon deliberately ignored meaning and focused instead on the number of possible states that could be distinguished or transmitted. Black hole physics is concerned with a similarly abstract notion of distinguishable physical states, although it asks very different questions.

John Archibald Wheeler took the idea a step further with his famous phrase it from bit, suggesting that physical reality itself may ultimately be grounded in information. Whether that bold idea turns out to be correct remains an open question.

What fascinates me is not which definition is right, but how many different meanings we attach to the same word. Information can mean knowledge, meaning, difference, uncertainty, or the physical state of the universe itself. The challenge is to be clear which sense we are using, because these are related ideas, but they are certainly not the same.

As we explore information in different contexts, we can become more careful about what we mean by the word. Rather than assuming there is one correct definition, we can ask which perspective best fits the situation. That simple habit helps us think more clearly and communicate with greater precision.