One of the strangest things about physics is that it quietly assumes something incredibly basic: that events actually happen. A detector clicks. A particle lands. A reaction completes. These moments feel so obvious that we rarely question them. But what if they aren’t just outputs of physics… what if they are the very thing that makes physics possible in the first place?
That’s the idea behind this new work. Instead of treating definite outcomes as the result of physical laws, the paper flips the logic: it shows that without definite outcomes—what I call physical facts—you don’t get time, and you don’t get laws. You don’t even get a physical world in any meaningful sense. You just get a space of possibilities with nothing actually happening inside it.
Time Needs Something to Happen
We usually think of time as something that flows independently of events. But if you look closely, time only becomes meaningful when something changes in a definite way. To say one moment comes “after” another, something has to be different—and that difference has to stick. If everything were perfectly reversible, if nothing ever settled into a definite state, there would be no real distinction between past and future.
The paper shows that the arrow of time—the fact that time has a direction—requires at least some events to be genuinely irreversible. Those irreversible events are exactly what we mean by physical facts: moments where the universe commits to one outcome and leaves a trace behind.
Laws Need Something to Be True
The same idea applies to physical laws. A law is only meaningful if it can, in principle, be right or wrong. But that requires something definite to compare it against. If every possible outcome remains equally “real,” then nothing ever actually happens, and there is no way to say whether a law is satisfied or violated.
In other words, laws don’t just describe possibilities—they describe what does happen. And that means there must be facts: definite states of the world that can serve as the truth-makers of those laws.
A Deeper Question: What Is a Physical World?
The key step in the paper goes even deeper. It shows that any theory that claims to describe a world—not just a set of mathematical possibilities—must distinguish between what is merely possible and what is actually realised. Without that distinction, you don’t have a universe—you have a catalogue.
Once you accept that, everything else follows. To realise one possibility rather than another, the universe must:
- distinguish it from alternatives
- commit to it
- and retain it in some stable way
Those three requirements are exactly what define a physical fact.
From Facts to Physics
Put it all together, and you get a striking conclusion:
If a universe has time and is governed by physical laws, it must be fact-producing.
Not as a feature. Not as an accident. As a requirement.
Even more interestingly, this leads to three structural constraints on any such universe:
- there must be a minimum scale of distinguishability
- every fact must leave an irreversible trace
- and there must be a finite capacity for how many facts can exist in a given region
These aren’t arbitrary assumptions—they fall out of the requirement that facts must exist at all.
Why This Matters
This shifts the way we think about physics at a very fundamental level.
Instead of asking:
“What laws govern the universe?”
we’re led to ask:
“What has to be true for there to be laws—and time—and a world at all?”
The answer, according to this work, starts with something deceptively simple:
The universe must be able to settle on what is actually the case.
And that—when you strip it back—is what a physical fact is.