CAUSAL MEMORY IN PHYSICS

Prologue: The Zeroth Law of Reality

A Hidden Line of Order  Guiding Insight
Physics appears diverse, yet its patterns of change follow a single
logic. To see it is not to invent new laws, but to notice a structure that
was always present.
Instantaneity never appears in nature.
Every system takes time to update itself. Heat requires duration to
spread. Light requires duration to travel. A particle requires duration to
respond. A black hole requires duration to ring down.
This quiet fact—so obvious that it escapes attention—will guide the
entire book.
We will read physical theories through one axis: the causal memory
scale, τc
.
This parameter measures how long a system must “settle itself” before
it can update its state. It is not a correction. It is not a technicality. It
is the structural parameter that unifies heat conduction, quantum mass,
and gravitational ringdown into a single line of order.
The present is never instantaneous.
It is always a window—however brief—through which the past
shapes what comes next.
When we restore this window to our equations, physics simplifies.
Disconnected phenomena align. Apparent paradoxes dissolve. A quiet
unification appears.
This book is an invitation to see that structure.

—Y.L., Bangkok, 2025