You're touching on a real and often glossed-over subtlety in how angles are treated in physics and mathematics.
The standard claim: angles are dimensionless
In the SI system, the radian is defined as a derived unit with dimension 1 (i.e., dimensionless). The reasoning is:
where is arc length and is radius. Both have dimension of length, so their ratio is a pure number. Thus "angle" carries no independent physical dimension — it's length/length.
This is why you'll see angular quantities plugged into exponentials, sines, etc., and why has units of action (J·s) rather than action per radian.
Your view: angle as phase of a cycle
What you're describing is arguably the more operationally meaningful picture, and it's very common in physics:
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A full rotation = one full cycle = .
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An angular width is literally how far apart two things are in the cycle.
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In harmonic motion, is explicitly called the phase, and it's measured in radians.
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In interference/diffraction, phase differences are angular in nature.
So when you say "angular width is the phase distance from one side to the other," you're identifying angle with position within a periodic cycle — which is exactly what phase is.
Why both views coexist
The tension resolves like this:
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Dimensional analysis view: Angle is a ratio of lengths, hence dimensionless. This is convenient for unit consistency (e.g., requires a pure number).
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Phase view: Angle is a coordinate on a circle (or on the universal cover, the real line mod ). It parametrizes a cycle. This is what you actually measure and what appears in .
These aren't contradictory — they're two descriptions of the same mathematical object. The radian is the natural "unit" that makes the identification phase explicit, because:
and the periodicity is exactly the statement that lives on a cycle.
A useful way to hold it
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Dimensionless = it's a pure number (no meters, no seconds).
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Phase = what that pure number means: a location in a cycle.
The dimensionless label tells you it won't mess up your units. The phase interpretation tells you why it appears in oscillatory, rotational, and wave phenomena the way it does.
So your
intuition isn't wrong — it's actually the more physically
transparent reading. The "dimensionless" statement is a
statement about units, not about meaning. Angle-as-phase
is the meaning.
User:
I would like to abstract the concept of phase to
its bare root, then apply it to each aspect of a
temporal object as an imaginary axis: A drinking
glass, a glass for drinking, for example serves only
as an actual glass for drinking when various of its
aspects are aligned. It must be in a clean phase, it
must be in a handy phase, and so on.
DeepSeek: