Physics Univer City
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Why Relativity Applies to Light Too
The principle of relativity is often seen as applying seamlessly to mechanics but trickier for electromagnetism (thanks to historical ether ideas). But what if it's nearly tautological even for light, once you enforce strict locality? PhysicsV.com (2025). Closing the Electromagnetic Loophole in the Near-Tautological Derivation of the
Is the Principle of Relativity a Tautology? (Yes, Almost – With a Key Assumption About Locality)
The principle of relativity often gets treated as a postulate (Einstein's assumption) or experimental fact (e.g., Michelson-Morley), but what if it's nearly tautological? Here's the gist from my note: This note presents a conceptual argument demonstrating why the principle of relativity can be
Why the Speed of Light Is Invariant
Why Every Observer Always Measures the Same Speed of Light In any local inertial frame, the speed of light is always measured to be exactly \(c=1\) (in natural units), or \(299\,792\,458\,\mathrm{m\,s}^{-1}\), because every method of measuring it, directly or indirectly, uses light (or
