What is a photon? (2017)
Unfortunately, like all such descriptions, this one misses the mark also.<p>I&#x27;ve <i>never</i> heard a good explanation for what a photon &quot;is&quot;, or any particle for that matter. That&#x27;s because physicists don&#x27;t know either.<p>No, seriously. Ask a randomly selected set of physicists about any core concept in Quantum Mechanics and you&#x27;ll discover that their answers diverge wildly. Ref: <a href="https:&#x2F;&#x2F;arxiv.org&#x2F;abs&#x2F;1301.1069" rel="nofollow">https:&#x2F;&#x2F;arxiv.org&#x2F;abs&#x2F;1301.1069</a><p>Basic things like: &quot;Are the <i>photons</i> quantised or is it just the <i>photon interaction with atomic orbitals</i> that&#x27;s quantised?&quot; I&#x27;ve personally asked this question and had working physicists confidently state that either the former or latter is true, and the other is false.<p>(PS: Compare this to biologists, chemists, or engineers. They all 100% agree on all core concepts. So do astronomers, and physicists studying classical mechanics and relativity. It&#x27;s only quantum mechanics that&#x27;s so fragmented.)<p>Ask any working QM researcher to clearly show how &quot;a single photon&quot; interacts with an electron in an orbital and they will without a doubt draw you a cartoon diagram. Never in the history of theoretical physics has anyone, ever, anywhere made a numerical visualisation of this. This is because both the QM mental model and the mathematical theory applies only to ensembles in potential wells.<p>This is a <i>very narrow</i> scope of applicability that was explicitly called out in the QM papers back in the early 1900s, but is now glossed over. People assume that what applies to a special case is the hard rule that applies to all things. It doesn&#x27;t. There are no photons in free space. There are no little hard particles of light.  You can&#x27;t have a point with a wavelength. You can&#x27;t have a single pure frequency with a finite duration. This is all gibberish, it&#x27;s just a simplification to make the maths tractable when done with pencil and paper for special cases! The output of this simplified model is a 0-dimensional scalar. It can&#x27;t do output much else, such a simulation of a full 3D interaction of any type.<p>Trying to work backwards from such an oversimplified model in order to explain the deep nature of reality is futile. This is like pointing at the bandwidth measurement in Windows Task Manager and saying &quot;we can understand how the Internet works by watching this number go up and down&quot;.