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6

You're having trouble telling the difference between the two because, as for many natural language words, I don't think there is a clearly defined difference and the difference arises from natural usage (as with the difference between "fruits" and "vegetables" in English). The following is my understanding of the difference. There is a well defined ...


5

Let me preface by saying that "coupling" is a favorite physicist word that is perhaps best described linguistically than rigorously; it's deployed in a few different situations. In general, we say that a coupling exists in quantum mechanics if the evolution of one part of the system depends on another quantity, which could be either classical or quantum. I'...


4

According to the Particle Data Group [1], Mesons are [strongly interacting particles that] have baryon number $\mathcal{B}=0$. In the quark model, they are $q\bar{q}'$ bound states of quark $q$ and antiquark $\bar{q}'$. This definition has two sentences, which in fact are somewhat different. The second one defines the quark-model mesons, that you're ...


2

In watchmaker lingo, a "retrograde" watch is a watch that has a hand on it (usually to tell you the day or date) that will advance along and then at the end of its "cycle" will snap backwards to its original position -- rather than loop around the way the hour, minute, and second hands do. This has nothing to do with the "retrograde motion" discussed in ...


1

I want to add an answer which I think supplements some of the other comments. @lemon notes that "gravity" refers to the pull towards the Earth while "gravitation" is more general, but notes that this is archaic. In fact, it is a very old term and the history is interesting, so take this as a "history of science" type answer. Disclaimer that all of what I ...


1

The simplest way I can think of correctly defining quantum physics is that it is the combination of our best and most correct theories of physics that does not include General Relativity. There are two relevant and important classes of physics for this explanation: classical physics and quantum physics. Physicists are people too. If we can achieve our ...



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