سياحة داخل مخ بشري.. (مقال علمي كتبته قديما)

Quote: Misconceptions about E = mc2 Although it is far less common today, one still sometimes hears of Einstein's equation entailing that matter can be converted into energy. Strictly speaking, this constitutes an elementary category mistake.In relativistic physics, as in classical physics, mass and energy are both regarded as properties of physical systems or properties of the constituents of physical systems. If one wishes to talk about the physical stuff that is the bearer of such properties, then one typically talks about either “matter” or “fields.” The distinction between “matter” and “fields” in modern physics is itself rather subtle in no small part because of the e q u i v alence of mass and energy. Nevertheless, we can assert that whatever sense of “conversion” seems compelling between mass and energy, it will have to be a “conversion” between mass and energy, and not between matter and energy.Finally, our observation obtains even in so-called “annihilation” reactions where the entire mass of the incoming particles seems to “disappear” (see, for example, Baierlein (p. 323, 2007). Of course, the older terminology of “matter” and “anti-matter” does not really help our philosophical understanding of mass-energy e q u i v alence and is perhaps partly to blame for misconceptions surrounding E = mc2.