Vacuum doesn’t have a temperature of its own, so space is not really that cold. It’s a great insulator too, meaning that your core body heat doesn’t get sucked away. Without an atmosphere to transfer heat away, the risk of exposure is somewhat mitigated. The saliva on your tongue may boil off, as it’s not pressurized…
M-theory is not a theory in the usual sense. It is a whole family of different theories, each of which is a good description of observations only in some range of physical situations. It is a bit like a map. As is weU known, one cannot show the whole of the earth's surface on a single map. The usual Mercator…
Feynman's graphical method provides a way of visualizing each term in the sum over histories. Those pictures, called Feynman diagrams, are one of the most important tools of modern physics. In QED the sum over all possible histories can be represented as a sum over Feynman diagrams like those below, which represent…