1–3 of 3
If the total energy of the universe must always remain zero, and it costs energy to create a body, how can a whole universe be created from nothing. That is why there must be a law like gravity. Because gravity is attractive, gravitational energy is negative: One has to do work to separate a gravitationally bound…
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…
Whether M-theory exists as a single formulation or only as a network, we do know some of its properties. First, M-theory has eleven space-time dimensions, not ten. String theorists had long suspected that the prediction often dimensions might have to be adjusted, and recent work showed that one dimension had indeed…