Zero Energy Universe?
February 13, 2014 8:41 AM Subscribe
Stephen Hawking has proposed that our universe has a total energy of zero, which allowed it to Bang into existence without violating any laws. Is this thesis falsifiable? If so, what is an example of something that might happen, which would contradict the zero-energy hypothesis?
posted by Eiwalker to Science & Nature (6 answers total) 2 users marked this as a favorite
Hawking writes: "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 is a law like gravity. Because gravity is attractive, gravitational energy is negative: One has to do work to separate a gravitationally bound system, such as the earth and moon. This negative energy can balance the positive energy needed to create matter, but it’s not quite that simple. The negative gravitational energy of the earth, for example, is less than a billionth of the positive energy of the matter particles the earth is made of. A body such as a star will have more negative gravitational energy, and the smaller it is (the closer the different parts of it are to each other), the greater the negative gravitational energy will be. But before it can become greater than the positive energy of the matter, the star will collapse to a black hole, and black holes have positive energy. That’s why empty space is stable. Bodies such as stars or black holes cannot just appear out of nothing. But a whole universe can." [Hawking (2010), The Grand Design, p. 180]