Can the universe arise from ... nothing?
Quantum mechanics, with all its paradoxes, nevertheless describes the properties of objects that exist in undistorted Newtonian space. The future theory of gravity should extend probabilistic quantum-mechanical laws to the properties of space itself (more precisely, space-time), deformed in accordance with the equations of the general theory of relativity. How to do this with the help of rigorous mathematical calculations, no one really knows.
However, the path to such a union can be considered at a qualitative level, and very interesting prospects appear here. One of them was examined by the famous cosmologist, Professor of Arizona University Lawrence Krauss in his recently published book “A Universe From Nothing”. His hypothesis looks fantastic, but does not contradict the established laws of physics.
It is believed that our Universe arose from a very hot initial state with a temperature of the order of 1032 Kelvin. However, it is possible to imagine the cold birth of universes from a pure vacuum - more precisely, from its quantum fluctuations. It is well known that such fluctuations give rise to a great many virtual particles that literally emerged from nonexistence and subsequently disappeared without a trace. According to Krauss, vacuum fluctuations are in principle capable of giving rise to equally ephemeral proto-universes, which under certain conditions go from a virtual state to a real one.
Universe without energy
What is needed for this? The first and most important condition is that the germ of the future universe must have zero total energy. In this case, it is not only not doomed to almost instant disappearance, but, on the contrary, can exist for an arbitrarily long time. This is due to the fact that, according to quantum mechanics, the product of the uncertainty of the energy value of an object by the uncertainty of its lifetime should not be less than the final value - the Planck constant.
Since the energy of an object is strictly equal to zero, it is known without any uncertainties, and therefore its lifetime can be infinitely long. It is thanks to this effect that two charged bodies located at very large distances are attracted or repelled from each other. They interact due to the exchange of virtual photons, which, due to their zero mass, extend to any distance. On the contrary, gauge vector bosons that transfer weak interactions, due to their large mass, exist only for about 10–25 seconds, as a result of which these interactions have a very small radius.
What kind of universe, albeit embryonic, with zero energy? As Professor Krauss explained to Popular Mechanics, there is nothing mystical about it: “The energy of such a universe is composed of the positive energy of particles and radiation (and possibly also scalar vacuum fields) and the negative potential gravitational energy. Their sum can be equal to zero - mathematics allows this. However, it is very important that such an energy balance is possible only in closed worlds, the space of which has a positive curvature. Flat and especially open universes do not possess such a property. ”
Miracles of inflation
What happens if the quantum fluctuations of the vacuum give rise to a virtual universe with zero energy, which, due to quantum randomness, got some time for life and evolution? It depends on its composition. If the space of the universe is filled with matter and radiation, it will first expand, reach its maximum size and collapse in gravitational collapse, existing only a negligible fraction of a second. Another thing is if there are scalar fields in space that can start the process of inflationary expansion. There are scenarios in which this expansion not only prevents the gravitational collapse of the “bubble” universe, but also turns it into an almost flat and limitless world. Thus, her life spans immeasurably - almost to infinity. Thus, the tiny virtual universe becomes quite real - huge and long-lived. Even if her age is finite, it may well exceed the current age of our universe. Therefore, stars and star clusters, planets, and even, what the hell is not joking, intelligent life can appear there. A full-fledged universe that emerged literally from nothing - these are miracles that inflation can do!The article “Worlds from the Void” was published in the journal Popular Mechanics (No. 7, July 2012). Do you like the article?
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