Chapter 13: Dark Energy is the Fifth Element

Max Planck, a German Physicist, postulated that energy existed in discrete chunks or quanta, to explain how we view radiation. Einstein proved that this, in fact, was a reality, and it was acceptable to think of radiation as a collection of individual photons. This led to the duality of light as a wave and as a particle. French Physicist Louis de Broglie recognized that this principle explained energy levels in all particles, like electrons and protons. What he discovered was that everything in nature has quantized energy levels. All objects have well-defined and discrete energy spectra.

Many people ask, “What is the lowest possible energy state?” Logically, most people would assume that it is zero, but the truth is that an energy state can never be zero. The Uncertainty Principle can be stated in terms of energy and time. Basically, it is impossible to measure, at the same time, to measure the time elapsed and the energy involved in any given process. If we consider a particle, which has a finite lifetime, we can conclude that there is an uncertainty in its lifetime, meaning that it cannot have a zero energy level. Two important observations come from this observation. First, the minimum energy level cannot be zero because it has a value, which is fixed by the uncertainty principle. Secondly, we can no longer think of parts of the Universe as “empty space”. We can pick any region of the Universe and consider it for a fixed amount of time, there is an uncertainty placed on the energy in that region- it cannot equal zero because of the Uncertainty Principle. Therefore, from these speculations, we can conclude that empty space is not simply empty- it actually has energy.

In conjunction with the Uncertainty Principle, we can assume that at any given moment, there is an uncertainty in the amount of energy present. It is possible that certain areas of space will have more energy than others. This energy can give rise to particles, which collide and disappear very rapidly. The energy continually presents itself in the form of various particles swaying in and out of existence.

One thing that I found very interesting was the author’s explanation of water. It had never occurred to me how the cracks in water form when water freezes. When water freezes and there are no cracks or fissures present, water is said to be symmetrical, however, this symmetry can be broken. The orientation of each water molecule is completely random, meaning that they have no preferred direction. Water molecules are weakly bound through each other by electrostatic forces, but are still able to freely move around. As water cools, its molecules slow down, and its electrostatic forced help to lock it into place in an order where they can all fit together. As a result of this random arrangement, each molecule chooses its own direction in space and water starts to solidify.

Each section of water begins to solidify independently. One location begins to freeze and then another begins to freeze. Each of the molecules at that site pick out a preferred direction at that site, and there is no guarantee that the preferred direction will be the same at all of the sites- most will be misaligned. When the different sections are misaligned, we are left with cracks and fissures. The cracks represent the separation between the different zones that have frozen and to tolerate the tension created by the misaligned water molecules.