Steven Hawking's Universe Episodes 3 & 4

Episode 3 of Steven Hawking's Universe was based upon the original assumption of alchemists that the world came from a mixture of the four elements: earth, air, fire & water. Alchemists searched for the origins of the universe. Democritus, an alchemist in the 5^th century bc, used the theory of an atom, meaning indestructible, as the smallest elements; believing that these four elements were atoms. He felt that by mixing them in specific proportions one might be able to figure out how the universe was created and recreate this phenomenon. Although his assumption was correct, his means was misleading. However, for more than 2000 years, Democritus' theory of the atom was accepted and remained a basis for all hypotheses regarding the formation of the universe. In the 1800s a Russian scientist, Mendeleev found that many of the chemical and physical properties among elements were similar. Scientists of the age knew that each element had its own weight, but did not make the connection between weight and properties. Mendeleev took this extra initiative and formed the periodic table of elements. Where he found holes in it, he predicted the weight of an unknown element that would come to be discovered and find its place in that spot of the table. He did not; however, find out why it was that some atoms were heavier than others.

Joseph Thomson was a British physicist, who had discovered electrons and was even able to calculate their mass. This discovery proved that atoms were not the smallest elements, that they also had a structure. X-rays were soon discovered and, consequently, Henry Baquerel discovered radioactivity in an accidental manner; by placing a small piece of uranium on a photosensitive plate. These discoveries drove Marie and Pierre Curie to figure out the intensity of this radioactivity; their work led to the discovery of polonium and radium. Observing the three forms of energy released was the achievement of British physicist Ernest Rutherford. Rutherford called each of these alpha, beta and gamma; after the first three letters of the Greek alphabet. Observations of each of these forms led to an advanced knowledge of the forms' properties. While working with Frederick Soddy, both were able to witness the physical change of the radioactive elements into lighter ones, which finally ended up as lead, through a process of decay. In another experiment, Rutherford noticed that when pushing positively charged alpha particles through a piece of gold foil in a tube that while most particles shot straight through, some bounced back. This led to the hypothesis that while atoms are mostly space, they contain a small but positively charged nucleus.

These discoveries while paired with the law of E=mc² seem to present a very striking argument for how the universe was originally created. Following the initial contraction and Big Bang concept, the particles of the atom were formed. In the blistering temperatures resultant of the Big Bang, protons and neutrons started to form. Hydrogen and Helium were the first elements to be created, but combinations and recombinations of these nucleic particles led to the elements we have now. Gravity played a part in the creation of the universe as well; it pulled together the cosmic mass to create stars and then, later, planets. As discussed in class, after awhile the process of recombination leads to the creation of lead, and a star's life is then over because it cannot hold up this heavy neucleus.

Episode 4 of Steven Hawking's Universe concerns the notion of mass within the universe. The idea of open, closed or flat universes describes potential, or lack thereof, of a universe's mass to determine its future. If there were enough mass to force a universe to contract in the future than it is a closed universe; if not enough, then an open universe. Should the expansion ultimately approach zero, then the universe is flat. Thus, astronomers have been attempting to calculate the mass of the universe to hopefully discover the future of the universe.

Years ago, a Swiss astronomer named Fritz Zwicky, was studying the motions of individual galaxies and found that they were moving entirely too fast, that they should have dispersed m/billions of years before. His conclusion was that there must be more matter than could be seen, that could account for this. In the 1950s, the American astronomer Vera Ruben found that spiral galaxies behaved in peculiar ways; Vera concluded that galaxies, including the Milky Way, contain much more dark matter than they do light-producing matter.

There have been many theories as to the composition of this dark matter. Some believe that Massive Compact Halo Objects (MACHOS), Weakly Interacting Massive Particles (WIMPS), or neutrinos. MACHOS are believed to be brown or black dwarfs, as well as large planets. WIMPS are thought to be particles with masses 10 or more times that of protons which could add a lot to dark matter. Neutrinos, on the other hand, are minute particles that formed in the early years of the universe which do not interact with anything. Although they are so small, their population may be so great that they could easily add to dark matter.

It is the amount of dark matter that will ultimately determine the fate of the universe; whether it is open, closed or flat. Theories of how such a fate may play out include ideas that soon one day the universe will begin to contract, in a way playing its creation backwards. If this is the case the unversed might be called a cyclical universe, where it continually plays out this sequence. If this is not the case, then one day stars will all die out, and one day it may end up dark; without any light-emitting objects. However, this conclusion is trillions of years away, when protons will all have decayed and black holes will have grown in size and sucked in other objects, only to shrink in size one day and evaporate themselves.

Stephen Hawking's Universe Vol 2 On the Dark Side. Dir. Hawking, Stephen. 1997. VHS. PBS/BBC, 1997.