Cosmology and our View of the World
Life, The Universe and Everything: Cosmology
Lead: Ethan Cline & James Kilpeck
Summary by Mary Awad
The origin of the universe and the origin of energys
I Big Bang Theory:
The discussion topic of this week centered around the formation of our universe and the formation of matter, lead by Ethan Cline and James Kilpeck. The explanation for the formation of the universe concentrated on the Big Bang theory, which states that the universe rapidly expanded from a dense and hot state. This Big Bang occurred approximately 13.8 billion years ago. During its expansion, the universe cooled, allowing for the further creation of matter. With the help of gravity, matter, almost exclusively hydrogen and helium that formed right after the big bang, accumulated to form stars. Cline and Kilpeck both argued that the Big Bang model explains how the universe is expanding; however, it cannot explain how the universe came to be. The best models that we possess can retrodict up to 10-37 seconds into the expansion. The current knowledge of physics cannot go back to 0 time.
Cline and Kilpeck pointed out in the discussion that the Big Bang theory is supported by experimental data. Such data was obtained from the cosmic microwave background explorer (COBE) experiment. The COBE or Explorer 66 was a satellite used to investigate the cosmic microwave background radiation of the universe. Through data gathered in the 1990s, scientists found the primordial seeds of the universe. The data agreed with the Big Bang theory. A student then asked, “What exactly is a cosmic microwave background?” James Kilpeck explained that 379,000 years after the Big Bang, the universe allowed light to propagate freely. The universe around this time was at 3000 Kelvin. The expansion has cooled the universe and thus the background radiation by a factor of 1000 to 3 Kelvin today. Therefore, the microwave radiation is of a much longer wavelength. These photons of light make up the detectable cosmic microwave background. From that point, the universe was no longer opaque. “How can we then see up until 10-37 seconds of the universe?” asked another student. James Kilpeck responded that we have multiple ways of retrodicting closer to the Big Bang; however, this was not elucidated with further detail.
The lecture then moved to distances in the universe. The distance to other celestial bodies is measured using parallax. This uses the difference in how an object is seen from two different points to measure the object’s distance. Using this we have been able to discover that the Earth is not in the center of the universe by the change in distance between Earth and celestial bodies. However, the Earth is in the center of the observable universe. The time it takes for light to reach earth from other galaxies can be incredibly large. For example, light from the star α-Centauri takes 4.3 years to reach Earth. Anything we observe in α-Centauri actually happened 4.3 years ago.
II ‘Vacuum’ and the Heisenberg Uncertainty Principle:
In order to explain further concepts, Kilpeck and Cline defined certain terms. The first term defined was ‘vacuum.’ A vacuum is a state of space devoid of matter and associated with low pressure; however, there is energy within a vacuum in space from which matter can arise. Matter production is balanced. Along with matter, anti-matter is also formed. Therefore, there is no net production of any one species. If the pair, matter and antimatter, recombine, they annihilate each other. This is called pair production and annihilation. If both occur within short enough time so that Heisenberg’s Uncertainty Relation, explained below, is satisfied there is no conflict with conservation of energy. Cline and Kilpeck showed to the class an equation that describes pair production. A vacuum was further described as a quantum state with the lowest possible energy. The energy permeating the vacuum will determine what matter can be produced. Dr. Laue pointed out that there is no true vacuum. He relates vacuum to the notion of purity. It is a description that can only be used in relative terms. One is more pure than the other. There is a vacuum of lower energy in comparison to another region of space-time.
In conjunction with matter production, the two discussion leads went on to talk about the Heisenberg uncertainty principle. This principle states that there is a limit to the precision with which position and momentum of a particle can be measured. In the same light, there is a relationship between energy and time. The more precisely a position of a particle is known, the less precisely its momentum can be known; as position is to momentum so is time to energy.
The uncertainty principle does not refer to observational errors due to technology or human error, but rather a more basic uncertainty with the wave-like property of quantum mechanics. Later in the conversation, Dr. Moebius stated that there is a limit to which we can probe in relation to time and energy. At a small enough time scale combined with energy, the answers for energy are no longer comprehensible. This minimum limit is Planck’s constant.
Further into the discussion a student asked, “How is the uncertainty principle associated with matter formation within a vacuum?” Ethan Cline clarified by stating that there is conservation of mass and energy as defined by physics. Therefore, to create a particle the amount of energy available has to be greater than or equal to the mass of the particle, multiplied by the speed of light squared according to Einstein’s famous relation. Thus through the uncertainty principle, it can be argued that within a short time scale, a large amount of energy could be available, and in turn a particle pair can be created within a vacuum. However, the pair particles created can recombine, annihilating each other. The uncertainty principle allows for this quantum fluctuation to maintain conservation of energy. James later mentioned that the production of matter and antimatter could be observed at the edge of the event horizon of black holes. Either matter or anti-matter can get caught within the grips of the immense gravity of the black hole eventually entering the black abyss. There can be, at the event horizon, accumulation of matter or antimatter. However, this does not explain the large accumulation of matter we see in our universe.
The class at this point began to discuss the use of certain terminology in science. Dr. Davis questioned the use of the word “uncertainty” when describing a physical system, claiming that it is a term that is more appropriate for describing our own perceptions of a system. The presenters then argued that this uncertainty is inherent to the equation. Ethan Cline explained the word “uncertainty” in science. The measurement of a distance, e.g. a foot, is only as precise and certain as that of the technology used to measure it. Furthermore, the measurement “a foot” is based on a certain constant of the universe that never changes. The measurement of that constant is again dependent upon the precision of the instrument used to measure it. Based on this definition, it appears that certainty is synonymous with precision. Later, the presenters made the distinction between observational precision and the inherent nature of uncertainty within the uncertainty principle.
Dr. Davis still questioned this definition because measurement is a form of observation. Dr. Moebius agreed with Dr. Davis about observer involvement. However, he stated that the uncertainty in energy, when measuring time precisely, intrinsically increases, regardless of the observer. Dr. Moebius also mentioned that there is a principle limit provided by the tools of nature. It is ingrained in our universe, that one cannot find tools that will measure both time and energy simultaneously without limit in precision.
Dr. Laue further pursued the argument about the use of “uncertainty” by stating the uncertainty principle stems from operator theory. The uncertainty principle involving energy and time does not commute; rather the commutator in the equation is Planck’s constant h divided by 2π. Dr. Laue went on to say that the uncertainty comes from the math. Dr. deVries pointed out that the time and energy relationship is a range. The more determinate one factor becomes the less determinate is its counterpart. Dr. deVries pointed out that this is an indeterminacy principle. Dr. Davis further defended his statement by claiming that if the observer is not involved in the precision or determinacy of the math, then a different word should be used, one which is less anthropomorphic. No general consensus in regard to the terminology was reached.
It was then proposed that math could be wrong. A student argued that math is a product of our observation. “Could there be error in this?” Ethan Cline refuted this statement by arguing that pure math is not necessarily wrong but rather the physics could be using the equation incorrectly. Ethan Cline mentioned that that we are using math that many have agreed on to be true. Dr. Laue added that math is testable in addition to being observable. Dr. Laue stated that the uncertainty principle is a principle because the math can be tested. He argued that our universe behaves in accordance with these calculations. Dr. Davis pointed out that the uncertainty principle takes on a lot more than a simple mathematical problem.
Another student questioned why an increase in the accuracy of one of the two variables leads to a decrease in the accuracy of the other variable. It was explained that the algebra detailed it so. The same student argued that the math could be wrong. Dr. Moebius stated that this equation is testable, has been tested in many different ways, and thus is considered to be true. Professor Moebius argued that we would not be able to use a laser had this equation not been true. Dr. deVries then argued that math itself is more or less a set of purely formal systems. There are several mathematical systems and nothing in the math details when or where it can be used. When aligning with physics, we must find the proper systems that will aid in the assortment and gathering of data. Through a matrix formulation, Heisenberg was able to account for his data. Schrödinger, through wave mechanics, was also able to show the relationship of particles in quanta through a different equation that was later found to be equivalent to Heisenberg’s equation. Once a mathematical system is found to match the data being used, it can be applied and further tested. Dr. deVries said that through this equation Heisenberg and Bohr were able to conclude that the universe at its fine-grained level is indeterminate. There is no particularly determinate structure where both energy and time or position and momentum are specifiable simultaneously. The universe is an “indeterminate soup.” Professor deVries went on to describe how this frustrated Einstein by quoting “Der Herr Gott würfelt nicht,” meaning God does not play dice.
Another term, ‘false vacuum,’ was defined in order to aid our understanding of how the universe formed. A false vacuum is unstable, because it is in a higher energy state than a true vacuum, and at any given time a false vacuum can decay into a true vacuum by means of a release of energy. This decay is thought to be the cause of inflation. Inflation cosmology is a widely accepted theory intricately interwoven with the Big Bang theory. It states that the universe began as a false vacuum and decayed into the vacuum state that is present now. The energy decay released immense amount of energy, causing our universe to expand very rapidly. The expansion and energy release also created all of the matter within our universe and is intricately linked to the Heisenberg uncertainty principle. Dr. Moebius compared the change of a false vacuum to a true vacuum with the conversion of liquid water to frozen water during which latent heat of ice is released. Ethan clarified that we do not know if we live in a false vacuum, as we cannot compare our energy state to another universe. Although there is no evidence available currently, there could be more vacuum states.
Dr. Laue asked if it is necessary for a false vacuum to exist before the beginning of a universe. Both presenters agreed that it is most likely necessary to have false vacuum decay at the beginning stages of a universe. This is because the false vacuum decay caused the inflation event, which formed our universe. Dr. deVries inquired when this event occurred and the response was sometime after the Planck epoch, around 10^-37 seconds into the Big Bang. Many students were confused about the nature of energy decay in a false vacuum. Ethan then explained that false vacuum space-time is much more curved and the release of energy into space will flatten space-time. This energy contributes to inflation and later generates matter. Dr. Laue explained that if there is hydrogen and oxygen mixed together they will do nothing, as soon as a catalyst is added, water forms and energy is released. This is similar to the decay of a false vacuum and the release of energy.
The next topic that was discussed was about the formation of matter. As stated previously, matter and anti-matter are made in equal amounts. If matter and anti-matter meet, however, the two will annihilate each other. In theory, there should be no accumulation of one species over the other; however, based on what one can observe, matter is clearly more abundant than anti-matter. There are few theories that could explain the accumulation of matter over antimatter. One theory states that there is a specific particle, Strange B meson, which favors decay into matter over antimatter. However, the Strange B meson only accounts for one galaxy worth of matter. Another theory predicts that antimatter is present, but is located at a great distance from matter. If anti-matter were present in the universe, a massive release of energy would be observed when pairs of matter and anti-matter particles collide; however, such an energy release has not been observed. So the question remains how did the universe accumulate such immense amounts of matter? A student then asked, “If the universe was built of antimatter rather than matter would the universe look the same?” After much discussions, the agreed upon conclusion was that the universe would be a mirror image of our current universe. The chemical and physical changes in this mirror universe were not detailed.
III Theories of the origin of the universe:
Both Cline and Kilpeck went on to summarize the reading in Cosmic Heritage by describing how well our universe is fine-tuned for life. For example, the ratios of the electromagnetic and strong forces are at the perfect range for element production. It was further stated that we could only exist in a universe that makes it possible to exist. This is fundamentally the Anthropic principle. Dr. Moebius pointed out that, although the Anthropic principle allows us to understand why the universe formed, this principle does not describe how the universe formed so fine-tuned for existence.
The topic of the discussion then shifted to the theories behind the formation of the Universe. Most of the theories listed below incorporate the Big Bang into the explanation with the exception of the simulation and religious theories.
The first theory discussed was that of the Hartle-Hawking State. This model proposes the state of the universe before the Planck epoch. The Hartle-Hawking state predicts that time did not evolve until Planck time. From here, time unfolded from the spatial dimensions. In the framework of this theory, it is impossible to say “before” the Big Bang. Furthermore, this theory predicts that the universe is finite but unbounded. An example of a finite but unbounded object is a sphere. It was then pointed out by Dr. Moebius and Dr. deVries that there is an issue with saying time formed “after” the Planck time as this means there was a temporal “before” time. Our language appears to not align well with models that, like the Hartle-Hawking model, have no time associated with states “before” or outside our universe.
Dr. Davis mentioned that the universe is thought to have arisen from a certain amount of “nothingness” that is not static in terms of energy to matter conversion. This system undergoes much change. There is therefore some notion of time in this system as time can be thought of as change. From here, the discussion moved on to defining time. Ethan Cline described time as an increment of an increase in entropy. James Kilpeck described a “second” as a certain distance that light travels within an increment. Another student went on to describe time as an incremental “ticking.”
The concept of space-time expansion was then addressed. Space-time is expanding between points that are not gravitationally bound. Dark energy is what is causing the expansion of the universe. The two leads stated that, “space-time is expanding into itself.” Dr. deVries pointed out that our universe is not expanding along a certain path. We are uncertain of what exists beyond our space-time. Therefore, it cannot be said that space-time expands into something unless there are multiple universes and higher dimensions.
Another model of the formation of the universe is the cyclic model. The cyclic model is a series of models that predict there is an infinite cycle of big bangs and big crunches. The universe expands then collapses on itself. This process is then repeated. Once the rate at which space-time expands exceeds the speed of light, certain events occur that lead to the big collapse. Contrary to the Hartle-Hawking state, the cyclic model predicts that time was present before the Big Bang. One of the cyclic models discussed was that of the Steinhardt-Turok model. The Steinhardt-Turok model predicts that there is a collision of M-branes, which is comparable to the collision of two parallel planes. These branes are in higher dimensional space and one of the two branes contains the visible four-dimensional universe. It was then pointed out that there is some data supporting this model through the WMAP probe, which mapped background radiation in the universe.
The next model presented was that of eternal inflation. The eternal inflation model predicts that there is a false vacuum “mother” universe outside of our universe that spontaneously decays into subuniverses. These subuniverses, now true vacuums, form into distinct universes. These subuniverses are all believed to be expanding. Within this theory, it is thought that each universe would have different constants for the physical laws. This model does not necessarily guarantee that each universe will be as fine tuned for life as ours. This is because false vacuums are not uniform. Therefore, the false vacuum universe will cause different physical constants for each universe.
Following this, less supported multiverse theories were proposed. One of these theories involves black hole universes. It states that there is a universe within a black hole. This theory argues that natural selection plays a role in black hole universes. If a universe is stable and creates black holes, the stable universe will create more black holes and, in theory, more universes. However, this theory may run into problems with the law of conservation of mass.
Another model of universe formation is that of the universe as a computer simulation. One such believer is Dr. Silas Beane who theorizes that we all live in a computer simulation. Dr. Beane argued that there would be noticeable upper limits of cosmic rays that have preferred directions; however, Dr. Beane has not as of yet observed data that supported his claims. Another theory is that we live within a hologram. At the base of a hologram model is string theory. The Universe is composed of higher dimensional strings that vibrate in such a way that they represent the world in three dimensions. However, the eternal inflation, black hole, computer simulation, and hologram models do not explain how the multiverse formed.
Religious concepts of the origin of the universe were then discussed. Most religions argue that the universe was formed by some greater being, a God or multiple Gods. The Genesis theory is held by Christians, Jews, and Muslims. This argues that a single God created the heavens and earth. However, it was noted that Pope Pius XII in 1951 claimed that the Big Bang theory was not incompatible with Genesis and that each day of creation took place over billions of years. Dr. Laue then explained the theory behind Pope Pius XII’s argument concerning the Big Bang. In the King James translations of the Old Testament from old Hebrew the “unspeakable tetragrammaton” written YHVH, is translated to “the lord”. However, this word was not meant to be translated because YHVH is an entity that is not understood.
Hinduism has many beliefs about the forming of the universe. Within the Rigveda, the Universe started as a cosmic egg that the universe hatched from. This is somewhat reminiscent of the Big Bang. In the Vishnu Purana scriptures, Vishnu in his bull form was said to have brought forth the universe from the cosmic waters. Vishnu Purana scriptures also state that the universe is formed from a point of intense heat. Within the Vishnu Purana, the universe is formed on a 311 trillion year cycle within which it expands and is destroyed. It is believed that a day in the life of god is 4.08 billion years long. A year in the life of God is 360 days. Gods only live for 100 years, after which a new God evolves from the Cosmos creating a new universe. Dr. Davis brought up the point that religious concepts and the multiverse concept are able to relieve individuals of explaining the origin.
It was concluded that there are many testable theories and many non-testable theories. However, it appears unlikely in our lifetime that we will find the answer to the universe’s origin.