Cosmology and our View of the World
The Beginning of the Universe
Lead: Kalika Bower & Sarah Brown
Summary by Elvir Zulkic
How it all began? -
The major theme of this week’s discussion presented by Kalika Bower and Sarah Brown was the beginning of our universe. How did it all begin? Kalika Bower started the discussion with summarizing the reading and talking about the Dalai Lama and his beliefs on the modern cosmology. The Dalai Lama believes that the universe is not eternal or static. Space, time and energy that we see and fill were created during the Big Bang. The Big Bang theory explains that the universe expanded from a very dense and hot state and that it continues to expand today. Expansion happens intentionally and expansion is chaotic. But God is the creator of everything. As a person that likes and enjoys science, I have a hard time believing that God, a mysterious entity, created everything around us. I believe that God is a product of our surrounding.
Buddhism, for example, is based on the belief that the interconnected material, consciousness, can’t be removed from the mind. Buddhism is also based on the belief that the universe goes thorough the cycle of birth and death. I don’t know of any experiments that suggest that the universe goes through the cycle of birth and death. But I also don’t know of any experiments that suggest that the universe is going to exist for eternity. Professor Moebius comments by saying that such experiments or observations would indeed be very hard to come by, as we can only observe what is happening within our observable universe, and over a very limited amount of time. These are very serious limitations when it comes to such questions. So, it is no surprise that there aren’t any such experiments or observations. We may never be able to test those for sure. The current best evidence suggests though, that our universe started 13.7 billion years ago and that it will continue to expand forever. In my mind, everything that has a beginning has to have an end. Even Professor Moebius suggested that it could be possible to have a universe that gets created at the Big Bang and gets destroyed. But Professor Moebius also comments that this is a possible scenario, and astronomers have debated this for a long time as one of the possibilities. However, the more recent evidence of the “Dark Energy” which pushes space apart does appear to speak against this scenario. Still the universe will “die” in the sense that even the longest living stars will run out of fuel and then die. So, no source of energy will be around anymore and then it gets only cold in the universe. This is seen as death by cold. But it is hard to say that the universe is going to die, when we know that the universe is expanding.
We are in space, which is expanding. But this expansion of space is not happening uniformly (as discussed below) throughout the universe that we know, the observable universe. What is this “observable universe?” The observable universe is the universe that we can see around us. We can only see approximately 10^13 billion light years around us. The phenomenon that allows us to see the “edge” (in terms of light) of this observable universe is the cosmic background radiation. So, if there is intelligent life somewhere else is the universe, would their observable universe also be 10^13 billion light year? The answer that Professor Moebius gave is “yes.” If there is intelligent life somewhere else in the universe their universe would also consist of only10^13 billion light years, but around their galaxy as the center of their observable universe. Kalika Brown posed a question to the class asking, “How does this allow the universe to have boundaries?” Professor Moebius answered by saying that, “It is not possible to conclude that the universe is finite.” I personally don’t believe that we will ever find out whether or not the universe has boundaries.
The universe that we know, the observable universe, is evolving through the expansion of space. Sarah Brown posed a question to the class asking, “Is our body expanding if space is expanding?” Professor Moebius, a physicist, replied to the question by saying that “space is expanding, but things with mass (our body) are not expanding because they are held together by the forces that surround them.” To me this answer makes perfect sense because if the planet Earth or the Sun were expanding, that would mean that they would eventually end up tearing apart.
Another question that was posed to the class was, “What is causing space to expand?” Professor Moebius answered this question in three steps. He said that the expansion of space is caused by dark energy, which constitutes 70% of all mass in the universe; i.e. the energy is pushing space apart. Dark matter contributes 25% of all mass. Normal matter (the stuff that we are used to) is approximately 5% of the total mass in the universe. So, where is the space that has matter? Matter exists everywhere. However, most of the matter (in the form of the galaxies) is concentrated in approximately 10^-4 of the entire space, which is just a small fraction. The remaining amount of matter between galaxies and beyond galaxies is dispersed much more. There is not a lot of matter outside galaxies, which could prevent space from expanding. Professor Moebius comments by saying that the important point is that only those regions of space expand effectively that have not much mass collected inside them. Galaxies and galaxy clusters have enough mass so that their gravitational force counteracts the dark energy, and no expansion is observed here. Atoms in these regions of space would not expand because they too have mass, and they are held together by electric forces. I understand that dark energy is the cause of space expansion. But from what I know, we can’t see dark matter or dark energy and there is no experiment that can prove that dark matter or dark energy exists. But then again, if space is expanding there has to be something that is causing the space to expand.
Then a question about a “black hole” was brought up to the class attention, “What happens to the matter that falls into the black hole?” Professor Moebius answered the question by simply saying that “any matter that falls into a black hole approaches the speed of light before it disappears for an outside observer.” We also can’t forget that we can’t see black holes. The only reason we know that black holes exist is because we can see when a black hole is destroying a planet or a star and because they make their mass known because other objects orbit around them. I know that the center of our Milky Way galaxy is a super massive black hole. The one thing that I don’t know is, whether or not there is a chance that this super massive black hole could swallow our solar system? Professor Moebius comments by saying that black holes are not “cosmic vacuum cleaners”, they don’t actively suck stuff in. Professor Moebius further comments by asking, what would happen to the Earth if our Sun turned into a black hole with the same mass that the Sun has now? He answered this question by saying that the Earth, and in fact all planets, would continue to orbit the Sun in their current orbits. The gravitational force of the sun would not change out here. Only because the resulting black hole would be so incredibly small (radius of 3 km), with the same mass, the gravitation at the event horizon (or the outer boundary of the black hole) would be infinity strong.
The discussion was brought back to the Big Bang theory and the Inflation theory. The Big Bang theory, as mentioned earlier, states that the universe expanded from a very dense and hot state. But there are things that the Big Bang theory does not explain. The big issue that the Big Bang theory has is not being able to explain the flatness of the universe. According to Inflation theory the observable universe is flat. Professor Moebius explained this by saying “it’s like standing on the surface of the Earth, we know that the Earth is spherical but when we look around us everything is flat, we can only see as far as our eyes will allow us to see.” We can’t see beyond the horizon, which would make us think that the Earth was flat.
Another issue with the Big Bang theory is that if we could travel back in time we would reach a point where the physics that we have today would simply not be applicable. This point is around 10^-42 seconds. The models that we have today don’t go beyond the 10^-42 seconds. This is where String theory comes into the play. String theory is supposed to explain things beyond the 10^-42 seconds. It is also supposed to connect the things before 10^-42 seconds and beyond 10^-42 seconds, the ultimate unification. If this unification is possible the String theory would be the theory of everything. What we can’t forget is that these are just models; there is no scientific experiment that tests whether strings exist. We have to be prepared to deal with the fact that these models could possibly be incorrect. I still have a hard time believing that strings, objects that we can’t see or know even if they exist, could be used to explain everything we ever wanted to know.
A question that was brought up by Sarah Brown was, “Why did things happen the way they did?” One part of the answer is that nuclear fusion in the early beginning of the Big Bang produced only elements such as: hydrogen, helium, and lithium. But none of the other elements important for life, such as nitrogen, oxygen, etc. were produced back then. These elements were only generated inside stars. Another part of the puzzle is the nuclei. Nuclei have a positive charge, which makes them repel when they come close to other nuclei. During the Big Bang the temperature was extremely high. This high temperature increased the movement of the nuclei, which made the nuclei collide more frequently and at higher velocity. But Professor Moebius comments again by saying that the answer to Sarah Browns question is much broader than just talking about nuclear fusion and nuclei. We know that the universe expanded fast and then the expansion slowed down. What caused this process to begin? Why did things happen the way they did? How did atoms and molecules form all the stuff that we see around us? It is beyond our scientific capability to answer all these questions with a hundred percent accuracy. If there is a creator that created the universe, our consciousness, and everything else that we see around us, then who created the creator? I believe that it is safe to say that neither religion nor science can answer the question, “Why did things happen the way they did?”