Monday, May 29, 2017

Some Proposals about the Beginning of our Universe


The theoretical physicist from Caltech, Sean Carroll gave a talk to the American Astronomical Society in January 2017 on the topic of what we know and don't know about the beginning of the universe. He has generously posted a copy of his presentation on his blog, preposterousuniverse.com. In this talk, Dr. Carroll speculates about how the gaps in what we don't know may be filled in by presenting a systematic classification of the main ideas developed over the last few years about what may have occurred before our universe began and brought our universe into existence. (Dr. Carroll does point out that to say our universe "came into existence" sounds like a process within time, but that time as we know it actually had a beginning with our universe.) In previous posts I have already discussed many of the things Dr. Carroll covers in his talk including (1) that our universe was in a state with very low entropy at its beginning, (2) that something like the Big Bang occurred about 13.8 billion years ago but we don't know what actually happened in the first trillionth of a trillionth of a trillionth of a second because (3) we don't have a quantum theory of gravity which may describe the initial conditions of our universe, even though (4) the equations of classical general relativity predict that our universe had an actual beginning.

Let's review what we do know: (1) About 13.8 billion years ago the universe was very hot and dense and was expanding rapidly while decelerating; (2) classical general relativity predicts that there was an actual beginning of our universe in a singularity; and (3) our early universe was in a very low entropy state which is quite hard to explain since low entropy is associated with an ordered, and improbable state. The last point presents tremendous challenges for any naturalistic proposal about how our universe came into existence.

In regards to what we don't know, Dr. Carroll presents four different classes of models about the space-time origin of our universe: (1) a bouncing model, (2) a cyclic model, (3) a hibernating model, or (4) a reproducing model.

Carroll says that bouncing models try to "smooth out the singularity through new degrees of freedom... or through intrinsically quantum effects." The Aguirre-Gratton model I described in a previous post is a bouncing model of the universe. Carroll lists some bouncing models as those proposed by Veneziano, Hawking, and others. Models that bounce repeatedly are cyclic models such as proposed by Steinhardt and Turok. Both bouncing and cyclic models have difficulty in explaining the initial low entropy of the universe. In fact, all early cyclic models from the 1970's and 1980's were discarded because they could not explain the low entropy of our universe. Hibernating universes are those that sit in some quasi-stationary state since eternity past, but then at some point experience a phase transition and begin to expand. Cyclic and hibernating cosmologies are problematic since they require infinite fine tuning in the past to explain the low entropy of the early universe. Finally, reproducing models, like that developed by Guth, propose that a high-entropy "parent" universe can spawn low entropy universes like ours. Carroll prefers these spawning universe models because he claims they can solve the low entropy problem.

In future posts I may elaborate more on some of these models as I have elaborated on the Aquirre-Gratton model in a previous post, but for now let me develop some conclusions that can be made from what we do know and what we don't know about the Big Bang. In addition, I will make some observations about how our knowledge of the origin of the universe relates to biblical pronouncements.

(1) All of the theoretical and observational physics that has been confirmed points to an actual beginning of our universe. We should definitely have more confidence in the predictions of known physics rather than speculative ideas. Even a quantum theory of gravity may ultimately require a real beginning.  (2) The above proposals still require an actual beginning to our universe (except maybe the hibernating model). Although they may have features like replacing a singularity at the beginning with an inflection point, that inflection point still serves as a beginning to our universe. (3) Any proposed model requires that physical laws operate before our universe. It is not a trivial question to ask where these laws came from, and why the laws are able to operate to give an actual universe. We apply descriptive laws to what we observe, but these physics principles are not just descriptive. They actually work and have creative power. It could be argued that a creator is required to even implement the working of nature. (4) Until we have some experimental evidence to confirm or refute these proposals, they remain outside the realm of observational science. If we were to ever find any evidence to confirm one of these ideas, then, and only then, would we be able to make some firm conclusions regarding any suggestions as to what happened at the beginning of our universe. The best current conclusions come from the best confirmed science which continues to suggest an actual beginning to our universe. The confirmed evidence points to a transcendent cause that brought our universe into existence. It would hardly be possible for scientific inquiry to give stronger evidence for God.

Next, let me make some observations from a biblical and Christian viewpoint. Initially, as I thought about Dr. Carroll's presentation, I considered that I might propose the idea that God created the universe as a "5th model" of the origin of the universe. But in fact, that is not precisely correct. While it is possible that a "5th model" would be that God supernaturally brought this universe into existence, and such an idea is certainly a reasonable (and maybe the best) conclusion based on the observational evidence, we also know that God is responsible for both natural and supernatural processes. More often than not, God uses natural processes to accomplish his purposes. Genesis 1:1 tells us that this universe had a beginning and that the heavens and earth were created by God. Hebrews 11:3 says that the things we see were made out of what was not visible. In these biblical passages we are not told the mechanism that God used to create the universe. Given what we know of God's methodology, it is possible that he actually used a physical, naturalistic process to begin this universe. Such a process would be consistent with the teaching of scripture. Consequently, I would conclude that even if one of the "naturalistic" proposals above was shown to be true, that would give further credence to the biblical description of the creation of this universe. It is possible that one of the above models is identical to the proposal that God created the heavens and the earth. Our universe clearly had a moment when it began to expand, and space, time, matter, and energy came into existence in this universe. Even if any of the proposals above were shown to be true, Genesis 1:1 would be an accurate description of the origin of our universe. The fact that this universe is not eternal and something like the Big Bang did occur, regardless of whether or not that Big Bang had a "natural" or "supernatural" cause, supports the biblical statement that our universe began and was created by God. The Bible describes a future universe that God will create. Is it unreasonable to speculate that he may have created past universes as well?

Am I weakening the cosmological case for God by suggesting that a "naturalistic" origin of our universe would still support the biblical record? Only if I were to promote "God of the gaps" arguments as the best evidence for God. Instead, I suggest that I am strengthening the argument for God because I am asserting that the established knowledge we already have about the origin of the universe completely coincides with the description of the creation of this universe in Genesis 1. Regardless of possible future discoveries, this conclusion is already confirmed and will not be nullified. Like other ideas in science that are so well validated they may be modified but not discarded, the Big Bang origin of the universe with the implication that the space, time, matter, and energy of our universe began to exist will not be discarded despite future discoveries. The biblical description of the origin of our universe is supported by science and will continue to be. Note also that the history of scientific discovery has consistently increased the evidence for an intelligent, transcendent creator who cares about humanity. Speculations about the origin and design in the universe have come and gone, but the actual facts discovered by science arguably have God as the best explanation. Theists like myself have invoked the Big Bang and the anthropic principle as evidence for God for decades and over those years the observational evidence has increased, not decreased. Scientific evidence that supports the hypothesis of a creator God is more abundant than ever and, I confidently predict, that as we learn more about the origin of the universe this trend will continue.

The opening figure is part of Dr. Sean Carroll's powerpoint presentation and is reproduced from http://www.preposterousuniverse.com/blog/2017/01/25/what-happened-at-the-big-bang/


3 comments:

  1. It must be remembered that before Darwin all religions including Christianity claimed their God had created humans and everything living in the form as it is living today and it was also believed the Earth was under ten thousand years old.

    Many enthusiastic religions and a minority of Christians still believe these things, however science has unquestionably eliminated those beliefs as being creditable and pushed the realm of God into the last bastion of creation, the universe.

    I predict this will also fall to the scrutiny of science over time, however the downfall may not just come from cosmological investigation but neurological specialists and Cognitive psychologists who are constantly discovering what our brain is capable of. It has already been claimed that that human concepts of spirits and Gods are derived from the mechanics of our brain.

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    1. Thanks for your comments. One of the reasons I began this blog was to dispel some common misconceptions about the relationship between science and Christianity. Your statement that "Before Darwin,,,Christianity claimed...the Earth was under ten thousand years old" is a common, but incorrect idea. The many meanings of the Hebrew word "yom" which is translated "day" has been known for thousands of years and biblical scholars, both Jewish and Christians, have realized that the time scale of creation is not described in the creation account. I have commentaries in my personal library from before Darwin wrote The Origin of the Species that describe the "days" of creation as unknown periods of time and the earth as "ancient". Of course there were many people, both religious and secular, that thought the earth was thousands of years old before evidence of its age was discovered, but it is a myth that the biblical record was strictly interpreted as supporting a universe that was only thousands of years old at any time in recorded history.

      The same can be said of your statement about the "how" of human creation. Basically, all people both religious and non-religious, believed that humans were formed in their present form. To say that belief is a "religious" belief that has been discarded, is simply false. And now, there are religious and non-religious people who believe that humans developed through the process of evolution.

      You seem to be ascribing physical processes that work well to evidence against God, and you are, therefore, implicitly appealing to God of the gaps arguments which, I believe, are not the best arguments to support a theistic worldview. I encourage you to read my post on "Finding God in Nature."

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  2. Hello,
    I have two questions about the origin of the universe. I know we don't have a quantum theory of gravity yet, but, do you think that we can still say the universe had a beginning? If you had to make a wager, would you bet that the universe will still have a beginning when we have a full theory of quantum gravity (even without a beginning "point")? This paper seems to think so and I wanted your thoughts - https://arxiv.org/abs/1010.5513 Second, when you talk about the universe having a beginning, do you mean only the parts that are observable, or do you think that the whole universe (even beyond what we can see, the observable universe) also had an absolute beginning? Sometimes people disagree about whether or not the evidence points toward only the observable universe having a beginning or if it is the whole thing. Thank you for your well reasoned posts.

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