William Lane Craig CV

Transcript

Existence of God (part 10)

Transcript of William Lane Craig's Defenders 2 class.

Excursus: Natural Theology
§ II. Kalam Cosmological Argument
Lecture 5

We have been talking about the Kalam Cosmological Argument. We looked at philosophical reasons to believe the key second premise that the universe began to exist. Last time we looked at the evidence for the beginning of the universe from contemporary Big Bang cosmology, which suggests that as you go back in time, the past is not infinite, but rather the past is finite and comes to a boundary point before which the universe literally did not exist. We ended by asking ourselves the question, “Is this standard model of the universe correct?” Or, more importantly, “Is it correct in predicting an absolute beginning of the universe?”

There is powerful evidence in favor of the Big Bang theory of the universe. We already mentioned the redshift in the light from distant galaxies, which indicates that the universe is expanding, so that as you extrapolate that back in time, it goes back to this point of beginning, as the universe was denser than it is today. In addition to that, the abundance of certain light elements in the universe, like helium, for example, which is very abundant in the universe, indicates that these light elements were formed very, very early in the history of the universe, when the universe was very dense and very hot. So the abundance of light elements like helium is supportive of the Big Bang model. Finally, in 1965, it was discovered that the entire universe is bathed with a background of microwave radiation – the same kind of radiation that operates in your microwave oven at home. This radiation background is a vestige of a very early, hot, dense state of the universe. So on the basis of the redshift, the abundance of the light elements, and the microwave background radiation, we have good grounds for thinking that the universe is in a state of cosmic expansion and that it goes back to a beginning such as what we have in the standard model.

Nevertheless, we also note that this standard model is going to have to be modified in certain ways. The model is based on Einstein’s General Theory of Relativity – which is his theory of gravity. The problem is that Einstein’s theory breaks down when the universe shrinks down to subatomic proportions. This is usually referred to as the Plank Time. This refers to the very early period of the universe during which the universe must be described by subatomic physics, not simply by Einstein’s General Theory of Relativity. The only problem is, nobody knows how to do that yet. We don’t know how to marry general relativity with quantum physics, or subatomic physics, in order to have a unified theory of gravity. That will need to be done. Moreover, the expansion is probably not constant as in the standard model. It is probably accelerating and may have gone through a super-rapid expansion in the past during a brief period of time.

But none of those adjustments, which do need to be made, need affect the fundamental prediction of a beginning of the universe. In fact, since Friedman and Lemaitre’s work back in the 1920s when the standard model was first proposed, scientists have proposed scores of alternative theories over the decades which were aimed at trying to avert the absolute beginning of the universe. We’ve seen the Steady State model, Oscillating models, Vacuum Fluctuation models, Inflationary models, Ekpyrotic models – all of these have been tried and failed to avoid the absolute beginning of the universe. Put more positively, what we can say is that any non-standard model which is viable, which is tenable, involves an absolute beginning of the universe, not an infinite past.1 That beginning may or may not be a beginning point, but even in theories like Stephen Hawking’s No Boundary proposal, in which the beginning is rounded off, the past is still finite, not infinite. The universe still comes to exist at some time in the finite past, even if it doesn’t do so at a sharply defined point.

In a sense, the history of 20th century cosmology can be seen as a series of failed attempts, one after another, to try to avert the absolute beginning predicted by the standard model. Unfortunately, the impression arises as a result in the minds of laymen that the field of cosmology is in constant turnover with no lasting results. It seems as though every other month features a new cosmological model on the cover of Scientific American magazine. But what the lay person doesn’t understand is that this parade of failed theories only serves to confirm the prediction of the standard model of an absolute beginning of the universe. That prediction has now endured through over 80 years of incredible advances in observational astronomy and creative work in theoretical astrophysics.

In fact, something of a watershed appears to have been reached in the year 2003 when three very famous cosmologists, Arvin Borde, Alan Guth, and Alexander Vilenkin were able to prove a theorem which shows that any universe at all which is in a state of cosmic expansion on average throughout its history cannot be eternal in the past but must have a past space-time boundary or beginning of its existence. What makes the Borde-Guth-Vilenkin theorem so remarkable is that it is independent of any description of the universe prior to the Planck time. That is to say, it doesn’t depend on having a quantum theory of gravity for its validity. Because we do not yet have a physical description of this early era of the universe, it has been fertile ground for speculations. In fact, one scientist has compared this to the regions on ancient maps which are labeled “Here there be dragons!” – you can fill in all sorts of imagined fantasies. But the Borde-Guth-Vilenkin theorem implies, whatever physical description we come up with for that early era of the universe, the universe must have a beginning at some time in the past. In fact, the Borde-Guth-Vilenkin theorem implies that even if our universe is just one of many universes as part of a grand multiverse, still the multiverse itself must have an absolute beginning. So even on the multiverse theories, it turns out that the universe began to exist.

Vilenkin is very blunt about the implications – here is what he writes on page 176 of his book Many Worlds in One:

It is said that an argument is what convinces reasonable men and a proof is what it takes to convince even an unreasonable man. With the proof now in place, cosmologists can no longer hide behind the possibility of a past-eternal universe. There is no escape; they have to face the problem of a cosmic beginning.2

We can fully expect that new theories will be proposed attempting to avoid the absolute beginning of the universe, and these theories are to be welcomed. We welcome attempts to falsify the prediction of the standard model. But we have no reason to think they will be any more successful in falsifying that prediction than their failed predecessors.3 Of course, it hardly needs to be said that scientific results are always provisional. But nevertheless, it is pretty clear which way the evidence points. Today the proponent of the Kalam Cosmological Argument stands squarely within the scientific mainstream in affirming the second premise of the argument that the universe began to exist.

Discussion

Question: Can someone go to your book and look at commentaries on these failed hypotheses.

Answer: Yes, these are discussed in the book Reasonable Faith in the chapter on the existence of God, where I go into more detail. If you want really extensive discussion, look at the article that Jim Sinclair and I did in the Blackwell Companion to Natural Theology. Sinclair is an expert in the area of cosmology, and he surveys an even wider range of models and more recent models attempting to avoid the beginning and shows how these cannot be extrapolated back to the infinite past. So Reasonable Faith and then also the Blackwell Companion article.

Question: On the Borde-Guth-Vilenkin theorem, I have some friends I talk to about this and, of course, the first question is, “Show me the article and show me the proof!” I have looked all over our databases, and I cannot seem to find their writings. I can’t find it even in the physics database. What articles are these in?

Answer: You can find the citation in Reasonable Faith of the article. It is in the arXiv on the web4, or it will be in the Blackwell Companion, where there is an extensive bibliography. Most of these are on the web. Scientific results are so current that published paper journals now serve only archival purposes. The most recent work is always put out on these internet archives. So the web addresses are given where you can find this. I have read the article myself. It is footnoted in Reasonable Faith or the Blackwell Companion.

Question: I have an article I had in my Bible for a few years. It says:

New Theories Stars Exploded Into Universe - In the most distant observations made yet, some astronomers think that they are seeing evidence that the universe emerged from its initial darkness in a dawn of light that came up like a thunderbolt across the cosmos. A lot of the first stars apparently did not come into existence gradually here and there – that had been the accepted theory. Instead the new and surprising view is the first starlight burst forth in a spectacular profusion. If this proves to be true, many theories of the early history and evolution of the universe may have to be revised.

It is very interesting that these scientists look and say, “Gosh, what we said don’t work!” It is amazing to me that they are so smart, but they won’t just check what is written in the Book. They ought to read the instructor’s book as to this is how He did it.

Answer: Well, I think it is important to understand the Bible is not a science textbook. It doesn’t intend to teach science, though I think it is consistent with science. In that article, I am not sure what they are getting at because starlight doesn’t appear until later in the history of the universe, once the stars have had a chance to form. We are talking about the very beginning of the universe, before there were any stars, so the stars would come some time later, after they had a chance to form.

Question: Consider the trillions and trillions of stars in the vast cosmos. Since the revealed Word of God says we are the crown of his creation, then, in all of that space out there, then that must be it. Would you agree?5

Answer: This is an interesting point to which theists and non-theists react differently, I have found. Non-theists look at the enormity of the universe, and humankind in comparison to it seems an insignificant speck, just nothing. So it means that man is worthless. He is just an ephemeral dot on the history of the cosmos. The theist, by contrast, looks at the enormity of the universe and thinks with the Psalmist, “What is man that you are mindful of him, human beings that you care for them?” (Psalm 8:4). It gives you a sense of the condescension of God that He would care about us and send His Son onto this little tiny planet to die for us. So, for me, when I contemplate the enormity of the universe, it magnifies my sense of the greatness of God and the extent of this condescension in reaching down to save even me – that little, insignificant dot down there named Bill Craig. Maybe people have concepts of God that are far too small. Maybe the enormity of the universe can help to expand our concept of God in a way that is more worthy of His greatness and His majesty and to realize how condescending He is to care about us and to save us.

The other thing, though, that needs to be said is what I mentioned a while before – the worth of mankind is not measured by size. You do not measure the moral worth of something by how big it is. If we are made in the image of God, as the Bible teaches, we are persons just as God is personal. Therefore, one human person is worth more than the entire material universe taken together because it is just matter. Now that is an awesome, incredible thought. One single human person, the most ignorant peasant, or homeless person, or little baby – that one person is worth more than the entire material universe taken together. Because that individual is a person in God’s image, rather than just a collection of atoms. We are not just a bag of chemicals on bones. We are persons. Therefore, as Jefferson says, we are endowed by our Creator with intrinsic, inalienable rights and moral value. So I see the greatness of the universe as something that can expand our vision of God but also something that is really quite irrelevant to our worth, which is determined on moral grounds, not on one’s size.

The last thing that one might want to say about that is that the human brain is the most complex structure in the entire universe. When you take all of those trillions and trillions of galaxies together, there is nothing in the universe as complicated as a single human brain. That is how complex and well designed we are. So that intricacy, that complexity in a microcosm is awe-inspiring as well and sets us apart from the rest of creation.

Question: We hear about all the science and how the evidence for creation occurred and yet trying to get that into textbooks as even a possibility is under attack. There seems to be a disconnect between what we hear out in the world and what the facts are.

Answer: I don’t think so. What you are thinking of there is the creation-evolution controversy, which cannot get into textbooks. But that is talking about the origin of life on this planet and the evolution of biological organisms on this planet. What we are talking about here is astronomy and the origin of the universe. And this is in the textbooks. If you pick up any textbook on modern astronomy and astrophysics, you will see a discussion of these various theories of how the universe originated, and they will talk about Steady State and the redshift and the expanding universe and things of that sort.6

Followup: But not intelligent design.

Answer: No, and I have not argued here for an intelligent designer. That is important to see. Although this is a Sunday School class, what I have been talking about the last couple of weeks isn’t religious. The statement “The universe began to exist,” the second premise of the Kalam Cosmological Argument, is a religiously neutral statement that you can find in any astronomy and astrophysics textbook. This isn’t creation science or intelligent design or anything of that sort. Now I think it has theological implications, which we will draw later on. But the fact that the universe began to exist is a theologically neutral, scientific claim that doesn’t presuppose the existence of God or anything like that. Therefore, it ought not to be objectionable in textbooks – although I noted with some amusement a few years ago in the Arkansas Creation Trial, Judge Overton’s decision said that the statement of the creation of the universe out of nothing is an inherently religious statement and therefore cannot be taught! I was amused at that because that is precisely what modern cosmology teaches, the creation of the universe out of nothing – unless you think that “creation” is a loaded term theologically. But it is often used in a neutral sense in astronomical discussions. That judge simply got it wrong.

Question: You said on this theory that the universe is accelerating. Why?

Answer: Yes, the most recent evidence shows that the expansion is actually speeding up rather than slowing down.

Followup: It seems logical it would be slowing down; why is it accelerating?

Answer: It is because there is a kind of anti-gravitational or reverse-gravitational force that kicks in at a certain point that, rather than pull things together the way gravity does, it pushes them apart. And this force becomes operative when the density of the universe drops to a certain level; then this kicks in and the acceleration takes place. The expansion actually speeds up! This is a discovery that has only been made since about 1998 and really was quite unexpected.

Question: Who first coined “Big Bang”?

Answer: This name “the Big Bang” was a derisive term for the Friedman-Lemaitre model which was coined by Fred Hoyle, the famous British astronomer. Hoyle was the proponent of the Steady State Theory, and he thought that to say that the universe originated out of nothing implied the existence of God, which Hoyle, as an atheist, just could not have. He thought if you had a Big Bang, you had a Big Banger, and that was unacceptable. So he propounded the Steady State Model, and he derided the Friedman-Lemaitre model by saying it teaches that a universe originated in a “big bang.” The name stuck, and that is what everybody refers to it as, even though, as I explained, it is really a misleading term because it makes it seem as if the universe came from an explosion from a central point out into nothing, and it is not that at all.

We have been looking at the evidence for the beginning of the universe from the expansion of the universe. As if this weren’t enough, there is a second scientific confirmation that the universe is not infinite in the past but had an absolute beginning. This comes from the field of thermodynamics and in particular the second law of thermodynamics. We will look at that evidence next.7


Notes

1 5:08

2 A. Vilenkin, Many Worlds in One: The Search for Other Universes (New York: Hill and Wang, 2006), p. 176.

3 10:02

4 http://arxiv.org/abs/gr-qc/0110012

5 15:21

6 20:10

7 Total Running Time 24:24