If you are familiar with popular scientific accounts of the universe, such as ‘Cosmos’ by Carl Sagan, then you know that a consistent theme is the smallness and insignificance of our lives when placed in the grander scheme of the universe. These commentaries relish the process of demoting human beings from the central and faith-based position they once occupied. But while Copernicus may have told us we are not in the geometric center of the universe, modern physics is putting human beings right back in the center of something far grander: the design plan that governs the fundamental laws of physics.
Modern science tells us that the universe was created about 13.7 billion years ago. At that first instant the universe was only the size of a tiny pinprick, but it rapidly began expanding outwards into its present size. You might think that if the rate of the Big Bang’s expansion were slightly faster then our present universe would be a bit larger, And if the rate were slightly slower then our universe would be a bit smaller. But modern science tells us that this view is mistaken. If the Big Bang’s rate of expansion were slower by just one part in 10^60, then the universe would have immediately collapsed back on itself a split second after the Big Bang first happened. No stars and planets would have formed, and life would be impossible. But if the force of the Big Bang’s expansion were faster by just one part in 10^60, then the universe would have expanded so rapidly that interstellar particles would never have been able to coalesce into stars and planets, also making life impossible.
Gravity is another example of fine tuning. Stars can divided into roughly three categories, red dwarfs, blue giants, and normal sun-type stars. The interplay between gravity, mass, and the star’s age determine which category a star falls into. You might think that just a small increase in the force of gravity would result in a small increase in one category and small decrease in the others. But modern science again shows that this is not true. If the force of gravity were just a tiny bit stronger then all stars would be red dwarfs, and red dwarfs are too cool to support life. If gravity were just a tiny bit weaker then all stars would be blue giants. And blue giants have too short of a lifespan – they burn themselves out too quickly – to lead to the development of life.
Other examples abound. If the nuclear strong force were just 2% stronger then atoms could not form out of subatomic particles and life would be impossible. If the nuclear strong force were just 5% weaker then the nuclear furnaces of early stars would never have been able to make heavier atoms out of hydrogen, and carbon-based life would be impossible. If the nuclear weak force were stronger then the nuclear fusion processes out of the early Big Bang would have turned all the matter of the universe into lumps of iron, making life impossible. Chemists have shown that the complex chemistry needed to form intelligent life is only possible in a universe with three spacial dimensions. Two or four (or more) dimensions would make life impossible. If the Pauli Exclusion Principle did not exist then complex chemistry would be impossible and all matter would super dense lumps.
The list goes on and on. Scientists have cataloged over 130 different improbable coincidences that are needed for life to happen. When you take all of these factors into account, a conservative estimate for the chance of a universe that supports life is 1 in 10^150. If the odds of winning the lottery are one in a million, then the the odds that our universe supported life are like winning the lottery 25 times in a row.
The Christian explanation of this is simple: God designed the universe to support human life. There are three main alternative explanations by atheists: law, chance, and the “multiverse” of countless other un-seeable universes.
Defense #1: Law
One hope for atheists is to find a law that explains away these improbable coincidences. The first attempt is called inflation theory. This theory holds that the universe initially “inflated” at a vastly accelerated rate before slowing down to its present rate of expansion. Inflation explains a few examples of fine tuning, such as the rate of the Big Bang’s expansion and the “smoothness problem.” But it does not explain the others, such as the fine tuning of the force of gravity.
Furthermore, inflation introduces its own coincidences. The various components that make up the cosmological constant have to be fine tuned to about one part in 10^53 (10^123 by some accounts) for inflation to succeed as a theory. The net effect is that inflation removes a couple improbable coincidences only to replace them with others.
Another hope for atheists is to find a “Grand Unified Theory” of physics, which would then specify the values for the universe’s basic physical laws. But this would actually work against atheism. A grand unified theory is simply a mathematical representation of our universe’s design plan (whether that plan is accidental or created by a higher power). And if the grand unified theory means that the universe can support life, then the conclusion is inescapable: supporting life is a part of the design plan of our universe.
Think of the fine tuning of the universe as a lottery and #527 is the winning ticket. A grand unified theory would mean that the lottery is rigged so that the winner will be #527. But if atheism is true, then there is no higher power making sure that the universe support life. So there is no reason that a grand unified theory would favor ticket #527. It could just as easily have favored ticket #1,385,987, or ticket #74,382, or something else. Out of all the possible lottery tickets, the universe is rigged to favor to favor #527. The odds have not gotten better for having discovered a grand unified theory. And now atheists have the added problem of grappling with life being a part of the universe’s design plan. At least now they can claim it was a lucky accident.
Atheists are well aware of this, and this realization is built into modern string theory. You may be familiar with string theory through Brian Greene’s book and TV show, “The Elegant Universe.” Greene describes string theory as an elegant and beautiful grand unified theory of physics. But recent years have not been kind. The discovery of dark energy has meant that string had to be patched up with duct tape and shoestring. Now string theory is an ugly Rube-Goldberg device, as one of its leading defenders, Leonard Susskind puts it. String theory now consists of a “landscape” of 10^500 different possible grand unified theories, one of which happens to be the grand unified theory that governs our universe and most of the others would lead to universes in which life is impossible. This allows atheists to search for the grand unified theory without being locked into the implication that life is a part of the universe’s design plan. String theory helps deflect the implications of a grand unified theory, but it does not improve the odds of a universe that supports life. That is why string theory is usually combined with the multiverse defense.
Defense #2: Chance. AKA “The Weak Anthropic Principle”
Given the unbelievable odds against a life supporting universe through chance alone (recall from above that this is like winning the lottery 25 times in a row), you would not think that anyone rational would hold up chance as an alternate explanation. This is where the weak anthropic principle enters the debate. The weak anthropic principle is probably the most complicated part of the debate about fine tuning. It has largely been rejected by professional scientists and philosophers (except when used in conjunction with the “multiverse” defense), but it remains popular among the general audience so you should be familiar with it.
The starting point is the realization that if the universe were not fine tuned for our existence, then we would not exist. From this you can draw the conclusion that we are only capable of observing a universe that does support life. However, at this point atheists subtly draw the incorrect conclusion that this means that we should not be surprised that our universe is fine tuned.
It is true that we are only capable of observing a fine tuned universe. But it is not true that we should not be surprised. The philosopher John Leslie has a clever thought experiment to help understand the distinction. Imagine that you are sentenced to death by facing a firing squad of 100 men with rifles at point blank range. The order to fire is given and you hear a massive bang of 100 rifles going off at once. Then you realize that you are alive and unharmed. You would not invoke the weak anthropic principle and claim that you were very lucky because 100 trained riflemen all missed at point blank range (chance). Instead you would look for a non-random explanation (design). Perhaps your friend secretly swapped their ammunition with blanks, or bribed the squad to miss on purpose.
Here is another way of thinking about the weak anthropic principle. Suppose you are a scientist on the front lines of cosmology and you are studying a hypothetical force with a value of 1000. You start to wonder about the life permitting values of this force. You can correctly invoke the weak anthropic principle to tell you that 1000 is a life permitting value (because if 1000 did not support life, then you would not exist. Since you do exist, 1000 must be a life permitting value). But the weak anthropic principle does not tell you anything else. If your studies told you that all the values from 1 to a million lead to a universe that supports life, then you would not be surprised to be alive. But if your studies told you that 1000 is the only value that supports life, then you would be very surprised that the universe supports life.
Another objection is that the invalid use of the weak anthropic principle leads to absurd conclusions. Consider the issue of abiogenesis – the initial creation of life. The first life form had to arise from non-living things. This is a difficult issue for secularly minded evolutionary biologists because that involves a very large jump in complexity. And you cannot use DNA and evolution to address it because there is no evolutionary mechanism for nonliving things. Christians hold this up as evidence for the existence of God, but atheists would claim that this is a “God of the gaps” argument. Atheists maintain that there is an as yet unknown mechanism to explain the origins of the first living cell. But if the weak anthropic principle really can be used as its proponents claim, then we don’t need that mechanism. We can simply invoke on the weak anthropic principle and random chance: if we didn’t lucky and have abiogenesis happen by chance, then we wouldn’t exist. Since we do exist, we must have gotten lucky.
Defense #3: The Multiverse
The weaknesses of the other defenses have led most secular scientists to adopt the multiverse defense. It holds that there exist countless billions of other universes that we can never see, touch, or otherwise interact with. No one quite knows where these other universes exist, although they may be in alternate dimensions (or “branes”). The important point is that these other universes each have different values for their physical forces. With so many universes, it is no longer surprising that one of them supports life.
This makes the multiverse defense the first reasonable atheist explanation for the fine tuning of the universe, but it pays a high price. It is tough for atheists to then argue that it is unreasonable to believe in a God that we can not see or touch when they believe in billions of universes that they cannot see or touch. At this point some Christians might be satisfied to have battled to a stalemate with atheists, but there are some very big problems with the multiverse defense that make it untenable.
The first problem with the multiverse is that it only explains why life exists in some universe. But it does not explain why life exists in our particular universe. It commits an example of what philosophers call the inverse gambler’s fallacy. The regular gambler’s fallacy holds that when you go through a losing streak you become “due” for winnings. This is a fallacy because past results do not influence the future. The odds don’t change just because you’ve been losing. The inverse gambler’s fallacy holds that when you win on your first try, it is only because someone else had already done the hard work of suffering through the losing streak, and the game became “due” for winnings. E.g. if you sit down to play blackjack and promptly win a lot of money, it is only because some other unlucky person had suffered through the “cold streak” and the table was now “due.”
Your chances of winning the lottery do not increase simply because millions of other people also bought lottery tickets. Sure, this means someone will probably win, but it does not increase the chances that the lucky winner will be you. But this is precisely what multiverse defenders tacitly claim: that our universe is more likely to support life because there are billions of other universes out there that probably do not.
A second problem with the multiverse defense is that it violates Occam’s razor. The explanation is more complicated than what it purports to explain. The multiverse requires countless billions of other universes as well some sort of meta-universe structure for containing the individual universes. All this in order to explain one improbable universe. Christians do not face this problem because Christians hold God to be very simple. The philosophical doctrines of divine simplicity (and alternate doctrines on how God is a simple being) get pretty abstract, but that has been the Christian teaching since Saint Augustine in the later Roman Empire, about 1000 years before the concept of Occam’s razor was invented. Since God is simple, that explanation should be preferred over the complex multiverse. Furthermore, Christianity only requires one additional thing – God. But atheism demands not just countless billions of other universes, but some meta-universe framework that can contain them all, and some sort of generator powerful enough to create a potentially infinite number of other universes.
A third problem is that there is no independent evidence for the multiverse. There is a lot of formidable sounding speculation, such as bubble universes being formed during the inflationary phase of the Big Bang, or universes being formed out of quantum vacuum fluctuations, but this is wholly speculative without any observational support. But there is independent evidence for the existence of God based on other arguments for His existence, such as the Kalam Cosmological Argument. A related problem is that the multiverse defense is completely ad-hoc. No one would even be suggesting that there is such a thing as a multiverse if it weren’t for the fact that life is so improbable.
A fourth problem is that the two best explanations for the multiverse are extremely susceptible to a modern form of the first cause argument for the existence of God, which is called the kalam cosmological argument. Out of the frying pan and into the fire. These two multiverse theories are chaotic inflation (which also goes by the somewhat inaccurate name of eternal inflation) and cosmological natural selection, or Smolin selection, after the inventor of the theory.
Chaotic inflation holds that other universes are formed during the inflationary period when our universe was expanding at an accelerated rate. During this period our universe can be thought of as a ocean wave, and other “bubble” universes are created out of the froth. Thus you can imagine one universe rapidly expanding and spinning off a bunch of daughter universes, which themselves and expand and create more universes. These bubble universes can be thought of as offspring, so just as all living things date back to a first living thing, all universes must trace there origins back to a single original universe. That first universe could not have been created from another universe, so it must have been created by God. The nuances of the Kalam cosmological argument are beyond the reach of this article, but it essentially points out that Christians can answer the question “who made God” by claiming “no one mad God, because God is eternal. He was always there.” But atheists cannot do the same in response to “who made the multiverse?” The popular multiverse scenarios predict that the multiverse was not “always there.”
Cosmological Natural Selection
Cosmological Natural Selection is an extremely clever form of the multiverse defense that deserves its own explanation. It is both more speculative and more interesting than eternal inflation scenarios. Smolin’s theory holds that the multiverse is formed because new universes are created “on the other side” of black holes in our universe. It purports to be a Darwinian solution to the cosmological design argument. The offspring universe that is created has the same physical laws as the parent universe, except that the various forces “bounce” and take on slightly different values. This means that the multiverse will evolve to become more and more efficient at forming black holes, because universes that are better at forming black holes will have more offspring. And here is Smolin’s prediction: the universes that are best at forming black holes are also very much like our own universe, and capable of supporting life.
Smolin’s cosmological natural selection theory is therefore the only multiverse theory to make a testable prediction. It also has the virtue of being able to withstand the inverse gambler’s fallacy, because all universes would evolve to the point of having laws similar to ours. After being largely ignored, Smolin’s theory has been getting more and more attention from the physics community in recent years, much of it skeptical. There are several challenges. The first is that Smolin’s theory requires that black holes lose some information. This actually became the topic of a famous bet between the Steven Hawking and other physicists. As we began to understand black holes better, Hawking has since acknowledged that he lost, and black holes do not lose information. Another challenge is that the force of gravity should be a stronger to maximize the number of black holes in our universe. A final challenge comes from the physicist Alexander Vilenkin, who has observed that the number of black holes would be maximized with a higher cosmological constant than we find in our universe. As with any new theory, the rebuttals and counter-rebuttals to these objections are flying. But so far it does not look good for Smolin’s theory.
A final problem with Smolin’s argument is that even if it salvages itself against the argument for fine tuning, it does so by making itself extremely vulnerable to the kalam cosmological argument, as described above for eternal inflation.
Further Reading
- Teleological Argument: Taxonomy of Objections
- The Teleological Argument and the Anthropic Principle Extremely rigorous article by William Lane Craig
- Robin Collins’ Home Page Robin Collins is a leading Christian philosopher advocating the teleological argument. You will find many good articles here.
