10 - The Anthropic Principle and the Multiverse Speculation

Note to readers: Starting with the next post, new posts will go up twice a month, on the 15th and the 30th of the month.

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As we look out into the universe and identify the many accidents of physics and astronomy that have worked to our benefit, it almost seems as if the universe must in some sense have known that we were coming.  - Freeman J. Dyson

In this post: What is the Anthropic Principle? What does it mean to assert that the Universe is "finely tuned"? How does the notion of the multiverse feature in this discussion?

In 1973, an international symposium was held in Krakow to honour Copernicus’ 500^th birthday. Among other things, it highlighted the Copernican Principle, which asserts that humans do not occupy a privileged position in the Universe. Reacting to this, Brandon Carter, a theoretical astrophysicist, stated in his presentation:

Although our situation is not necessarily central, it is inevitably privileged to some extent.^{Note 1} Only in a universe capable of eventually supporting life will there be living beings that can be capable of observing that universe.

The latter part of this quote (underlined) he named the Anthropic Principle. It later became became known as the Weak Anthropic Principle (WAP). He and other cosmologists also proposed a number of more adventurous versions, each called a Strong Anthropic Principle (SAP), which we will ignore in this post.^{Note 2}

Well, duh!! If the universe had not developed in such a way that it could support life we wouldn’t exist, and there would be no one to observe it! This is a logical tautology.

Nonetheless, Carter had everyone’s attention. At that particular conference, at that particular time, and in that context, his statement caused a powerful stir among its audience.

Why? Because everybody could see that, in fact, our species had evolved and could observe the universe. And they all, being scientists, understood that a major set of “Anthropic coincidences” (AC) had to have happened to enable our existence, perhaps many more than the laws of probability, operating randomly, could have produced over a mere 10 to 15 billion years.

One question that the WAP raises is: What are the ACs that had to happen in order for you and me to exist at this time, and what are the odds against them all happening?

Stephen Hawking, in A Brief History of Time, wrote of one such AC:

If the rate of expansion one second after the big bang had been smaller by even one part in a hundred thousand million million, the universe would have re-collapsed before it ever reached its present size. On the flip side, if the expansion rate had been a mere fraction greater than it was, galaxies, stars and planets could never have formed, and we wouldn’t be here. 

The behaviour of water is another example of an AC. Ice floats because it is approximately 9% less dense than water. If ice did not float, living organisms would not be able to exist in water, since without the insulation provided by the layer of ice, lakes and ponds would freeze solid during winter. Water is quite unique, the only non-metallic substance that expands when it freezes, becoming less dense than its liquid state.

Using his own list of ACs, Hugh Ross, a Canadian astrophysicist, has calculated the probability of sentient life on earth as less than 1 chance in a trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion. Assuming he is right, that amounts to 10144, to 1, which are very long odds indeed. Ontario Lotto Max, Ontario’s provincially run lottery, offers a mere 28, 633,528 to 1 chance of winning. Only If someone bought one ticket for more than a thousand separate lotteries and won each and every one of them, would that equal the odds of our universe having evolved sufficiently to produce the human species at this time. This sort of consideration has led some observers to remark that the Universe appears to be “finely tuned” for life.

Reflecting on why there is so much evidence in support of a finely tuned universe, we can come with several responses, the most obvious being:

1. The Universe is in fact finely tuned, which suggests an intelligence driving it. Needless to say, avid theists prefer this response. 
2. Like the Big Bang, a Universe capable of evolving life that can, in turn, observe the Universe, is something that just happened, the result of random chance. Once the Big Bang is acceptable on that basis, why not the ACs? 
3. Perhaps our Universe is one of an infinite set of universes, each one possibly having different starting conditions and governing rules. Wouldn’t that increase the likelihood of producing at least one universe capable of supporting life and evolution? 

In 1952, Erwin Schrodinger, a Nobel Prize-winning Austrian physicist and pioneer in Quantum Theory, first hypothesized the concept of the multiverse, based on one possible aspect of String Theory. The multiverse is the hypothetical set of simultaneously existing universes (including our Universe) that together comprise the totality of existence. This is the reality suggested in response #3 to the concept of the finely tuned Universe.

For many years the concepts of String Theory and the multiverse have been stiffly resisted by much of the scientific world because they are neither falsifiable nor provable. If you cannot devise a test that will either prove or disprove a statement, it cannot be accepted as a hypothesis worth examining using the scientific method. This is often cited as the reason science cannot have anything to do with examining or researching religious ideas, the existence of a deity or any spiritual or non-materialistic hypothesis.

Interestingly, while the Anthropic Principle continues to be (rightly) identified as neither falsifiable nor provable, that identification no longer seems to be consistently applied the the multiverse. The concept has become so commonly cited that most people now believe it is a real hypothesis, only waiting to be proven. Multiverse, here we come!!!

Let’s not misunderstand. The Anthropic Principle does not prove there is a deity; it is probably inadequate alone as support for such a conclusion. And, some claim that the principle equally supports an atheist conclusion. But to choose an alternative that is less likely, and that flies in the face of other scientific theories is a form of evasion. But, except for the Internet, the Anthropic Principle is not very much addressed today.

In 1992, Robert Jastrow wrote God and the Astronomers, a great read explaining why some scientists are reluctant to accept any form of transcendent intelligent Creator:

There is a kind of religion in science; it is the religion of a person who believes there is order and harmony in the Universe…This religious faith of the scientist is violated by the discovery that the world had a beginning under conditions in which the known laws of physics are not valid, and as a product of forces or circumstances we cannot discover…

This does not necessarily apply to all scientists — but to enough of them to hamper progress in finding out the answer to the most important question in science and religion, that being: Why? There is a lot to read to fully understand impact and significance of the anthropic principle and the various ACs supporting it. Hard work but worth it.^{Note 3}