Q&A: A Question About the Anthropic Principle
A Question About the Anthropic Principle
Question
Hello Honorable Rabbi,
I am currently reading your book, and a question came up for me regarding your treatment of the anthropic principle, particularly at the stage where you discuss the laws of physics.
It seems to follow from your remarks that the probability of life coming into being is essentially zero given the laws of physics—and moreover, that any slight change in the laws of physics would completely eliminate the possibility of life.
To say, “Well, here we are,” does not remove the question at all—after all, that is precisely the source of the question that requires an explanation.
So far, so good.
It seems to me that the problem with this is that you assume that “life” exists only in the form familiar to us—that is, self-replicating DNA coils and so on. Life in this specific sense is indeed a statistically negligible phenomenon. But one can imagine, at least theoretically, that some other combination of molecules could also have created “life,” though in a different sense from the one familiar to us. This only becomes more acute when one moves to systems governed by different laws—if all the laws are different, there is no reason to assume that life would appear דווקא in the form familiar to us. In this sense, the anthropic principle seems to me entirely justified: you begin from something that exists and ask about it, and that biases the statistics—but in fact there are countless other possibilities that you could be counting as well.
Is that not so?
I hope I managed to make myself clear.
Answer
You explained yourself very clearly indeed. This is a common claim (Dawkins already raises it), but it is mistaken. Life, in any sense whatsoever, is supposed to be complex. The claim that there are many kinds of complexity is correct, but by the very definition of complexity, the number of complex entities is negligible compared to those that are not complex. There are many more non-complex entities. Therefore, the probability of a complex entity arising is inversely proportional to its complexity, regardless of how many kinds of entities with that level of complexity there may be.
This is essentially the concept of entropy, which measures complexity (or uniqueness), and the second law of thermodynamics says that the entropy of a given state is a measure of the probability of reaching it by chance (that is, in a closed system without a guiding hand from outside).
Just one more important point. The complexity of a state or of an entity is defined mathematically in a completely objective way and does not depend on a starting point. Entropy measures it. Therefore, the determination of how complex and special a state is has nothing at all to do with our point of departure.