Zoticus: What is this Anthropological Cosmological Principle?
Paracelsus: You mean "Anthropic Cosmological Principle.
Zoticus: I do? Anthropic Cosmological Principle.
Paracelsus: Did you see the sun rise this morning?
Zoticus: I did. 5:45. Rising over the north part of the Diablo Ridge. The dog is always puzzled by the sunrise. She stops and looks around, as if the sudden increase in brightness conveys some opportunity or threat...
Paracelsus: OK. The sun rose the furthest north it ever does--in your experience at least--right?
Paracelsus: And 5:45 is the earliest the sun ever rises, at least around here, yes?
Paracelsus: And if I asked you to explain to me why it was that the sun rises earliest, 5:45, and furthest north on June 21, and does this every year, what answer would you give?
Zoticus: Well, I would say that humans could only evolve on a planet of roughly 4,000 miles in radius in an orbit roughly 93 million miles from a G-type star.... That we could only evolve on a planet that was rotating, hence days and nights.... That the axis of rotation would not be perfectly aligned with the normal to the plane of earth's orbit, hence sometimes the days are longer. And June 21 just happens to be the day that the earth's axis of rotation points closest to the sun.
Paracelsus: So days are of different length--with June 21 the longest--because?
Zoticus: Spontaneous symmetry breaking--some day has to be the longest.
Paracelsus: And 5:45?
Zoticus: No significance: it depends on exactly how tilted the earth's axis of rotation is and what latitude we are at.
Paracelsus: So in answer to the question, "Why does the sun rise at 5:45 on June 21, which is the longest day of the year?" you give an answer that relies partly on spontaneous symmetry breaking, partly on chance and accidents, and partly on the Anthropic Sunrise Principle: Sunrises are very rare in this universe--go to a point at random and you will have to wait a long time to see one--but sunrises are common in places where humans have evolved. Hence given that we are humans who have evolved here, we should not be surprised to see a sunrise once a day.
Zoticus: But this doesn't explain why the sunrise is something that everybody sees...
Paracelsus: But "everybody" doesn't see the sunrise, if by "everybody" you mean "observers at every point in space." Only a very few observers in very particular places see the sunrise--hence the right explanation has to be one in terms of chance, contingency, and the Anthropic Sunrise Principle.
Zoticus: But that is unsatisfying.
Apollonius: Permit me, then, to interrupt. June 21 is the longest day of the year because that is the day the sun enters the constellation of the Dioscuri. The stars Castor and Pollux have a unique attraction to Helios--remember, Castor was the horse-tamer, and they were both sons of Leda the Swan, and brothers of Helen of Troy. Helios--the sun--gathers strength from proximity to Castor and Pollux, and so June 21 is the day that the sun stays up the longest because it is the strongest. Our trained astrologers are hoping to find a way to renormalize our calculations so that we will be able to post-dict your 5:45 number, but there are a substantial number of technological mathematical problems yet to be resolved. We hope that new developments in mathematics--the "zero" it is called--will improve the accuracy of our calculations.
Paracelsus: But that's completely false!
Apollonius: It is, however, satisfying in a way that the Anthropic Sunrise Principle is not.
Zoticus: And the relevance to the Anthropological...
Zoticus: Anthropic Cosmological Principle.
Paracelsus: Just this: the answers to the big questions physics is now asking may be equally unsatisfying--that the laws of nature are very different elsewhere in places beyond are vision, and are what they are by chance and contingency, and we're here to see them via evolution and the environment we need to survive.
Zoticus: But that's very unsatisfying...