Friday, December 26, 2008

Review of The Physics of Christianity, by Frank Tipler

Most readers know that I am very interested in the ideas of Frank Tipler. I consider myself a Soft Tiplerianist in the sense that I relate deeply to Tipler’s high level concept that future technology may be able to resurrect the dead of past ages by some kind of “copying them to the future" and, in the spirit of “There are more things in Heaven and Earth...”, allow myself to contemplate such possibilities. There may be a point where consciousness becomes a important factor in the destiny of the universe, where conscious beings develop the capability to choose and build the universe they _want_ to inhabit, and invite the dead of past ages to join the party by copying them to the future. I have used “Soft Tiplerianism” to indicate this soft rationalist, high level and not detailed concept that will, I hope, be detailed and realized by future scientists and engineers.

In The Physics of Immortality, Tipler proposed that intelligent beings of a far future epoch close to the gravitational collapse of the universe (the so called Big Crunch) may develop the capability to steer the dynamics of the collapsing universe in such a way as to make unlimited subjective time, energy, and computational power available to them before reaching the final singularity. Having done so, they may wish to restore to consciousness all sentient beings of the past, perhaps through a “brute force” computational emulation of the past history of the universe. So after death we may wake up in a simulated environment with many of the features assigned to the afterlife world by the major religions. (from my Interview with Frank J. Tipler of November 2002).

I don't think we know enough physics to guess the specifics of how our descendants in the far future may do spacetime engineering, and I don't think we can guess the motivation of beings very different from us. In other words we cannot know _how_ they will be able to engineer spacetime, and we cannot know _why_ they may choose to resurrect sentient beings of past ages. But I think in The Physics of Immortality Tipler makes a good case to show _that_ future sentient beings may be capable of spacetime engineering at the grandest scale. He shows that some high level visions of religions, such as the cosmic role of life and consciousness and the possibility of the resurrection of the dead, may be basically compatible with science.

Tipler has been criticized, by both sides, for mixing religion with science. He has also been criticized for making wrong scientific assumptions. For example, it appears that the expansion of the universe is accelerating and that the universe, left to itself, will never enter the gravitational collapse phase which is a prerequisite for the Omega Point scenario to happen (see below for Tipler's proposed workaround). As a Stone Age (20th and 21st centuries) scientist, Tipler is certainly wrong on many points that will be corrected by future scientists. But dismissing him as a crank is really like dismissing Leonardo as a crank because his aircraft sketches wouldn’t fly, which is just stupid. Leonardo was a genius who got the _concepts_ right, and later engineers equipped with more detailed knowledge have realized his visions.

I have read the new book of Frank Tipler, The Physics of Christianity, only recently, because it has received some very bad reviews from very smart people like John Walker. In his new book, Tipler tries to zoom much below the higher level concepts described in the first book and show that some specific myths of a specific religion, Christianity, may be basically compatible with science.

The first part of the book is a concise summary of fundamental physics as it is understood today. Tipler does not use mathematics, but I don't think the book is really understandable to people with no background in theoretical physics. To those who do have a background in physics, I recommend reading also the professional versions of his summary: The structure of the world from pure numbers and Feynman-Weinberg Quantum Gravity and the Extended Standard Model as a Theory of Everything. Tipler assumes Everett's Many World Interpretation of quantum physics as the only viable and valid interpretation, and claims that, contrary to the opinion of most theoretical physicists, Feynman and Weinberg developed in the 60s a basic skeleton of a valid theory of quantum gravity. Intrigued by this claim, I am reading the Feynman Lectures on Gravitation. I am unable to judge the validity of Tipler's claim at the moment -- I was trained in theoretical physics and, with some effort, I am still able to read and understand Tipler's maths and physics, but alas not fluently enough.

After his summary of modern physics, Tipler refines his Omega Point model of the far future history of the universe and suggests that, by purposefully annihilating baryons, sentient life will be able to stop the accelerating expansion of the universe and start its gravitational collapse, which is a necessary prerequisite for his Omega Point scenario. I don't know if our descendants will choose or need to do that, but I am very keen of the "fix what you don't like" transhumanist attitude attitude supported by Ray Kurzweil‘s last sentence in The Age of Spiritual Machines: “So will the Universe end in a big crunch, or in an infinite expansion of dead stars, or in some other manner? In my view, the primary issue is not the mass of the Universe, or the possible existence of antigravity, or of Einstein’s so-called cosmological constant. Rather, the fate of the Universe is a decision yet to be made, one which we will intelligently consider when the time is right”. According to Tipler, life will choose a big crunch in order to achieve an Omega Point, and resurrect sentient beings of past ages in appropriate computational realities fueled by the unlimited computing power available.

The diagram above, which is the heart of Tipler's cosmology, has time on the vertical axis and the radius of the universe on the horizontal axes. Reality is really a multiverse in Everett's MWI sense, and different branches of the multiverse (universes) are shown as different curves in the diagram. All universe begin and end as singularities. Another singularity (the vertical line) is found "at the edge of the multiverse" and can be defined as the limit of all paths across universes, at a constant time and heading to smaller sizes. It can be seen that Tipler thinks that intelligent life will be able to trigger a gravitational collapse (perhaps through baryon annihilation) in all universes.

In the second part of the book, Tipler tries show that some specific myths of a specific religion, Christianity, may be basically compatible with science. He identifies the three singularities in the diagram with the three persons of the Trinity. The Son, Jesus, can be identified with the singularity at the edge of the multiverse. The virgin birth of Jesus, his incarnation, his resurrection, and several specific miracles are discussed and "explained" in terms of modern physics in the framework of Tipler's cosmology. Well...

With his extensive knowledge of physics and religion, Tipler tries to show that his conclusions are plausible and even proposes falsifiable experiments to prove them. But I think the second part of the book is "not in the same universe" as the first one, and much less interesting. I find it off-topic like, say, describing in detail the provincial geography of the Earth in a cosmology essay on the large scale structure of the universe. I am very interested in Tipler's cosmic vision and interpretation of the fabric of reality, but I just don't find "details" like the virgin birth interesting enough.

Of course, most Christians do find them very important. But when I hear hoof beats I think horse not zebra. So, regardless of the validity of Tipler's speculations in the second part of the book, I still think of Jesus the son of Joseph as a great _man_, one of the greatest of our history. The Mind near the Omega Point may well choose to consider Jesus, among the countless sentient inhabitants of spacetime, as especially worth of attention and encouragement, but I don't think it will need to mess with the details of human biology, or with the chemistry of water and wine. I think the first part of The Physics of Christianity is a great book, a revised and streamlined version of The Physics of Immortality with some new very interesting insights and more intuitive metaphors. But I don't care much for the second part.