Touching The Limits Of Knowledge

Cosmology and our View of the World


Anthropic Principle - Multiple Universes, Lead: Mike Battles, Ed Pinsley, David Schrier


Summary by Dan Vorosmarty:


Anthropic Principle - Multiple Universes

Ed began discussion by talking about the genesis of the Strong Anthropic Principle.

Strong Anthropic Principle (SAP): The universe must have those properties which allow life to develop within it at some stage in its history.

In the mid-50’s there was some deliberation among physicists as to how many dimensions that we live in and it was proved that you can only have stable orbits when three spatial dimensions exist. (Stable orbits being an assumed prerequisite to the sustainability and repeatability of life.) The necessary conclusion to this argument is that life can only exist within three spatial dimensions. Apparently three dimensions allow for material elements both large and small. The larger scale is described by relativity and astronomy, and the smaller scale is described by quantum mechanics. Although it wasn’t mentioned, I’m assuming three dimensions allows for a stable border between those two extremes that allow for complex chemical structures and their support systems.

This talk of physical quantities and scale led into a discussion of the Weak Anthropic Principle.

Weak Anthropic Principle (WAP): The observed values of all physical and cosmological quantities are not equally probable but they take on values restricted by the requirement that there exists sites where carbon based life can evolve and by the requirement that the Universe be old enough for it to already have done so.

In less verbose terminology, this means that humans could only have come into being in an area of space where conditions were stable enough for carbon-based life to exist; i.e. solar systems with stable physical laws. The stability of these systems can only be created in a universe that is the same or similar to ours. In this sense, the WAP implies that our existence would be acting as a “selection mechanism,” because without the correct conditions to allow us to observe (the conditions for our existence), there could be no observations and thus no universe as we know it. Basically, our existence proves that the universe we observe evolved towards the goal of production of observers.

There was some deliberation over the wording of this definition “not equally probable” versus “not necessarily equally probable.” I’m not quite sure what this discrepancy was about. Maybe it’s that what we observe is not due to random probability, “not equally probable,” but rather due to the restriction that sites exist where carbon based life can exist. The possibility of these sites existing is not completely deterministic or completely random, “not necessarily equally probable.” This line of reasoning led to a discussion about whether or not the laws of probability are independent of the universe one exists in.

Mike took this opportunity (the discussion of other possible universes) to pose the question, “must the observer exist in order for the universe to exist?” The role of the observer becomes active in this conception of a universe and leads to the idea that if life or at least subjective observation does not exist, then no universe is possible. This is the age-old koan, “if a tree falls in the woods with no one to hear it does it make a sound?” This reversal of cause and effect (existence being creative and creation being existent) likely defies objective observation but gives subjectivity (the way we all exist and think no matter how rational one may become) poignancy that is lacking in scientific understanding. One criticism of this idea was that if the universe is dependant upon observers, did the universe just “pop into existence” as soon as humans came along? Humans have the ability to look to the past or the future so the universe could have existed leading up to us. The past has been created in the present and it becomes the past when we categorize it as such even though it is still contained within us.

The presenters brought us back to the Anthropic Principle by suggesting some necessary conditions for our universe to exist as it is now. They reiterated the stability of three spatial dimensions, the ratio between the mass of the proton and electron, the speed of light, and “Time’s arrow” and its relation to the second law of thermodynamics. The overview of the second law of thermodynamics sparked some discussion among the physicists that “Time’s arrow” only works within the confines of a closed system. Is the universe a closed system? Size and scale are important and necessary for carbon based life. Humans and our scale level are the geometric mean between an atom and a planet. A planet is the geometric mean between an atom and the size of the universe. This seemed to imply a fractal self-similarity at different scale levels (reminiscent of the Gaia/System Theory discussion). Mike brought up the fact that the planets in our solar system exist at rigidly defined distances from each other and with the sun as the center of our solar system. This method of relative geometric distances was used in the past to predict the existence of the asteroid belt and Neptune as necessary masses to keep the planets in a solar orbit. If these relative distances and masses are necessary at one scale level to keep a balance, then it is not a stretch of the imagination to infer that other systems at different scale levels have that same necessity. Furthermore, the smaller systems themselves must have an appropriate relative distance to the larger systems in order to strike a balance or orbit to keep the universe integral through different scale levels.

The next topic discussed by the presenters was the Final Anthropic Principle.

Final Anthropic Principle (FAP): Intelligent information processing must come into existence in the Universe, and, once it comes into existence, it will persist.

A question posed by the group for clarification among the class was, “what is intelligent information processing and does it necessarily apply to humans?” One example brought up was that when radio waves produced by human technologies (intelligent information processing) are created, they propagate a disturbance throughout the universe until the universe no longer exists (basically infinitely). The discussion then diverged to the uncertainty principle and things that may be “astonishingly improbable.” A criticism of this line of thinking from Tom Davis came up in the form, “assigning improbability to any observation makes no sense since that observation exists within our universe.” For example, the striking homogeneity at minuscule scales, how can a probability be assigned to that? It was suggested that probability was an inappropriate term. For example, in trying to calculate a probability for the alphabet there are 26 restrictions. Calculating probabilities for constants of this universe have no restrictions meaning that our best guess for other universes is that they are exactly the same as ours or parallel.

The “inverse gambler’s fallacy” was brought up by the presenters as a counter to the need for multiple universe theory to explain the existence of our perfectly fine-tuned universe. The analogy goes like this: you have a die with six sides labeled 1-6, 6 represents our universe or a fine tuned universe. The fallacy comes into being when the gambler believes that rolling the dice more often increases the probability that a six will land face up (a fine tuned universe will be created). This analogy is extended to multiple universe theory because it may be a fallacy to believe that the existence of more than one universe increases/increased the probability that this universe would be fine-tuned to support life. A counter to this counter was brought up by Dave and Mike who suggested that this analogy fails to account for the possibility that each successive roll of the die recreates the initial conditions of the roll. It is possible that “within a fractal network of multi-universes, with infinite interconnection each time the die is rolled, the possibility of creating a fine-tuned universe increases due to overall systemic control directed by previous failures and triumphs of universe creation.” This idea seems to coincide with the FAP suggesting that any universe created after this one will perpetuate intelligent information processing since it came into existence in this universe.

The rest of the class discussion consisted of an overview of cosmological physics pertaining to the flatness of the universe and the relationship between the Big Bang theory and Inflationary theory, but I’ll leave that to the physics majors.