March
The following guest article is authored by Amon Twyman.
Part 2: The Anthropic Principle
Excerpt from “Shock Level Five: Augmented Perception, Perceptuo-Centrism, and Reality”
This is the second of three excerpts from a paper which provides a little theoretical background to the presentation I will be giving at the Humanity+ UK 2010 conference. My presentation will make sense without reading these excerpts of course, but the additional context might provide extra value for those people who have read them. Enjoy!
The anthropic principle (Carter, 1973) is based upon the observation that conditions in the universe as we observe it are exactly what they need to be in order for us to exist. That is to say, there are a number of ways in which the universe might be described or measured, and in every case where such a measurement would need to fall within extremely narrow parameters in order for human beings to exist, it does. Let us momentarily leave aside objections to this kind of reasoning or consideration of its value, and take a brief look at a few illustrative observations.
Dicke (1961) noted that if the universe were one order of magnitude (i.e. ten times) younger or older than it is understood to be, then human life could not exist. One order of magnitude younger, and there would not have been sufficient time to build up requisite levels of vital elements (such as carbon) by nucleosynthesis, meaning that small rocky planets like Earth would not exist. One order of magnitude older, and most stars (other than the dimmest red dwarfs) would have turned into white dwarfs, and stable planetary systems would have ceased to exist.
Dicke also argued that the density of matter in the universe is observed as having almost exactly the critical value required to prevent a Big Crunch (i.e. a future return to Big Bang conditions). Weinberg (1987) has additionally noted that if the cosmological constant (which appears to be the primary contributor to the critical density of matter in the universe) were one order of magnitude larger, then the universe would suffer catastrophic inflation (precluding the formation of stars).
Similarly, the dimensionless physical constants (also known as fundamental physical constants), such as the “fine-structure constant” which describes the strength of electromagnetic interactions, are observed as having exactly the values required to balance the four fundamental interactions (electromagnetism, strong interaction, weak interaction, and gravitation), thus permitting the formation of the commonly-observed matter from which life has emerged. Small changes in the relative strengths of the four fundamental interactions would also have implications for our understanding of the universe’s age and structure, in turn making it all the more remarkable that their observed values fall within the narrow range compatible with human existence.
A “weak” form of the anthropic principle asserts that our location in the spacetime continuum is in some way privileged, in that it can support our kind of life. Whereas the weak form allows for the possibility that the universe may have spacetime regions inhospitable to human life (such as periods in the very early or late life of the universe), the “strong” form asserts that the fundamental physical parameters of the entire universe must be such as to allow for the existence of observers at some point during its existence. Alternative interpretations of the principle have been proposed, including the possibility of multiple universes, only some of which are capable of supporting observers (Stenger, 2000).
Perhaps the most common objection to the anthropic principle (in either form) is that it is merely a tautology. In other words, one might object that it is unsurprising that the universe should have exactly the characteristics required to support human existence, since if it were otherwise then we would not be here to observe it. It may be the case that the anthropic principle is indeed merely a tautology, requiring no special explanation of the observed state of affairs (such as the existence of alternative universes, or that we live in a simulation of some kind), but if that is so then we must accept one of three corollaries:
- First corollary: That sentient observers could (and would) exist in a universe radically different to our own, in which there may be little matter recognizable to us, and therefore no small rocky planets or stable star systems.
- Second corollary: That the presence of sentient observers is in no way a special or “privileged” situation, and our universe has no greater intrinsic value than one in which no life can exist.
- Third corollary: That life is in some way valuable and requires recognizable conditions to exist, and therefore the very existence of our observed universe represents an extraordinary statistical unlikelihood.
Nick Bostrom (2002) has noted an alternative to such possibilities; that a selection effect or “anthropic bias” appears to be behind the anthropic principle. It may be the case that a statistically remarkable “just right” universe (as ours appears to be), or any of the other explanations mentioned above, are not required to explain our observations. It could be the case that our universe simultaneously manifests all possible values for every potentially observable parameter (only some of which we are capable of perceiving or even existing within, by virtue of our physical structure), or at least that it manifests a wider range of values than the very small set we are capable of observing or existing within.
If the above characterization of the universe offends one’s intuition, then we might consider an equivalent gestalt or metaverse which simultaneously manifests all possible values for all possible variables, and which has our observable universe (with its specific values for observed variables) embedded within it. The difference between this metaverse scenario and the idea of multiple universes is that we have no need to assume that there could be no communication between the observable universe and the “outside” metaverse.
We do, however, need to consider the question of whether the only threshold between these two zones of existence would be perceptual, or if there might be some more fundamental form of boundary.
One might reasonably object that the difference between universe and metaverse could not be merely perceptual, because if things in the metaverse were “real” in any valuable sense, then we should be able to interact or engage with them despite not being able to perceive them. What evidence do we have of such invisible phenomena? Of course, these are exactly the kind of thing discussed in the previous part of this essay, such as patterns only observable in the ultraviolet spectrum (by butterflies or humans with special equipment) or astronomical phenomena explicated by false-colour imaging.
Moreover, some conditions within the observed universe are not vital to our existence (e.g. the structure of snowflakes), while other, normally imperceptible conditions may be critical to the development of life (e.g. dark matter). The picture beginning to emerge here is that of three qualitatively different zones of existence:
- The observable universe,
- A “deep” metaverse of (potentially all) physical values incompatible with our human existence, and
- A “penumbra” composed of phenomena physically compatible with our existence, yet imperceptible under normal circumstances.
The universe/metaverse model described above is what physicists would refer to as a phase space (Gibbs, 1901), because we are envisaging a hypothetical “space” (the metaverse) in which all possible states of a system are simultaneously represented. A phase space depicted as a graph usually describes a system with two or three dimensions, whereas our metaverse would be better called multi- or n-dimensional. Within this n-dimensional phase space, then, human beings would only exist within a subset of those points where their existence is physically possible. Our observable universe would be a second, nested subset of “conditions we are capable of perceiving”.
“Travelling” from the observable universe into the penumbra would simply be a matter of adjusting one’s perceptual capabilities until specific imperceptible phenomena may be perceived.
As discussed in the previous section, humans have taken the first tentative forays in this direction over the last century or so. Travelling further into the deep metaverse may not be possible (even if such a thing as a metaverse exists), since to do so would require us in some sense to leave behind the space defined by physical phenomena supportive of human existence, to see if there exist real physical phenomena supportive of other forms of life.
To a transhumanist (albeit a radical one), such a transition is not necessarily impossible.
“Leaving the space defined by physical phenomena supportive of human existence” does not mean dying, but transforming oneself into a form of life other than human by technological means. Hans Moravec (1999) has speculated about ways in which such a transition might take place, describing a process of transferring minds into bodies capable of existing in universes with (for example) speeds of light slightly different to our own.
On that speculative note, let us conclude the arguments in this section. The interpretation of the anthropic principle described above suggests that we find ourselves in a reality with particular characteristics because they are the characteristics we are equipped to perceive. Hypothetical differently equipped beings would, by this account, be expected to perceive the universe as having different characteristics. Therefore, we should not consider this to be a solely human-centric or “anthropic bias” (as suggested by Nick Bostrom), but rather more broadly as a perceptuo-centric bias. If we consider the observations underlying the anthropic principle to be caused by perceptuo-centric bias, we may refer to this interpretation of the principle as perceptuo-centrism.
Perceptually augmented trans- or posthumans would be in a position to take advantage of aspects of reality beyond those readily apparent to unmodified humans. Examples of posthuman perceptual abilities might run from the mundane (e.g. night vision, hearing radio signals or unencrypted digital communications) to the relatively radical (e.g. combining online information, pattern recognition systems and augmented reality, in order to see clouds of biographical data following people around, among other applications). A perceptuo-centrist interpretation of the anthropic principle, however, suggests that such abilities may represent the mundane end of a much more exotic set of possibilities. Perceptually augmented posthumans may indeed find that some of the apparently immutable aspects of the universe are in fact merely markers of the perimeter of human perceptual capability.
[Please see Part 3 for continued discussion]
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Many Minds Interpretation of QM?
8 April 2010 at 4:25 amhttp://en.wikipedia.org/wiki/Many-minds_interpretation