The Physical Constraints As Biosignature
- Dear Friends,
This is quite long, but well worth the read. I'm only sending an excerpt. Click the link to read the whole article.
Love and Light.
The Physical Constants as Biosignature
An anthropic retrodiction of the Selfish Biocosm Hypothesis by James N. Gardner
Two recent discoveries have imparted a renewed sense of urgency to investigations of the anthropic qualities of our cosmos: the value of dark energy density is exceedingly small but not quite zero; and the number of different solutions permitted by M-theory is, in Susskind's words, "astronomical, measured not in millions or billions but in googles or googleplexes."
Originally published in the International Journal of Astrobiology May 2005. Reprinted on KurzweilAI.net February 28, 2006.
Goal 7 of the NASA Astrobiology Roadmap states: "Determine how to recognize signatures of life on other worlds and on early Earth. Identify biosignatures that can reveal and characterize past or present life in ancient samples from Earth, extraterrestrial samples measured in situ, samples returned to Earth, remotely measured planetary atmospheres and surfaces, and other cosmic phenomena." The cryptic reference to "other cosmic phenomena" would appear to be broad enough to include the possible identification of biosignatures embedded in the dimensionless constants of physics. The existence of such a set of biosignaturesa life-friendly suite of physical constantsis a retrodiction of the Selfish Biocosm (SB) hypothesis. This hypothesis offers an alternative to the weak anthropic explanation of our indisputably life-friendly cosmos favored by (1) an emerging alliance of M-theory-inspired cosmologists and advocates of eternal inflation like Linde and Weinberg, and (2) supporters of
the quantum theory-inspired sum-over-histories cosmological model offered by Hartle and Hawking. According to the SB hypothesis, the laws and constants of physics function as the cosmic equivalent of DNA, guiding a cosmologically extended evolutionary process and providing a blueprint for the replication of new life-friendly progeny universes.
The notion that we inhabit a universe whose laws and physical constants are fine-tuned in such a way as to make it hospitable to carbon-based life is an old idea (Gardner, 2003). The so-called "anthropic" principle comes in at least four principal versions (Barrow and Tipler, 1988) that represent fundamentally different ontological perspectives. For instance, the "weak anthropic principle" is merely a tautological statement that since we happen to inhabit this particular cosmos it must perforce by life-friendly or else we would not be here to observe it. As Vilenkin put it recently (Vilenkin, 2004), "the anthropic' principle, as stated above, hardly deserves to be called a principle: it is trivially true." By contrast, the "participatory anthropic principle" articulated by Wheeler and dubbed "it from bit" (Wheeler, 1996) is a radical extrapolation from the Copenhagen interpretation of quantum physics and a profoundly counterintuitive assertion that the very act of observing the
universe summons it into existence.
All anthropic cosmological interpretations share a common theme: a recognition that key constants of physics (as well as other physical aspects of our cosmos such as its dimensionality) appear to exhibit a mysterious fine-tuning that optimizes their collective bio-friendliness. Rees noted (Rees, 2000) that virtually every aspect of the evolution of the universefrom the birth of galaxies to the origin of life on Earthis sensitively dependent on the precise values of seemingly arbitrary constants of nature like the strength of gravity, the number of extended spatial dimensions in our universe (three of the ten posited by M-theory), and the initial expansion speed of the cosmos following the Big Bang. If any of these physical constants had been even slightly different, life as we know it would have been impossible:
The [cosmological] picture that emergesa map in time as well as in spaceis not what most of us expected. It offers a new perspective on a how a single "genesis event" created billions of galaxies, black holes, stars and planets, and how atoms have been assembledhere on Earth, and perhaps on other worldsinto living beings intricate enough to ponder their origins. There are deep connections between stars and atoms, between the cosmos and the microworld.... Our emergence and survival depend on very special "tuning" of the cosmosa cosmos that may be even vaster than the universe that we can actually see.
As stated recently by Smolin (Smolin, 2004), the challenge is to provide a genuinely scientific explanation for what he terms the "anthropic observation":
The anthropic observation: Our universe is much more complex than most universes with the same laws but different values of the parameters of those laws. In particular, it has a complex astrophysics, including galaxies and long lived stars, and a complex chemistry, including carbon chemistry. These necessary conditions for life are present in our universe as a consequence of the complexity which is made possible by the special values of the parameters.
There is good evidence that the anthropic observation is true. Why it is true is a puzzle that science must solve.
It is a daunting puzzle indeed. The strangely (and apparently arbitrarily) biophilic quality of the physical laws and constants poses, in Greene's view, the deepest question in all of science (Greene, 2004). In the words of Davies (Gardner, 2003), it represents "the biggest of the Big Questions: why is the universe bio-friendly?"
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