Thursday, January 31, 2013

Stephen Hawking and Leonard Mlodinow, The Grand Design (2010)

Imagine that approximately 160,000 - 200,000 years ago, a huge asteroid miles across is hurtling toward the earth as the earth's gravity draws it in toward a cataclysmic event.  The asteroid strikes the African continent in an area that is now called Ethiopia, Kenya, Uganda, and Zambia.  Many forms of life are destroyed by the impact of this asteroid, including the entire population of an incipient large-brained species among the genus Homo, Homo sapiens (subspecies idaltu), that walked upright. Other species, including one which some have labeled Homo rhodensiensis, are destroyed as well.  At the time of this catastrophe, there were relatively small numbers of this incipient species, homo sapiens, alive.  As a consequence, the species homo sapiens went extinct, and modern homo sapiens (subspecies sapiens) never emerged.  To the north of Africa in the area now known as the Middle East and Europe, the species Homo neanderthalensiswho is believed by some to have evolved from a common ancestor with Homo sapiens,  Homo rhodesiensis (or perhaps Homo heidelbergensis), is not directly impacted by this catastrophe.  Only this species within the genus Homo survives.

One of the mysteries of Homo neanderthalensis is whether this species had the capacity for the spoken word and language (see August 31, 2009 post).  The earliest humans (e.g. 160 - 200,000 years ago at the time of our imaginary encounter with the asteroid in Africa) are not believed to have  developed language as we know it.  At best, early humans and some of their predecessors may have enjoyed some kind of capability for communicating by gesture or perhaps making sounds, what some have labeled a proto-language.  Exactly when the human capacity for language evolved is unclear, but it was at least 50,000 years ago ( the time of the out-of-Africa migration) if not earlier, in Africa.  (See also February 15, 2012 post).  Homo neanderthalensis was still a viable north-of-Africa species within this time frame, but if Homo neanderthalensis was already out-of-Africa in this time frame and language first emerged in Africa, this suggests that Homo neanderthalensis may not have had a language capacity.  For purposes of our asteroid story, let us assume that Homo neanderthalensis did not have the capacity for language (despite its large brain) and let us assume, as a consequence of the catastrophe brought about by our imaginary asteroid, that because Homo sapiens went extinct and never invaded the European habitat of Homo neanderthalensis, the latter remained undisturbed by another Homo species.

We can now imagine a number of alternative "histories" over the next tens or hundreds of thousands of years after the asteroid catastrophe for life on earth that might have evolved.  One such history witnesses that Homo neanderthalensis becomes the dominant hominid species on the earth, migrating across to North America and South America, into southern Asia, and back to Africa.  Another history witnesses the extinction of Homo neanderthalensis and the disappearance of the genus Homo entirely from the earth.  Other histories involve one of the first two just described plus the emergence of another large-brained species, perhaps an evolved Neanderthal or perhaps another evolving hominid species in Africa.  Undoubtedly, there are many other such "histories" that can be imagined, but in the interest of keeping these speculations simple, in any of the above scenarios it is possible if not most likely that 160 - 200,000 years after our imaginary asteroid struck the earth, the earth would be much different than it is today.  If the Neanderthals did not go extinct and survived today under the first scenario, we still don't know what their capacity for creating social structures and institutions might have been much less there capacity for creating technology as part of their historical evolution.  There is some evidence that their capacity for creating social structures would have been quite different than homo sapiens as Neanderthals may have lived in much smaller social units comprised of extended families, whereas humans lived in somewhat larger groups whose members included individuals from outside the family.  (See November 21, 2012 post).  It is possible that their brain structures may have been similar to homo sapiens given that the cranial capacity is similar to humans, but this is by no means certain.  What I am getting at, however, is the possibility that Neanderthals may have never had or developed the communications and language skills of humans, and this would have significant impact on how they perceived the world around them, including developing ideas, as homo sapiens later did, of the physical universe beyond the earth or even the biosphere on and around the earth.  In such a circumstance, we can imagine that no species would have developed an idea or belief in a creator of the universe; there would be no idea of a "god," and there would be no religious institutions.  Human social evolution described by Richard Boehm in Moral Origins (November 21, 2012 post) may never occur either. 

Physicist Stephen Hawking is a homo sapien who has spent all his adult life contemplating the physical universe beyond the earth, its origin(s), and the physical laws that describe its behavior.  Together with physicist Leonard Mlodinow (see November 20, 2011 post), they consider three questions, assuming that there are laws of nature:
  • What is the origin of the laws?
  • Are there any exceptions to the laws, i.e., miracles?
  • Is there only one set of possible laws?
The first question is readily recognized as posing the question whether there was a Creator who established the laws of nature?  Or did the laws evolve as a result of some spontaneous event?

The second question examines whether the laws of nature establish a deterministic system or whether there are occasions when the laws are suspended, accomplishing something that physical law would not permit.  This question was resolved by Spinoza in the negative  (see December 17, 2012 post), and Hawking does likewise, although he notes that there is a long line of physicists before him who felt differently.

The third question receives a lot of attention in this book, The Grand Design, and draws on Richard Feynman's sum over histories approach to quantum mechanics.  This is a probabilistic approach to epistemology attributable to the uncertainty (Heisenberg's uncertainty principle) in determining the specific historical pathway that an object takes to its present or future position.  For Feynman, the object of interest was a particle that we cannot see.  Particles can take an infinite number of paths to reach an endpoint, and each pathway has a probability associated with it.    As others have explained:

"The crucial point is that these different [probability] amplitudes have a wavelike nature, and as they spread through space they interfere with each other, their respective wave patterns either reinforcing or canceling each other out at various points. And if you sum over all the amplitudes of all the different paths, i.e. you sum-over-histories, then the different amplitudes will reinforce or cancel each other in such a way that the only path that survives this interference process is the one that the particle actually follows."

I'm not sure we can apply the sum-over-histories approach to the non-quantum world that earthbound hominids live in, such as the alternative histories of hominid evolution I described at the top, and it may just be mathematically too difficult because of the difficulty in describing "laws" applicable to animal evolution that would tell us who dies, who survives, and who prevails among those who survive.  But the evolutionary pathway is just as probabilistic as the elements of nature.  The real point here is the analytical model that Hawking brings to bear on looking at the universe:  something he calls model-dependent realismThis concept goes back to the debate between Niels Bohr and Albert Einstein and what Bohr described as "observer dependent reality."  (See July 30, 2011 post).  For Einstein, he was certain that there was a reality that was independent of the observer; a tree falls in the woods even though no one has witnessed it falling.  For Hawking, our understanding of physical reality is dependent on what the observer perceives and senses, and it is quite possible that different observers will witness the same thing differently.  As noted in a prior post, Michael Shermer, borrowing Hawking's concept and applying it to his views of human belief, described a belief dependent realism.  (See June 12, 2011 post ).  The ultimate question for Hawking (and Shermer) is this:  it is pointless to ask whether a theory or model or belief is real, but only whether the theory or model or belief agrees with observation.  It is possible that more than one theory or model of explains the way things really are and observations can agree with both of them, and Hawking cites particle and wave duality as one example of co-existing models of the same thing.  Likewise, Hawking says "no single theory can describe every aspect of the universe."  It is likely that we will find multiple models explain our observations of different aspect of the universe.  Shermer, of course, is concerned about how certain tendencies of the human mind (biases) color our observations and cause us to believe something that is not real.

This is an epistemological issue.  It is different than the question of whether something actually exists.  Hawking does not deny that the observer and the observed are parts of the world that has an objective existence. 

The Grand Design is devoted in substantial part to explaining that the universe had a beginning and that beginning can have occurred spontaneously.  It then discusses what we know about how the microscopic elements that were present at the spontaneous beginning and, shortly thereafter, could yield the universe of complex compounds that we find in the universe we intelligent humans observe today.  Hawking asks us to think of the expanding universe as the surface of a bubble, and to imagine the formation of bubbles of steam in boiling water.  Many tiny bubbles (in our model, corresponding to alternative universes, each with very different or similar sets of physical laws) appear and then disappear again while still of microscopic size.  Since they do not last long, these "universes" (and their different physical laws) do not, as the universe that we humans now observe, develop galaxies and stars needed to create elements heavier than hydrogen, helium and lithium, like carbon that is essential for life and intelligent life.  But then, Hawking invites us to further consider, a few bubbles are able to grow large enough so that they are safe from collapse and they continue to expand at an ever-increasing rate and they form the bubbles of steam we are able to see.  These "bubbles" correspond to that beginning of universes in a state of inflation.  Others have described this scenario as well, such as Steven Weinberg in The First Three MinutesIn the beginning there were tiny bubbles . . . and now there is a very large universe that includes intelligent life.  No help from a creator is needed to explain how the universe went from Point A to Point B.  But would imagination and storytelling ever have emerged?

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