I’ve been procrastinating over this topic
for some time, probably a whole year, such is the epistemological depth hidden
behind its title; plus it has religious as well as scientific overtones. So I
recently re-read John D. Barrow’s The
Constants of Nature with this specific topic in mind. I’ve only read 3 of
Barrow’s books, though his bibliography is extensive, and the anthropic
principle is never far from the surface of his writing.
To put it into context, Barrow co-wrote a
book titled, The Anthropic Cosmological
Principle, with Frank J. Tipler in 1986, that covers the subject in
enormous depth, both technically and historically. But it’s a dense read and The Constants of Nature, written in
2002, is not only more accessible but possibly more germane because it
delineates the role of constants, dimensions and time in making the universe
ultimately livable. I discussed Barrow’s The
Book of Universes in May 2011, which, amongst other things, explains why
the universe has to be so large and so old if life is to exist at all. In March
this year, I also discussed the role of ‘chaos’ in the evolution of the
universe and life, which leads me (at least) to contend that the universe is
purpose-built for life to emerge (but I’m getting ahead of myself).
We have the unique ability (amongst species
on this planet) to not only contemplate the origins of our existence, but to
ruminate on the origins of the universe itself. Therefore it’s both humbling,
and more than a little disconcerting, to learn that the universe is possibly
even more unique than we are. This, in effect, is the subject of Barrow’s book.
Towards the end of the 19th
Century, an Irish physicist, George Johnstone, attempted to come up with a set
of ‘units’ based on known physical constants like c (the speed of light), e
(the charge on an electron) and G (Newton’s gravitational constant). At the
start of the 20th Century, Max Planck did the same, adding h
(Planck’s quantum constant) to the mix. The problem was that these constants
either produced very large numbers or very small ones, but they pointed the way
to understanding the universe in terms of ‘Nature’s constants’.
Around the same time, Einstein developed
his theory of relativity, which was effectively an extension of the Copernican
principle that no observer has a special frame of reference compared to anyone
else. Specifically, the constant, c, is constant irrespective of an observer’s
position or velocity. In correspondence with Ilse Rosenthal-Schneider
(1891-1990), Einstein expressed a wish that there would be dimensionless
constants that arose from theory. In other words, Einstein wanted to believe
that nature’s constants were not only absolute but absolutely no other value. In his own words, he wanted to know if “God had any
choice in making the world”. In some respects this sums up Barrow’s book,
because nature’s constants do, to a great extent, determine whether the
universe could be life-producing.
On page 167 of the paperback edition
(Vintage Books), Barrow produces a graph that shows the narrow region allowed by
the electromagnetic coupling constant, α, and the mass ratio of an electron to a proton,
β, for a habitable universe with
stars and self-reproducible molecules. Not surprisingly, our universe is
effectively in the middle of the region. On page 168, he produces another graph
of α
against the strong coupling constant, αs,
that allows the carbon atom to be stable. In this case, the region is extraordinarily
small (in both graphs, the scales are logarithmic).
I was surprised to learn that Immanuel Kant was
possibly the first to appreciate the relationship between Newton’s theory of
gravity being an inverse square law and the 3 dimensions of space. He concluded
that the universe was 3D because of the inverse square law, whereas, in fact,
we would conclude the converse. Paul Ehrenfest (1890 – 1933), who was a friend
of Einstein, extended Kant’s insight when he theorised that stable planetary
orbits were only possible in 3 dimensions (refer my post, This is so COOL, May
2012). But Ehrenfest made another revelation when he realised that 3
dimensional waves were special. In even dimensions, different parts of a ‘wavy
disturbance’ travel at different speeds, and, whilst waves in odd dimensions
have disturbances all travelling at the same speed, they become increasingly
distorted in dimensions other than 3. On page 222, Barrow produces another
graph demonstrating that only a universe with 3 dimensions of space and one of
time, can produce a universe that is neither unpredictable, unstable nor too
simple.
But the most intriguing and informative chapter
in his book concerns research performed by himself, John Webb, Mike Murphy,
Victor Flambaum, Vladimir Dzuba, Chris Churchill, Michael Drinkwater, Jason Prochaska
and Art Wolfe that the fine structure constant (α) may have been a different value in the far distant past by the
miniscule amount of 0.5 x 10-5, which equates to 5 x 10-16
per year. Barrow speculates that there are fundamentally 3 ages to the universe,
which he calls the radiation age, the cold dark matter age and the vacuum
energy age or curvature age (being negative curvature) and we are at the start
of the third age. He simplifies this as the radiation era, the dust era and the
curvature era. He contends that the fine structure constant increased in the
dust era but is constant in the curvature era. Likewise, he believes that the
gravitational constant, G, has decreased in the dust era but remains constant
in the curvature era. He contends: ‘The vacuum energy and the curvature are the
brake-pads of the Universe that turn off variations in the constants of
Nature.’
Towards the end of the book, he contemplates the
idea of the multiverse, and unlike other discussions on the topic, points out
how many variations one can have. Do you just have different constants or do
you have different dimensions, of both space and/or time? If you have every
possible universe then you can have an infinite number, which means that there
are an infinite number of every universe, including ours. He made this point in
The Book of Universes as well.
I’ve barely scratched the surface of Barrow’s
book, which, over 300 pages, provides ample discussion on all of the above
topics plus more. But I can’t leave the subject without providing a definition
of both the weak anthropic principle and the strong anthropic principle as
given by Brandon Carter.
The weak principle: ‘that what we can expect to observe must be restricted by the condition
necessary for our presence as observers.’
The strong principle: ‘that the universe (and hence the fundamental parameters on which it
depends) must be such as to admit the creation of observers with it at some
stage.’
The weak principle is effectively a
tautology: only a universe that could produce observers could actually be observed.
The strong principle is a stronger contention and is an existential one. Note
that the ‘observers’ need not be human, and, given the sheer expanse of the
universe, it is plausible that other ‘intelligent’ life-forms could exist that
could also comprehend the universe. Having said that, Tipler and Barrow, in The Anthropic Cosmological Principle,
contended that the consensus amongst evolutionary biologists was that the
evolution of human-like intelligent beings elsewhere in the universe was
unlikely.
Whilst this was written in 1986, Nick Lane
(first Provost Venture Research Fellow at University College London) has done
research on the origin of life, (funded by Leverhulme Trust) and reported in New Scientist (23 June 2012, pp.33-37)
that complex life was a ‘once in four billion years of evolution… freak
accident’. Lane provides a
compelling argument, based on evidence and the energy requirements for cellular
life, that simple life is plausibly widespread in the universe but complex life
(requiring mitochondria) ‘…seems to hinge on a single fluke event – the
acquisition of one simple cell by another.’ As he points out: ‘All the complex
life on Earth – animals, plants, fungi and so on – are eukaryotes, and they all
evolved from the same ancestor.’
I’ve said before that the greatest mystery
of the universe is that it created the means to understand itself. We just
happen to be the means, and, yes, that makes us special, whether we like it or
not. Another species could have evolved to the same degree and may do over many
more billions of years and may have elsewhere in the universe, though Nick
Lane’s research suggests that this is less likely than is widely believed.
The universe, and life on Earth, could have
evolved differently as chaos theory tells us, so some other forms of
intelligence could have evolved, and possibly have that we are unaware of. The Universe
has provided a window for life, consciousness and intelligence to evolve, and
we are the evidence. Everything else is speculation.
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