Recently
I read two books that touched upon the issue of cosmic fine-tuning, a
question that I have often written about on this blog. One excellent
book is the rather poorly titled book “Modern Physics and Ancient
Faith” by Stephen M. Barr, a physics professor at the University of
Delaware (which doesn't at all brush away religious thinking as an
ancient relic, despite the title). In that book there is an
interesting discussion of “anthropic coincidences” that are
necessary for our existence. One example given is that of a parameter
called v. On pages 126-127 the book makes these interesting comments:
The long technical name of the parameter v is “the vacuum expectation value of the Higgs field.”....The value of v is a great puzzle to particle theorists; in fact, it is one of the central puzzles of physics. What is puzzling is that in reasonably simple theories v seems to want to come out to be, not 1, but a number like 1017, i.e, 100,000,000,000,000,000...As far as the possibility of life emerging in our universe is concerned, it would be a disaster for v to be 100,000,000,000,000,000. It would also be a disaster if it were 100,000,000,000,000, or if it were 100,000,000, or if it were 100,000, or if it were 100. Indeed, it would be a disaster if it were 10, or 5, or even 1.5. It would probably be a disaster if v were even slightly different from the value it happens to have in the real world.
So
nature “hit the bullseye,” a very distant bullseye, it would seem.
This is only one of many astonishing “coincidences” required for
our existence. Barr lists seven other such cases, one of which is
even more dramatic: the fine-tuning of the cosmological constant. As
Barr puts it on page 130 of his book:
In
order for life to be possible, then, it appears that the cosmological
constant, whether it is positive or negative, must be extremely close
to zero – in fact, it must be zero to at least 120 decimal places.
This is one of the most precise fine-tunings in all of physics.
To
their credit, modern cosmologists and physicists have been very open
and candid about discussing such “coincidences.” I could easily
fill up a longish blog post doing nothing but quoting all of the
physicists and cosmologists who have remarked on how remarkably
fit-for-life or seemingly fine-tuned our universe seems to be. But
there is one exception. Physicist Marcelo Gleiser will have none of
this thinking. On page 232 of his book A Tear at the Edge of
Creation, Gleiser stubbornly says, “There is absolutely no
evidence that our Universe is fit for life.”
If
I didn't know that some physicists make enormously silly assertions
about infinities of parallel universes, and ask you to believe there
are an infinite number of copies of yourself, I might call the
previous statement by Gleiser the silliest thing I have ever heard
from a physicist. It's a statement that would only make sense if you
were a robot scanning a biologically lifeless universe.
Gleiser
provides no real scientific statements or references to back up his weird
claim that there "is absolutely no evidence that our Universe
is fit for life.” He merely gives a little armchair reasoning that does not hold up to scrutiny.
First,
Gleiser attempts to persuade us that someone reasoning that the
universe is fit for life is like someone coming into a library and
concluding that all of the books were made for him, or that all of
the books were made for English-speaking readers like himself. But
this analogy isn't appropriate, and doesn't correspond to the type of
reasoning made by those who point out the ways in which the universe
is fine-tuned for life.
Let's
imagine a scale of claims ranging from the very specific to the
very general.
- Things are arranged in a way that benefits (or makes possible) me in particular.
- Things are arranged in a way that benefits (or makes possible) people who speak my language.
- Things are arranged in a way that benefits (or makes possible) humans in general.
- Things are arranged in a way that benefits (or makes possible) carbon-based life forms.
- Things are arranged in a way that benefits (or makes possible) some type of life, rather than preventing any type of life.
Gleiser
is suggesting that those who say that the universe is remarkably fit
for life are like people who make the first assertion, or possibly
the second assertion. But they are not. Almost all claims of cosmic
fitness or cosmic-fine tuning involve claims like the last of these
claims, claims that are extremely general and cannot be attacked on a
basis of assuming an intention too specific. So Gleiser's library
analogy isn't fair, and doesn't back up his claim. It's particularly
weak for Gleiser to be using a library analogy to try to back up a
claim of cosmic non-fitness for life (as a library consists of
manufactured objects that were designed for a specific purpose).
Gleiser
then goes on to give this reasoning:
This
reasoning does nothing to establish Gleiser's strange claim that
there “is absolutely no evidence that our Universe is fit for life.” In his
fish analogy he is talking about a particular organism that is
adapted to a particular local parameter (the water temperature);
cold-water fish are adapted to cold water, and warm water fish are
adapted to warm water. But none of the main “anthropic
coincidences” mentioned in discussions of cosmic fitness involve
merely local conveniences, nor do any of them involve things to which
the human organism or earthly life has adapted itself to. Instead,
they involve things that are prerequisites for any type of life at
all – and most of them involve things that are prerequisites for
any type of universe with stable solid matter and stable stars. So
Gleiser's little fish analogy falls flat. Again, the analogy has no
relevance to the typical discussions of physics and cosmic fitness.
Gleiser
then gives this reasoning:
Think of the billions, probably trillions, of barren worlds in our galaxy alone. I can't read the message “just right” for life written in so many dead worlds.
This
makes no sense at all. Since planets can have different distances
from a star, there will inevitably be some planets that are barren
because they are too cold or too hot. But the existence of such
planets does nothing to discredit a claim of cosmic fitness for life,
particularly since some of these “barren” planets (such as
Jupiter) help indirectly to allow life to flourish (if Jupiter didn't
exist, our planet would get hit by too many comets and asteroids,
many of which are diverted by Jupiter's gravity). “Fitness for
life” simply means having the characteristics that allow life to
exist, not some much more extravagant claim such as “designed in a
way that results in 100% of available planets bearing life.”
Finally,
Gleiser lamely asks: “If the constants of nature are so fit for
life, why is life so difficult to find?” The answer is: it isn't,
and it's all around us. As for looking for extraterrestrial life,
we've just begun to do that, and we still haven't spent the money
needed to make a very serious effort in that regard (as spending on
SETI has been “peanuts” compared to what was spent on big physics
projects such as the Large Hadron Collider) .
Gleiser's reasoning on this topic is without merit, and I smell a very
stubborn denialism in his claim that “there is absolutely no
evidence that our Universe is fit for life.” Quite to the contrary,
many modern physicists and cosmologists have admitted that there is
abundant evidence that the universe is astonishingly fit for life. Read here for more about this topic.
Only some of the lucky "coincidences" needed for life's existence
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