both of Merrit Island, Florida, watch as the
space shuttle Discovery lifts off from Cape Canaveral
on 29 October 1998.
by Gregg Newton/Reuters
is designed for humans
raise far more troubling questions
than they can
It's easy to describe, but difficult to categorize:
The anthropic principle holds that if such phenomena as,
...and a number of other deep characteristics of the Universe differed at all, human life would be impossible.
According to its
proponents, the Universe is fine-tuned for human life.
In Douglas Adams's antic novel The Hitchhiker's Guide to the Galaxy (1979), mice are 'hyper-intelligent pan-dimensional beings' who are responsible for the creation of the Earth.
What if the Universe
isn't so much anthropic as mouse-thropic, and the appearance and
proliferation of Homo sapiens was an unanticipated side effect, a
It appears that Adams
favored a puddle-thropic principle. Or at least, the puddle
The Australian astrophysicist Brandon Carter introduced the phrase 'anthropic principle' at a conference in Krakow, Poland in 1973 celebrating the 500th anniversary of the birth of Copernicus.
Copernicus helped evict the Earth - and thus, humanity - from its prior centrality, something that the anthropic principle threatens (or promises) to re-establish.
In other words, if the
Universe were not structured in such a way as to permit us to exist
and, thus, to observe its particular traits, then - it should be
obvious - we wouldn't be around to marvel at its suitability for our
Hawking noted that,
In short, a change so
small it challenges the imagination, and the Big Bang would have
turned into a kind of Big Crunch.
Einstein was troubled by the fact that gravity would cause the Universe to collapse onto itself (that Big Crunch), so he surmised a constant - essentially out of thin air - that pulled in the opposite direction, causing the cosmos to remain stable.
The American physicist Steven Weinberg - not a religious believer - points out that if this now-confirmed constant were just a smidgeon larger, the Universe would be vaporously insubstantial.
It would never have
stopped expanding at a rate that precludes the formation of
galaxies, never mind planets or mammals such as ourselves.
Any younger - i.e., if the Big Bang had occurred in the more recent past - and it would not have allowed enough time for nucleo-synthesis to stock the Universe with elements heavier than hydrogen and helium.
There would be no medium-size, rocky planets and thus, no us. By the same token, if the Universe were substantially older than it is, most stars would have matured into white and red dwarfs.
They would be too old to remain part of what astrophysicists call the 'main sequence', and unable to support stable planetary systems.
The four fundamental interactions connecting mass and energy,
...also appear balanced precisely as needed to produce matter and, ultimately, life.
Put it all together and
there appears to be a significant case for the anthropic
What to believe?
It holds that, as Carter had pointed out, whatever conditions are observed in the Universe must allow the observer to exist. In short, if these constants weren't as they are, we wouldn't be around to worry about them.
To this, Hawking added that even slight alterations in the life-enabling constants of fundamental physics in this hypothesized multiverse could 'give rise to universes that, although they might be very beautiful, would contain no one able to wonder at that beauty'.
The weak version of the
anthropic principle thus poses a logical conundrum.
Martin Gardner, a
former maths and science writer for Scientific American, dubbed it
the 'completely ridiculous anthropic principle' (CRAP).
One is contained within Einstein's remark:
Posing whether 'God had any choice' was Einstein's way of asking if the manifold characteristics of the physical Universe, such as the speed of light, the charge of the electron and the proton, etc, are fixed or susceptible to alternatives.
If fixed, they might appear to have been organized with carbon-based life in mind, but were actually not 'free parameters' in the first place.
Note that Einstein was asking if the deep laws of physics might have in fact fixed the various physical constants of the Universe as the only values that they could possibly have, given the nature of reality, rather than having been ordained for some ultimate end - notably, us.
At present, we
simply don't know whether the way the world works is
the only way it could; in short, whether currently identified laws
and physical constants are somehow bound together, according to
physical law, irrespective of whether human beings - or anything
else - eventuated.
Given the abundance of other possible locations, if humans existed simply as a result of chance alone, we'd find ourselves (very briefly) somewhere in the very cold empty void of outer space, and would be dead almost instantly.
Might this, in turn, contribute to the conclusion that our very existence is evidence of a beneficent designer?
But we're not the outcome of a strictly random process:
It isn't a coincidence that we occupy a planet that is suitable for life, if only because we couldn't survive where it isn't.
It's no more amazing that
the Earth isn't a hot gas giant than the fact that no matter how
tall or short a person might be, her legs are always precisely long
enough to reach the ground.
is like a golf ball being amazed
that it ended up
wherever it did..
More than three centuries ago, in his chapter on 'The Principles of Nature and of Grace, Based on Reason' in Philosophical Papers and Letters (1714), the German philosopher, mathematician and physicist Gottfried Leibniz noted that,
Here, I'm especially fond of the American philosopher Sidney Morgenbesser's reply to Leibniz, that,
But there is something, and of course, if there weren't, there wouldn't be any opportunities for complaint.
This is not only an
answer to the question of whether the Universe has been
fine-tuned for 'us'; it also points to a more general merging of
statistics, logic and common sense, namely the difference between
probabilities before and after an event.
What is the likelihood that someone could predict the entire sequence, in advance, and without any hanky-panky?
And yet, among the
near-infinity of possibilities, they had to come out some way, and -
miracle of miracles - they did!
But the outcome - wherever the golf ball ends up - isn't a miracle at all.
Neither is it evidence of
divine intervention, nor of the golf course having been designed so
as to arrange for that particular eventual placement of the ball,
since it had to be somewhere. For us to marvel at the fact of our
existing (in a Universe that permits that existence) is comparable
to a golf ball being amazed at the fact that it ended up wherever it
Every person exists because a particular egg (1 out of roughly 500 ovulated by the person's mother in her lifetime) encountered a particular sperm (1 out of roughly 150 million produced by the person's father in a single ejaculation).
According to the
perspective and logic of the anthropic principle, every member of
the human population of roughly 7.5 billion can therefore insist
that his or her existence was foreordained, evidence of a me-thropic
Physics has additional possible explanations for what masquerades as cosmic fine-tuning.
Of these, one of the more intriguing (albeit difficult to grasp) is the possibility of 'multiverses', which revisits the question of probabilities before versus after an event, albeit in a somewhat different guise.
Here is the British astrophysicist Martin Rees:
Shanks suggests that the multiverse hypothesis 'does to the anthropic Universe what Copernicus's heliocentric hypothesis did to the cosmological vision of the Earth as a fixed centre of the Universe'.
Post-Copernicus (and Kepler, Galileo and others), the Earth is known to be just one planet among many, in one galaxy among many. Perhaps we're just the occupants of one universe among many.
Interestingly, even as he demoted the Earth, Copernicus himself placed the Sun in the centre of the Universe, just as he assumed that planetary orbits were perfect circles.
This was an assumption common in early astronomy, based on the notion that the 'heavenly bodies' are perfect, just as, in their geometry, circles are perfect. Galileo, too, presumed circular planetary orbits.
It was the German mathematician and astronomer Johannes Kepler - using data from his fellow astronomer Tycho Brahe - who showed the world that they are elliptical.
Like the human body, the cosmos is far from perfect.
But like the human body,
it is good enough to have permitted our existence.
occurs at the level of galaxies,
and those with a potential for life
are more likely
Such exoplanets would have to be associated with stars that, for example, don't emit massive amounts of X-rays or other forms of radiation.
This all presumes 'life
as we know it'. Maybe there are beings out there who cheerfully
bathe in levels of what terrestrial biologists know as lethal
amounts of energy, or who get by, even thrive, on insufficient
energy to sustain a perseverating entity that would qualify - to us
- as alive.
According to theory - the same theory that gives rise to, among other things, the very real computer on which I am writing - matter, at its most fundamental level, is made up of probabilistic wave functions, which only transition to 'reality' when a conscious observer intervenes to measure or perceive it.
In the famous
'double-slit experiment', light is revealed
to be either a particle or a wave
only after it is measured as one or the other. Prior to this,
photons do not, in a sense, exist as clear-cut entities; afterward,
At the same time, the
fact that one of the world's most renowned physicists floated this
as a genuine possibility gives at least some credence to the notion
that perhaps this or some other inverted version of the weak
anthropic principle shouldn't be rejected out of hand.
Just as the physical
qualities of air have selected for the structure of bird wings, and
the anatomy of fish speaks eloquently about the nature of water,
maybe the nature of the physical Universe has in the most general
sense, selected for life, and thus, for us.
What if natural selection occurs at the level of galaxies, or even universes, such that those offering the potential for life are more likely to replicate themselves? If so, then compared with life-denying galaxies, life-friendly ones might conceivably have produced more copies of themselves, providing greater opportunities for life forms such as ourselves.
Aside from the rampant
unlikelihood of this 'explanation', it remains unclear how or why
such pro-life galaxies would be favoured over their more barren
If so, then what sort of universes would be favored - 'selected for', as biologists put it?
This conveniently explains (if explanation is the correct word) why our Universe contains black holes:
It also leads to the supposition that perhaps intelligent beings can contribute to the selective advantage of their particular universe, via the production of black holes, and who-knows-what-else...
the gaps - and thus, 'God' -
In it, an extraterrestrial intelligence advises the heroine to study transcendental numbers - numbers that are not algebraic - of which the best-known example is pi.
She computes one such number out to 1020 places, at which point she detects a message embedded in it.
Since such numerology is fundamental to mathematics itself and is thus, in a sense, a property of the basic fabric of the Universe, the implication is that the cosmos itself is somehow a product of intelligence.
The message is clearly an artificial one and not the result of random noise. Or maybe the Universe itself is alive, and the various physical and mathematical constants are part of its metabolism.
Such speculation is great
fun, but it's science fiction, not science.
Calling upon God whenever there is a gap in our scientific understanding may be tempting, but it is not even popular among theologians, because as science grows, the gaps - and thus, God - shrinks.
It remains to be seen
whether the anthropic principle, in whatever form, succeeds in
expanding our sense of ourselves beyond that illuminated by science.
I wouldn't bet on it.
Just because the anthropic principle is shaky at best, this need not, and should not, give rise to an alternative 'misanthropic principle'.
Regardless of how special
we are (or aren't), aren't we well-advised to treat everyone -
including the other life forms with which we share this planet - as
the precious beings we like to imagine us all to be...?