Is the Weak Anthropic Principle (WAP) really so remarkable? Let's remind ourselves what it is; It states if the universe wasn't hospitable to life, we wouldn't be here to witness or ponder it. In fact I wonder should we call this a principle at all? A principle is a law, WAP is not, it's more of a truism (e.g. night follows day), or a self-evident statement, an obvious fact, it proves nothing, it adds nothing, does not help in any way or serve any practical purpose towards answering the important questions on the purpose of life or of the universe. It doesn't address it philosophically or scientifically. WAP use to just exist in philosophical circles but has recently crossed over to the world of physics - maybe it should be handed back!

And worse still, the Strong Anthropic Principle (SAP) goes a step or two further implying that the universe was designed for us humans, and we are its ultimate purpose from day one, all of 13.7 billion years ago. As if it was in some way compelled to end up in its present form in order to bring us to life - how conceited is that? Was the universe expecting us then to paraphrase Freeman Dyson (Freeman Dyson, Disturbing the Universe, Harper and Row, New York, 1979)? This SAP idea seems similar to a God based creation found in many world religions. Wasn't it Fred Hoyle that once suggested that someone or something was 'monkeying' with the laws of physics to facilitate the production of life?

Yes, we live in a fruitful universe, but are we humans just a side effect of this universe anyway, i.e. wouldn't the universe exist regardless of whether we exist or not? Then again maybe I shouldn't be so fast to discount that contention that the universe is fine tuned to produce conscious beings as SAP advocates? As let's not forget an interpretation of quantum physics where the conscious observer has the vital role, there is no reality without an observer, so no observer means no universe, see here.

So what started this big AP fuss anyway? It seems to have arisen from the so-called cosmic coincidences uncovered in modern physics and cosmology which make it seem that the universe is designed and finely tuned in such a way that intelligent life like ourselves will emerge.

Fine Tuned Universe - the unlikely coincidences that led to us

Is it Providence or Coincidence ? Proponents of AP use this 'fine tuned universe' argument as evidence of the AP and God.

Why is there something rather than nothing? Some fortunate circumstances for us humans which allowed life to evolve are;

1. Single star system - rather than the binary or multiple star systems which are more common throughout the universe. Stable planetary orbits are much more likely around single star systems, allowing enough time for life to evolve.

2. Eccentricity of orbit and its effect on planetary weather. Earths eccentricity is close to zero (1.7%), i.e. near circular, which is fortunate for us as large orbital eccentricities are not conducive to life. They result in extreme temperature variations. Mercury, a good example of this has a variation of about 100 degrees Celsius due to its 20% eccentricity.

3. Habitable zone - Planet Earth lies in the habitable zone, where liquid water can exist, essential for life to evolve. Our nearest neighbours Venus and Mars lie just outside it.

4. Triple Alpha Process, a nuclear fusion process which occurs in giant stars and gets dispersed through supernova, is the only source of Carbon, which all life is based on. And this seemingly is a very unlikely event.

5. Weak nuclear force - if it were a bit weaker no stars could form and no us. If the strong nuclear force were slightly stronger, it's thought Hydrogen would convert to Helium easier, leaving no free Hydrogen, so no H₂O.

6. Very slight changes in protons or neutron mass would prevent stars from forming and therefore no us.

7. Cosmological constant were greater by a tiny amount (123 decimal places) then no galaxies would form, so no us.

8. The electrical force is around 10⁴⁰ times greater than the gravitional force. So the mutual repulsion between positively charged protons in the nucleus is extremely balanced with their mutual gravitional attraction. Alter this ratio by a tiny amount and there is no us.

Regarding particles we can sum up and say if the relative masses of elementary particles deviated ever so slightly from what they are now, stars and the complex molecules that lead to life could never have developed. And the same can be said for the relative strength of the physical forces.

The above list is just a sample, there are many more examples. So what's with all this preciseness? Is it all merely a coincidence? Or is there a designer? If there is a designer (what we tend to call God) and we are to exist then there was very little room for alterations to many of the fundamental physical constants and laws. Despite the colossal odds did they all just happen to fall within the extremely narrow range of values required for our existence? How easy is it to dismiss the idea of a designer now? As Paul Davies (Cosmic Jackpot: Why Our Universe Is Just Right for Life) wrote, "The cliche that 'life is balanced on a knife-edge' is a staggering understatement in this case: no knife in the universe could have an edge that fine." An inconvenient truth for many scientists appears to be the case.

And to paraphrase Professor Jim Al-Khalili in his book Paradox, today, each of us are at the end of a long and highly improbable chain of events that stretches all the way back to the origin of the universe itself. Break any one of the links in that chain and you would not be here.

Then again if the fine tuning of the Universe were different, perhaps we humans wouldn't have evolved, but a different non-carbon (I'm not a carbon chauvinist!) based life form may have evolved, suited to whatever conditions would have allowed, and that life form (whatever it may be) would be asking the same thing; how did the universe produce life that can observe and ponder it. Does this scenario negate the AP?

Also what does a conscious observer or to ponder the universe mean? At the early stages of evolution on Earth, say microbes 3 billion years ago or dinosaurs 150 million years ago, does the AP still hold true? Can/does that microbe or dinosaur 'witness' the universe? When, with regard to evolution of life, does AP come into effect, at what stage of brain/mind evolution?

And when we discuss these crucial laws/constants how certain are we that they apply everywhere in the universe, or that they were applicable to every time in its history? Cracks are beginning to emerge in these once sacred cows of constants. Maybe the universe isn't as finely tuned as we might think.

Alpha (α), the 'magic number' according to Richard Feynman is a crucial fundamental constant. This so-called 'coupling constant' is a pillar in physics and central to our entire description of the universe. It measures how electrically charged elementary particles (eg. electrons) interact with electromagnetic radiation (photons). But it turns out it may not be constant after all. When alpha is measured in a laboratory and compared to measurements from a distant light source such as a 12 billion light year distant quasar, a tiny but hugely significant difference is found. So this fundamental physics constant describing the strength of the force between electrically charged particles may be different in other parts or other times of our universe. It's central to AP principle and according to adherents of AP if it were 4% bigger or smaller stars would not reach their evolutionary stage of producing carbon or oxygen. But it seems it may vary after all, or at least one of its three constituent constants - speed of light, electron charge, planks constant - changes - but which one?

Omega (Ω), the mass/energy density parameter of the universe (=1) is such that the universe can expand at a suitable rate to allow galactic formation. If it were a little less than the value of 1 we would have a big crunch scenario, the universe would collapse before any galaxies formed. If it had a value of a little greater than 1 then matter would be pushed further and further apart and gravity would be too weak to allow galaxy formation, the big freeze scenario. But do we know precisely the deviation from value 1 that would rule out any galaxy formation, or if it had a different value could galaxies form for a long enough period of time to allow life to evolve. What is the deviation amount, what is the length of time a galaxy requires to produce life - we can't be certain of this, so we shouldn't use it as evidence of AP surely! Just how delicate is this so-called delicate balance people suggest it is as a result of Omega = 1.

Multiverse to the rescue

Anyway one way to avoid the AP quandary is if many co-existing universes accompany our own as theorised in modern cosmology. This, the multiverse theory, undermines the AP. Nature would eventually get around to producing life given enough universes with different combinations and values of constants and laws. So if all types of universes exist, then it's no surprise we ended up in one whose conditions and parameters (eg. constants and laws) are just right for us to evolve and ask the difficult questions. Countless other universes may exist right now (some may even have expired already as they've had their big crunch or big freeze and died) where life both did emerge or didn't emerge - some life-friendly, some not so - depending on whether the laws of physics (speed of light, strength of G, omega, etc) suited it's emergence. This implies our existence in our universe is not so improbable after all!

Multiverse

Of course to-date there is no evidence to support the multiverse theory, it's just theoretically and mathematically possible but it may be just a matter of time before evidence is garnered, (Note: the multiverse theory also helps resolve the time travel Grandfather paradox enigma and may even shed light on the origin of the Big Bang - perhaps our universe began when two universes somehow collided resulting in what we detect as the big bang).

So multiverses could exist, each one with its own spatial dimensions, coexisting alongside each other, and never interacting other than perhaps through gravity leakage - a sometimes mentioned dark matter explanation. As in the dark matter enigma maybe just the gravitational effect of ordinary matter in a parallel universe on matter in our universe.

And further support of the Multiverse theory surfaced in March 2014 as the first evidence of the predicted gravitational waves may have been discovered. A newly discovered feature of the polarization pattern of cosmic microwave background radiation indicates gravitational waves created by rapid (many times the speed of light) space-time expansion of the infant universe. Many theoretical physicists such as Alan Guth (MIT) and Andrei Linde (Stanford University) believe these waves are strong evidence of inflation in the first moments after the Big Bang. And inflation theory strongly favours a multiverse over just one boring single universe! See here.

Conclusion