#8 The Finely Tuned Universe
Have you ever tried balancing arbitrarily shaped rocks on top of each other? Kind of like what Luke was trying to do practicing his Jedi skills with Yoda in the Return of the Jedi. But, of course, without the use of the Force.
Many of us have challenged ourselves, at some point in our life, to balance as many rocks on top of each other as possible. What was your highest tally? Depending on the type of rocks used, my guess is anywhere from five to ten would be the maximum score for most people.
Rock stacking – as it is officially called – is actually a sport. Competitions are held around the world for it. While most people can manage only a few rocks, the current world record hovers in the range of 30-40 rocks.
Rock stacking looks pretty easy but when you actually start stacking rocks, you realize how delicate and fragile the entire structure is. One wrong move and the whole thing comes crashing down like a pack of cards. You have to be extremely meticulous in aligning the rocks to keep the structure standing. Every new rock added to the top of the stack makes the move much more challenging.
The fabric of our universe is calibrated upon a precise framework similar in principle to the delicate structure of stacked rocks – but much more intricate.
Finely Tuned Constants
Our universe is constituted and driven by a series of finely tuned numerical constants. This set of numerical constants is extremely unique and highly specific. These constants are special in that their numerical values cannot be deduced from any other mathematical formula or physical quantity in the universe. The constants are completely independent of everything else that we know. Their values exist arbitrarily – out of nowhere.
How do we know about these constants? Through experimentation in physics and theoretical calculations using mathematics. What is bizarre is that when the value of any one of these constants is changed slightly from their inherent value, theoretical calculations show that the fundamental structure of the universe or the laws that govern it would come crashing down – just like the stack of rocks. Only a very precise value – or an extremely minute range – would keep the universe stable and in balance.
There are multiple finely tuned constants that drive our universe. Getting the precisely correct value for any one of them is like stacking tons of rocks on top of each other without falling. A slight deviation would bring the entire stack – or our universe – crashing down. Sir Martin Rees – the famous British cosmologist and astrophysicist – has enumerated these findings succinctly in his book Just Six Numbers.
The physics of this subject is a bit deep and complex, and is discussed in slightly more detail in my book. I will try to keep it easy here and give a very simplistic overview of a few such numerical constants to give an idea of what we’re talking about. If you need more details, you can read my book, or for a full discussion on this subject, get hold of Dr. Rees’ book.
The Force Ratio
Every body attracts every other body with a gravitational force. The larger the body size, the stronger the gravitational force. That is the reason gravity on Jupiter – a much larger planet – is a lot stronger than on Earth. The converse is also true. The smaller the object, the weaker is the force of gravity.
At the extremely minuscule atomic level, the gravitational force between atoms becomes negligible. The much stronger electromagnetic force between the positively charge proton and the negatively charged electron becomes the dominant force in an atom. The ratio of the electromagnetic force to the gravitational force in an atom is 1036 – or 1 trillion trillion trillion. This ratio turns out to be extremely sensitive to the existence of complex life on Earth.
If this ratio were sufficiently smaller than it is now – meaning gravitational force were stronger – habitable planets like Earth would not flourish and complex life would never arise. You and I would not be here. At the same time, life would not evolve to its complex form if the ratio were sufficiently larger. Either way, the ratio that exists today makes the physics of the universe conducive for complex life to exist.
Nuclear Efficiency
Soon after its birth, our early universe primarily carried hydrogen atoms within it. The heavier hydrogen atoms among them – with one proton and one neutron in their nuclei – combined with each other to form helium atoms. During such a fusion, 99.3% of the mass of two heavy hydrogen nuclei is used to create the mass of the resulting helium nucleus. The remaining 0.7% of the mass is converted into energy.
This mass-energy conversion factor of 0.007 is dictated by the strong force that binds protons and neutrons together in an atom’s nucleus. If the strong force were slightly less – so that this factor were 0.006 instead of 0.007 – protons and neutrons would not bind together. Helium and other heavier atoms would never form. The only atoms pervading the universe would be hydrogen atoms. There would be no structure in the universe. And certainly no life.
If the strong force were slightly higher – so that the mass-energy conversion factor were 0.008 instead of 0.007 – protons would readily bind to the nucleus even without the aid of neutrons. All the hydrogen atoms would readily convert to helium and higher atoms. Without any hydrogen atoms left, there would be no stars, no water, and no life. The mass-energy conversion factor of 0.007 is extremely fine tuned to give rise to meaningful structure, including life, in the universe.
The Density Ratio
Our universe began with the Big Bang, the explosive force that pushed everything out with forceful expansion. At the same time, all the expanding matter exerted gravitational attraction within it that pulled everything back. These two dominant and opposing forces – one pushing out and the other pulling in – created a tug-of-war that would define the structure of our universe.
If the expansion force had been stronger than the gravitational force soon after the Big Bang, our universe would have expanded very rapidly. Gravity would not have been strong enough to bring matter together to form galaxies, stars, and planets. If the gravitational force had been stronger than the expansion force, our universe would have contracted and collapsed onto itself. There would be no meaningful structure left in the universe.
It turns out that the conditions in the early universe were so precise that neither force dominated the other. The density of the early universe was exactly in the range that allowed it to expand sharply in its early stages yet permitted gravity to be strong enough to coalesce all the expanding matter into galaxies, stars, and planets. Had the density of the early universe been outside this extremely thin sliver of allowable range, our universe would have either spread out without any structure or collapsed onto itself.
Early Universe Ripples
Right at the beginning of the Big Bang – 10-35 sec. after the Big Bang, to be exact – our universe began an inflationary phase in which it expanded at an exceedingly fast rate. The composition of the super dense matter at the beginning of the inflationary phase determined how matter expanded and dispersed throughout the expanding universe during the inflation.
Our universe had very slight irregularities in its composition of matter at the beginning of the inflationary phase. These irregularities, when inflated, resulted in an uneven composition of matter dispersed throughout the universe. Some patches of matter in the universe were denser than others and resulted in the formation of galaxies. Less dense patches expanded and resulted in vast empty spaces that we find in the universe.
A particular measure of the amplitude of the irregularities in our universe has been found to be equal to 10-5 at the beginning of the Big Bang. If this quantity were slightly smaller, our universe would be smoother with loosely shaped dormant galaxies, and fewer and weaker stars. If it were slightly larger, our universe would be highly turbulent with gigantic black holes, and intense and lethal cosmic radiation. Either way, it would not have been possible to have life friendly habitable systems.
The Cosmological Constant
The Big Bang caused our early universe to expand forcefully at its beginning. At the same time, the gravitational attraction of all the matter in the universe pulled the universe back from expanding. It would seem intuitive that, with time and due to gravity, the rate at which our universe is expanding would slow down. Our observations, however, show that the opposite is true.
It turns out that the rate at which our universe is expanding is increasing with time. In other words, our universe is expanding faster and faster. Scientists posit that there must be other invisible constant force – not yet discovered – that is pushing our universe faster apart. They call this mysterious force “dark energy”. Calculations have shown that this force is determined by a cosmological constant whose value is 0.7.
Again, this constant seems to be fine tuned to provide the right structure to our universe. If this constant had been larger than a particular value, then the expansion force of the universe would have overwhelmed the gravitational force. Stars, galaxies, and heavenly bodies would not have been able to form to give the universe its structure. A counter argument exists if the cosmological constant were much smaller.
Anyone with a perceptive mind can see on a cursory level – even if they haven’t studied deep physics – that our universe has an exquisite structure built into it. They can observe that there is balance and harmony in the way the universe runs. Disorder and chaos are not the characteristics by which our universe is structured or functions. The same is true for the finely tuned constants.
One has to possess deep knowledge of the physics of the universe to realize that it could not have evolved into the present form had it not been for the numerous independent, finely tuned, arbitrarily existing constants. We’ve looked at only a few of them but there are more. They include the masses of the six kinds of quarks, the three kinds each of leptons and neutrinos, and the Higgs boson. Physicists have identified more than 25 fundamental constants that seem to have arbitrary – yet perfectly fitting – values.
Each one of these finely tuned constants existing in the universe represents a much more delicate calibration than successfully stacking tons of rocks on top of each other. Out of all the possible numerical values, only a certain combination – or a very narrow range of it – will yield the perfect outcome. It is like hitting a cosmic jackpot of universal proportions. Suffice to say, the mysteries of the universe become more complex the more we dive deeper into it.
It is easy to dismiss the fine-tuning of the universe to a cosmic jackpot, but is it a rational, professional, and scientific approach? Or is it a convenient way to not talk about it and sweep the issue under the rug?