Some characteristics of the physical world

The issue of the origin of the physical world is important, because it can cast the light on the question of whether it is purposeful. A purposefulness would imply that sentience is not only necessary to investigate reality, but is also its essential ingredient. On the other hand, if the universe is the result of random meaningless events, sentience may be only an accidental by-product. Examining some characteristics of the physical world can help in determining the likelihood of the above possibilities.

One striking feature of the universe relevant to this question is its orderliness, conformity to formula and rational laws perfectly suited for life. It is often (somewhat inaccurately) referred to as the Anthropic principle. The universe could have been chaotic, but it is not - it is very orderly. The Big Bang theory does not predict that all its properties have to be so finely tuned. There are infinite possibilities of bad balance that were far more likely to emerge if it was only down to chance. Any of them could have produced a universe that was incapable of generating stable stars, planets and life. Some examples will be highlighted to bring home how remarkable this is.

 

The Big Bang

To have a universe that will sustain galaxies, stars, planets and life, the conditions at the beginning must be right within very narrow ranges. The universe had to start with the right density, amount of inhomogeneity of radiation, and the initial rate of expansion.

Apparently, there was a slight excess of matter over antimatter (baryons over anti-baryons, electrons over positrons, etc.) at the initial stages of the universe. If this excess had been smaller, there would have not been enough matter for galaxies and stars to be formed. If it had been greater, there would have been too much radiation for planets to emerge.

The initial inhomogeneity (‘lumpiness') in the distribution of radiation was also necessary for the appearance of stars and galaxies. However, too much inhomogeneity would have led to black holes being created before stars.

If the original velocity of expansion had been one millionth greater, the heavier elements and stars would never have come into existence; if it had been one million millionth smaller, the universe would have collapsed before it was cool enough for the elements to form.

The present theories do not imply that this set of conditions had to exist. There are many other possible combinations that would not support stars, planets and life.

 

Subatomic particles

Each particle has a few defining properties which determine its behaviour. These properties are always and everywhere the same. For example, all electrons have a charge of -1 and a spin of ½; all positrons have identical properties to electrons, but a charge of +1; all protons have also the same charge and spin, but a much greater mass. There are a countless number of particles with these characteristics, but no known particles with intermediate features between the two kinds. Moreover, their features seem to be mutually tuned. For example, despite their huge difference in mass, for a reason unknown to science, the electrical charges of electrons and protons match precisely. If they did not, all material configurations would be unstable and the universe would consist of nothing more than radiation and a relatively uniform mixture of gases. This can hardly be just an accident. The celebrated scientist Hawking writes:

The remarkable fact is that the values of these numbers seem to have been very finely adjusted to make possible the development of life. For example, if the electric charge of the electron had been only slightly different, stars either would have been unable to burn hydrogen and helium, or else they would not have exploded... One can take this either as evidence of a divine purpose in Creation and the choice of the laws of science or as support for the strong anthropic principle[3]. (1988, p.138-139)

 

Four forces

Present day science claims that the four forces (gravity, electromagnetism, strong and weak nuclear forces) govern all events in the physical universe. These too are, for inexplicable reasons, finely tuned. If any of them was slightly different, the universe (and, therefore, life) could not exist.

If gravity was just a little bit weaker, galaxies would fly apart and stars would burn out prematurely. There would not be enough gravity to pull the debris from dead stars into new interstellar dust clouds. The formation of new suns and planets would be impossible. On the other hand, if gravity had started out even a fraction stronger, then the rate of collisions between stars would have been so great that any typical solar system, such as this one, would not have survived long enough to produce stable planets and life.

If the exertion of electromagnetic force altered in any way, chemistry would not exist, which again means no stars and planets, and no physical life.

The same applies to the strong force that holds the core of atoms together. If it was slightly weaker, the particles would not be able to form the nucleus of an atom. If it was a little stronger, protons would coalesce without the necessity of neutrons being around. The single proton that forms the nucleus of hydrogen, would be unstable. So, hydrogen, one of the basic building blocks of the universe, would not exist. Moreover, in the first case the stars would not be able to shine, and in the second they would inflate and explode before there was any chance to form planets and life on them.

If the weak nuclear force (responsible for various forms of radioactive decay) had slightly different properties the stars could not burn and the elements necessary for life, such as carbon, oxygen and nitrogen, could not be formed inside them.

This is not all. If these four forces were not mutually aligned in the way they are, the universe also could not exist. Any change in the relationship between these forces would result in the complete impossibility of material reality.

 

Stellar objects

Supernovae, or stellar explosions, are important for life. All the necessary elements (carbon, nitrogen, oxygen, iron, etc.) are manufactured in the interior of the stars. If these elements are to accumulate in planets such as the Earth, they must be released from the stellar interiors and disperse throughout the cosmos. This is one of the results of supernova explosions (moreover, the shock waves that they generate are probably important in initiating the condensation of interstellar gas and dust into planetary systems). However, supernovae are also highly destructive. If they were too close to a planetary system, their radiation would obliterate any life. So, supernovae must occur at a very precise rate, and the average distance between them and between all stars must be within a relatively narrow range. The distance between stars in this galaxy is about 30 million miles. If this distance was smaller, planetary orbits would be destabilised. If it was greater, the debris thrown out by a supernova would be so diffusely distributed that planetary systems (like this one) would never be formed. Interestingly, as a great number of stellar objects have been created, the universe appears to be speeding up (the present science cannot explain why), which minimises the destructive effects of supernovae.

The same precision is also apparent with regard to the ratio of longevity between galaxies and stars. Galaxies last several times longer than the lifetime of an average star, which allows the atoms scattered by an earlier generation of supernovae within a galaxy to be gathered into second-generation solar systems.

 

Complex structures

Not only are the properties of the universe precisely ordered to allow the formation of stellar bodies, but they are also synchronised to allow the formation of complex structures, such as molecules (which, of course, must come later). If this was not the case, the creation of the chemical compounds instrumental for life and planetary systems capable of sustaining life would be impossible. Here are some examples:

Chemistry is the process of building up different molecular structures that need to be relatively stable to interact and to form new structures. This could not have happened if some nuclear constants such as the fine structure constant (α) and the electron-to-proton mass ratio (β) were slightly different. If these constants had a higher value, the long chains of molecules such as DNA, could not be formed; if they had a lower value, atoms would not be stable.

Other constants are also crucial: the fact that protons and neutrons have almost, but not quite the same mass, also turns out to be essential. If this value was much different, protons would decay before they could form stable nuclei. A neutron is heavier than a proton by 0.14%, but this small difference is important because it exceeds the total mass of an electron. If it had not, electrons would combine with protons to form neutrons, leaving no hydrogen. Moreover, if the neutron did not outweigh the proton in the nucleus, the active lifetime of the sun and similar stars would be reduced to a few hundred years, not enough for the formation of planets and life. Similarly, that electrons weigh so much less than protons or neutrons is crucial for the existence of chemicals essential for life. Otherwise, molecules like DNA could not maintain their precise and distinctive structures (the electron mass determines the overall size of atoms, and the spacing between the atoms in a molecule).

If the nuclear constant force increased by only 0.3%, it would bind two neutrons; an increase of 3.4% would bind two protons, in which case all the hydrogen would have burned to helium in the early stages of the Big Bang, and so no hydrogen compounds or stable stars could have been formed. On the other hand, a decrease of 9% would unbind protons and neutrons, which would prevent the formation of elements heavier than hydrogen. The consequence of either variation would be that larger elements, including carbon (the basis for organic life), could not exist. A small increase in electromagnetic force would have the same effect.

There is exactly the right amount of heavy subatomic particles (baryons) in the universe to allow the formation of planets. If this amount was marginally greater, the higher density of stars would substantially increase the probability of interstellar encounters that would affect the stability of planetary orbits and by doing so destroy any possible life.

The creation of complex atoms and molecules was also only possible because the properties of the basic elements were well synchronised, and there is no known reason why it should be so. The first nuclei to be formed were those of hydrogen and subsequently helium, but they are too inert to create more complex atomic structures. Carbon served as a catalyst enabling the formation of heavier elements. This required large amounts of carbon in the first place. If two helium nuclei react, they can produce a nucleus of beryllium, a highly unstable isotope that almost immediately disintegrates into helium. To produce carbon, beryllium needs to enter into reaction with helium, which is only possible because the combined energy of the beryllium and helium nuclei is slightly smaller than the energy of carbon - the product of that reaction. However, if so produced carbon reacted with helium, it would be reduced to oxygen. This does not happen because their combined energy is slightly higher then that of oxygen, so it is not a ‘resonance reaction'. Here again is a most improbable fine-tuning of energy levels for four entirely different elements, but without it, more complex structures (including planets, and life forms) could not emerge.

 

Symmetries

The very existence of consistent and rational physical laws (that follow certain mathematical rules) is not something that should be taken for granted and begs a question. But this is not all. Precision and regularity does not apply only to physical laws. Physicist Murray Gell-Mann discovered that when the properties of sub-atomic particles like protons and neutrons are plotted on graphs, they take the form of hexagons and triangles, with the known particles sitting at various points within them. Gell-Mann predicted other sub-atomic particles that science had yet to discover, on the basis of gaps in these patterns. He also predicted that particles in fact consist of ‘sub-sub-atomic' particles (now known as quarks). All his predictions proved correct. Similar patterns, generally know as ‘symmetries', have since turned up often in successive theories of physics.

  • [3]. The strong anthropic principle implies in this case the multiple universes hypothesis, which will be discussed later on.