The first 3 seconds or 3 minutes of the Universe after the Big Bang have been described, as well as the first 300 thousand years or the first 3 million – all very short times compared to the total age of some 15 billion years. This describes the evolution of elementary particles and radia-tion and the separation of the 4 fundamental forces. It goes on to describe the formation of galaxies and their clusters, and of stars and their evolution to white dwarfs, neutron stars or black holes. It deals with the very small and the very large – the extreme ends of the Cosmic Zoom.
Even the formation of atoms is described, as naked nuclei capture orbiting electrons. At first there is only hydrogen, with a bit of helium, until some stars are born, live and die to form heavier nuclei in their last moments. With the death of stars, it is “dust to ashes” one way, not, as with us, “dust to dust, ashes to ashes” and around again in a cycle.
The evolution of life on Earth has also been well described, although several versions of the original creation story are still circulating. Macromolecules to cells, prokaryotes to eukaryotes, unicellular to multicellular…a multi-varied and often told story.
We even know something about the pre-biotic or (shall we say) peri-biotic (just before and just after) chemistry of life, the “small molecules to macromolecules” stage and the selection of the functional macromolecules from among the non-functional ones. Yet this is much less well known and still doubtful. It is as if, in our knowledge, we jump straight from physics into biology, leaving the in-between chemistry somewhat hazy and fuzzy.
There is an even larger gap, and that is a discussion of phases rather than components, that is, physical chemistry. Components are the chemical species (elements or compounds), assemblages of particular molecules. Phases are the solids, liquids, gases, and plasmas (the ancient Greek “elements” of earth, water, air, and fire – only it is more complicated than that); each crystalline solid is a separate phase, some liquids can mix in solutions (as can some solids and liquids, or gases and liquids) while some are immiscible as separate phases, and gases are all one phase, always miscible. Phases can be either pure substances (elements or compounds) or solutions, but not mixtures.
Components and phases are connected by the elegant and beautiful “phase rule”, F = C + 2 – P, where F = degrees of freedom, C = number of components, P = number of phases, and “2” standing for temperature and pressure (if we also consider other variables such as gravity or surface tension or electrical potential, this number would increase). On the basis of this law, we can then draw phase diagrams, (usually plotting either pressure versus temperature for one-component systems, or temperature versus composition [ratio of components] for a two-component system at constant pressure) in which a phase with two degrees of freedom is an area, a phase with one degree of freedom is a line, and a phase with zero degrees of freedom is a point. All this is well-known and practiced in physical chemistry, metallurgy, mineralogy, etc., but little known in popular science.
How much do we know about the evolution of phases on planets such as the Earth? This would constitute the “missing middle” of the range between the very large and the very small to which we alluded in the beginning. Yet it is the part of the Cosmic Zoom where we live, the part which we know best in commonsense experience, yet not so well in its scientific aspects. Perhaps we prefer to study the exotic rather than the commonplace.
The planets are made of stony phases, ices (which can melt to liquids or vaporize to gases if the temperature is high enough), and gases, sometimes with an inner metallic core which is invisible, but whose presence is inferred from magnetic properties or from density considerations.
The stony phases, of course, are multiple as solids, but in the liquid phase (magma, which is like slag in metallurgy) they may be miscible or not. Three possible liquid magma phases have been mentioned, called siderophilic (iron-loving), lithophilic (stone-loving), and chalcophilic (limestone-loving). The ices may be methane, ammonia, or water, i.e. the hydrogen compounds of carbon, nitrogen, or oxygen, all elements (non-metals but non-halogens) in the first complete octet row of the Periodic Table of the elements. The gases can be vapors from the ices or carbon dioxide, nitrogen, oxygen, or several others; but mainly (when it comes to quantities of gases present on all the solar planets) hydrogen with a little bit of helium, like most matter in the Universe.
The inner planets (Mercury, Venus, Earth, and Mars) are the stony planets, though Earth also has (melted) ice in its hydrosphere, gases in its atmosphere, and a core of metallic iron. The outer planets (Jupiter, Saturn, Neptune, and Pluto) are largely hydrogen, which is gaseous on the outside but is probably in a “metallic” phase under the intense pressure in the inside; but the numerous satellites of the outer planets have ices and also some stone. Jupiter’s satellite Io is peculiar in having a lot of sulphur, both solid on the surface (where if would form a distinct phase) and in the atmosphere. The comets are made up largely of ices with some admixture of dust (“dirty snowballs”). Asteroids and meteorites are stony.
The Earth’s biosphere features prominently two phases: oil and water. Water has been mentioned before as one of the melted ices and as the main constituent of the Earth’s hydrosphere (oceans, streams and lakes), but the oil phase is new and peculiar to life forms.
Living organisms, of course, consist of far more than oil and water, but all the myriad components can usually be classified as hydrophilic (water-loving) and lipophilic (oil-loving), the latter also called hydrophobic (water-hating). It is a real polarity: anything that loves oil hates water, and vice versa. Hydrophilic compounds are generally attracted to water because they are polar, i.e. can exhibit electrically positive and negative groups just like water; while lipophilic compounds, such as long hydrocarbon chains, are non-polar (uncharged or electrically neutral).
A cell membrane is intimately composed of both hydrophilic and lipophilic components, in a precise architecture, and could not function or exist at all without their interplay. Natural oils and fats have hydrophilic heads (the COOH end-groups of fatty acids) and lipophilic tails (the long hydrocarbon chains), and these are lined up in a double layer with lipophilic tails inside the membrane and hydrophic heads on both the inner and outer surface of the cell, sticking out into the hydrophilic cytoplasm inside the cell and the hydrophilic inter-cellular spaces outside.
Anything trying to go through the membrane in either direction has to pass through the oily barrier, which most molecules cannot do. So special channels are provided for the passage of ions and other small molecules, some of them provided with energy-intensive “pumps” working against an osmotic gradient. The channels are protein molecules spanning the membrane, with lipophilic portions inside the membrane and functional hydrophilic portions sticking out, for receiving chemical messages to change their configurations to admit or bar ions depending on functional demands.
A hydro-lipo balance is just as important for health as an acid-base balance or a redox balance or an electrolyte balance (K vs. Na vs. Ca) in nerve-muscle discharge. Women’s bodies have more fat than men’s bodies (which have more muscle); hence the smooth curves of women’s bodies and the greater physical strength of men. Women also float better in water because of their higher fat content (fat being lighter than water) and so may be better swimmers; while in athletic feats involving muscle strength or speed, such as weight-lifting or running, men are superior. As well, fat layers protect women better against cold and provide food reserves for pregnancy and lactation. Women are built for endurance, men for quick exertion. Perhaps this is why women live longer than men. Women and men represent different ideals of beauty. This is well illustrated in classical ballet and figure-skating, where ballerinas usually do the graceful pirouettes and the male dancers lift them up as if they were light as feathers.
Some organic (i.e. carbon-containing) liquids are hydrophilic and some are lipophilic. Ether is lipophilic, and so can be used for extracting dissolved substances from water solution, because it does not mix with water. When ether and water are put together in the same vessel, they form two distinct layers with a meniscus (boundary) between them. However, some other organic liquids, such as ethyl alcohol, have both polar and non-polar groups, and so can mix with either ether or water. When alcohol is added to the two-layered ether-water system, and the whole is stirred or shaken, the components will all dissolve in each other and form a single phase. In a way, the alcohol acts as a “mediator” to reconcile the opposites of the hydro-lipo antagonism.
An emulsifier such as soap makes oil and water mix on a coarser scale; not as molecules going into a common solution, but as droplets (sometimes of tiny colloidal size) dispersed or suspended in a continuous water medium. (This is how soap removed dirt from surfaces, since dirt particles are often coated with oil.) Like the fatty acids in a cell membrane, soap molecules (sodium or potassium salts of fatty acids) have polar heads and non-polar tails, which enable them to coat small oil droplets or dirt particles and thus “emulsify” them.