giovedì 25 luglio 2013


Post n. 12 English

The universe originated 13.6 billion years ago. Studies show it was the Big Bang to have led the way to the origin of life.
The facts that lead to similar claims are the so-called "natural constants". As reported by the physicist Paul Davies in "Una fortuna cosmica" in 2007, the story begins in
1950. At that time physicists could not understand how carbon was formed in stars. The fusion of two nuclei of helium gives out beryllium, if which bumps another helium nucleus should give out carbon. The problem is that Beryllium is unstable and
decomposes before it can be hit by a helium nucleus. The carbon and therefore life would not have existed. Fred Hoyle who solved the problem proposed that the Beryllium presented a peak of nuclear energy, or what physicists call resonance, which would extend its existence by a few fractions of a second. It has been shown that beryllium has actually this resonance and it is thanks to this trifle energy that the synthesis of carbon is possible and therefore the origin of life.
Davies also mentions both the strong nuclear force, like the force that binds protons in the nucleus, and the force of attraction between electrons (-) and protons (+).
If these forces were slightly more intense or less intense even by 1%, the universe would be completely different and life impossible. The same considerations apply to the force of gravity and the weak nuclear force: the force that controls the decay of the neutrons. Reflecting on these and other facts, around the late 70s, the astrophysicist Brandon Carter coined the term "anthropic principle" to indicate a universe cut right for life.
Respectful scientists expresses ideas that go in that direction even if they do not accept the anthropic principle, as the physicist Freeman Dyson said: "The more I examine and study the details of its architecture, the more it is evident the universe, somehow, already knew “we were coming ".
The famous biologist Simon Conway Morris goes even further when he says: "There is as we could say an inevitable intelligence in the universe".  And Paul Davies seems to believe in the existence of a purpose in the mechanisms of the universe at a fundamental level, not accidental and without an agent pre-existing purposes miraculous. As it is for some scientists, Life is in the laws of the universe.
However, it is a topic on which we have very little to say so we limit ourselves by writing down facts. We leave cosmologists and physicists final outcome of future insights and to philosophers and theologians their ultimate meaning.
The stars, through nuclear fusion of hydrogen, they formed the nuclei of natural chemical elements. In particular, in stars with a mass greater than 1.5 solar masses, begin the formation of carbon (C), nitrogen (N), oxygen (O). As the mass increases, the temperature of the core increases too and elements with greater mass are formed. And finally, the collapsing and consequently, the explosion of massive star about ten times the sun’s mass, and all the natural heavy elements formed. All these elements are dispersed in space. Starting from the Big Bang, through the nuclear fusion of hydrogen, the stars took about 5 billion years to fertilize the space. In this first phase of the universe, the amount of carbon, nitrogen and oxygen was poor, and rocky planets could not exist because there wasn’t enough silicon.
On how the universe in the future will change when the relations between elements will vary is still a topic under study.
At this present state in the universe for every million hydrogen atoms, there are 350 of carbon, nitrogen 110 and 670 of oxygen, while most of the remaining elements are about  the unit or much less. So biogenic elements (H, C, N, O) are by far, the most abundant elements in the universe. We can therefore imagine the atoms of carbon, nitrogen, oxygen immersed in an atmosphere of hydrogen. The matter in space is very thin and subjected to the most diverse conditions of temperature and radiation. However, in the long run, these elements ionized by ultraviolet rays and through random collisions, become molecules of very simple substances. In fact radio astronomy has identified some molecules in the space formed by these elements, mainly: methane (CH4), ammonia (NH3), water (H2O), hydrogen cyanide (HCN),  formaldehyde (HCHO), carbon monoxide (CO), and in smaller quantities other simple molecules such as formic aldehide, urea, simple alcohols and ketones.
Part of these substances are destroyed by ultraviolet rays that then later reform in other places. Since the temperature in those areas is around -250 ° C, a large part gets
frozen on
dust particles away from the deadly rays. The elements produced by stars and simple molecules together with dust particles (silicates, metal oxides, ice crystals)  become clouds of gas and dust that give birth to planetary systems, when highly concentrated.
In conclusion, we can say that planetary systems all start with the same ingredients.
So, what is the chemistry with these ingredients?
Our solar system originated 4.5 billion years ago. At that time the nebula of gas and dust formed and asteroids too.
Fragments of asteroids have crashed on earth in the form of meteorites; in the last two centuries, more than a thousand have been collected and catalogued. These meteorites, called chondrites because of the presence of chondrules, beads of melted material; therefore, they are from the same primordial material from which other bodies of the solar system were formed.
Alan E. Rubin, geochemist at the University of Los Angeles conducted a study on chondrites and presented the results of his research named, "I segreti dei meteoriti primitive" Le Scienze, April 2013. The intention of Rubin was only to build a map of the structure of the solar nebula. From this research, we can draw out some useful information for our purpose.
So chondrites represent 80% of the meteorites fallen on Earth. The study of the chemical characteristics led to identify a dozen groups.
All these groups are included in four classes: enstatite chondrites formed between 0.5 and 1.5 AU (1 astronomical unit Sun-Earth distance), ordinary chondrites over the two UA, Rumuruti chondrites from 2.5 to 3 UA and finally between 3 and 4.5 UA the carbonaceous chondrites. Beyond this distance begins the area of ​​the gassy planets. So these meteorites originated from the proximity of the Sun to Jupiter’s orbit, in completely different environmental conditions depending on: temperature, radiation, particle velocity, shock waves, etc.
Well, among all these different environmental conditions only the carbonaceous chondrites contain carbon compounds. And what are these compounds? Simple organic substances and mainly amino acids, which are the constituents of proteins.
According to JB Haldane substances essential for the origin of life originated, in the prebiotic era, on our planet, starting with the primordial nebula of gas with energy input.
In 1953, S. Miller confirmed this hypothesis.
After Miller, researchers conducted several experiments in the most different environmental conditions, using gas mixtures similar to those contained in the clouds of gas and dust.
Well, as Miller they obtained different compounds of carbon.
And what are these compounds? Simple organic substances and mainly amino acids.
So after 4.5 billion years it does not seem that the chemistry has changed that much.
And then, how many clues do we need to be convinced that, among the constituents of the macromolecules essential for life (nucleic acids and proteins), only the amino acids were present in the prebiotic era?
Now, the same ingredients in the clouds of gas and dust that gave rise to other planetary systems. In these planetary systems, the environmental conditions were roughly similar to our solar system. We can assume then that even in those places, probably, amino acids formed. And as long as the universe will not change the quantitative ratios of biogenic elements, it is likely that solar systems in formation will synthesize amino acids.
Some scientists, as reported by Dimitar Sasselov in “Un’altra terra" in 2012, are
Elab. da:
seeking a synthetic      Biology and alternative Biochemistry. In this context, the complex organic compounds and their reactivity are represented by the metaphor of a chemical landscape that is a map with valleys and mountains. The valleys represent the initial conditions, the mountains instead alternative biochemistry that you might have on other planets according to the environmental conditions.
It isn’t really clear what is meant by synthetic and alternative, but if you think of a biochemical without amino acids we’d be discussing about nothing.
As for life and its origin, if we still want to use the metaphor of the chemical
landscape, amino acids occupy the only hill and all around is inanimate matter makes us a flat salt desert.
Nothing had to go wrong with the origin of life. The amino acids can’t be replace and since the laws of physics and chemistry are universal, their properties are unique and universal. It is from the amino acids where a particular type of matter, organic matter, the matter of life originates.
The question often asked, could there be organisms that were using D amino acids (Right) instead of L (Levo) and Ribose L instead of D; and why not! However, it is unlikely that they are around the universe. As we will explain, also supported by some experimental data, the choice of Levo in amino acid is probably a consequence of the asymmetry of water. Life needs water in liquid state and water in all the universe has the same asymmetry.
In Miller’s experiment and in meteorites over 60 different amino acids have been identified. Life on earth uses only 20 and, when life originated, perhaps it only used 12 to 15, as for the others life added them much later. It is very likely that the choice of amino acids was a consequence of the environmental conditions of our planet, if not all at least part of it.
Finally, as discussed in the previous article "Proteins: its constituents. Seven strokes of luck ", inanimate matter provides the matter: amino acids, with all the right properties for life. It creates a chemical void so that the creation of life doesn’t go wrong. Inanimate matter also provides a fairly large number of amino acids, so that life can choose the right ones according to the environmental conditions on the planet.
What to say!
Come to think, Paul Davies says in "Da dove viene la vita", 2000: "Placing categories and concepts from the human world on the nature, is undoubtedly dangerous. Yet, after all, human beings are also products of nature, and if humans have a purpose, that means at some point, it must be because of nature, and therefore it is in its genes. [...] Is it possible that the purpose of nature is an intrinsic property, at a cellular level or even subcellular? There is no agreement on the answers to these questions, but an explanation of the origin of life will never be complete if these questions are not addressed. "
However, it is a subject on which we have very little to say therefore we limit ourselves to registering data. Let the philosophers and theologians decipher their ultimate meaning.
What about aliens? So far still similar to us ... or so.

Giovanni Occhipinti


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