The Universe is immense, estimates suggest at least two trillion galaxies. Our galaxy holds 100 to 400 billion stars. One of those stars, our sun, has eight planets orbiting it. Planet Earth has a biosphere, a complex web of life, at its surface. The thickness of this layer is about twenty kilometers. This layer, our biosphere, is the only place where we know, for now, life exists.
The existence of life on Earth depends on the distance from the Sun, neither too close nor too far away, to receive enough energy to allow water to exist as a liquid on its surface. The interstellar cloud of gas and dust that gave rise to Earth contained enough radioactive elements to power a churning core for billions of years. This creates a magnetic core and magnetic field which protects the atmosphere from the drag of the solar wind and life from cosmic radiation. The planetary core is a terrific source of geothermal energy, allows the cycling of raw materials, and spawns a magnetic field around the planet to protect it from harmful radiation. Planets with low mass are not suitable for habitation because low mass means low gravity. Low gravity further means that the planet won’t be able to retain an atmosphere, as constituent gases will easily reach escape velocity and be lost in open space.
A big moon to stabilize our axial wobble; Earth is tilted with respect to the sun, and teeters as it spins. This tiny wobble can shift the climate from hot to icy every 41,000 years—and might vary more without the moon’s stabilizing pull.
An ozone layer to block harmful rays. Ancient plantlike organisms in the oceans added oxygen to the atmosphere and created a high-altitude layer of ozone that shielded early land species from lethal radiation.
A planet must also rotate on its axis and revolve around its parent star to be habitable. Furthermore, if life on the planet is to be given a chance to evolve, certain other conditions have to be met in its rotational motion. There should be some axial tilt perpendicular to its orbit, which will result in seasons on the planet or celestial object.
The atmosphere itself, trapping heat to prevents water from freezing, shields the surface from harmful radiation, provide and regulates the balance of chemicals needed for life, such as, nitrogen, carbon dioxide, oxygen, water. Water, which may have actually formed from the hydrogen and oxygen present in very building blocks of the planet itself and naturally, the universal solvent of life. And of course, oxygen. The first single-celled organisms lived in an unbreathable atmosphere, composed of gases such as methane and ammonia. Around 2.4 billion years ago, the so-called Great Oxidation Event took place, when the atmosphere began to be populated by oxygen in its breathable molecular form, which is attributed to the emergence of photosynthetic cyanobacteria.
Earth’s mean temperature is determined primarily by its energy balance, including the key variables of solar insolation (increasing during Earth history), greenhouse gas forcing and albedo. Greenhouse forcings occur due to changes in the level of gasses that share two properties: they are transparent to visible light, but absorb the infrared, which we typically perceive as heat. Although the atmosphere allows most of the visible light through, many of the gasses there—water vapor, carbon dioxide, methane, etc.—absorb infrared radiation, converting it to rotational and vibrational energy. This raises the energy content of the atmosphere and thus the average temperature. The more greenhouse gasses present, the greater the chances of the infrared light being absorbed before it escapes into space. If all other influences are kept constant, increased levels of greenhouse gasses will necessarily produce increased atmospheric temperatures. The distribution of heat at the Earth’s surface is modified by orbital variations and paleogeographic patterns driven by tectonics, which in turn can drive feedbacks that lead to whole-Earth changes in albedo or greenhouse gas forcing. Thus, over multi-million-year timescales, Earth’s climate shifts in response to gradual changes in continental configuration, the opening or closing of ocean gateways, and the plate tectonic, which, together, drive long-term changes to the carbon cycle and the biosphere. These long, slow changes modify the effects of solar forcing, not least by changing the balance between sources of CO2 (from volcanic activity) and its sinks (starting with chemical weathering and progressing through sequestration in sediments).
The sources of Earth’s evolving chemical complexity are the energies of solar diurnal disequilibria and the energies of physicochemical gradients at hot hydrothermal vents. The diurnal disequilibria arise naturally when Earth’s rotation converts ‘constant’ solar radiation into cyclic energy gradients that drive chemical reactions at Earth’s oceanic and rocky surfaces; hydrothermal vents release metallic ions and other compounds into the ocean, enriching the ocean’s molecular complexity. How these versatile biomolecules came into being is one of the questions about the origin of life. Amino acids, nucleobases, and various sugars are even found in meteoroids. However, for a peptide to be formed from individual amino acid molecules, very special conditions are required that were previously assumed to be more likely to exist on Earth.
Earth, an ancient, extremely complex, multiple, all-planetary, thermodynamically open, self-controling system of living and non-living matter which accumulates and redistributes immense resources and energy and determines the composition and dynamics of the Earth’s biosphere, lithosphere, cryosphere, atmosphere and hydrosphere.
Life is an astonishingly emergent property of matter, full-blown in its complexity today, some billions of years after it started out in presumably some very simple form. The fundamental question is whether life as we know it – it’s astonishing chemical complexity – is a very improbable occurrence or a nearly inevitable evolution of dynamic off-equilibrium chemical matter.
Different chemistries driven by solar radiation and by hydrothermal vents interact, particularly at the three-phase boundary of irradiated tidal seashores, and thus further increase the chances of life’s emergence. Thus, the evolution of primordial chemical compositions and processes was initially driven by Earth’s diurnal cycles that caused repeated colloidal phase separations – the appearances and disappearances of first microspaces. Today’s microbial cell cycle can be viewed as an ‘evolutionary echo’ from the cyclic chemical disequilibria of the rotating surface of Hadean Earth. The cell cycle had (partially) decoupled from physicochemical diurnal gradients when the stabilization of lipid-protein membranes and information processing allowed cell heredity to take root.
All life as we know it consists of the same chemical building blocks. These include peptides, which perform various completely different functions in the body – transporting substances, accelerating reactions, or forming stabilizing scaffolds in cells. Peptides consist of individual amino acids arranged in a specific order. The exact order determines a peptide’s eventual properties.
A prominent feature of life is the ordered information stored in DNA/ RNA, and how such information appeared from abiotic processes is a crucial issue. Abiotic emergence of ordered information stored in the form of RNA is an important unresolved problem concerning the origin of life. A polymer longer than 40–100 nucleotides is necessary to expect a self-replicating activity, but the formation of such a long polymer having a correct nucleotide sequence by random reactions seems statistically unlikely. However, our universe, created by a single inflation event, likely includes more than 10100 Sun-like stars. If life can emerge at least once in such a large volume, it is not in contradiction with our observations of life on Earth, even if the expected number of abiogenesis events is negligibly small within the observable universe that contains only 1022 stars.
The RNA world hypothesis postulates an early era when RNA played both the genetic and catalytic roles before the DNA-protein world came into being. This is widely accepted due to strong supporting evidence including catalytic activities of RNA, especially its central role in a ribosome. However, a more fundamental and unsolved problem is how an RNA polymer long enough to have a self-replicating RNA polymerase activity (i.e., RNA replicase ribozyme) emerged from prebiotic conditions and then triggered Darwinian evolution.
The classical world has been grasped as a set of equilibria, steady states, and permanence. Recent works bridging biology, neuroscience, cosmology and quantum physics turn these perspectives on their head. Biocentrism proposes a unifying theory of everything and approaches life from a cosmological standpoint, where consciousness creates reality and life is not an end-product but a force that is key to the understanding of the universe. From a quantum perspective the universe is a buoyant set of change, becoming, and unceasing creation and destruction of particles and waves.
Quantum information processing can be safely said to be an interpretation of quantum physics. It is the assessment that the world and the universe are strongly entangled and in a constant superposition. Moreover, the universe and reality are an unceasing process of transformations – very much in the tenure of the first law of thermodynamics. The world is entirely quantum, and the conventional or classical reality is just a moment in the dynamics of coherence-decoherence-recoherence. Information, i.e. information processing is the very transformation – say, from plasma to energy to matter to life, in the history of the universe, so much so that it is never lost; rather, it is unceasingly transforming. The story of the transformation of information is the very story of the universe and of living beings, including human beings. This theory takes life’s origin to the beginning of the universe. Because it involves interactions at the quantum level, it may also mean a theory of everywhere, in which the separation between living and nonliving is not a fundamental difference of nature between them, but a difference in the amount of energy and complexity of information that is being integrated, organized, stored, transformed and exchanged at any single moment.
Although they still need to be proven falsifiable, such theories invite, challenges us to shift our perception.