The appearance of hadrons can serve as a starting point for reconstructing the successive transformations of matter. This history goes beyond an inventory of the constituents present at each stage. The term transition of organisation describes the process more precisely. Constituents can keep their identity while entering into new relations, under new constraints, within structures endowed with collective properties.
Each transition can be studied through five complementary dimensions:
Composition: the constituents present.
Configuration: their spatial, dynamic or functional organisation.
Interaction: the forces, exchanges and relations that link them.
Environment: the physical or chemical conditions that make the organisation accessible.
Persistence: the mechanisms that allow the structure to last.
This grid connects very different scales within a single material history. It shows how transformations, fluctuations and instabilities can be channelled into regimes durable enough to take part in a new organisation.
From quark–gluon plasma to hadrons
In the primordial Universe, quarks and gluons took part in an extremely hot and dense medium known as the quark–gluon plasma. The expansion of the Universe progressively lowered its temperature and modified the regime of the strong interaction. The colour-carrying degrees of freedom reorganised themselves into hadrons that are globally neutral with respect to colour charge, notably protons and neutrons.
Hadrons form collective quantum systems. Valence quarks, gluons and quark–antiquark pairs take part together in a dynamic organisation maintained by confinement and by the interactions described by quantum chromodynamics.
The formula uud identifies the valence quarks of the proton. Its mass, its cohesion and its internal structure derive largely from the collective dynamics of quarks and gluons. This stage brings into being a durable material organisation whose global properties are maintained within a permanent internal activity.
The persistence of the proton depends on a regime of interaction bringing together its constituents, their quantum configuration and the dynamics of the strong field. Its identity is maintained through the internal fluctuations that animate it.
From hadrons to nuclei. Protons and neutrons become the constituents of a new level of organisation. The nuclear interaction, arising from the strong interaction between their components, allows certain nucleons to associate into nuclei.
During the first minutes of the Universe, primordial nucleosynthesis produces mainly hydrogen and helium nuclei, accompanied by small quantities of deuterium, helium-3 and lithium. The majority of heavier nuclei appear much later in stars and during particularly energetic stellar events.
Within a nucleus, the proton takes part in a collective organisation. Its behaviour depends on the number of protons and neutrons present, on their quantum arrangement, on their energy levels, on nuclear attraction and on electrical repulsion between the positive charges.
Duration varies with configuration. Some associations produce stable nuclei. Others give radioactive isotopes whose transformation occurs after a variable interval. The most unstable arrangements disappear almost immediately.
The nuclear level opens a new space of possibilities. The number of nucleons, their proportion and their configuration determine which nuclei are accessible and their capacity to persist.
From nuclei to atoms. During the first few hundred thousand years, the temperature of the Universe keeps ordinary matter in the form of a plasma of nuclei and free electrons. Cooling then allows electrons to bind durably to nuclei. About 380,000 years after the Big Bang, the first neutral atoms form, mainly hydrogen and helium.
A new organisation appears:
nucleus + electrons bound by the electromagnetic interaction → atom
The electrons occupy quantum states characterised by energy levels and probability distributions. Their organisation around the nucleus determines the possible exchanges of energy and the future chemical associations.
The number of protons fixes the identity of the element. The electronic configuration shapes a large part of its chemical behaviour. The atom opens a domain of properties founded on the organisation of electrons and on their interactions with neighbouring nuclei.
Electronic structure makes varied bonds possible and prepares the appearance of chemical diversity.
From atoms to stars
The first hydrogen and helium atoms are distributed through a Universe marked by small variations of density. The densest regions progressively attract more matter under the effect of gravitation. This accumulation forms vast clouds whose collapse gives birth to the first stars.
Stellar organisation introduces a major change of scale. Hadrons, nuclei and atoms are structured by quantum or electromagnetic interactions at the microscopic scale. A star results from the collective behaviour of an immense quantity of matter bound by gravitation.
Gravity acts at long range and accumulates the contributions of the whole mass of the system. The structure of the star emerges from the global distribution of matter, from the pressure of the plasma, from temperature, from nuclear reactions and from the transport of energy between core and surface.
The Sun persists in a dynamic regime in which gravity compresses the plasma and internal pressure sustains the structure. A contraction of the core raises the temperature and intensifies the fusion reactions. The energy released increases the internal pressure. An expansion lowers the temperature and slows fusion. These feedbacks temporarily maintain hydrostatic equilibrium.
The stability of the Sun rests on a permanent activity. It continually transforms hydrogen into helium, transports energy, radiates into space and loses matter through the solar wind. Its components move and are transformed while its global structure retains its coherence.
The Sun represents a collective and dynamic physical organisation, distinct from the biological living. Its persistence depends on flows, constraints, feedbacks and a history of its own. Stars also play a decisive role in producing the elements needed for later chemical organisations.
From stars to heavy elements. Stellar nucleosynthesis progressively transforms light nuclei into heavier ones. Stars produce notably carbon, oxygen, neon, silicon and iron according to their mass, their temperature and the different phases of their evolution.
More energetic phenomena enrich this diversity. Supernovae, neutron capture and neutron-star mergers take part in the formation of many elements heavier than iron.
Stars disperse part of this matter into space through their winds or during the final stages of their evolution. New clouds form from matter enriched by several stellar generations. These clouds give birth to new stars, to rocky planets and to environments favourable to a more complex chemistry.
A large part of the hydrogen present today dates back to the earliest cosmic times. Carbon, oxygen, nitrogen, phosphorus, calcium and iron were produced and then dispersed by generations of stars.
The history of terrestrial matter belongs within this stellar history. The constituents of the biological living come from cosmic organisations that made their existence possible.
From atoms to molecules
Atoms can associate into molecules through the sharing, transfer or redistribution of their electrons. Chemical bonds, geometry, available energy, temperature, pressure and medium determine the structures obtained.
A water molecule contains two hydrogen atoms and one oxygen atom. Its bent geometry produces an asymmetric distribution of charge that allows it to establish hydrogen bonds with neighbouring molecules. This architecture explains a large part of its physical and chemical properties.
Diamond and graphite likewise illustrate the role of configuration. Both are made of carbon. In diamond, the atoms form a rigid three-dimensional network. In graphite, they organise into sheets that slide over one another and allow certain electrons to circulate.
Chemistry opens an immense space of diversification. A limited number of elements produces a multitude of molecules, crystals, polymers and reaction systems thanks to the variety of possible bonds and arrangements.
Each configuration modifies the accessible properties. Geometry, polarity, reactivity and interactions with the medium determine the place a molecule can occupy within a wider organisation.
From molecules to chemical networks. Molecules take part in networks of reactions in which the product of one transformation becomes the reagent of another. Some compounds accelerate reactions. Some cycles sustain themselves thanks to an input of energy. Some structures form compartments that locally modify chemical conditions.
The continuity of the network depends on flows of matter, on the regeneration of reagents, on the transformation of products, on catalysis and on the maintenance of energy gradients.
Hydrothermal systems, mineral surfaces, wetting and drying cycles or lipid compartments create conditions favourable to certain reactions. The environment takes a direct part in organising transformations by concentrating molecules, supplying energy or orienting certain reaction pathways.
A chemical network sustains itself as long as the necessary resources and conditions remain available. The reactions form a collective regime capable of prolonging its activity through time.
A change in temperature, concentration, acidity or energy supply may interrupt this functioning or favour another chemical organisation.
From chemical networks to the first biological organisations
The passage to the biological living requires the coupling of several capacities: compartmentation, catalysis, exploitation of energy gradients, replication, transmission of variations and selection.
A membrane creates an interior space. Catalytic reactions organise the transformations. Gradients supply a source of energy. Replication prolongs certain structures through time. The transmission of variations opens the way to evolution.
The biological threshold appears when these processes become interdependent and take part together in the reproduction of an organisation capable of varying.
A cell continually transforms, degrades and replaces its components. Its continuity depends on the coordination of the processes that rebuild its membrane, renew its molecules, exploit the available energy and transmit hereditary information.
The biological living introduces an active persistence. The organisation produces part of the conditions necessary for its own continuity. It regulates its exchanges, repairs certain degradations and renews its constituents.
Variations fulfil several functions. Some are corrected, others tolerated, and others become transmissible. Selection acts on this diversity across generations and progressively transforms populations.
The precise origin of this autonomy remains an open question. Current research explores the self-assembly of membranes, autocatalytic networks, molecules capable of replication and the coupling between energy gradients and chemical reactions. These lines of enquiry describe several plausible stages of a transition whose complete history remains to be reconstructed.
From cells to organisms. Cells become the components of higher levels of organisation. In multicellular organisms they differentiate, coordinate their activities and limit part of their autonomy for the sake of the persistence of the whole.
A muscle cell, a nerve cell and an immune cell generally possess the same genetic inheritance. Their functional identity depends on gene expression, on their form, on their interactions and on their place within the organism.
The unity of the higher level is sustained by mechanisms of communication, regulation, repair and control. A local perturbation may be compensated by the other tissues. A damaged cell may be repaired, replaced or eliminated.
Cancerous proliferation shows the consequences of a breakdown of collective constraints. A cell favours its own multiplication at the expense of the organisation on which its survival depends.
The persistence of the organism rests on the cooperation of its components, the coordination of their functions and the regulation of their conflicts. The higher level channels cellular dynamics toward the maintenance of the whole.
What this chain reveals
The history can be represented in simplified form:
quarks and gluons → hadrons → nuclei → atoms → stars and heavy elements → molecules → chemical networks → cells → organisms
This representation summarises a succession of levels of organisation. Each arrow condenses several transformations, the intervention of new constituents and the appearance of particular environmental conditions.
Electrons join nuclei during the formation of atoms. Stars produce and disperse the heavy elements. Planetary environments then bring together the physical and chemical conditions required for complex molecules and reaction networks.
Each level answers constraints of its own and produces a particular regime of persistence. A star, a molecule and a cell occupy different scales and mobilise different interactions.
The relevant variables change with scale. Quantum chromodynamics describes quarks, gluons and hadrons. Nuclear physics studies nuclei. Atomic physics describes electronic states. Astrophysics analyses stars and the production of the elements. Chemistry studies bonds and molecular reactions. Biology examines organisations capable of metabolism, reproduction, adaptation and evolution.
These disciplines describe different levels of one and the same material history. The fundamental laws remain present at every stage. Collective properties also require concepts suited to the scale considered.
A continuity founded on transformation. Since the first hadrons, some constituents persist, others are transformed, and new configurations become accessible.
A proton integrated into a nucleus keeps its fundamental properties. Its behaviour depends on its relations with the other nucleons. An atom engaged in a molecule keeps its nucleus. Its electrons take part in chemical bonds. A molecule integrated into a cell keeps its chemical structure. Its production, its location and its use depend on a biological network.
At each level, the earlier organisations open new possibilities and impose constraints of their own. A sufficiently persistent structure can take part in a wider organisation whose properties emerge from the relations between its components.
The fundamental transformation may be formulated thus:
At each transition, certain sufficiently persistent structures take part in a new organisation in which new interactions, new constraints and new capacities appear.
These transitions emerge when composition, configuration, interactions and environment make accessible a regime capable of lasting.
The stability encountered through this history takes several forms. The proton maintains its properties within a permanent quantum dynamics. The star preserves its global structure by transforming its matter and radiating energy. The cell prolongs its organisation by continually renewing its constituents.
Persistence rests on a channelled transformation. Constraints organise the flows, limit certain variations and make possible regimes capable of lasting.
The same grid accompanies the whole chain:
composition → configuration → interaction → environment → persistence
It makes it possible to reconstruct the continuity running from the first hadrons to the biological living. Certain fluctuations and transformations become the drivers of a new organisation when constraints orient them toward a regime coherent enough to maintain itself, to renew itself or to support a further level.