Mass, Its Origin

The Creation of Mass

Approximately 13.8 billion years ago, at the moment of the universe's birth, the early universe was in a state where space was extremely condensed, with the distance between particles shorter than the particles' wavelengths. There was no mass, but unimaginably immense energy was condensed into a tiny space. Particles interacted directly within each other's wave regions, mixing uniformly so that the universe exhibited uniform density and temperature in all directions. The essence of heat is particles moving at tremendous speeds, condensed into a narrow space and colliding with each other. When particles possessing immense velocity (kinetic energy) in a confined space collide incessantly, the temperature of that system rises. In the early universe, space itself was extremely small, and the frequency of particle collisions and their kinetic energy were extremely high, making the particles' wavelengths even shorter. When the early universe was extremely hot, all particles moved at the speed of light and possessed no mass. At this stage, all particles were indistinguishable, and gravity, the strong force, the weak force, and electromagnetism were unified into a single force—a state of perfect symmetry.






As the universe ceased its rapid expansion, immense energy stored within the vacuum poured forth. The vacuum energy accumulated during the period of rapid cosmic expansion, known as inflation, converted into matter after the rapid expansion ceased, creating an extremely hot state. This energy transformed into the kinetic energy of elementary particles with negligible or very light mass. As these particles moved extremely rapidly in confined spaces, exchanging energy with each other, they raised the temperature of the entire universe to an extreme level. As particles approached each other, they exchanged energy and momentum, causing the energy to spread evenly and form an extremely high overall temperature (a state of thermal equilibrium). The kinetic energy of particles moving near the speed of light in a confined space dominated over energy due to mass, and this energy density manifested as a temperature beyond imagination.







Light (photons) does not directly carry charge, but in the early universe where energy was extremely high, light particles collide violently with each other, creating electrons and positrons or transforming back into light, exchanging energy intensely. In this process, the paths of particles are deflected and energy is redistributed; macroscopically, this appears as particles colliding and generating heat. According to Einstein's theory of relativity, energy and mass are fundamentally equivalent. Even particles with immense energy but no mass form a kind of influence (field) through that energy itself. Particles in the early universe possessed such immense energy that even a slight brush caused them to exchange energy through strong forces (such as strong nuclear force, electromagnetic force). Though lacking physical bodies, their energy waves became entangled, intertwined, and bounced off each other. Quantum mechanically, particles resemble clouds or waves rather than points. When massless particles are densely packed in a confined space, the probability of these waves overlapping becomes extremely high. At this point, particles scatter by absorbing or emitting each other's energy, resembling countless beams of light interfering and fluctuating within a narrow room. Massless particles maintain and transfer heat not through the friction of rigid bodies colliding, but through the process of powerful energy waves pushing each other, mixing, and exchanging energy in confined spaces. They have no form, but their energy is so immense that they cannot simply pass each other by.







Immediately after the Big Bang, when all particles were moving at the speed of light, the universe was extremely hot for a very brief period. During this time, the Higgs field could not exert its force. All fundamental particles at this stage had zero mass. Without mass, all particles traversed the cosmic space at the speed of light. It was like light flying through an empty space with no resistance whatsoever. After the rapid expansion ceased, particles could no longer fly through empty space; they had to pass through the Higgs field. The strength of their interaction with the Higgs field determined their mass. Particles with large mass, like quarks, interact very strongly with the Higgs field, making movement difficult and slowing them down. This degree of difficulty in movement becomes the mass we measure. Particles with small mass, like electrons, interact weakly with the Higgs field. Particles with no mass, like photons, interact not at all with the Higgs field. Therefore, they still move at the speed of light.






As the temperature cooled with the expansion of space, a single immense force split into multiple strands. As the temperature dropped, gravity separated first. As the temperature fell further, the strong force separated. When the temperature dropped to about 1,000 trillion degrees, the weak force and the electromagnetic force separated. This process is physically identical to the phase transition phenomenon that occurs when water freezes into ice: the disordered water molecules adopt a specific lattice structure (order). As the system spontaneously sought a lower-energy, stable state, symmetry broke (Spontaneous Symmetry Breaking). This is the same physical flow as hot water cooling and solidifying into ice when left undisturbed. The process of symmetry breaking is the crystallization of the universe, transforming from a hot, simple state (where everything was one) into a cold, complex state (where diverse particles and forces exist) as it cooled. This symmetry breaking allowed particles to acquire mass, enabling the birth of the material world we know. Particles like quarks strongly interacted with the Higgs field and gained mass, while particles like photons remained unaffected, retaining zero mass. In this process, particles acquired distinct properties, becoming electrons, quarks, neutrinos, and so on.







The mass of a particle is an inertial property arising from its interaction with the Higgs field, but spin and color charge are important properties that particles possess even if they have no mass (or almost no mass). The gluon, a massless particle with color charge, is the mediator of the strong nuclear force and has zero mass. However, gluons possess color charges in combinations of red, green, and blue (and their antiparticles), enabling them to interact with each other. Despite having no mass, their color charge enables strong interactions (quantum chromodynamics). The photon, a massless particle with spin (intrinsic angular momentum), is the mediator of the electromagnetic force and has zero mass. The photon has spin 1, is electrically neutral, but possesses a polarization state (direction). This relates to the transverse wave nature of electromagnetic waves. The electron is a massive fermion (spin 1/2), where spin is a quantum mechanical angular momentum inherent to the electron, distinct from its mass or charge. In other words, both particles possess intrinsic spin (intrinsic angular momentum), but the photon is a gauge boson (carrying electromagnetic interactions) while the electron is a particle constituting matter. Even particles with zero mass can possess spin (intrinsic angular momentum) and color charge (strong interaction charge). While spin and color charge are intrinsic, fundamental properties of elementary particles arising from gauge symmetry, mass is a property conferred through interaction with the Higgs field and is not an essential proof of a particle's existence. Spin and color charge define a particle as its intrinsic properties, while mass appears as a symmetry-breaking attribute.







The universe initially had no distinctions, but after particles combined, symmetry broke and specific directionality (order) emerged. As the universe expanded and the temperature dropped below approximately 10 trillion degrees, rapidly moving quarks were bound by the strong force to form protons and neutrons. When the strong force temperature fell below about 1 billion degrees, protons and neutrons combined to form light atomic nuclei like helium. Approximately 380,000 years later (at 3,000K), electrons became captured around these nuclei, finally giving birth to neutral atoms. Much later, gravity acted on regions where gas gathered and density increased, forming stars and galaxies. From a physics perspective, particles clustering together is a process of moving towards a more stable, lower-energy state. When particles clump together and bond, they release excess energy outward. If the temperature of the entire universe is higher than this binding energy, the bonds break immediately. However, once the temperature drops sufficiently low, particles that have bonded cannot gain enough energy to break apart again and remain in a bound state. This is because at high temperatures, particles move too fast to stick together, but as the universe cooled through expansion and their speeds slowed, the fundamental forces of nature snatched them up and bound them together.






As particles gained mass and slowed down, their temperature dropped further, leading to the emergence of new properties through binding that had not existed before. Quarks, which had existed individually, clumped together to form particles of entirely different properties: protons and neutrons. When protons and electrons bound together to form neutral atoms, the universe underwent a complete transformation in nature, shifting from an electromagnetically opaque state (plasma) to a transparent state (formation of neutral atoms). Particles are not finished products designed from the outset, but rather the products of cooling. As the universe cooled, gauge symmetry broke and energy condensed, allowing particles to acquire their own mass and charge. The processes of binding and differentiation determined the characteristics of elementary particles.







One trillionth of a second after the universe was born, energy dispersed due to cosmic expansion, causing temperatures to drop below the critical point. In the early universe, when temperatures were extremely high, energy overflowed, preventing the Higgs field from maintaining a special state. It existed in a symmetrical state where all directions were identical (unstable equilibrium, disorder). As the universe cooled, it locked into a specific eigenstate (the lowest non-zero energy state, order). Particles in the early universe, filled only with kinetic energy and moving at the speed of light, slowed down as the universe cooled and interacted with the Higgs field, acquiring the property of mass. Quarks gathered to form protons, and electrons bonded to create atoms. Without mass, neither stars, nor Earth, nor humans could have been created.