Can the known particles and interactions explain consciousness?

At a foundational level, the entirety of existence is governed by a limited set of particles and forces. This raises the question: how do these fundamental components give rise to human consciousness?

Theoretically, everything in the physical universe relies solely on the same basic elements and interactions that are discovered when matter is dissected down to its minutest scales. Living organisms can be segmented into cells, which consist of organelles; these organelles break down into molecules, which are further made up of atoms; atoms contain electrons and atomic nuclei; while electrons are indivisible, atomic nuclei are composed of quarks and gluons. Thus, it should be feasible to utilize these fundamental building blocks—quarks, gluons, and electrons—in various configurations to elucidate all aspects of our daily experiences.

However, with only these basic components and the four fundamental forces, can we truly account for everything, including conscious beings? This is undeniably a substantial challenge. This week's inquiry from Ottho Heldring questions the likelihood that such complexity arises purely from natural conditions and random occurrences:

> “I have always been intrigued by how the particles and forces within the original quark-gluon plasma align perfectly to form: > > 1.) atomic nuclei, which when paired with electrons, > 2.) create atoms (each possessing unique attributes), > 3.) leading to the formation of countless molecules (each with distinct properties), > 4.) capable of supporting life, > 5.) which can attain consciousness, > 6.) ultimately resulting in astrophysicists?” > > “This exact alignment seems far too coincidental.”

Is this assertion accurate? Let’s examine the available evidence to gain insights.

All particles outlined in the Standard Model—the known constituents of the universe, excluding the currently mysterious dark matter and dark energy—are categorized into two groups: fermions and bosons. Fermions represent the building blocks of matter: quarks and leptons. Quarks combine to create protons, neutrons, and other heavy composite particles, while leptons include charged particles that orbit protons and neutrons (e.g., electrons) as well as low-mass, uncharged particles that barely interact with their surroundings: neutrinos.

Bosons are equally critical, as they mediate all non-gravitational forces and interactions between particles. There are 12 distinct bosons, yet they are grouped to describe three primary interactions:

1. The 8 gluons, which mediate the strong nuclear force, only act on particles with color charge: quarks, antiquarks, and gluons.
2. The 3 weak bosons (W+, W-, and Z?) are massive and mediate the weak nuclear force, interacting with all fermions.
3. The 1 photon is responsible for the entirety of electromagnetic force, affecting all charged particles, excluding neutrinos and antineutrinos.

These forces exhibit unique behaviors. For instance, the electromagnetic force operates over long distances: two charged particles will attract or repel each other in direct proportion to their charges and inversely proportional to the square of the distance between them. The force diminishes with distance but never completely disappears. Conversely, two opposite charges can neutralize each other, leading to an electrically neutral state where the electric force approaches zero at larger distances.

On the other hand, the strong nuclear force behaves differently. At very close distances, the strong force between color-charged entities approaches zero; however, as the distance increases, the force intensifies, provided there's a net color charge. If color-neutral, the force likewise drops to zero, mirroring the behavior of neutral electromagnetic entities.

For simplicity, we can set aside the weak nuclear force, except to note that it facilitates the decay of unstable particles into those with lower rest mass.

To grasp the types of structures possible in the universe, one must revisit its early stages to observe what emerges and why. In the initial moments of the hot Big Bang, conditions were dense and energetic, leading to frequent collisions that produced vast quantities of all fundamental particles (and their antiparticles). However, as the universe expanded and cooled, the energy available for creating new particles diminished, but particle-antiparticle pairs could easily annihilate. Unstable particles decayed through weak interactions into more stable forms.

After a brief duration, the universe consisted primarily of photons, electrons, positrons, neutrinos, and a slight excess of up and down quarks over their antiparticles.

The first step involves up and down quarks binding to form protons and neutrons. This occurs because up and down quarks possess electric charges of +2/3 and -1/3, respectively. At extremely short distances, electromagnetic forces repel like charges, yet the strong nuclear force becomes significant when pushed apart, acting like a stretched spring that snaps back.

Why, then, do only protons and neutrons arise from these quarks?

To create a color-neutral particle, three fermions are needed. Thus, one can have either two up quarks and one down quark (forming a proton) or one up quark and two down quarks (creating a neutron). However, a trio of identical quarks is impossible due to the Pauli Exclusion Principle, which forbids two identical fermions from occupying the same quantum state. A proton or neutron can contain two identical fermions if one is "spin up" and the other is "spin down," but a third identical quark cannot be included. The combination of strong and electromagnetic forces explains the existence of protons and neutrons.

From protons and neutrons, larger and more complex atomic nuclei can be formed. The strong and electromagnetic forces play crucial roles here. While protons repel each other due to electromagnetic forces, neutrons neither attract nor repel other neutrons or protons. However, if protons and/or neutrons come close enough, their internal quarks can interact, allowing them to exchange gluons and experience the strong nuclear force.

Overall, protons and neutrons are color-neutral; hence, at great distances, the strong nuclear force diminishes and can often be disregarded. Yet, at short distances, the interaction between quarks in a proton-proton, neutron-neutron, or proton-neutron arrangement becomes substantial. If high temperatures and densities are present, stable combinations of protons and neutrons can lead to various heavy atomic nuclei.

All stable atomic nuclei possess a positive charge, while electrons, which remained after most positrons annihilated with electrons, carry a negative charge. Although electrons do not feel the strong nuclear force, they are influenced by the electromagnetic force, resulting in attraction towards atomic nuclei due to opposite charges. This interaction allows electrons to occupy various orbitals around atomic nuclei.

Given that electrons are far lighter than atomic nuclei—1836 electrons equal the mass of a single proton—the nuclei remain nearly stationary at the atom's center, while electrons orbit rapidly in cloud-like formations around them. The principles of quantum mechanics, particularly the Pauli Exclusion Principle, dictate the configurations of electron shells, influencing how different types of atoms bond with one another.

With lower temperatures, atoms can combine in virtually limitless arrangements. While atoms are electrically neutral, they consist of positive and negative charges:

• In certain scenarios, electrons can transfer from one atom to another, forming ions and ionic compounds.
• Alternatively, neutral atoms can bond with one another, resulting in a vast array of combinations and molecules.
• Once ions, compounds, and molecules form, they can interact with one another.

Recall that protons and neutrons can bind to create atomic nuclei, even though they are individually "color-neutral." The quarks within each particle exert forces on the quarks of adjacent particles. Likewise, negatively charged electrons and positively charged atomic nuclei within molecules can influence one another, forming larger molecules and enabling diverse molecular mechanisms, such as lock-and-key and electric-charge-sensitive channels.

Through the interplay of a few fundamental particles and the properties of two fundamental forces, we can transition from basic matter constituents to highly complex molecules.

How, then, do we progress from molecules to life, and subsequently, to consciousness?

Life emerged from non-life, a process still under investigation. However, it appears that electromagnetism and gravity, given the right conditions and the presence of intricate molecules, are sufficient. Life has adapted and evolved over billions of years, leading to the rich diversity we see today, including humans. It seems that what defines a living being is simply the presence of electricity: the movement of electrons. While there are many theories regarding consciousness and its ties to quantum mechanics, it's possible—perhaps even likely—that basic electrical activity (i.e., the flow of electrons in a brain or nervous system) is all that is required, given the appropriate arrangements of atoms and molecules.

Indeed, it is astonishing that using only the four fundamental forces—gravity, electromagnetism, strong, and weak nuclear forces—we can construct atomic nuclei, atoms, molecules, and life, ultimately leading to consciousness. Some conscious beings have even reached the point where they study the universe itself. We can unravel how the universe operates and how we came to exist within it, with some individuals pursuing careers as astrophysicists, delving into the cosmos for a fleeting moment in cosmic history.

Yet, this phenomenon is not necessarily miraculous. Provided that nature adheres to a few fundamental rules:

• Some forces may be negligible at short distances but increase with greater separations,
• Others are strong at close range but diminish over larger distances,
• There are various types of charges, with some always attracting and others repelling or attracting based on their relative types,

complex structures and seemingly infinite possibilities will inevitably manifest. With the right configurations, electrons can traverse various pathways, creating electric currents that sustain life processes and potentially give rise to the phenomenon we recognize as consciousness.

If the laws of physics were significantly different, our existence would be impossible, and thus we would not be here to ponder these questions. Unfortunately, we possess only this single universe, with its specific rules and limitations, to investigate. Until we either encounter another universe or uncover the reasons behind the laws and regulations that govern our own, inquiries such as “Do the rules of our universe stem from a cause or designer?” will remain outside the domain of science, beyond our capacity for understanding.

Ethan is on medical leave until May 6th. Please enjoy this republication of an article from the "Starts With A Bang" archives!

"Starts With A Bang" is authored by Ethan Siegel, Ph.D., who has written "Beyond The Galaxy," "Treknology," and "The Littlest Girl Goes Inside An Atom." New works, including the "Encyclopaedia Cosmologica," are forthcoming!