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Main positions:Director, High Performance Computing Platform, PKU
Degree:Doctoral degree
Status:Employed
School/Department:Institute of Theoretical Physics

Lei Yian

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Education Level: Postgraduate (Doctoral)

Administrative Position: Associate Professor

Alma Mater: Peking University

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Current position: Lei Yian Homepage / Blog
Fermions: From Mystery to Electromagnetic Physics
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Abstract

For over a century, the dichotomy between fermions and bosons has been enshrined as a foundational—yet unexplained—principle of quantum theory. The Pauli exclusion principle, in particular, has often been treated as an irreducible axiom, divorced from physical mechanism. In contrast, the Global Approximation Interpretation of quantum mechanics proposes that fermionic antisymmetry is not an intrinsic, mystical property but a natural consequence of electromagnetic interactions among charged particles, governed by spin–magnetic moment coupling and energy minimization. By examining phenomena such as spin pairing, orbital symmetry, and magnetic repulsion, we demonstrate that the so-called “quantum rules” of textbooks emerge transparently from classical electrodynamics operating under quantum constraints. This framework not only demystifies quantum statistics but also yields a concrete, computable physical picture for understanding phenomena ranging from chemical bonding and superconductivity to magnetic ordering and even biological processes.

The Mystification of Quantum Statistics

Standard quantum mechanics categorizes particles into two immutable classes: bosons, which obey Bose–Einstein statistics and may occupy the same quantum state, and fermions, which follow Fermi–Dirac statistics and are constrained by the Pauli exclusion principle—no two identical fermions may share all quantum numbers. This division is typically presented as a fundamental, intrinsic attribute of nature, leading to a circular explanatory loop:

Why can’t two electrons occupy the same state? Because they are fermions.
Why are they fermions? Because their wavefunction must be antisymmetric.
Why must it be antisymmetric? Because they are fermions…

This tautology reveals a critical gap in conventional quantum theory: it prescribes how to compute outcomes but rarely explains why they occur. The Global Approximation Interpretation offers a mechanistic resolution:

  • Quantum statistics arises from the collective electromagnetic behavior of charged particles.

  • The Pauli exclusion principle is not a postulate but a consequence of magnetic repulsion between parallel spins, which enforces spatial separation to minimize total energy.

Chapter 1: The Relativity of Statistical Properties

1.1 The Context-Dependence of Particle Statistics

Contrary to textbook dogma, particle statistics are not immutable. Empirical evidence shows that statistical behavior depends on composition, dimensionality, and interaction:

  • Cooper pairs: In superconductors, two spin-½ electrons form a spin-singlet (total spin 0) bound state that behaves as a boson, condensing into a single macroscopic quantum state.

  • Composite particles:

    • Helium-4 (integer spin) → boson

    • Helium-3 (half-integer spin) → fermion

    • Deuterium nucleus (integer spin) → boson
      These examples demonstrate that statistics follow total spin, not “identity.”

  • Anyons: In two-dimensional systems like the fractional quantum Hall regime, quasiparticles exhibit fractional statistics and charge (e.g., e/3), proving that dimensionality and topology fundamentally reshape statistical behavior.

1.2 Lessons from Quasiparticles

In condensed matter systems, collective excitations manifest as quasiparticles whose statistics reflect the symmetry of their underlying modes—not any immutable essence:

  • Phonons (lattice vibrations) → bosons

  • Magnons (spin waves) → bosons

  • Polarons (electron–phonon composites) → fermionic or bosonic, depending on coupling

Thus, statistics are emergent, not elementary.

Chapter 2: Spin—From Abstract Quantum Number to Physical Magnetic Moment

2.1 Spin as a Measurable Electromagnetic Property

Spin is not “intrinsic rotation” but the orientation of a magnetic dipole moment. The quantum numbers s = ±½ correspond to two physically distinct alignments of this moment—commonly labeled “up” and “down”—which are directly measurable via magnetic interactions.

2.2 The Energetic Preference for Spin Pairing

Opposite-spin configurations (↑↓) minimize magnetic interaction energy:

  • Parallel spins (↑↑): Strong magnetic repulsion → higher energy → unstable

  • Antiparallel spins (↑↓): Magnetic moments cancel → lower energy → stable

Electrons pair with opposite spins in atoms and molecules not because of an abstract symmetry rule, but because energy minimization favors it.

2.3 How Pairing Transforms Statistics

Total spin determines collective behavior:

  • Single electron (s = ½) → fermion

  • Paired electrons, antiparallel (S = 0) → boson

  • Paired electrons, parallel (S = 1) → fermion (requires spatial antisymmetry to avoid magnetic repulsion)

This explains why Cooper pairs undergo Bose–Einstein condensation: their net bosonic character emerges from electromagnetic optimization.

Chapter 3: Universal Energy-Level Structure—Symmetry from Optimization

3.1 Ground-State Symmetry

The ground states of bound systems—hydrogen 1s orbital, harmonic oscillator, etc.—are spatially symmetric. This is not a mathematical imposition but a consequence of kinetic energy minimization, which favors delocalization.

3.2 Symmetry Breaking in Excited States

  • Fermions: Identical spins enforce antisymmetric spatial wavefunctions, compelling electrons into distinct orbitals (e.g., Hund’s rule).

  • Bosons: No such restriction; multiple particles can occupy the same excited state, enabling coherence (e.g., lasers, BECs).

3.3 The Unity of Symmetry and Energy

Wavefunction symmetry is not imposed a priori but emerges from energy competition:

  • Spatial symmetry + spin antisymmetry → minimal total energy (ground state)

  • Spatial antisymmetry + spin symmetry → higher kinetic energy but reduced magnetic repulsion (excited states)

Thus, symmetry is a thermodynamic outcome, not a metaphysical constraint.

Chapter 4: The Energetic Origin of the Pauli Exclusion Principle

4.1 From Axiom to Physical Mechanism

The Pauli principle arises from magnetic repulsion between parallel spins:

  • Identical-spin electrons repel magnetically → energy increases → system lowers energy by spatial separation → wavefunction becomes antisymmetric.

This is not a mysterious “exchange force” but classical magnetostatics operating in quantum systems.

4.2 The Physical Meaning of Antisymmetry

The condition

�(�1,�1;�2,�2)=−�(�2,�2;�1,�1)ψ(r1,s1;r2,s2)=ψ(r2,s2;r1,s1)

ensures that electrons with identical spins avoid spatial overlap, thereby minimizing magnetic interaction energy. Antisymmetry is thus a natural consequence of energy optimization.

4.3 Electromagnetic Basis of Chemical Bonding

Covalent bonds (e.g., in H₂) form only when electrons pair with opposite spins, eliminating magnetic repulsion and enabling orbital overlap. Bond stability is therefore electromagnetic—not abstractly quantum.

Chapter 5: Emergence of Collective Phenomena

5.1 Superconductivity: Fermion “Bosonization”

In BCS theory:

  • Electrons attract via phonon-mediated coupling.

  • Spin pairing cancels magnetic repulsion, enabling close approach.

  • Resulting pairs act as bosons → macroscopic quantum condensation.

5.2 Spin Ordering in Magnetic Materials

  • Ferromagnetism: Parallel spins lower exchange energy but require spatial separation to mitigate magnetic repulsion.

  • Antiferromagnetism: Antiparallel alignment allows orbital overlap while minimizing total energy.

5.3 Quantum Hall Effect: Dimensionality and Interaction

In 2D electron gases under strong magnetic fields:

  • Electrons occupy quantized Landau levels.

  • Coulomb and magnetic interactions drive formation of fractional states and anyonic excitations, where statistics become topologically encoded.

Chapter 6: Quantum Effects in Life—Subtle, Not Mystical

6.1 Photosynthesis Efficiency

High quantum yield in photosynthetic complexes stems from precise spin control:

  • Opposite-spin electron pairs enable efficient, unblocked transfer.

  • Parallel spins would cause spatial exclusion, reducing efficiency.

6.2 DNA Stability

Molecular stability relies on electromagnetic spin alignment:

  • Antiparallel spin pairing in base pairs (e.g., A–T, G–C).

  • Spin-matching in hydrogen bonds.

  • Delocalized π-electrons in aromatic rings adopt spin configurations that minimize repulsion.

Quantum biology, thus, operates on electromagnetic principles, not magic.

Chapter 7: Technological Applications

7.1 Spintronics

  • Magnetic tunnel junctions: Spin-polarized currents enable high-density, non-volatile memory (MRAM).

  • Spin transistors: Electric fields control spin orientation for low-power logic.

7.2 Quantum Computing

  • Topological qubits: Non-Abelian anyons offer inherent fault tolerance.

  • Majorana fermions: Emergent quasiparticles enable nonlocal, decoherence-resistant encoding.

7.3 Novel Material Design

Understanding fermionic behavior enables:

  • Engineering of spin-ordered magnets (e.g., skyrmion hosts).

  • Optimization of pairing symmetries in high-Tc superconductors.

  • Design of topological insulators with protected edge states.

Chapter 8: Philosophical Reflection—Return to Physical Reality

8.1 Reduction and Understanding

Quantum statistics reduces to three physical ingredients:

  1. Electromagnetic interactions of charged particles

  2. Energy minimization under constraints

  3. Boundary conditions and spatial symmetries

This framework replaces mysticism with mechanism.

8.2 Emergence and Coherence Across Scales

A unified picture emerges:

  • Microscopic: Spin–magnetic interactions

  • Mesoscopic: Pauli exclusion, Fermi surfaces

  • Macroscopic: Superconductivity, magnetism, topological order

All are linked by energy-driven self-organization.

8.3 Science vs. Mysticism

True science refuses to accept “because it is so” as an answer. It:

  • Asks why

  • Seeks connections across scales

  • Explains complexity through simple, testable principles

Mystification halts inquiry; physical understanding propels it.

Conclusion: Toward a Deeper Understanding

Fermions are not enigmatic entities ordained by cosmic decree. They are the natural manifestation of electromagnetic systems under spin–energy constraints. The Pauli exclusion principle is not a postulate but a consequence of magnetic repulsion forcing spatial separation. This perspective:

  • Provides an intuitive, visualizable physical model

  • Enables quantitative energy-based calculations

  • Inspires next-generation materials and devices

Most profoundly, it reaffirms a core tenet of science: the quantum world is rational, knowable, and governed by elegant, physical laws—not inscrutable axioms.