Lecture on Julian Barbour's Theory of Time and Cosmology

Challenging Conventional Time Concepts

• Traditional belief: The arrow of time is explained by increasing entropy (disorder).
• Barbour's theory: Newton's laws suggest the opposite, with the universe becoming more ordered.
• Time is an abstraction derived from changing shapes, not a measurable quantity.

Julian Barbour and Shape Dynamics

• Developed theory while working independently from the academic mainstream.
• Funded research by translating Russian journals for 28 years.
• Shape Dynamics: Universe doesn't evolve through time; time is the succession of static configurations (like film frames).

Concepts of Space, Time, and Dimension

• Time: Abstraction deduced from change (Ernst Mach's idea).
• Space and time are relational, not absolute (Leibniz and Mach's perspectives).

Mach's Principle

• Critique of Newton's absolute space and time.
• Physics described holistically: motion relative to all matter in the universe.
• Inertia involves mutual accelerations, not absolute frameworks.

Triangles and Shape Dynamics

• Example: Universe as three particles forming a triangle.
• Time is perceived change between these configurations.
• Complexity: A key measure of order, inversely related to entropy.

Cosmology and Physics

• Barbour's theory aligns with Newton's universe potentially having a more ordered big bang.
• Questioning standard cosmological models like inflation.
• Discusses potential for a universe without a need for external rulers or time.

Complexity vs. Entropy

• Complexity: Scale-invariant, grows with order (contradicts second law of thermodynamics).
• Entropy: Not scale-invariant, tied to systems in a box.

Quantum Mechanics and Relational Concepts

• Discussion on the relational aspects of quantum mechanics.
• Proposes complexity as a time-like variable for quantum gravity.
• Suggests quantum mechanics can be about probabilities of shapes.

Etymology and Philosophy

• Discusses etymology of terms like "idea" and "pattern".
• Speculative thoughts on consciousness and divine aspects.

Conclusion and Future Outlook

• Barbour's ideas challenge long-held beliefs in physics.
• Open discussions on the role of experimental setups in observing phenomena.
• Encourages further exploration of relational concepts and shape dynamics.