Science in Practice – Exam-Revision Notes

Definition of Science

• Systematic observation & experimentation + resulting knowledge base.
• Latin origin scientia (knowledge); “scientist” enters language in $19^{\text{th}}$ century.

Core Purposes

• Uncover natural laws; build testable, predictive explanations.
• Replace supernatural causation with natural, falsifiable accounts.

Early Human Context

• Homo sapiens ≈$300{,}000$ years old; no evidence of formal science at origin.
• Written symbols emerge ≈$6{,}600$ BC → enables record-keeping & mathematics.

Key Historical Milestones

• $660$ BC – Thales: first mathematical proof (Thales’ theorem); natural causes for phenomena.
• Classical Greece:
  • Democritus: atomic hypothesis.
  • Eratosthenes: Earth’s circumference within $10\%$ accuracy.
  • Aristotle: deductive & inductive reasoning, early empiricism.
• $1000$ AD – Ibn al-Haytham: documented experimental optics; recognisable method.
• $17^{\text{th}}$ century – Bacon & Descartes: formal empiricism; Newton et al.: mechanistic, deterministic universe.
• $20^{\text{th}}$ century – Relativity, quantum theory, natural selection: probabilistic, system-of-systems view.

Evolution of the Scientific Method

• Thales: Observation → Natural hypothesis.
• Aristotle: Observation → Hypothesis → Logical consistency.
• Modern: Observation → Falsifiable hypothesis → Prediction → Experiment → Revise/build theory.

Shifts in Worldview

• Organismic (Aristotle): qualitative, purpose-driven Nature.
• Mechanistic (Newtonian): universe = deterministic clockwork.
• Probabilistic (Modern): events described statistically; Nature non-deterministic.

Theories vs. Laws

• Theory: explains why (e.g., evolution by natural selection).
• Law: describes what happens without mechanism (e.g., Conservation of Energy: $\Delta E = 0$ in an isolated system).