ASTRO 200g – Lecture 2A & 2B Notes: Science, Non-Science & Mātauranga

Students should be able to:
- Reflect on the historical context and current frontiers of astrobiology.
- Define science, distinguish hypothesis vs theory, and recognise what is not science.
- Convey a basic understanding of Mātauranga (knowledge of everything visible in the Universe).
- Explain how Mātauranga relates to Western science.
- Communicate core ideas of pūrākau (myth/ancient story) and maramataka (lunar calendar; literally “turning of the Moon”).
- Show a basic grasp of mauri (life-force/essence) in Nature.
Required reading: Hikuroa, D. (2017) “Mātauranga Māori—the ūkaipō of knowledge in New Zealand”, JR Soc NZ, 47(1), 5-10.

Age of Universe: $13.8\,\text{Gyr}$ (billion years).
Observable radius: $46\,\text{Gly}$ (giga-light-years; $1\,\text{Gly}=10^{9}\,\text{ly}$ ).
1 light-year: $9\times10^{12}\,\text{km}$ .
Speed of light: 3\times10^{5}\,\text{km\,s^{-1}}.

1️⃣ Vast & Old
- Universe likely infinite; we see out to $46\,\text{Gly}$ ; formed $13.8\,\text{Gyr}$ ago.
2️⃣ Elements of Life Are Widespread
- Spectroscopy detects C, H, O, N, P, S, amino acids & complex organics in nebulae, meteorites, comets.
3️⃣ Physical Laws Are Universal
- Identical physics/chemistry everywhere ⇒ plausible that biology obeys similar constraints.

Biology = Physics + Chemistry set within a planet’s geology.
If physical/chemical laws are universal, biology might be universal too.
Life on Earth is resilient:
- Found in virtually every environment (deep-sea vents, Antarctica, acidic hot springs).
- Ancient fossils prove organisms thrived under very different atmospheric/oceanic conditions.
- Hence, extraterrestrial life need not resemble modern terrestrial life.

Metrodorus of Chios (4th c. BC): atomic theory; argued multiple worlds are more plausible than a single world—analogy: “one ear of wheat in a vast plain.”

Giordano Bruno (1548-1600): advocated “plurality of worlds”; envisioned innumerable suns with orbiting Earth-like planets; executed for heresy.

Erwin Schrödinger – What is Life? (1944): described life thermodynamically as creation of order from disorder (“negative entropy”).
- Tied biology to the 2nd Law of Thermodynamics: living systems export entropy to maintain internal order.

Late 19th-century astronomy: canals on Mars (Schiaparelli → Lowell) & swampy Venus; shown later to be observational artefacts.
Carl Sagan (1978) highlighted these as lessons in scientific humility.

1965 Mariner 4 fly-by imaged cratered, arid Mars ⇒ shattered assumptions of a thriving Martian civilisation.
1970s Viking Landers: first in-situ life-detection experiments on Mars.

Enceladus: Cassini detected south-polar water plumes ⇒ subsurface ocean, hydrothermal energy, potential habitability.
Exoplanets:
- Transit & radial-velocity surveys revealed thousands of planets, including rocky worlds in habitable zones.
- Goal: statistically assess how common Earth-like planets are and search for atmospheric biosignatures (e.g., $O<em>2$ , $CH</em>4$ disequilibria).

Science: systematic pursuit of patterns in Nature to make testable, predictive models.
Assumes the Universe is consistent & predictable.
Data acquired via repeatable observation & measurement (empiricism).

Hypothesis: untested, specific, falsifiable proposition.
Theory: broad, simple model explaining diverse data; repeatedly validated, yet always open to refinement (e.g., Gravity, Evolution, Plate Tectonics).
Fact: direct observation (e.g., apple falls); theory explains why.

Appears scientific but lacks one or more hallmarks; e.g., UFO mythology, Martian “face”, astrology, some cosmetic claims.

Realms outside empirical testing: religion, ethics, aesthetics—valuable but use different epistemologies.

Indigenous knowledge system encompassing astronomy, ecology, medicine, genealogy, ethics.
Methodologies include:
- Pūrākau – narrative encoding ecological & cosmological data.
- Maramataka – lunar phases guiding planting, fishing, ritual.
- Observation over generations, calibrated by environmental feedback—empirical within its context, though packaged differently from Western science.
Relationship to Science
- Complementary: Mātauranga provides long-term data sets, ethical frameworks (e.g., kaitiakitanga/guardianship) that can enrich scientific inquiry.
- Differences: holistic vs reductionist; spiritual aspects (mauri) intertwined with physical observations.

Search for life raises questions of planetary protection, contamination, and stewardship of other worlds.
Historical missteps (e.g., Bruno’s execution, canal myth) illustrate dangers of dogma & biased interpretation.
Integrating Mātauranga promotes inclusivity, decolonises research, and anchors science within cultural responsibility.

Speed of light: c = 3\times10^{8}\,\text{m\,s^{-1}}.
Entropy change: \Delta S > 0 for isolated systems (2nd Law).
Negative entropy (life): local \Delta S < 0 by exporting heat/waste.
Light-year distance: $d = c \times t_{1\,\text{year}}$ .
Habitability factors: liquid water, energy source, essential elements, time.

Builds on Lecture 1’s cosmic timeline by zooming into life’s requirements.
Prepares for upcoming units on extremophiles, planetary missions, and detailed Mātauranga case studies (e.g., Matariki star cluster timing harvests).