Scientific Method, Earth Structure, and Cosmic Origins
Fundamentals of Scientific Inquiry
One can consider a range of general characteristics that define scientific work.
The Role of Questions
Posing questions is a crucial aspect of science. The ability of scientists to ask critical questions about reality is fundamental.
Hypothesis Formulation and Testing
The formulation of hypotheses starts from an idea based on observations or the knowledge of those who have previously studied the phenomenon. Making assumptions is a key moment. Statistical hypotheses are necessary to demonstrate an idea’s scientific validity. It is possible to conduct experiments; this procedure leads to the formulation of theories.
The formulation of hypotheses forms a kind of tree of knowledge which must be consistent and demonstrable.
The Principle of Falsifiability
There is no absolute knowledge, only provisional conjectures. The best way to achieve certainty in science is to try to disprove any hypothesis. By demonstrating the falsity of a hypothesis, it will be rejected. If this process leads to a new path, an alternative hypothesis will become more likely. Any hypothesis must be falsifiable, meaning it offers the possibility of being rebutted. If it cannot be proven false, it should be considered provisional.
Cosmological and Solar System Origins
The Big Bang Theory Explained
The Big Bang theory proposes:
- Initially, all matter and energy were concentrated in a single point.
- This primeval atom expanded sharply in a massive explosion, the Big Bang.
- Simple atoms were generated.
- As the universe expanded, the temperature decreased, allowing matter to condense and astronomical structures to emerge.
Solar System Formation Requirements
Any theory regarding the origin of the solar system must explain the following:
- The Sun and the planets revolve in the same direction.
- Planets travel in nearly circular orbits lying mostly in the same plane.
- The rotational motion of most planets occurs in the same direction as their revolution.
- Planets near the Sun are small, dense, and rocky, while the outer planets are large and lighter (gas giants).
- All planetary bodies show evidence of impacts.
Planetesimal Theory of Formation
About 5 billion years ago, materials in the solar nebula began to stir. The material condensed and concentrated in the center due to gravitational force, increasing the core temperature and initiating thermonuclear reactions – thus marking the birth of the Sun. Solar emissions blew lighter materials outward. Denser materials concentrated near the center, forming planetesimals in different orbits. The planets formed near the Sun gave rise to the rocky inner planets, while lighter materials formed the distant gas giants. Subsequently, the planets cooled and created atmospheres with light gases.
Understanding Earth’s Structure and Dynamics
Methods for Observing Earth’s Interior
Indirect Measurements and Lab Tests
Measurements are based on assessing some physical properties of the planet or studying rocks that can be compared with materials presumed to constitute the Earth’s interior. Laboratory tests attempt to duplicate the conditions found deep within the Earth.
Seismic Wave Analysis
The study of seismic waves provides the most complete indirect data about the structure and composition of the Earth’s interior.
- P-waves (Primary waves): These compress and expand the material they pass through, moving in the same direction as the wave’s propagation. They can travel through solids and liquids.
- S-waves (Secondary waves): These deform the material particles they cross, causing them to vibrate perpendicular to the direction of wave propagation. They can only travel through solids.
- Surface waves: These are formed when P and S waves reach the Earth’s surface and cause the most damage during earthquakes.
Introduction to Plate Tectonics
Plate tectonics describes the Earth’s lithosphere as being like a puzzle, divided into a series of rigid fragments called lithospheric plates. These plates are not static but change slowly yet steadily in size, shape, and position. This lithospheric dynamic involves friction between the plates and pushes them, which in turn triggers different geological processes of internal origin and influences those of external origin.
Types of Tectonic Plate Boundaries
The interactions between plates occur at their boundaries:
- Convergent Margins: Boundaries where two plates collide.
- Divergent Margins: Boundaries where two plates separate.
- Transform Faults (Lateral Motion): Boundaries where two plates slide laterally past each other.