Fundamental Scientific Concepts: From Cosmos to Earth

The Greenhouse Effect

The Greenhouse Effect refers to the increase in a planet's temperature caused by solar heat retained by gases in its atmosphere.

Electromagnetic Waves and Spectrum

Electromagnetic wave propagation is the form of electromagnetic radiation traveling through space. The Electromagnetic Spectrum is a set of waves ranging from the longest (radio waves) to the shortest (gamma rays).

Human Actions Causing Air Pollution

Significant human activities contribute to air pollution:

• Burning fossil fuels like oil or coal
• High traffic densities in cities
• Agricultural activities such as rice fields or swamps
• Industrial processes
• High-tension power lines, telephone antennas, and artificial lighting

The Miller Experiment

In the 1950s, an experiment was conducted that demonstrated several organic compounds could form spontaneously under conditions simulating the early atmosphere of Earth. Researchers designed a tube containing gases similar to those in Earth's early atmosphere and a pool of water mimicking the early ocean. Electrodes discharged an electric current within the gas-filled chamber, simulating lightning. After a full week, the contents of the liquid pool were analyzed. They found that several organic amino acids were formed spontaneously from these simple inorganic materials. These molecules joined in the pool water and formed coacervates. This experiment, along with considerable geological, biological, and chemical evidence, supports the theory that the first life forms spontaneously arose through chemical reactions.

Cosmology: Big Bang and Big Crunch

The Big Bang Theory

In physical cosmology, the Big Bang theory is a scientific model that attempts to explain the origin of the universe and its subsequent development from a singularity. Technically, this concept describes the expansion of the universe from a primordial singularity, where this expansion follows from a collection of solutions to the equations of general relativity, known as Friedmann-Lemaître-Robertson-Walker models. The term "Big Bang" specifically refers to the time when the expansion of the observable universe began (as measured by Hubble's Law), and in a broader sense, to the cosmological paradigm explaining its origin and evolution.

The Big Crunch

The Big Crunch refers to the possibility that the universe might cease to expand and instead contract due to gravitational forces, ultimately ending in a massive implosion of matter and energy. This scenario is the opposite of the Big Bang, where matter, energy, and space would converge again as they were before the Big Bang. Whether this event occurs depends on the value of the gravitational constant mentioned in the Theory of Relativity.

Desalination Process

Desalination is the process of removing salt from seawater or brackish water to obtain fresh, potable water.

Human Family Tree

Key species in the human family tree include: Homo antecessor, Homo heidelbergensis, and Homo sapiens.