Shapes, States, and Origins of the Universe
Shape of the Universe
The universe has three possible shapes, but it’s currently believed to be nearly flat. The shape depends on its density relative to a critical density:
- Closed Universe: If the density (k) is greater than the critical density, the universe is closed and finite, like a sphere.
- Hyperbolic Universe: If the density (k) is less than the critical density, the universe is open and infinite, like a saddle.
- Flat Universe: If the density (k) is equal to the critical density, the universe is open and flat.
States of the Universe
- Open Universe: The universe is expanding infinitely from the Big Bang.
- Closed Universe: The force of gravity would slow the expansion of the universe and cause its contraction, forming a cosmic egg, which would again burst into an expansive universe. The explosions (Big Bang) and contractions (Big Crunch) are called beats.
Movement of Lithospheric Plates
When lithospheric plates move (k), they can move away from, approach, and even rub against each other. This movement can cause earthquakes.
Species
A species is a group of individuals that can reproduce with each other and produce fertile offspring. There are two main theories on the origin of species: creationism and evolution.
Hypothesis of Early RNA
Eigen, in 1981, proposed that the first RNA molecule (k) was capable of containing genetic information to control other biological processes. Today, RNA is known to be present in many viruses. It is believed that RNA evolved and became the DNA molecule, which is more stable.
Natural Selection
Natural selection eliminates less adapted individuals, allowing the fittest to reproduce.
Theory of Punctuated Equilibrium
Presented in 1972 by American paleontologists, this theory attempts to answer some questions about life that Neo-Darwinism could not explain. The observed fossils suggest that biological structures (k) may have experienced a gradual transformation. The transformation is slow and continuously develops at the same time and is an evolutionary line.
Polymers
Polymers are substances consisting mainly of organic compounds of carbon and hydrogen, which form long chains of high molecular weight. To obtain a polymer, hundreds of thousands of monomer molecules must join chemically.
- Homopolymers: Formed by the consistent use of the same monomer.
- Copolymers: Formed by the union of different monomers.
Types of Polymers
- Thermoplastics: Form long chains of carbon atoms. They behave rigidly when cold but become pliable when heated, so they can be shaped by fusion and subsequent solidification in a mold.
- Thermosets: More resilient and fragile, they do not support recycling and decompose when heated.
- Elastomers: Similar to rubber, they are capable of being deformed under pressure and recovering their original shape when the pressure is released.
Ecosystems
Ecosystems are dynamic systems, a natural community formed by living organisms (biocenosis) and their physical environment (biotope), where each element interacts.
Ecology
Ecology is the science that studies ecosystems.
Sustainable Development
Sustainable development is that which meets present needs without compromising the ability of future generations to meet their own needs.
Biodiversity
Biodiversity is the number of species in a community. Around two million distinct species have been found on Earth.