The Big Bang and the Universe’s Evolution: From Heliocentrism to Dark Energy
**Aristarchus of Samos and the Heliocentric Theory**
Aristarchus of Samos made significant contributions to astronomy. He proposed the heliocentric theory, which regarded the Sun as the center of the universe, and made precise measurements to study the nature of the stars.
**Geocentric vs. Heliocentric Models**
What is the fundamental difference between the geocentric model and the heliocentric model? The geocentric model posits that the Earth is located at the center of the universe, and the Sun and other planets revolve around it. The heliocentric model places the Sun at the center, with the Earth and the remaining planets revolving around it.
**Galileo’s Persecution**
Why was Galileo persecuted? His invention and development of the microscope led to changes in scientific knowledge, and he was persecuted by the Catholic Church because of it.
**Cosmology and Einstein’s Equations**
What is the role of cosmology in Einstein’s equations? Einstein’s study of cosmology predicted an expanding universe model. However, he introduced a factor into his equations to alter the result to an immobile universe, as the concept of an expanding universe was not accepted by society at the time.
**Conclusions of Friedmann and Lemaître**
What conclusions did Alexander Friedmann and George Lemaître reach? They proposed a dynamic model where galaxies move away from each other, indicating that the universe was expanding. This implied a model where all galaxies were once united.
**Big Bang vs. Steady State Models**
How do the Big Bang and Steady State models resemble and differ from each other? The Big Bang model proposes that the universe is finite and dynamic, originating from an explosion from a singular, immaterial point. The Steady State model supports the expansion of an infinite universe that has no definitive beginning, with matter being continuously generated by unknown mechanisms.
**Hubble’s Law and Modern Cosmology**
How does Hubble’s law relate to modern cosmology? Hubble measured the position of spectral bands of chemical elements present in galaxies at different distances from Earth. He compared these spectra with those obtained in the laboratory and discovered that absorption bands showed a displacement towards longer wavelengths (redshift), which was more pronounced the farther away the galaxies were.
**The Phenomenon of Redshift**
What is the meaning of the phenomenon known as redshift? This phenomenon is due to the Doppler effect, indicating that galaxies are moving away from each other.
**The Usefulness of Cepheid Stars**
Why are Cepheid stars useful? Cepheid stars are a type of very bright star whose brightness varies, describing a regular cycle. This allows them to be used as a measure of distance between galaxies.
**Chemical Elements Formed After the Big Bang**
What type of chemical elements formed after the Big Bang? Initially, light elements like hydrogen (H), helium (He), and lithium (Li) were formed. Later, heavier elements were created.
**The Era of Nucleosynthesis**
What occurred during the era of nucleosynthesis?
**Formation of the Universe According to the Big Bang Theory**
How and when was the universe formed according to the Big Bang theory? At t = 0, approximately 13.7 billion years ago, all matter, the four forces of the universe (gravity, electromagnetic force, strong nuclear force, and weak nuclear force), energy, and empty space were in the form of an intangible singularity. This singularity was very dense and hot, with no radius. The current laws of physics have serious difficulties describing the external conditions at that time.
**The First Atoms**
When did the first atoms appear in the universe? They appeared in the Planck era, the first instant.
**The Planck Era: The Frontier of Physics**
Why is the Planck era called the frontier of physics? Because, until now, there is no theory that can describe with exactitude the characteristics and properties of that fleeting instant.
**Materialization of the Universe**
How could the universe have materialized energy within one second? The temperature and density were so high that the four fundamental forces of the universe were grouped, forming a force called the electronuclear force. Matter was sealed in the form of energy.
**The Absence of Antimatter**
Why is antimatter not detected in the universe? Antimatter does not absorb or emit radiation.
**Quarks and Subatomic Particles**
What subatomic particles are formed from quarks? Protons and neutrons.
**Particle Accelerators**
What are particle accelerators, and what are they used for? Where is the LHC located, and what mysteries will its mission unravel? Particle accelerators are instruments used to accelerate particles using magnetic fields in astronomy and physics. The Large Hadron Collider (LHC) is located at the European Organization for Nuclear Research (CERN). Its objective is to simulate events that occurred after the Big Bang.
**Cosmic Microwave Background Radiation**
What is the relation to the cosmic microwave background, and how can it be captured? It is proof of the existence of the Big Bang. After the Big Bang, the radioactive source would have spread and stretched to very large wavelengths. It is captured through the detection of microwave radiation.
**Irregular Distribution of Galaxies**
What may be the cause of the irregular distribution of galaxies in the universe? Dark matter is a type of matter present in galaxies and throughout the universe, whose nature is unknown. It does not emit or absorb electromagnetic radiation, which prevents us from detecting it directly. Its existence can only be inferred from its gravitational effects on galaxies.
**The Role of Dark Matter**
What role does dark matter play? It forms an invisible fabric that serves as a cosmic skeleton, binding bright galaxies together.
**Dark Energy and the Universe’s Evolution**
How does dark energy affect the development and evolution of the universe? It accelerates the expansion of the universe, acting as a repulsive force against gravity. Some scientists equate it to Einstein’s cosmological constant, while others attribute it to a fifth essence.