Ages of darkness punctuated by attempts to sip doses of light that erase the features of heresy and intellectual regression that prevailed in Europe between the fifth and fifteenth centuries AD, and ended at the hands of elite European scientists such as the philosopher “Descartes” and the astronomer “Galileo Galilei” and the mathematicians “Isaac Newton” and “Gottfried” Leibniz”, and others who made a unique scientific boom that lasted for centuries later and passed through several countries and made emperors in science, all of whom contributed to formulating the foundations of the modern scientific model in mathematics and physics, especially in astronomy.
Despite the fondness of philosophers, astronomers, and physicists in explaining cosmic phenomena scientifically, such as explaining the solar system model, historical records did not indicate any serious attempts to study the emergence of the universe scientifically in that era, and this was described by the world of theoretical physicist “Steven Weinberg.” (Steven Weinberg), winner of the 1979 Nobel Prize in Physics: “I remember, during my time as a student and working on my own research in the fifties of the last century, that the study of the primordial universe and its genesis was no longer one of the fields to which a distinguished scientist might devote his time.” .1
But thin threads lead us to a seemingly forgotten scientific paper presented by a Catholic priest and astronomer named “Georges Lemaître” in 1927, in which he proposes a convincing mathematical model for Albert Einstein’s equations of general relativity, assuming a special case for the universe to be in a state of expansion.2
As well as other threads that take us in the pages of history to what is earlier than that to the famous physicist and cosmologist “Alexander Friedmann”, who published his scientific thesis consisting of ten pages and entitled “On the Curvature of Space” in 1922, in which he formulated mathematical solutions The equations of general relativity have more than one possible model, whether assuming that the universe is expanding or contracting, and he was not really interested in the shape of the universe or its origin, but only interested in mathematical models.
Those mathematical models and those ideas remained ink on paper that did not find deaf ears, and whenever they found a way to be the subject of some discussion for a scientific session, they were ignored and resented by the mass of scientists at the time, for them the universe could not expand because the meaning behind its expansion is that in a moment What was applied to himself and then suddenly everything began to move away from each other from stars, planets and others, and this will be called later by the Big Bang Theory, which suffered in its early appearance.
Big Bang..or another theory?
Watching the night sky may leave a strong impression of a fixed, unchanging universe, as the stars appear to be in their positions and the planets revolve in stable elliptical orbits, as their movement was described by the astronomer “Johannes Kepler” four centuries ago, and comets roam the Earth’s sky at specific intervals such as Halley’s comet, which appears every 75 A year, everything seems to be stable, which supports the theory proposed by elite astronomers such as “Herman Pandey” and “Thomas Gold” and the famous scientist “Fred Hoyle”, who seemed very fanatical about his theory, which is the theory of the “steady state of the universe” (Steady State Theory). ) which was practically crystallized in the forties of the last century.
The steady state theory of the universe is the historical counterpart to the Big Bang theory, and it states that the universe was, is and will remain the same, and there was no beginning, and that’s all there is to it. However, two revolutionary discoveries completely overthrown this theory and strengthened the Big Bang theory until it became approved in the corridors of universities and in scientific research centers.
The first discovery..the redshift
Much of the credit for overturning mankind’s concepts of the universe goes to the astronomer Edwin Hubble, who appeared in the first half of the last century using his 100-inch telescope from the top of Mount Wilson in California, as he was able to perceive That the universe is not confined to our galaxy only, but there are many galaxies surrounding us, after he observed the neighboring Andromeda galaxy (Andromeda or the Mystic Galaxy) and calculated the distance between us, and found that it is eight times the farthest star from Earth inside our Milky Way galaxy. Then in 1929, his revolutionary discovery led him to ascend the prestigious scientific ranks when he noticed that these galaxies were moving away from the Earth at very high speeds.4
The Doppler phenomenon reveals whether objects are moving away from us or approaching and is used in speed radars
Hubble used a physical phenomenon called the “Doppler Effect” that was discovered by the physicist who bears his name “Christian Doppler” (Christian Doppler) in 1842, and this phenomenon depends on the property of the movement of waves, whether in the presence or absence of a material medium. If there is a light or sound wave coming towards us that was detected from a non-moving source, we will find that the wavelength is constant, and we can say that the wavelength is the distance between the peaks of similar and similar wave units.
But if the light or sound source moves towards us, we will notice a contraction in the wavelength with the passage of time while observing the wave, and the reason is that the distance between the peaks of similar wave units begins to shrink and be compressed. Conversely, when the source of the waves is away from us, the wavelength is elongated because the distance between the peaks of the wave units increases and expands with time.
This physical phenomenon can be projected onto the study of the movement of celestial bodies, because the light emitted by stars is nothing but electromagnetic waves whose wavelength is contracted or stretched according to the movement of the star. Astronomically, the light wave as it approaches is called a blue shift, because blue has the shortest wavelength in the visible spectrum, and if the wave moves away, it shows a red shift.
This indicates that it is far from us, and then it was concluded that the universe is not as the scene of the sky of the earth reduces it to its stillness and stability, but rather that this universe is in a state of expansion and expansion. Which drew the eyes of scientists to the first concrete evidence of the idea of the beginning of the universe from a single point.
The cosmic microwave background as observed by the Planck probe in 2013.
The second discovery: the cosmic microwave background radiation
The English writer William Shakespeare says in his pastoral comedy “As You Like It”: The world is a theater, and people in it are actors, everyone enters and exits from it.
Shakespeare must have been right in saying that this universe looks like a huge theater and every detail in it bears a sign for something. As soon as the era of the golden achievements of the Hubble astronomer in space science ended, another golden age began with the leadership of the theoretical physicist “George Gamow” who He is known for his humorous and sarcastic personality.
In the forties of the last century, “Gamow” changed his scientific interests from the theory of relativity to astronomy, as he believed that this field is rich in undiscovered information yet, as all we know about the universe at that time is that it is dark and in an expanding state only.
Gamov was fond of believing that the world started from a single point, with a huge explosion that pushed the entire universe with all its mass and energy, and at the same time wondering about the possibility of the existence of remnants of “celestial fossils” in the universe of this great explosion that occurred billions of years ago? It seemed to him a frustrating question beyond his ability to answer, as space science is not based on laboratory experiments, but on observation and mathematical analysis.
However, this did not prevent him from putting his own mark in partnership with his students “Ralph Alpher” and “Hans Bethe” in a research paper entitled “The Theory of the Origin of Chemical Elements” in 1948, which attempts to explain the origin of the spread of chemical elements in the universe with the assumption of a massive nuclear explosion that occurred in the beginning. According to this theory, after the initial explosion, the nuclei of the first atoms were formed by the fusion of two and three pairs of subatomic particles, which are neutrons of equal charge and positively charged protons. Greek-.