Question -Define various theories related to the universe??
✯ 𝑷𝒓𝒆𝒇𝒂𝒄𝒆 :-
Astronomy is written in clear non-technical language, with the occasional touch of humor and a wide range of clarifying illustrations. It has many analogies drawn from everyday life to help non-science majors appreciate, on their own terms, what our modern exploration of the universe is revealing. The book can be used for either a one-semester or two-semester introductory course (bear in mind, you can customize your version and include only those chapters or sections you will be teaching.) It is made available free of charge in electronic form (and low cost in printed form) to students around the world. If you have ever thrown up your hands in despair over the spiraling cost of astronomy textbooks, you owe your students a good look at this one.
☞︎︎︎ There are various theories about universe given by different different philosopher, scientist etc.
☆ Aristotle's theory
☆ Ptolemy's theory
☆ Copernican theory
☆ Johannes Kepler , Galileo Galilei - 1609 theory
☆ Newton's theory
☆ Hubble's theory
★ 𝗔𝗿𝗶𝘀𝘁𝗼𝘁𝗹𝗲 𝗧𝗵𝗲𝗼𝗿𝘆 :-
Nature of Aristotelianism
The extent to which Aristotelian thought has become a component of civilization can hardly be overestimated. To begin, there are certain words that have become indispensable for the articulate communication of thoughts, experiences, and problems. Some words still carry their Greek form, whereas others have become established in their more important meanings as Latin equivalents of Aristotle’s own words. The centuries-long impact of Aristotelian schooling lies at the root of the establishment of the following vocabulary: “subject” and “predicate” in grammar and logic; “form” (information, transform) and “matter” as expressing the two correlative aspects of something that has acquired or acquires something else that is possibly essential to it; “energy” as the active power inherent in a thing; “potential” for what is latent but can be released; “substance” and “essence,” “quantity” and “quality,” “accidental,” “relation,” “cause” (and the many meanings of “because” corresponding to the four causes), “genus” and “species” (general, special), “individual,” “indivisible” (atomic)—these constitute only a small sample of terms that still carry the mark of Aristotle’s philosophy.
Beyond language, features that cumulatively or severally characterize Aristotelianism include, in philosophical methodology, a critical approach to previous, contemporary, or hypothetical doctrines; the raising and discussing of doctrinal difficulties; the use of deductive reasoning proceeding from self-evident principles or discovered general truths; and syllogistic forms of demonstrative or persuasive arguments.
In epistemology, or the theory of knowledge, Aristotelianism includes a concentration on knowledge either accessible by natural means or accountable for by reason; an inductive, analytical empiricism, or stress on experience, in the study of nature-including the study of humans, their behaviour and organizations leading from the perception of contingent individual occurrences to the discovery of permanent, universal patterns; and the primacy of the universal, that which is expressed by common or general terms.
In metaphysics, or the theory of the ultimate nature of reality, Aristotelianism involves belief in the primacy of the individual in the realm of existence; in the applicability to reality of a certain set of explanatory concepts (e.g., 10 categories; genus-species-individual, matter-form, potentiality-actuality, essential-accidental; the four material elements and their basic qualities; and the four causes—formal, material, efficient, and final); in the soul as the inseparable form of each living body in the vegetable and animal kingdoms; in activity as the essence of things; and in the primacy of speculative over practical activity.
★ 𝙋𝙩𝙤𝙡𝙚𝙢𝙮'𝙨 𝙏𝙝𝙚𝙤𝙧𝙮 :-
The Earth was the center of the Universe according to Claudius Ptolemy, whose view of the cosmos persisted for 1400 years until it was overturned - with controversy - by findings from Copernicus, Galileo, and Newton.
An Astronomer in Ancient Times Claudius Ptolemy (about 85–165 CE) lived in Alexandria, Egypt, a city established by Alexander the Great some 400 years before Ptolemy’s birth. Under its Greek rulers, Alexandria cultivated a famous library that attracted many scholars from Greece, and its school for astronomers received generous patronage. After the Romans conquered Egypt in 30 BCE (when Octavian defeated Cleopatra), Alexandria became the second-largest city in the Roman Empire and a major source of Rome’s grain, but less funding was provided for scientific study of the stars. Ptolemy was the only great astronomer of Roman Alexandria.
Ptolemy was also a mathematician, geographer, and astrologer. Befitting his diverse intellectual pursuits, he had a motley cultural makeup: he lived in Egypt, wrote in Greek, and bore a Roman first name, Claudius, indicating he was a Roman citizen - probably a gift from the Roman emperor to one of Ptolemy’s ancestors.
A Geocentric View Ptolemy synthesized Greek knowledge of the known Universe. His work enabled astronomers to make accurate predictions of planetary positions and solar and lunar eclipses, promoting acceptance of his view of the cosmos in the Byzantine and Islamic worlds and throughout Europe for more than 1400 years.
Ptolemy accepted Aristotle’s idea that the Sun and the planets revolve around a spherical Earth, a geocentric view. Ptolemy developed this idea through observation and in mathematical detail. In doing so, he rejected the hypothesis of Aristarchus of Samos, who came to Alexandria about 350 years before Ptolemy was born. Aristarchus had made the claim that the Earth revolves around the Sun, but he couldn’t produce any evidence to back it up.
★𝘾𝙤𝙥𝙚𝙧𝙣𝙞𝙘𝙪𝙨 𝙏𝙝𝙚𝙤𝙧𝙮 :-
Copernican heliocentrism is the astronomical model developed by Nicolaus Copernicus and published in 1543. This model positioned the Sun at the center of the Universe, motionless, with Earth and the other planets orbiting around it in circular paths, modified by epicycles, and at uniform speeds. The Copernican model displaced the geocentric model of Ptolemy that had prevailed for centuries, which had placed Earth at the center of the Universe.
Although he had circulated an outline of his own heliocentric theory to colleagues sometime before 1514, he did not decide to publish it until he was urged to do so later by his pupil Rheticus. Copernicus's challenge was to present a practical alternative to the Ptolemaic model by more elegantly and accurately determining the length of a solar year while preserving the metaphysical implications of a mathematically ordered cosmos. Thus, his heliocentric model retained several of the Ptolemaic elements, causing inaccuracies, such as the planets' circular orbits, epicycles, and uniform speeds, while at the same time using ideas such as:
-The Earth is one of several planets revolving around a stationary sun in a determined order.
-The Earth has three motions: daily rotation, annual revolution, and annual tilting of its axis.
Retrograde motion of the planets is explained by the Earth's motion.
-The distance from the Earth to the Sun is small compared to the distance from the Sun to the stars.
★ 𝙅𝙤𝙝𝙖𝙣𝙣𝙚𝙨 𝙆𝙚𝙥𝙡𝙚𝙧, 𝙂𝙖𝙡𝙞𝙡𝙚𝙤 𝙂𝙖𝙡𝙞𝙡𝙚𝙞 - 1609 𝙏𝙝𝙚𝙤𝙧𝙮 :-
Kepler's Laws of Planetary Motion In 1605 he announced The First Law: Planets move in ellipses with the Sun at one focus.
The figure below illustrates two orbits with the same semi-major axis, focus and orbital period: one a circle with an eccentricity of 0.0; the other an ellipse with an eccentricity of 0.8. Kepler's Laws of Planetary Motion They describe how :-
(1) planets move in elliptical orbits with the Sun as a focus,
(2) a planet covers the same area of space in the same amount of time no matter where it is in its orbit,
(3) a planet's orbital period is proportional to the size of its orbit (its semi-major axis).
★ 𝙉𝙚𝙬𝙩𝙤𝙣'𝙨 𝙏𝙝𝙚𝙤𝙧𝙮 :-
Newton's theory of gravity predicts that the gravitational force on any object is proportional to its mass, while his second law of motion predicts that the resulting acceleration is inversely proportional to the object's mass.
Newton's Law of Inertia: Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that state by forces impressed upon it.
★ 𝙃𝙪𝙗𝙗𝙡𝙚'𝙨 𝙏𝙝𝙚𝙤𝙧𝙮 :-
Hubble's Law basically states that the greater the distance of a galaxy from ours, the faster it recedes. It was proof that the Universe is expanding. It was also the first observational support for a new theory on the origin of the Universe proposed by Georges Lemaitre: the Big Bang.
Hubble's law, which says simply that a galaxy's velocity (or as is sometimes plotted, its redshift) is directly proportional to its distance, also tells us something important about the state of the universe. If the universe is static and unchanging, there should be no correlation between distance and velocity.
☞︎︎︎ 𝐶𝑜𝑛𝑐𝑙𝑢𝑠𝑖𝑜𝑛 :-
All theme there theories are partial theories . Thus a unified theory regarding the universe is necessary. As the universe appeared to be following certain laws. Even the beginning must michael some laws. Those laws should be found to have a unified theory about the universe. Scientist have only two partial theories to explain the universe. One is the general theory of relativity and the other is the quontum theory. The first to is on a large scale and the second is a miniscale . Thus to explain the universe a unified theory is essential. It satisfies man's undying curiosity to know the unknown. So that be can solve the mystery of the universe.
THANK YOU
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