If you wait long enough there’ll be a moment. That’s how we know ancient civilisations, such as Egyptian, Indian and Greek watched the Heavens (skies) everyday and tried to understand certain patterns to guide them in their earthly life. Changing patterns in the sky would tell them when the seasons would change, among other things. “Red sky at night, shepherd’s delight. Red sky in the morning, shepherd’s warning” was used by Western shepherds for planning the next day’s work. Meitei ancients watching the sky, knew that nong manglabadi nong tagani ie dark cloud in the sky will bring rain.
The ancients in the West believed their gods lived in the skies and named the constellations after them. Orion and Scorpius for example, are among the 48 constellations identified by the Greek astronomer Ptolemy in 200 CE. Ancient Indians called the Pole Star Dhruv-Tara (Dhruv-star). Dhruv was a devotee of Vishnu. Our Meitei forefathers believed their supreme God Atiya Sidaba Mapu, lived in Soraren (sky).
Over the centuries, the science of astronomy began to emerge, beginning with the Greek and Hellenistic (Greek Empire after Alexander’s conquest) astronomers. They applied mathematics and physics in an attempt to explain their movements and whereabouts in the sky, which they called space.
In the Ptolemic model of the universe, the Earth was the centre of the Universe. Polish astronomer Copernicus (1543 CE) changed all that. He said the Sun was at or near the centre of the Universe, and the Earth, spinning on its own axis once daily, revolves annually around the Sun. Italian physicist Galileo, with his newly invented telescope, discovered that Jupiter had 4 moons (satellites) revolving round it.
Einstein (1879-1955) changed profoundly our understanding of physics. His works influenced the philosophy of sciences. He is best known for his equation, E = mc2, that the equivalent energy (E) can be calculated as mass (m) multiplied by the squared speed of light (c).
At school I had an idea that the sky is the vast space above our head or above the Earth. But, I didn’t know the sky continues (bends) beneath the Earth and Australians stand upside down. I’ve heard about the word cosmos, such as cosmic energy and cosmic ray that had no real meaning. I never knew what cosmos is until, modern science explained it.
We know what’s meant by world ie the Earth together with all the life upon it including humans. The universe as we understand, is “the whole world” including time and space, containing the solar system, stars, galaxies etc. Theoretical physicist Stephen Hawking explains for Joe bloke the beginning of the universe as the “Big Bang”. Astronomer Edwin Hubble shows us the expanding and accelerating universe though his telescope.
In physics, the definition of universe is mind-bending. So is cosmos that is defined as the “spacetime continuum”. Sounds interesting, but what’s spacetime continuum? Cosmos for laymen is universe, containing everything that exists including time, space, matter, which are governed by physical laws and organised in an orderly system. It’s opposite of “chaos”, which was the first state of the universe after the Big Bang.
I have briefly mentioned above about space that was believed by ancients, including even, Isaac Newton in the 19th century, to be an empty expanse where gods lived. Newton is known as the father of classical physics with his famous apple story, the gravitational force, and other physical laws, such as the Three Laws of motion.
New physics at atomic levels, led by atheist Albert Einstein (20th century) has changed certain concepts in Newton’s classical physics, such as the nature of space and the existence of Newton’s universal gravitational force, by means of mathematics and equations.
Einstein proved that there is no such thing as Newton’s gravity or gravitational force. It’s fictitious. He explained it by his gravitational field ( field is a region in which each point is affected by a force) model that, rather than two particles attracting each other (old Newtonian concept), the particles distort spacetime through their mass, and this distortion is what is perceived and measured as a “force”. And matter moves in certain ways in response to the curvature of spacetime.
Einstein’s theory of relativity (now called specific relativity), and quantum mechanics, describe what is space. But the simplest explanations I’ve ever read are from books on physics by the Italian physicist Carlo Rovelli, who has made many contributions to the physics of space and time.
To understand Einstein’s revolutionary wisdom, it’s good to know a bit about his unbecoming background. Einstein was left in Germany in a high school when his parents moved to Pavia in northern Italy in 1895 for better living. His father was an electric engineer and was installing the first AC electrical power plants in the Padan plains (Italy). The 16-year-old boy couldn’t stand the rigors of a German High school and joined his parents in Italy.
There, he had been fascinated by the ‘electromagnetic field’, which turned the rotors in the power stations that his father was building. A few years before Einstein’s birth, two great British physicists, Michael Faraday (English) and James Maxwell (Scottish) discovered “electromagnetic field” (EMF). This field has a real existence everywhere in space. It can vibrate and oscillate like the surface of the ocean, carrying radio, television and microwaves. Heinrich Hertz, a German physicist first proved conclusively the existence of EMF and applied Maxwell’s theories to the production and reception of radio waves in 1886.
Einstein loafed aimlessly for one year before he registered at the Polytechnic Institute of Zurich in Switzerland. He found lectures there, boring and so he preferred to study mostly at home. To pass his exams he borrowed lecture notes from his friend. After graduation he worked at the Swiss Patent Office in Berne, Switzerland (1902-1909) where he developed his theory of relativity and others.
In 1905, at the age of 25, he published three articles: one showed mathematically that atoms exist by calculating the dimensions of atoms and thus proving matter is granular; the second established the foundation of quantum theory that explains the nature and behaviour of matter and light at the atomic and subatomic levels, helping in the invention of transistors and computers; and the third set out the theory of relativity, showing time does not pass identically for everyone.
Einstein then revisited Newton’s theory of “universal gravity” as it was incompatible with his theory of relativity. It took 10 years before he solved the problem with his new ‘theory of gravity’ known as the ‘General Theory of Relativity’ in 1916.
Newton imagined that bodies attract each other by a “force”, the “gravitational force” without any known thing between them, and that bodies move in space that was an empty container like a gigantic box that enclosed the universe.
Einstein, 300 years later, while trying to understand how Newton’s ‘gravitational force’ worked and how it could be described mathematically, had an epiphany that Newton’s ‘gravitational force’ is not diffused in Newton’s space through which things move. The gravitational force is the space itself and space is matter, which is one of the ‘material’ components of the world. It’s an entity, a thing that undulates, curves, twists, and moves like the surface of the sea. It’s flexible.
It occurred to him that we are not enclosed in space – an invisible rigid infrastructure and that, the Earth does not move around the Sun because of a mysterious force but, because it is racing in a space which inclines, like a marble that rolls in a curved funnel, and because the Sun curves space around it, planets circle around the Sun.
Einstein, not an outstanding mathematician, knew that a mathematical genius of the 19th century, Carl Friedrich Gauss, known as “the prince of mathematicians”, had written mathematical formulae to describe two-dimensional undulating surfaces, such as the surfaces of the hills, and following him, his student Bernhard Riemann had produced a doctoral thesis to prove that ‘the properties of a curved surface are captured by a particular mathematical object, which is now known in physics as “Reimann’s curvature” and indicate with the letter “R”.
Einstein wrote an equation, which says ‘R’ is equivalent to the energy of the matter that proves that the space and the gravitational field are the same: Rab – 1/2Rgab = Tab. It means space curves where there is matter. The equation describes how space bends around a star, and because of this curvature planets orbit around the star, and light deviates from a straight line. Indeed, in 1919, during a solar eclipse this deviation of light was measured and Einstein’s prediction verified.
Einstein’s equation shows time too, curves like space, and time passes more quickly high up a mountain than at the sea surface; the whole space can expand or contract, and it cannot stand still. In 1930, the expansion of the universe was actually observed by Hubble’s telescope. The equation predicts the expansion ought to have been triggered by the explosion of a young, extremely small and extremely hot universe, known as the “Big Bang”. This is proven by the mapping of cosmic Background Radiation in 1965.
So, cosmos is ‘space-Time continuum’ ie four-dimensional (3 of space and 1 of time) reference frame in which all physical objects may be located.