Written by Hala Abdelhamid
Stephen Hawking, world-known physicist, wrote A Brief History of Time in 1988. He wanted to show the world the real beauty of theoretical physics. He believed his own theories could be simplified to the extent that it could be understood by 8 th graders with an 8 th grade knowledge of mathematics and physics. Moreover, one of his main objectives was to make the “complicated” knowledge of theoretical physics more accessible to normal people.
The earliest biggest revolution in physics was caused by Galileo Galilei. He was one of the first of the Copernican theory (Earth revolves around the sun). Moreover, his experiments on motion were used as a basis in Newton’s law of motion, as he confirmed that a ball increases speed as it falls. This indicated that a force causes a change in speed. Not only that,
but he proved the Copernican theory by observing the planet’s orbits by a telescope. Unfortunately, his theories were widely rejected by the Catholic church as he stated that the Bible was not intended to explain science, and if it contradicted science then it is allegorical.
After decades of research, Isaac Newton causes another massive revolution in physics. His book “Philosophiae Naturalis Principia Mathematica” is considered the most important work ever done by a scientist up until now. Not only did Newton put a theory on “how bodies move”, he also showed how to accurately calculate their motion after his invention of calculus. Newton developed a universal law of gravity, which states that each body exerts a force on the other and the distance between the bodies is inversely proportional to the magnitude of the force exerted. He went on to prove that gravity also causes the moon’s elliptical orbit around Earth. This led to the thesis “If the stars exert a force on one another, then they should not remain motionless,’’ and “The stars should fall all together at some point.” Newton argued
that there was an infinite number of stars over an infinite space, therefore there is no center and they would not fall.
However, the infinite universe theory was later rejected, as if we had an infinite universe each point could be regarded as a center, which will obviously not stop collisions from occurring. The main point in Newton’s universal theory is that it liminated the possibility of “absolute rest.” Newton also calculated the distance from each star to Earth by its own light’s color.
The most recent revolution caused in the world of physics was due to Albert Einstein’s theory of relativity. Einstein clearly pointed out he was abandoning the idea of “absolute time” which was a basis in Newton’s theory. The fundamental postulate of the theory of relativity was that the laws of science should not differ for freely moving observers, regardless of their speed. Einstein’s second most popular theory E=mc (power 2) states that nothing can move up to the speed of light. After years of researching how to add gravity to the equation, Einstein proposed the theory of general relativity. His newest theory shocked the world by stating that gravity was not a force, it is rather a consequence of the curvature of the space-time fabric. He introduced the idea of a “geodesic” which is the nearest straight line path in the curve of
space-time in which particles and energy follow. A major prediction of the theory was the deflection of light, which was experimentally proved and states that light deflects due to the curvature of space-time. Einstein argued that there was a static universe made to expand, therefore he added the cosmological constant to his equations to make hit possible. He
also introduced an “antigravity” force in which he stated it existed in the fabric of space-time itself. However, one of the most important expectations of the general theory of relativity was that the universe was not “infinite”: it had a beginning and will obviously have an end. However, the biggest downfall in Einstein’s scientific career was his inability to combine quantum mechanics and general relativity into one whole theory of quantum gravity. This theory has not been discovered yet, but it is predicted that such a theory could lead us to the ultimate theory of everything.
Hawking ends the book with a probable explanation on the features of a unified physics theory. It states that there are 3 possibilities: there is an ultimate theory that we might figure out in the future, there is no theory as the universe is just an ultimate sequence of events, or there are no theories beyond a certain extent which can predict events happening
around. However, Hawking still holds in the possibility that the “God” theory is a scientific controversy itself and that we might need to put in mind that the universe might have existed infinitely without a start or find the natural features of “God.”
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