Science is at the forefront of everything. It allows us to learn about how nature and the universe work. As a result, we come across scientific laws and theories.
First of all, what are scientific theories and laws? Scientific laws can generally be reduced to a mathematical equation. Thus, we can obtain the result we want with certainty under appropriate conditions and with appropriate data. Scientific theories, on the other hand, are explanations based on evidence obtained through observation and research. They do not have a mathematical equation like scientific laws.
Big Bang Theory
According to the Big Bang Theory, the result of experiments and research by Einstein, Hubble, Lemaitre, and many other scientists, the universe was formed 14 billion years ago in a big bang. Before the explosion, the universe contained all matter compressed into a single point. After the explosion, the single point gradually expanded to become the present universe. The effect of the explosion continues to this day, and the universe is still expanding.
Hubble’s Law
As a result of his astronomical research, Hubble discovered that there are galaxies other than the Milky Way in the universe and that these galaxies are getting farther and farther away from our own. Hubble’s greatest achievement was discovering that this divergence is directly proportional to the distance between galaxies. The farther away one galaxy was from another, the faster it moved away. Hubble’s Law; Speed = Hubble Constant x Distance. The Hubble Constant gives the rate at which the universe is expanding. It varies with time. The currently accepted value is 70 km/s for 1 megaparsec.
NASA named the world’s first space-based optical telescope after American astronomer: Hubble Space Telescope
Kepler’s Laws of Planetary Motion
Kepler explained the orbits of the planets around their suns in three fundamental laws.
According to Kepler’s Laws of Planetary Motion:
- Each planet moves in an elliptical orbit with the sun at one of its focal points.
- The line connecting a planet to the sun scans equal areas at equal time intervals. As shown in the picture, the two orange areas are equal to each other. Thus, planets slow down as they move away from their sun and speed up as they move closer.
- The square of a planet’s orbital period is directly proportional to the cube of the length of the major axis of the ellipse it orbits.
Newton’s Law of Universal Gravitation
Newton came up with a revolutionary idea 300 years ago: two objects exert a gravitational force on each other regardless of their matter or mass. This law is reduced to the equation F = G × [(m1m2)/r²], which most of us saw in high school. r is the distance between the two objects, m is the mass of the two objects, and G is the gravitational constant. Thanks to this law, we can explain the motion of planets, satellites, etc.
Newton’s Laws of Motion
Newton’s laws of motion are three laws that establish relationships between the forces acting on an object and its motion.
- As long as no force acts on an object, it maintains its state of motion. If it is at rest, it stops; if it is moving at a constant speed, it continues to move at a constant speed.
- The net force on an object is equal to the product of its mass and acceleration. So F = m x a.
- For every action, there is a reaction of equal and opposite magnitude.
Laws of Thermodynamics
Thermodynamics is the study of how energy works in a system. This system can be the inside of an engine, the center of the Earth, or the universe itself.
Energy cannot be created out of anything; existing energy cannot be destroyed; it only transforms from one form to another.
The efficiency of a system can never be one hundred percent. This is because entropy (i.e., disorder) in the universe is constantly increasing, so some entropy is lost as energy is converted into work; as the temperature approaches absolute zero, motion decreases. As the temperature approaches absolute zero, the disorder gradually decreases and stabilizes at a fixed number. The absolute temperature is 0 Kelvin or -273 C.
We have all surely heard ‘Eureka! After Archimedes discovered the buoyancy of water in the shower, he started running outside naked and shouting ‘Eureka.’ So what is this buoyancy? Water pushes objects with a density less than their density towards its surface. The object starts to float due to this repulsive force arising from density differences. This force is reduced to F = the volume of the object sinking x its mass x its gravitational acceleration.
Bernoulli’s Principle
Bernoulli’s principle states that along a frictionless flow, an increase in velocity causes a simultaneous decrease in the pressure or potential energy of the fluid. You can see the equation in the picture. Bernoulli‘s equation is a very important equation often used in airplane wings and car engines.
Evolution and Natural Selection
According to many scientists, all living things originated from a single ancestor. As a result of evolution and natural selection, living things have been divided into many different species: plants, fungi, animals, bacteria, etc. Natural selection is how organisms more fit for life reproduce and pass on their genes to the next generation. This leads to the extinction and elimination of those not fit for life. Creatures that cannot adapt to the environment become extinct, while those that can adapt to the environment evolve over time – over a period of thousands of years. In other words, bears whose pelts can turn white and thicken continue to live in the poles, while bears that cannot undergo these changes have disappeared.
General Theory of Relativity
According to Einstein, gravity is not a simple force acting on mass and objects but a force that affects space and time to a greater extent. As the figure shows, due to gravity, the dimensional lines are curved, not straight. Think of the world on a map and the world on a globe. If you move straight ahead on the globe, you move diagonally downwards on the map.
Heisenberg Uncertainty Principle
According to the Heisenberg Uncertainty Principle, when you can determine the position of an electron very precisely, you cannot calculate the momentum of that electron with the same precision. Or vice versa. The reason for this is that the electron is both a wave and a particle. So, when we calculate the position of an electron, we think of it as a particle, but when we calculate its momentum, we have to think of it as a wave.
Gases in which the forces of attraction and repulsion between molecules are neglected or ignored are called ideal gases. In reality, no gas is ideal, but a gas approaches ideal with low pressure and high temperature. The partial pressure of any ideal gas in a volume is equal to the pressure of that gas measured in another container of the same volume. Consequently, the total pressure of a mixture of ideal gases is equal to the sum of the partial pressures of the gases in it.
Bonus: Atomic Theory
Atomic theory is a scientific theory that explains the nature and behavior of matter. It states that all matter is made up of small particles called atoms, which are composed of a nucleus containing positively charged protons and neutrally charged neutrons, surrounded by negatively charged electrons. The theory also explains how atoms can combine to form molecules and compounds, and how they can undergo chemical reactions. Atomic theory has played a significant role in the development of modern chemistry and physics, and it continues to be a fundamental concept in these fields.