10 scientific laws and theories everyone should know

10 scientific laws and theories that everyone should know.

Scientists from planet Earth use a ton of tools to try to describe how nature and the universe at large work. That they come to laws and theories. What is the difference? Scientific law can often be reduced to a mathematical statement like E = mc²; this statement is based on empirical data and its truth, as a rule, is limited to a certain set of conditions. In the case of E = mc² - the speed of light in vacuum.

Scientific theory often seeks to synthesize a series of facts or observations of specific phenomena. And in general (but not always) there is a clear and testable statement about how nature functions. It is not at all necessary to reduce scientific theory to an equation, but it actually represents something fundamental about the workings of nature.

Laws and theories both depend on the basic elements of the scientific method, such as creating hypotheses, performing experiments, finding (or not finding) empirical data, and drawing conclusions. After all, scientists should be able to replicate the results if the experiment is to become the basis for a generally accepted law or theory.

In this article, we'll look at ten scientific laws and theories that you can brush up on, even if you don't use a scanning electron microscope that often, for example. Let's start with an explosion and end with uncertainty.

The Big Bang Theory

If it is worth knowing at least one scientific theory, then let it explain how the universe reached its current state (or did not reach, if refuted). Based on research by Edwin Hubble, Georges Lemaitre and Albert Einstein, the Big Bang theory postulates that the universe began 14 billion years ago with massive expansion. At some point, the universe was confined to one point and encompassed all the matter of the current universe. This movement continues to this day, and the universe itself is constantly expanding.

The Big Bang theory gained widespread scientific support after Arno Penzias and Robert Wilson discovered the cosmic microwave background in 1965. Using radio telescopes, two astronomers have discovered cosmic noise, or static, that does not dissipate over time. In collaboration with Princeton researcher Robert Dicke, a couple of scientists have confirmed Dicke's hypothesis that the original Big Bang left behind low-level radiation that can be found throughout the universe.

Hubble's Law of Cosmic Expansion

Let's hold Edwin Hubble for a second. While the Great Depression was raging in the 1920s, Hubble pioneered pioneering astronomical research. He not only proved that there were other galaxies besides the Milky Way, but he also found that these galaxies were rushing away from our own, and this movement he called recession.

In order to quantify the speed of this galactic movement, Hubble proposed the law of cosmic expansion, aka Hubble's law. The equation looks like this: speed = H0 x distance. Velocity is the speed at which galaxies are moving away; H0 is the Hubble constant, or parameter that indicates the rate of expansion of the universe; distance is the distance of one galaxy to the one with which the comparison is made.

The Hubble constant was calculated at different values ​​for quite a long time, but at present it is frozen at a point of 70 km / s per megaparsec. It's not that important for us. Importantly, the law is a convenient way to measure the speed of a galaxy in relation to our own. And more importantly, the law established that the universe consists of many galaxies, the movement of which can be traced back to the Big Bang.

Kepler's laws of planetary motion

For centuries, scientists have battled with each other and with religious leaders over the orbits of the planets, especially whether they revolve around the sun. In the 16th century, Copernicus put forward his controversial concept of a heliocentric solar system, in which the planets revolve around the sun rather than the earth. However, it was only with Johannes Kepler, who relied on the work of Tycho Brahe and other astronomers, that a clear scientific basis for the motion of the planets emerged.

Kepler's three laws of planetary motion, formed at the beginning of the 17th century, describe the motion of planets around the Sun. The first law, sometimes called the law of orbits, states that the planets revolve around the sun in an elliptical orbit. The second law, the law of areas, says that the line connecting the planet to the sun forms equal areas at regular intervals. In other words, if you measure the area created by a line drawn from the Earth from the Sun and track the movement of the Earth for 30 days, the area will be the same regardless of the Earth's position in relation to the origin.

The third law, the law of periods, makes it possible to establish a clear relationship between the orbital period of a planet and the distance to the Sun. Thanks to this law, we know that a planet that is relatively close to the Sun, like Venus, has a much shorter orbital period than distant planets like Neptune.

Universal law of gravitation

Today this may be the order of things, but more than 300 years ago Sir Isaac Newton proposed a revolutionary idea: any two objects, regardless of their mass, exert gravitational attraction on each other. This law is represented by the equation that many schoolchildren face in the senior grades of physics and mathematics.

F = G × [(m1m2) / r²]

F is the gravitational force between two objects, measured in newtons. M1 and M2 are the masses of two objects, while r is the distance between them. G is the gravitational constant, currently calculated as 6, 67384 (80) · 10−11 or N · m² · kg − 2.

The advantage of the universal law of gravitation is that it allows you to calculate the gravitational attraction between any two objects. This ability is extremely useful when scientists, for example, launch a satellite into orbit or determine the course of the moon.

Newton's Laws

While we're on the subject of one of the greatest scientists ever to live on Earth, let's talk about some of Newton's other famous laws. His three laws of motion form an essential part of modern physics. And like many other laws of physics, they are elegant in their simplicity.

The first of the three laws states that an object in motion remains in motion unless an external force acts on it. For a ball that is rolling on the floor, the external force can be friction between the ball and the floor, or a boy who hits the ball in a different direction.

The second law establishes a relationship between the mass of an object (m) and its acceleration (a) in the form of the equation F = m x a. F is the force measured in newtons. It is also a vector, that is, it has a directional component. Due to the acceleration, the ball that rolls on the floor has a special vector in the direction of its movement, and this is taken into account when calculating the force.

The third law is quite informative and should be familiar to you: for every action there is an equal reaction. That is, for every force applied to an object on the surface, the object is repelled with the same force.

Laws of Thermodynamics

The British physicist and writer C.P. Snow once said that the non-scientist who did not know the second law of thermodynamics was like the scientist who had never read Shakespeare. Snow's now famous statement emphasized the importance of thermodynamics and the need even for people far from science to know it.

Thermodynamics is the science of how energy works in a system, be it the engine or the core of the Earth. It can be reduced to several basic laws, which Snow outlined as follows:

You cannot win.

You will not avoid losses.

You cannot quit the game.

Let's figure it out a bit. By saying that you cannot win, Snow meant that since matter and energy are conserved, you cannot gain one without losing the other (ie E = mc²). It also means that you need to supply heat to run the engine, but in the absence of a perfectly closed system, some heat will inevitably go into the open world, which will lead to the second law.

The second law - losses are inevitable - means that due to the increasing entropy, you cannot return to the previous energetic state. Energy concentrated in one place will always tend to places of lower concentration.

Finally, the third law - you can't get out of the game - refers to absolute zero, the lowest theoretically possible temperature - minus 273.15 degrees Celsius. When the system reaches absolute zero, the movement of molecules stops, which means that the entropy will reach its lowest value and there will not even be kinetic energy. But in the real world, it's impossible to reach absolute zero - just get very close to it.

Strength of Archimedes

After the ancient Greek Archimedes discovered his principle of buoyancy, he allegedly shouted "Eureka!" (Found it!) And ran naked across Syracuse. So the legend says. The discovery was so important. Also, legend says that Archimedes discovered the principle when he noticed that the water in the bathroom rises when the body is immersed in it.

According to the buoyancy principle of Archimedes, the force acting on a submerged or partially submerged object is equal to the mass of the liquid that the object displaces. This principle is essential in density calculations as well as in the design of submarines and other ocean going vessels.

Evolution and natural selection

Now that we've established some of the basic concepts of how the universe began and how physical laws affect our daily lives, let's turn our attention to the human form and find out how we got there. According to most scientists, all life on Earth has a common ancestor. But in order for such a huge difference between all living organisms to form, some of them had to turn into a separate species.

In a general sense, this differentiation has occurred in the process of evolution. Populations of organisms and their traits have gone through mechanisms such as mutations. Those with traits that were more favorable for survival, such as brown frogs that camouflage themselves well in the swamp, were naturally selected for survival. This is where the term natural selection comes from.

You can multiply these two theories for a lot, a lot of time, and in fact it was Darwin who did it in the 19th century. Evolution and natural selection explain the vast variety of life on Earth.

General theory of relativity

Albert Einstein's general theory of relativity was and remains the most important discovery that forever changed the way we view the universe. Einstein's major breakthrough was his claim that space and time are not absolute, and gravity is not just a force applied to an object or mass. Rather, gravity is related to the fact that mass bends space and time itself (space-time).

To make sense of this, imagine that you are driving across the earth in a straight line eastward, say, from the northern hemisphere. After a while, if someone wants to accurately determine your location, you will be much south and east of your starting position. This is because the Earth is curved. To drive straight east, you need to consider the shape of the earth and drive at an angle slightly north. Compare a round ball and a piece of paper.

Space is pretty much the same thing. For example, for the passengers of a rocket flying around the Earth, it will be obvious that they are flying in a straight line in space. But in reality, the spacetime around them bends under the influence of the Earth's gravity, causing them to simultaneously move forward and stay in Earth's orbit.

Einstein's theory had a huge impact on the future of astrophysics and cosmology. She explained a small and unexpected anomaly in the orbit of Mercury, showed how starlight bends, and laid the theoretical foundations for black holes.

Heisenberg Uncertainty Principle

An extension of Einstein's theory of relativity told us more about how the universe works and helped lay the groundwork for quantum physics, leading to a completely unexpected confusion in theoretical science. In 1927, the realization that all the laws of the universe in a given context are flexible led to the startling discovery of the German scientist Werner Heisenberg.

Postulating his uncertainty principle, Heisenberg realized that it is impossible to simultaneously know with a high level of accuracy the two properties of a particle. You can know the position of an electron with a high degree of accuracy, but not its momentum, and vice versa.

The concept became known as wave-particle dualism and became the foundation of quantum physics. Therefore, when we measure the position of an electron, we define it as a particle at a certain point in space with an indefinite wavelength. When we measure momentum, we consider the electron as a wave, which means we can know the amplitude of its length, but not the position.