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Introduction to the Major Laws of Physics

 Over the years, one thing scientists have discovered is that nature is generally more complex than we give it credit for. The laws of physics are considered fundamental, although many of them refer to idealized or theoretical systems that are hard to replicate in the real world.

Like other fields of science, new laws of physics build on or modify existing laws and theoretical research. Albert Einstein's theory of relativity, which he developed in the early 1900s, builds on the theories first developed more than 200 years earlier by Sir Isaac Newton.

Law of Universal Gravitation

Sir Isaac Newton's groundbreaking work in physics was first published in 1687 in his book "The Mathematical Principles of Natural Philosophy," commonly known as "The Principia." In it, he outlined theories about gravity and of motion. His physical law of gravity states that an object attracts another object in direct proportion to their combined mass and inversely related to the square of the distance between them.

Three Laws of Motion

Newton's three laws of motion, also found in "The Principia," govern how the motion of physical objects change. They define the fundamental relationship between the acceleration of an object and the forces acting upon it.

• First Rule: An object will remain at rest or in a uniform state of motion unless that state is changed by an external force. 
• Second Rule: Force is equal to the change in momentum (mass times velocity) over time. In other words, the rate of change is directly proportional to the amount of force applied. 
• Third Rule: For every action in nature there is an equal and opposite reaction. 

Together, these three principles that Newton outlined form the basis of classical mechanics, which describes how bodies behave physically under the influence of outside forces.

Conservation of Mass and Energy

Albert Einstein introduced his famous equation E = mc2 in a 1905 journal submission titled, "On the Electrodynamics of Moving Bodies." The paper presented his theory of special relativity, based on two postulates:

• Principle of Relativity: The laws of physics are the same for all inertial reference frames. 
• Principle of Constancy of the Speed of Light: Light always propagates through a vacuum at a definite velocity, which is independent of the state of motion of the emitting body.

The first principle simply says that the laws of physics apply equally to everyone in all situations. The second principle is the more important one. It stipulates that the speed of light in a vacuum is constant. Unlike all other forms of motion, it is not measured differently for observers in different inertial frames of reference.

Laws of Thermodynamics

The laws of thermodynamics are actually specific manifestations of the law of conservation of mass-energy as it relates to thermodynamic processes. The field was first explored in the 1650s by Otto von Guericke in Germany and Robert Boyle and Robert Hooke in Britain. All three scientists used vacuum pumps, which von Guericke pioneered, to study the principles of pressure, temperature, and volume.

• The Zeroeth Law of Thermodynamics makes the notion of temperature possible.
• The First Law of Thermodynamics demonstrates the relationship between internal energy, added heat, and work within a system.
• The Second Law of Thermodynamics relates to the natural flow of heat within a closed system.
• The Third Law of Thermodynamics states that it is impossible to create a thermodynamic process that is perfectly efficient.

Electrostatic Laws

Two laws of physics govern the relationship between electrically charged particles and their ability to create electrostatic force and electrostatic fields. 

• Coulomb's Law is named for Charles-Augustin Coulomb, a French researcher working in the 1700s. The force between two point charges is directly proportional to the magnitude of each charge and inversely proportional to the square of the distance between their centers. If the objects have the same charge, positive or negative, they will repel each other. If they have opposite charges, they will attract each other.
• Gauss's Law is named for Carl Friedrich Gauss, a German mathematician who worked in the early 19th century. This law states that the net flow of an electric field through a closed surface is proportional to the enclosed electric charge. Gauss proposed similar laws relating to magnetism and electromagnetism as a whole.

Beyond Basic Physics

In the realm of relativity and quantum mechanics, scientists have found that these laws still apply, although their interpretation requires some refinement to be applied, resulting in fields such as quantum electronics and quantum gravity.

The Basics of Physics in Scientific Study

 Physics is a systematic study of the natural world, particularly the interaction between matter and energy. It is a discipline that attempts to quantify reality through a precise application of observation coupled with logic and reason.

In order to make use of such a discipline, you must first understand certain fundamentals. Only by learning the basics of physics can you build upon it and dive deeper into this field of science. Whether you are pursuing a career in physics or merely interested in its findings, it certainly is fascinating to learn about.

What Is Considered Physics?

To begin the study of physics, you must first understand what physics actually means. Understanding what falls within the realm of physics—and what does not—helps focus the field of study so you can formulate meaningful physics questions.

Behind every question in physics lies four very important terms you will want to understand: hypothesis, model, theory and law. 

Physics can be either experimental or theoretical. In experimental physics, physicists address a scientific problem using techniques such as the scientific method in an attempt to prove a hypothesis. Theoretical physics is often more conceptual in that physicists are focused on developing scientific laws, such as the theory of quantum mechanics. 

These two forms of physics are related to each other and connected to other forms of scientific study. Quite often, experimental physics will test the hypotheses of theoretical physics. Physicists themselves can specialize in a variety of fields, from astronomy and astrophysics to mathematical physics and nanotechnology. Physics also plays a role in other fields of science, such as chemistry and biology.

The Fundamental Laws of Physics

The goal of physics is to develop precise models of physical reality. The best case scenario is to develop a series of very fundamental rules to describe how these models function. These rules are frequently called "laws" after they have been used successfully for many years.

Physics is complicated, but it does fundamentally rely on a number of accepted laws of nature. Some are historical and groundbreaking discoveries in science. These include Sir Isaac Newton's Law of Gravity as well as his Three Laws of Motion. Albert Einstein's Theory of Relativity and the laws of thermodynamics also fall into this category.

Modern physics is building off those monumental truths to study things such as quantum physics which explores the invisible universe. Similarly, particle physics seeks to understand the smallest bits of matter in the universe. This is the field where strange words like quarks, bosons, hadrons, and leptons enter the scientific dialogue that makes headlines today.

The Tools Used in Physics

The tools that physicists use range from the physical to the abstract. They include balance scales and laser beam emitters as well as mathematics. Understanding this wide range of tools and the methods for applying them is essential to understanding the process that physicists go through in studying the physical world.

The physical tools include things like superconductors and synchrotrons, which are used to create intense magnetic fields. These can be applied in studies like the Large Hadron Collider or practically in the development of magnetic levitation trains.

Mathematics is at the heart of physics and is vital in all fields of science. As you begin to explore physics, fundamentals such as using significant figures and going beyond the basics of the metric system will be important. Math and physics go much deeper as well and concepts like vector mathematics and the mathematical properties of waves are crucial to the work of many physicists.

History's Famous Physicists

Physics does not exist in a vacuum (even though some physics is practiced in an actual vacuum). The forces of history have shaped the development of physics as much as any other field in history. Quite often, it is useful to understand the historical perspectives which led to our current understanding. That includes the ​many incorrect paths that were faltered along the way.

It is also useful and intriguing to learn about the lives of the famous physicists of the past. The ancient Greeks, for instance, combined philosophy with the study of natural laws and are particularly known for an interest in astronomy.

In the 16th and 17th centuries, Galileo Galilei further studied, observed, and experimented with the laws of nature. Though he was persecuted in his time, he is regarded today as "the father of science" (coined by Einstein) as well as modern physics, astronomy, and observational science.

Galileo inspired and was followed by famous scientists like Sir Isaac Newton, Albert Einstein, Niels Bohr, Richard P. Feynman, and Stephen Hawking. These are just a few of the names of physics history that have shaped our understanding of how our world works. Their abilities to challenge accepted theories and devise new ways of looking at the universe have inspired physicists who continue to achieve scientific breakthroughs.