FUNDAMENTAL FORCES OF NATURE - A force is defined as a push or pull that changes an object's state of motion or causes the object to deform. Newton defined a force as anything that caused an object to accelerate. The force of gravity pulls you down into your seat, toward the Earth's center. You feel it as your weight. Why don't you fall through your seat? Well, another force, electromagnetism, holds the atoms of your seat together, preventing your atoms from intruding on those of your seat. Electromagnetic interactions in your computer monitor are also responsible for generating light that allows you to read the screen. Gravity and electromagnetism are just two of the four fundamental forces of nature, specifically two that you can observe every day. The remaining two forces work at the atomic level, which we never feel, despite being made of atoms. The strong force holds the nucleus together. Lastly, the weak force is responsible for radioactive decay, specifically, beta decay where a neutron within the nucleus changes into a proton and an electron, which is ejected from the nucleus. Without these fundamental forces, you and all the other matter in the universe would fall apart and float away. The first force that you ever became aware of was probably gravity. Gravity holds the moon, planets, sun, stars and galaxies together in the universe in their respective orbits. It can work over immense distances and has an infinite range. Isaac Newton envisioned gravity as a pull between any two objects that was directly related to their masses and inversely related to the square of the distance separating them.

 

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Fundamental Forces Of Nature

What are the four fundamental forces of nature?

BY CRAIG FREUDENRICH, PH.D.

 

As you sit in front of your computer reading this article, you may be unaware of the many forces acting upon you.

A force is defined as a push or pull that changes an object's state of motion or causes the object to deform.

Newton defined a force as anything that caused an object to accelerate -- F = ma, where F is force, m is mass and a is acceleration.

The familiar force of gravity pulls you down into your seat, toward the Earth's center. You feel it as your weight.

Why don't you fall through your seat? Well, another force, electromagnetism, holds the atoms of your seat together, preventing your atoms from intruding on those of your seat.

Electromagnetic interactions in your computer monitor are also responsible for generating light that allows you to read the screen.

Gravity and electromagnetism are just two of the four fundamental forces of nature, specifically two that you can observe every day.

What are the other two, and how do they affect you if you can't see them?

The remaining two forces work at the atomic level, which we never feel, despite being made of atoms. The strong force holds the nucleus together.

Lastly, the weak force is responsible for radioactive decay, specifically, beta decay where a neutron within the nucleus changes into a proton and an electron, which is ejected from the nucleus.

Without these fundamental forces, you and all the other matter in the universe would fall apart and float away.

Let's look at each fundamental force, what each does, how it was discovered and how it relates to the others.

Gravity Getting You Down?

 The first force that you ever became aware of was probably gravity.

As a toddler, you had to learn to rise up against it and walk. When you stumbled, you immediately felt gravity bring you back down to the floor.

Besides giving toddlers trouble, gravity holds the moon, planets, sun, stars and galaxies together in the universe in their respective orbits.

It can work over immense distances and has an infinite range.

Isaac Newton envisioned gravity as a pull between any two objects that was directly related to their masses and inversely related to the square of the distance separating them.

His law of gravitation enabled mankind to send astronauts to the moon and robotic probes to the outer reaches of our solar system.

From 1687 until the early 20th century, Newton's idea of gravity as a "tug-of-war" between any two objects dominated physics.

But one phenomenon that Newton's theories couldn't explain was the peculiar orbit of Mercury. The orbit itself appeared to rotate (also known as precession).

This observation frustrated astronomers since the mid-1800s.

In 1915, Albert Einstein realized that Newton's laws of motion and gravity didn't apply to objects in high gravity or at high speeds, like the speed of light.

In his general theory of relativity, Albert Einstein envisioned gravity as a distortion of space caused by mass.

Imagine that you place a bowling ball in the middle of a rubber sheet. The ball makes a depression in the sheet (a gravity well or gravity field).

If you roll a marble toward the ball, it will fall into the depression (be attracted to the ball) and may even circle the ball (orbit) before it hits.

Depending upon the speed of the marble, it may escape the depression and pass the ball, but the depression might alter the marble's path.

Gravity fields around massive objects like the sun do the same.

Einstein derived Newton's law of gravity from his own theory of relativity and showed that Newton's ideas were a special case of relativity, specifically one applying to weak gravity and low speeds.

When considering massive objects (Earth, stars, galaxies), gravity appears to be the most powerful force.

However, when you apply gravity to the atomic level, it has little effect because the masses of subatomic particles are so small.

On this level, it's actually downgraded to the weakest force.

Let's look at electromagnetism, the next fundamental force.

Keeping It Together with Electromagnetism

If you brush your hair several times, your hair may stand on end and be attracted to the brush. Why?

The movement of the brush imparts electrical charges to each hair and the identically charged individual hairs repel each other.

Similarly, if you place identical poles of two bar magnets together, they will repel each other.

But set the opposite poles of the magnets near one another, and the magnets will attract each other.

These are familiar examples of electromagnetic force; opposite charges attract, while like charges repel.

Scientists have studied electromagnetism since the 18th century, with several making notable contributions.

In 1785, famed French physicist Charles Coulomb described the force of electrically charged objects as directly proportional to the magnitudes of the charges and inversely related to the square of the distances between them.

Like gravity, electromagnetism has an infinite range.

In 1819, Danish physicist Hans Christian Oersted discovered that electricity and magnetism were very much related, leading him to declare that an electric current generates a magnetic force.

British-born physicist and chemist Michael Faraday weighed in on electromagnetism, showing that magnetism could be used to generate electricity in 1839.

In the 1860s, James Clerk Maxwell, the Scottish math and physics whiz, derived equations that described how electricity and magnetism were related.

Finally, Dutchman Hendrik Lorentz calculated the force acting on a charged particle in an electromagnetic field in 1892.

When scientists worked out the structure of the atom in the early 20th century, they learned that subatomic particles exerted electromagnetic forces on each other.

For example, positively charged protons could hold negatively charged electrons in orbit around the nucleus.

Furthermore, electrons of one atom attracted protons of neighboring atoms to form a residual electromagnetic force, which prevents you from falling through your chair.

But how does electromagnetism work at an infinite range in the large world and a short range at the atomic level?

Physicists thought that photons transmitted electromagnetic force over large distances.

But they had to devise theories to reconcile electromagnetism at the atomic level, and this led to the field of quantum electrodynamics (QED).

According to QED, photons transmit electromagnetic force both macroscopically and microscopically; however, subatomic particles constantly exchange virtual photons during their electromagnetic interactions.

But electromagnetism can't explain how the nucleus holds together. That's where nuclear forces come into play.

May the Nuclear Forces Be with You

The nucleus of any atom is made of positively charged protons and neutral neutrons. Electromagnetism tells us that protons should repel each other and the nucleus should fly apart.

We also know that gravity doesn't play a role on a subatomic scale, so some other force must exist within the nucleus that is stronger than gravity and electromagnetism.

In addition, since we don't perceive this force every day as we do with gravity and electromagnetism, then it must operate over very short distances, say, on the scale of the atom.

The force holding the nucleus together is called the strong force, alternately called the strong nuclear force or strong nuclear interaction.

In 1935, Hideki Yukawa modeled this force and proposed that protons interacting with each other and with neutrons exchanged a particle called a meson -- later called a pion -- to transmit the strong force.

In the 1950s, physicists built particle accelerators to explore the structure of the nucleus.

When they crashed atoms together at high speeds, they found the pions predicted by Yukawa.

They also found that protons and neutrons were made of smaller particles called quarks. So, the strong force held the quarks together, which in turn held the nucleus together.

One other nuclear phenomenon had to be explained: radioactive decay.

In beta emission, a neutron decays into a proton, anti-neutrino and electron (beta particle).

The electron and anti-neutrino are ejected from the nucleus.

The force responsible for this decay and emission must be different and weaker than the strong force, thus it's unfortunate name -- the weak force or the weak nuclear force or weak nuclear interaction.

With the discovery of quarks, the weak force was shown to be responsible for changing one type of quark into another through the exchange of particles called W and Z bosons, which were discovered in 1983.

Ultimately, the weak force makes nuclear fusion in the sun and stars possible because it allows the hydrogen isotope deuterium to fom and fuse.

Now that you can name the four forces -- gravity, electromagnetism, the weak force and the strong force -- we'll see how they compare and interact with one another.

Comparing the Fundamental Forces

From the fields of QED and quantum chromodynamics, or QCD, the field of physics that describes the interactions between subatomic particles and nuclear forces, we see that many of the forces are transmitted by objects exchanging particles called gauge particles or gauge bosons.

These objects can be quarks, protons, electrons, atoms, magnets or even planets.

So, how does exchanging particles transmit a force? Consider two ice skaters standing at some distance apart.

If one skater throws a ball to the other, the skaters will move farther away from each other. Forces work in a similar way.

Physicists have isolated the gauge particles for most of the forces. The strong force uses pions and another particle called a gluon.

The weak force uses W and Z bosons. The electromagnetic force uses photons.

Gravity is thought to be conveyed by a particle called a graviton; however, gravitons haven't been found yet.

Some of the gauge particles associated with the nuclear forces have mass, while others don't (electromagnetism, gravity).

Because electromagnetic force and gravity can operate over huge distances like light-years, their gauge particles must be able to travel at the speed of light, perhaps even faster for gravitons.

Physicists don't know how gravity is transmitted.

But according to Einstein's theory of special relativity, no object with mass can travel at the speed of light, so it makes sense that photons and gravitons are mass-less gauge particles.

In fact, physicists have firmly established that photons have no mass.

Which force is the mightiest of them all? That would be the strong nuclear force.

However, it acts only over a short range, approximately the size of a nucleus.

The weak nuclear force is one-millionth as strong as the strong nuclear force and has an even shorter range, less than a proton's diameter.

The electromagnetic force is about 0.7 percent as strong as the strong nuclear force, but has an infinite range because photons carrying the electromagnetic force travel at the speed of light.

Finally, gravity is the weakest force at about 6 x 10-29 times that of the strong nuclear force. Gravity, however, has an infinite range. 

Physicists are currently pursuing the ideas that the four fundamental forces may be related and that they sprang from one force early in the universe.

The idea isn't unprecedented. We once thought of electricity and magnetism as separate entities, but the work of Oersted, Faraday, Maxwell and others showed that they were related.

Theories that relate the fundamental forces and subatomic particles are called fittingly grand unified theories. More on them next.

Uniting the Fundamental Forces

Science never rests, so the work on fundamental forces is far from finished.

The next challenge is to construct one grand unified theory of the four forces, an especially difficult task since scientists have struggled to reconcile theories of gravity with those of quantum mechanics.

That's where particle accelerators, which can induce collisions at higher energies, come in handy.

In 1963, physicists Sheldon Glashow, Abdul Salam and Steve Weinberg suggested that the weak nuclear force and electromagnetic force might combine at higher energies in what would be called the electroweak force.

They predicted that this would occur at an energy of about 100 giga-electron volts (100GeV) or a temperature of 1015 K, which occurred shortly after the Big Bang.

In 1983, physicists reached these temperatures in a particle accelerator and showed that the electromagnetic force and weak nuclear force were related.

Theories predict that the strong force will unite with the electroweak force at energies above 1015 GeV and that all the forces may unite at energies above 1019 GeV.

These energies approach the temperature at the earliest portion of the Big Bang. Physicists are striving to build particle accelerators that might reach these temperatures.

The largest particle accelerator is the Large Hadron Collider at CERN in Geneva, Switzerland.

When it comes online, it will be capable of accelerating protons to 99.99 percent the speed of light and reaching collision energies of 14 tera-electron volts or 14 TeV, which is equal to 14,000 GeV or 1.4 x 104 GeV.

If physicists can show that the four fundamental forces indeed came from one unified force when the universe cooled from the Big Bang, will that change your daily life? Probably not.

However, it will advance our understanding of the nature of forces, as well as the origins and fate of the universe.

Craig Freudenrich, Ph.D., is a freelance science writer. He earned a B.A. in biology from West Virginia University and a Ph.D. in physiology from the University of Pittsburgh School of Medicine. He has over 25 years experience in biomedical research, science education, and science writing.

https://science.howstuffworks.com/environmental/earth/geophysics/fundamental-forces-of-nature.htm

 

The wild-haired brilliant guy behind the first force we're going to talk about

This little guy is about to find out what gravity is all about. 

C'mon, everyone knows that opposites attract, even Paula Abdul.

Dr. Hideki Yukawa, right, receives the Nobel Prize for physics in Stockholm from then Crown Prince Gustaf Adolf of Sweden Dec. 10, 1949, for his postulation on the meson.

The magnet core of the Large Hadron Collider might one day unite the strong force with the electroweak force.

THE VISIBLE SPECTRUM - Wavelengths and Colors - Light from 400–700 nanometers (nm) is called visible light, or the visible spectrum. Light outside this range may be visible to other organisms but cannot be perceived by the human eye. Colors of light that correspond to narrow wavelength bands (monochromatic light) are the pure spectral colors learned using the ROYGBIV acronym: red, orange, yellow, green, blue, indigo, and violet. Some people can see further into the ultraviolet and infrared ranges than others, so the "visible light" edges of red and violet are not well-defined. Violet light has the shortest wavelength, which means it has the highest frequency and energy. Red has the longest wavelength, the shortest frequency, and the lowest energy. The spectrum was first described with seven colors. The visible spectrum does not encompass all the colors humans perceive because the brain also perceives unsaturated colors and colors that are a mixture of wavelengths. Mixing colors on a palette produces tints and hues not seen as spectral colors.

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The Visible Spectrum

Wavelengths and Colors

by Anne Marie Helmenstine, Ph.D. 

The human eye sees color over wavelengths ranging roughly from 400 nanometers (violet) to 700 nanometers (red).

Light from 400–700 nanometers (nm) is called visible light, or the visible spectrum, because humans can see it.

Light outside this range may be visible to other organisms but cannot be perceived by the human eye.

Colors of light that correspond to narrow wavelength bands (monochromatic light) are the pure spectral colors learned using the ROYGBIV acronym: red, orange, yellow, green, blue, indigo, and violet.

Wavelengths of Visible Light

Some people can see further into the ultraviolet and infrared ranges than others, so the "visible light" edges of red and violet are not well-defined.

Also, seeing well into one end of the spectrum doesn't necessarily mean you can see well into the other end of the spectrum.

You can test yourself using a prism and a sheet of paper.

Shine a bright white light through the prism to produce a rainbow on the paper. Mark the edges and compare the size of your rainbow with that of others.

The wavelengths of visible light are:

Violet: 380–450 nm (688–789 THz frequency)

Blue: 450–495 nm

Green: 495–570 nm

Yellow: 570–590 nm

Orange: 590–620 nm

Red: 620–750 nm (400–484 THz frequency)

Violet light has the shortest wavelength, which means it has the highest frequency and energy.

Red has the longest wavelength, the shortest frequency, and the lowest energy.

The Special Case of Indigo

There is no wavelength assigned to indigo. If you want a number, it's around 445 nanometers, but it doesn't appear on most spectra.

There's a reason for this. English mathematician Isaac Newton (1643–1727) coined the word spectrum (Latin for "appearance") in his 1671 book "Opticks."

He divided the spectrum into seven sections — red, orange, yellow, green, blue, indigo, and violet — in keeping with the Greek sophists, to connect the colors to days of the week, musical notes, and the known objects of the solar system.

So, the spectrum was first described with seven colors, but most people, even if they see color well, can't actually distinguish indigo from blue or violet.

The modern spectrum typically omits indigo. In fact, there is evidence Newton's division of the spectrum doesn't even correspond to the colors we define by wavelengths.

For example, Newton's indigo is the modern blue, while his blue corresponds to the color we refer to as cyan. Is your blue the same as my blue? Probably, but it may not be the same as Newton's.

Colors People See That Aren't on the Spectrum

The visible spectrum does not encompass all the colors humans perceive because the brain also perceives unsaturated colors (e.g., pink is an unsaturated form of red) and colors that are a mixture of wavelengths (e.g., magenta).

Mixing colors on a palette produces tints and hues not seen as spectral colors.

Colors Only Animals Can See

Just because humans can't see beyond the visible spectrum doesn't mean animals are similarly restricted.

Bees and other insects can see ultraviolet light, which is commonly reflected by flowers. Birds can see into the ultraviolet range (300–400 nm) and have plumage visible in UV.

Humans see further into the red range than most animals. Bees can see color up to about 590 nm, which is just before orange starts. Birds can see red, but not as far toward the infrared range as humans.

Some people believe the goldfish is the only animal that can see both infrared and ultraviolet light, but this notion is incorrect. Goldfish cannot see infrared light.

Anne Marie Helmenstine, Ph.D.

Introduction

Ph.D. in biomedical sciences from the University of Tennessee at Knoxville - Oak Ridge National Laboratory.

Science educator with experience teaching chemistry, biology, astronomy, and physics at the high school, college, and graduate levels.

ThoughtCo and About Education chemistry expert since 2001.

Widely-published graphic artist, responsible for printable periodic tables and other illustrations used in science.

Experience

Anne Helmenstine, Ph.D. has covered chemistry for ThoughtCo and About Education since 2001, and other sciences since 2013. She taught chemistry, biology, astronomy, and physics at the high school, college, and graduate levels. She has worked as a research scientist and also abstracting and indexing diverse scientific literature for the Department of Energy.

In addition to her work as a science writer, Dr. Helmenstine currently serves as a scientific consultant, specializing in problems requiring an interdisciplinary approach. Previously, she worked as a research scientist and college professor. 

Education

Dr. Helmenstine holds a Ph.D. in biomedical sciences from the University of Tennessee at Knoxville and a B.A. in physics and mathematics with a minor in chemistry from Hastings College. In her doctoral work, Dr. Helmenstine developed ultra-sensitive chemical detection and medical diagnostic tests.

ThoughtCo and Dotdash

ThoughtCo is a premier reference site focusing on expert-created education content. We are one of the top-10 information sites in the world as rated by comScore, a leading Internet measurement company. Every month, more than 13 million readers seek answers to their questions on ThoughtCo.

For more than 20 years, Dotdash brands have been helping people find answers, solve problems, and get inspired. We are one of the top-20 largest content publishers on the Internet according to comScore, and reach more than 30% of the U.S. population monthly. Our brands collectively have won more than 20 industry awards in the last year alone, and recently Dotdash was named Publisher of the Year by Digiday, a leading industry publication.

https://www.thoughtco.com/understand-the-visible-spectrum-608329

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THE STUDY OF CALCULUS - Before calculus was invented, all math was static: It could only help calculate objects that were perfectly still. But, the universe is constantly moving and changing. No objects - from the stars in space to subatomic particles or cells in the body - are always at rest. Indeed, just about everything in the universe is constantly moving. Calculus helped to determine how particles, stars, and matter, actually move and change in real time.

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Calculus

An Introduction to the Study of Calculus

The branch of mathematics studies rates of change

by Deb

Calculus is the study of rates of change.

The principals behind calculus date back centuries to the ancient Greeks, as well as to ancient China, India and even medieval Europe.

Before calculus was invented, all math was static: It could only help calculate objects that were perfectly still.

But, the universe is constantly moving and changing. No objects - from the stars in space to subatomic particles or cells in the body - are always at rest.

Indeed, just about everything in the universe is constantly moving. Calculus helped to determine how particles, stars, and matter, actually move and change in real time.

History

Calculus was developed in the latter half of the 17th century by two mathematicians, Gottfried Leibniz and Isaac Newton.

Newton first developed calculus and applied it directly to the understanding of physical systems.

Independently, Leibniz developed the notations used in calculus.

Put simply, while basic math uses operations such as plus, minus, times, and division (+, -, x, and ÷), calculus uses operations that employ functions and integrals to calculate rates of change.

The Story of Mathematics explains the importance of Newton's fundamental theorem of the calculus:

"Unlike the static geometry of the Greeks, calculus allowed mathematicians and engineers to make sense of the motion and dynamic change in the changing world around us, such as the orbits of planets, the motion of fluids, etc."

Using calculus, scientists, astronomers, physicists, mathematicians, and chemists could now chart the orbit of the planets and stars, as well as the path of electrons and protons at the atomic level.

Economists to this day use calculus to determine the price elasticity of demand.

Two Types of Calculus

There are two main branches of calculus: differential and integral calculus.

Differential calculus determines the rate of change of a quantity, while integral calculus finds the quantity where the rate of change is known.

Differential calculus examines the rates of change of slopes and curves, while integral calculus determines the areas of those curves.

Practical Applications

Calculus has many practical applications in real life, as the website, teachnology explains:

"Among the physical concepts that use concepts of calculus include motion, electricity, heat, light, harmonics, acoustics, astronomy, and dynamics. In fact, even advanced physics concepts including electromagnetism and Einstein's theory of relativity use calculus."

Calculus is also used to calculate the rates of radioactive decay in chemistry, and even to predict birth and death rates, the science website notes.

Economists use calculus to predict supply, demand, and maximum potential profits. Supply and demand are, after all, essentially charted on a curve - and an ever-changing curve at that.

Economists refer to this ever-changing curve as "elastic," and the actions of the curve as "elasticity."

To calculate an exact measure of elasticity at a particular point on a supply or demand curve, you need to think about infinitesimally small changes in price and, as a result, incorporate mathematical derivatives into your elasticity formulas.

Calculus allows you to determine specific points on that ever-changing supply-and-demand curve.

https://www.thoughtco.com/definition-of-calculus-2311607