What is physics? History, Discoveries, and Branches of Physics
What is physics? History, Invention, Discoveries, and Branches of Physics

Humans were always curious about the world around them. Various bright and heavy celestial objects in the night sky have always been fascinated humans since ancient times. Regular repetition of day and night, annual cycle of seasons, eclipses, tides, rainbows, and many other phenomena have always been a source of wonder for humans. The inquisitive and imaginative human mind has always responded to all these wonders and tries to find different ways to understand and express them. Humans always pay very keen attention to know the world around them, which results in the origin of science.

Actually, the word science comes from the Latin verb 'Scientia' which means 'to know'. In Sanskrit the word Vijñãn and also in Arabic word Ilm convey a similar meaning, which is 'knowledge'. Science has many branches, Physics is one of them. If you are unfamiliar with this physics and want to know more about it then this article is for you. From this article, you will know about the following things.

• What is Physics?
• What is Scientific method?
• Unification and Reduction
• Hypothesis in Physics
• Mathematics in Physics
• Branches of Physics
• History of Physics
(Some physicists and their contributions, Discoveries, and Inventions)
What is Measurement? (Beginner's Guide)
What is Measurement

Measurement is the very basis of all scientific studies and experimentations. It also plays an important role in our day-to-day life. When it comes to building a table, putting a picture on the wall, timing a race, we need to be able to do measurements. Because it answers questions such as: how big, how long, how deep, how heavy the things are?

But to measure in a scientific way, we need to know some basic things about measurement. So in this tutorial, we are going to discuss some basic aspects of measurement, such as

• What is measurement?
• What is the physical quantity?
• What are the fundamental quantities?
• What are the derived quantities?
• What is the unit?
• What are the fundamental units?
• What are the derived units? 
• What are the systems of units in measurements?
• The CGS units
• The MKS units
• The FPS units
• Instruments for measurement
What is force? definition and types of force with example
What is force

From ancient times many philosophers have used the concept of force in the study of stationary and moving objects and simple machines, but thinkers like Aristotle and Archimedes retained the fundamental errors in understanding what is force. According to Aristotle, a force is anything that causes an object to undergo “unnatural motion”.  After that most misconceptions about motion and force were finally corrected by Galileo Galilei and Sir Isaac Newton. Here in this article, we are going to discuss some basic things about the force - that what force is, types of forces, and more about it. Below is a table of contents of what you will know from this article.

• What is force?
• How force is measured?
• What is balanced and unbalanced force?
• What is the net force?
• What is the push and pull action of force?
• What are the types of forces?
• What is frictional force?
• What is centripetal and centrifugal force?
• What are the fundamental forces of nature?
What is Special Theory of Relativity?
Special Theory of Relativity


What is Special Theory of Relativity?

The Special Theory of Relativity, also known as Special Relativity, is a scientific theory developed by Albert Einstein in 1905 regarding the relationship between space and time. Basically, this theory explained how to interpret the motion between different inertial (i.e constant speed or no acceleration) frames of reference, and also talked about the speed of light in a vacuum. This theory is based on two postulates the principle of relativity and the principle of the speed of light.

The principle of relativity: 

The laws of physics are invariant (i.e not changeable),  in all inertial frames of reference (i.e the frame of reference with constant speed or no acceleration).

The principle of the speed of light: 

The speed of light in a vacuum is the same for all observers, regardless of their motion relative to the source of light or observer. ( The speed of light in the vacuum are represent with the symbol c and the value of it is 299,792,458 meters per second or about 186,000 miles per second).


This Special Relativity is applicable only in the special cases (that is why this name) where the motion is uniform. It only explains such motion where the object moves in a straight line at a constant speed. If the object starts to accelerate or do anything that changes the nature of the motion then this theory stops there.

But objects are not always in the inertial (or non-accelerating) frame of reference they are also in non-inertial (or accelerating) frames of reference. Hence, Einstein was trying to include acceleration in his theory. Then In 1915, he published his General Theory of Relativity that can explain the general cases of any sort of motion.

Consequences of Special Theory of Relativity

Space-time continuum:

In Einstein’s special relativity he created a fundamental relation between space and time. Where the physical universe consists of four dimensions - the three dimensions of space (length, width, and height…or up/down, left/right, and forward/backward) and the fourth one is the dimension of time. This 4-dimensional space in the universe is referred to as the space-time continuum.


The reason why time is considered as the 4th dimension in relativity because the 3-dimensional coordinate system can't describe every event completely. That is why we have to include the time coordinate in describing events fully in space along with the time.

Mass variation:

According to special relativity, the mass of an object in a frame of reference at rest is called its rest mass m0. Now if the object travels at a constant speed v then the mass will not remain constant. This mass variation can be measured by this formula - 


Where,
m =  mass of the object in motion
m0 =  rest mass
v =  speed of the object
c = speed of light in vacuum

case (1):

When the velocity of the object v is very small compared to the velocity of light c (i.e v2/c2 is negligible compared to one), then m = m0.

case (2):

When the velocity of object v is comparable to the velocity of light c (i.e √(1-v2/c2) is less than one), then the mass of the moving object appears greater than its rest mass, (i.e m>m0).

case (3):

When the velocity of the object v is equal to the velocity of light c, then the mass of the moving object is possessed infinite mass.


Length contraction:

In special relativity, it has been found that the measurement of the length of a rod in a fixed frame of reference is not the same as when measured by an observer in a moving frame of reference with a velocity corresponding to the rod. This means there is a length variation that happens in the observation. This length variation can be measured by this formula - 


Where,
l  = length of the object at motion
l0 = length of the object at rest
v =  speed of the object
c = speed of light in vacuum

Case (1):

When the velocity of the rod v is very small compared to the velocity of light c (i.e v2/c2 is negligible compared to one), then l = l0.

Case (2):

When the velocity of rod v is comparable to the velocity of light c (i.e √(1-v2/c2) is less than one), then the rod appears shorter than its length when seen at rest (i.e l<l0).

Case (3):

When the velocity of the rod v is equal to the velocity of light c, then the length of the rod becomes zero (i.e l = 0).

In the hole process, the rod remains unchanged along the perpendicular direction but the contraction takes place in the direction of motion. Since the contraction of the rod takes place, the phenomena are known as the length contraction.

Time dilation:

In classical mechanics, time is regarded as an absolute quantity. But in special relativity, it is considered to be a relative entity based on the measurement of time in the frame of references in relative motion. The variation of the time in relative motion can be measured by this formula -



Where,
t = time in motion
t0 = time at rest
v =  speed of the object
c = speed of light in vacuum

case (1):

When the velocity of the object v of the moving frame of reference is very small compared to the velocity of light c (i.e v2/c2 is negligible compared to one), then t = t0.

case (2):

When the velocity of object v of the moving frame of reference is comparable to the velocity of light c (i.e √(1-v2/c2) is less than one), then the time observation of the moving frame of reference appears greater than its in rest, (i.e t>t0).

case (3):

When the velocity of the object v of the moving frame of reference is equal to the velocity of light c, then T = infinite. But Infinite time is meaningless, so we have come to the conclusion that no material body can move at the speed of light.


Mass energy relation:

According to classical physics, there are two entities of nature - matter and energy. They are both immortal. That is, matter or energy is not destroyed, only one form of energy can be converted into another form of energy, similarly, it is applicable to matter. From all these things came the law of conservation of mass and conservation of energy.


Until Einstein, the concepts of mass and energy were seen as completely separate. He proved that the principles of conservation of mass and conservation of energy are part of the same large, unified principle, the conservation of mass-energy.

In modern physics, according to Einstein's theory of relativity matters can be converted into energy and energy can be converted into matters because a fundamental relationship exists between these two kinds of entities. This relationship between mass and energy was first correctly deduced by Einstein, which is known as the mass-energy relation.

According to the mass-energy relation,


Where E = energy, m = mass of the objects, c = speed of light (299,792,458 m/s) in vaccum


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What is Energy? Definition, Different kinds of energy
What is Energy

Just as some things in nature remain unchanged for a long time, similarly too many things are constantly changing. During each change, each object exchanges some energy with its surrounding material. The various changes we see in various substances are due to this exchange of energy. Since people understood how energy changes occur from one form to another, modern civilization has become possible.

In everyday life we use energy in a variety of ways - we use energy for walking and cycling, driving on roads and boats through the water, cooking food in the oven, lighting our homes and offices, making products, and sending astronauts into space, etc. In all of these activities, energy is being continuously exchanging from one object to another.

What is energy?


In physics, energy is defined as the ability to do work. Where the work is said to be done on an object when a force makes changes in the position of the objects. And the force is something that can change the shape and position of the objects.


According to classical physics, there are two entities of nature - matter and energy. They are both immortal. That is, matter or energy is not destroyed, only one form of energy can be converted into another form of energy, similarly, it is applicable to matter. From all these things came the law of conservation of mass and the law of conservation of energy.

However, in modern physics, according to Einstein's theory of relativity, it is possible to convert matter into energy and energy into matter. From which the law of conservation of mass energy is obtained.
What is an LED? Definition, Types, Working Principle, and Uses
We all know, for a long time people used oil lamps, hurricanes to illuminate the night. At that time, the invention of the bulb gave a new direction to science. Now modern technology uses a lot of devices to generate light such as tungsten lamp, CFL, LED, etc. In all of them, the most efficient device to produce light is LED.


If you do not know much about it, this article is for you. Today, I am going to unlock the details of the LED. In this article, you will know -

1. What is an LED?
2. Symbol of LED
3. What are the types of LEDs?
4. How does LED work?
5. Uses of LEDs
What is Matter? Definition, States of Matter

What is Matter?


According to classical physics, anything in this universe that has mass and volume (that occupies some space) is called matter. Matters are all around us, these are some things that you are seeing and touching every day such as rock, trees, anything you consume as food, whatever you drink, and the oxygen that you take in through breath are all matters.

Matter exists in different states (also known as phases) such as - solid, liquid, and gas – for example, water exists as ice ( solid form), liquid water, and gaseous steam – but other states of matter are possible such as plasma, Bose-Einstein condensates, fermionic condensates, and quark-gluon plasma.

All matters that we know so far are made up of atoms which are composed of electron, proton, and neutron. Atoms come together to form molecules, which act as building blocks for all kinds of matters. According to classical physics, matter, which is made up of electron, proton, and neutron is considered to be a particle for scientific interpretation.

But the concept of matter is further complicated when it comes to quantum mechanics. In the quantum mechanics view, matters behave both like particles and waves which is also known as the duality nature of matter.

But the matter we are talking about is only 5% of the entire universe. The remaining 95% of the universe is made up of dark matter and dark energy, which is completely unknown to us.
What is Artificial Intelligence (AI)? Explained
What is Artificial Intelligence (AI)?

Contents:

1. What is Artificial Intelligence (AI)?
2. History of Artificial Intelligence (AI)
3. Types of Artificial Intelligence (AI)
4. How does Artificial Intelligence (AI) Work?
5. Applications of Artificial Intelligence (AI)

What is dark energy? Explained
What is dark energy

Matters that we know such as planets, stars, galaxies, trees, rocks, etc they are only 5% of the universe. About 27% is dark matter and 68% is dark energy. Both dark matter and dark energy are invisible to us.

So, how do we know that dark energy exists? What research has been done about it? If all these questions come to your mind and you want to know about it, then this article is for you. Today, I am going to unlock the details of the dark energy. In this article, you will know -

1. What is dark energy?
2. What is dark matter?
What is dark matter? Explained
What is dark matter

Matters that we know such as planets, stars, galaxies, trees, rocks, etc they are only 5% of the universe. About 27% is dark matter and 68% is dark energy. Both dark matter and dark energy are invisible to us. Dark matter is made up of such particles that do not absorb, reflect, or emit light, that is why they cannot be seen directly nor be detected by observing electromagnetic radiation.

So, how do we know that dark matter exists? What is it made of? What research has been done about it? If all these questions come to your mind and you want to know about it, then this article is for you. Today, I am going to unlock the details of the dark matter. In this article, you will know -

1. What is dark matter?
2. What is dark energy?
3. Dark matter research
What is Electromagnetic Radiation? Explained
What is Electromagnetic Radiation

Introduction

Actually, we are all surrounded by electromagnetic radiation. The light we see around us is a type of electromagnetic radiation. However, it is a small part of the electromagnetic spectrum. In addition to this visible light, many other rays surround us that are not visible to our naked eyes such as radio waves, microwaves, infrared rays, ultraviolet rays, x-rays, and gamma rays. These are all electromagnetic radiation.


If you do not know much about it, this article is for you. Today, I am going to unlock the details of the electromagnetic radiation. In this article, you will know -

1. What is Electromagnetic Radiation?
2. What is Electromagnetic theory?
3. What is Electromagnetic Spectrum?
4. Measuring electromagnetic radiation
What is Electromagnetic Spectrum? Explained
What is Electromagnetic Spectrum

Introduction

In addition to the ray we see with our eyes, there are many rays in the universe that are not visible to the naked eye. To study all those rays, based on their differences in frequency and wavelength, a scientific scale system called electromagnetic spectrum (EMS) has been created.


If you do not know what the electromagnetic spectrum is, this article is for you. Today, I am going to unlock the details of the electromagnetic spectrum. In this article, you will know -

1. What is Electromagnetic Spectrum?
 a) Radio waves
 b) Microwaves
 c) Infrared rays
 d) Visible light
 e) Ultraviolet rays
 f) X-rays
 g) Gamma rays

What is Nuclear Fission? Explained
What is Nuclear Fission

Introduction

Among the technologies we use today to generate electricity, the most efficient way to generate electricity is nuclear power plants. 
Because nuclear power plants generate electricity with the help of nuclear energy. In these power plants, heat energy is generated through nuclear fission of atoms which is then used to generate electricity.

If you don't know what nuclear fission is, this article is for you. Here I am going to unlock the details of nuclear fission. In this article, you will know

1. What is Nuclear Fission?
2. What is Nuclear Energy?
3. Calculation of Nuclear Energy
4. Uses of Nuclear Energy

What is Radioactive Decay? Explained
What is Radioactive Decay

Introduction:

In a previous article, we learned about radioactivity. There we learned that radioactivity is a nuclear phenomenon where the unstable nucleus tries to come to a steady-state by spontaneously emitting alpha particle (𝛼), beta particle (𝛽), and gamma (𝛾) radiation. In this article, we are going to discuss radioactive decay to complete radioactivity.

If you do not know what is Radioactive decay, this article is for you. Today, I am going to unlock the details of the Radioactive decay. In this article, you will know -

1. What is Radioactive decay?
2. Types of Radioactive decay
a) Alpha emission
b) Bita emission
c) Gamma emission

What is Radioactivity? Explained
What is Radioactivity

Introduction:

In nature, there are some atoms whose nucleus is in an unstable state. For this instability, atoms emit some ionizing radiation or particles from the nucleus and try to be stable. This phenomenon of particle emission from the nucleus of atoms is known as radioactivity.

If you do not know what is radioactivity, this article is for you. Today, I am going to unlock the details of the radioactivity. In this article, you will know -

1. What is Radioactivity?
2. Why Radioactivity occur?
a) Radioactive substances
b) Radioactive isotopes
c) Nature of radioactivity
3. Discovery of Radioactivity
4. Use of radioactivity

What is 5G Network? Explained
What is 5G Network

What is 5G Network?


5G Network is the fifth-generation mobile network technology. It is the latest repetitive cellular technology to increase the speed and responsiveness of the wireless network. It will deliver new levels of performance in speed, capacity, and latency and will work in high efficiency that will empower new user experiences and connect new industries.


5G NR speed can be slightly higher than the 4G NR speed. With 5G, data will be delivering up to 20 Gigabits-per-seconds peak data rates and 100+ Megabits-per-second average data rates.
What is X-ray? Explained
What is X-ray

Introduction:

In the late 18th century and the beginning of the 19th century, a special type of ray was found that has profoundly influenced various branches of science today. Yes, I'm talking about the unknown ray of that time, which is now known as X-rayWhatever the field, it may be the medical field, engineering, science exploration, etc, x-rays are now widely used.

If you do not know what is x-ray, this article is for you. Today, I am going to unlock the details of the x-ray. In this article, you will know -

1. What is X-ray?
2. Discovery of X-ray
3. Types of X-ray spectrum
 a) Continuous X-ray spectrum
 b) Characteristics X-ray spectrum
4. How X-ray is Created?
5. Different uses of X-rays
6. Dangers of X-ray

What is Big Bang Theory? Explained
What is Big Bang Theory

Introduction:

For a long time, people have questioned how our universe was created? For which people start trying to find the answer. Now we have six major theories and concepts that try to explain the origin of our universe. These six theories are like that - Big Bang theory, Steady State theory, Eternal Inflation theory, Oscillating Universe theory - (Cyclic model), Oscillating Universe theory -  (Branes model), and Exotic theories - ( Hologram, Creationism, Simulation). Among them, one of the best theory is the Big Bang theory.


In all six theories, the Big Bang theory is the most accepted scientific theory today. Because all experimental data is fitted into this theory or another way this theory is fit into our experimental data.  If you do not know what is big bang theory, this article is for you. Today, I am going to unlock the details of the Big Bang theory. In this article, you will know -

1. What is the Big Bang theory?
2. Big Bang Theory - Timeline
 a) Plank epoch
 b) Inflation Epoch
 c) Cooling Epoch
 d) Structure Epoch
3. History of Big Bang theory

What is Quantum Computer? Explained
What is Quantum Computer

Computers have become a very important part of our lives. Whatever the point of research, space exploration, and technological advancement, nothing is possible without a computer. In the past few centuries, we have reduced the size of the computer or even the power of computing has been greatly enhanced. If we use the example of today's smart phone's computing power, then it is much better than the military computer which was the equivalent of a room.

Despite all those things, our classical computer today is not perfect in many ways. If you talk about their general limitations, then it is their speeds. Because it takes a lot of time to solve complex mathematical equations. 


Among other problems, storage space issues and energy consumption plays a very important role. For this, we need a computer that is many times better than today's computer.

Companies like Google, IBM (International Business Machines Corporation), and Intel are using the rules of quantum physics to create computers that we can be called futures computers. These computers are named Quantum Computers.

This kind of computer has been built or even used in small calculations. Now, these companies are trying to make this computer at a bigger level. 

If these computers start to be built at a larger level,  then they will replace the computers used today. If you do not know what is quantum computer then this article is for you. In this article, you will know -

1. What is Quantum computer?
2. How Quantum computer work?
3. Problems with making Quantum computers
4. What a Quantum computer can do?

What is String Theory? Explained
What is String Theory

Introduction:

If we see in the eyes of science then we use two different types of theories to understand the whole universe - the first theory is the General Theory of Relativity and the second is the Quantum Field Theory.

If we talk about the bigger objects like stars, planets, etc in this universe then we use the General Theory of Relativity to understand the behavior of this universe.

Where we use the Quantum Field Theory to understand the structure of matter and interaction of energies in the atomic and subatomic levels.

Both of these theories work very well within their respective domains. This means that if an object is larger in size, then the General Theory of Relativity will work there. And if an object is smaller in size or very less in mass, then the Quantum Field Theory will work there.


But why there are two different theories for understanding the behavior of the universe?

So, can we not formulate a theory that will be able to explain the bigger levels and quantum levels phenomena occurring in the universe?

This type of thinking of physicists gives rise to a new theory that we know in the name of string theory. The peculiarity of this theory is that it talks about quantum gravity and multiple dimensions

And it also helps to answer some questions that are related to the BigBang's previous universe, which are still mysterious in modern physics. If you do not know what is string theory then this article is for you. In this article, you will know -

1. What is String Theory?
2. What are the Fundamental Forces? 
3. What is the Standard Model of Elementary Particles?
4. What does String Theory say?
5. What are Multiple dimensions in string theory?
6. What is Quantum gravity in string theory?