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Physics Behind Gravitational Waves

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by: Panhchaka Meng; 

Media student preparing for Joint Degrees in Journalism and Media;

De Montfort University

Issue on Friday, the 10th of March, 2017 on paltform at Leicester International College, UK

Gravitational Waves


Theories to explain gravity in the universe had found for centuries. Having started from the Principle of Relativity of Galileo, it was studied again by Newton in his three Laws of Motion and Universal Gravity. Then, Lorentz expanded more on this in his transformation equation, known as Lorentz Transformation. Finally, gravitational waves were well proven by Einstein's theory of Special Relativity.


He concludes that there is a relation between an object having

Mass (M) and speeding up or having acceleration (a') with

Force (F') to another moving object having mass (m),

speeding up with acceleration (a") with Force (F") . 

1. Principle of Relativity

The theories were concluded in an attempt to reveal the fact about gravity in the universe. In the early of 17th century (1600s), Galilei concluded his hypothesis that every object in a system moving in constant speed and constant direction is seen from an observer in the system as stable.

Let's imagine the earth is in a system, called solar system;

therefore, an observer on earth, using a very sophisticated

observatory lenses, still sees that the sun is stable and 

concludes that earth rotates around the sun. This does not

true as the earth is in the same system as the sun. Whether 

the sun and the earth move in constant speed and direction

(up or down) or not, the observer cannot tell because he is 

in the system as well. In fact, the solar system is one of the 

systems in a galaxy, called the Milky Way.

Comparing the image of the Milky Way (in page 2 below the earth image) to "water drains down the drainage", Galileo concluded that the sun and the earth moved, but no one on earth can tell because we are in the same system like people

on board a ship in the middle of the ocean do not know for

sure the ship is moving without seeing the shore. However, gravitational waves cannot be taken out from the theory because it only explains that every objects are

pulled down by gravity. If so, wondering where in the universe

the earth is right now. 

2. Newton Laws of Motion and Universal Gravity

The theories about Universal Gravity became argumentative

hypothesis for many scientists. In the end of 17th century (1600s), Newton founded his laws of objects in motion.


Galileo Galilei (1564-1642) is an Italian scientists.

His specialisation are mathematics, physics, astrology,

philosophy and engineering.

Born in Pisa, Italy, he inspired with the inclined Pisa Tower,

where he experimented gravity.

He also inspired with Copernicus' theory.

The laws were laid out as: 

F'=M x a' and F"=m x a" and F'=F". This is called inertia, meaning the two moving objects affect each other causing balancing force.

The theories proved the earth and the sun are moving constantly.

Nonetheless, the laws did not prove whether gravitational waves existed. 

In a private collection


More for You!

Did you know that our solar system situates in

Orion Arm?

One of the arms that form the spiral galaxy, called

the Milky Way (right). Orion arm has 

width of 3,500 ligth year and length of 1,000 light year.

[ a light year = 9.461x 10^12 Kilometres ]


  • NASA (2015) Charting the Milky Way From Inside Out. [online] Available from: [Accessed 27/Feb/2017]
  • id. (2016) Gravitational Waves Detected 100 Years After Einstein's Prediction.
  • id. (2004) Was Galileo Wrong?
  • HELDEN, A. V. (2016) Galileo. [e-encyclopedia] Available from:  [Accessed 27/Feb/2017]
  • TANGIENT LLC (n.a.) Newton's Law of Universal Gravity. [online] Available from: [Accessed 3/Mar/2017]
  • WESTFALL, R. S. (2016) Sir Issac Newton. [e-encyclopedia] Available from: [Accessed 27/Feb/20177]

© Bettmann/Corbis

"What Goes up Must Go down"

 Issac Newton (1643-1727) is an English Scientist.

His specialisation are mathematics, Physics and astrology.

His knowledge of science was mostly acquired from 

Copernicus'sKepler'sGalileo's and Descartes' theories.

His famous theory explains the universe

differently including why the earth is held in place in the universe.

Credits: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

Courtesy of Stanford University


Gravitational Waves (cont.)

In addition to Galilei's and Newton's theories, the new theories helped scientists of the 20th century easily explore the mysteries in the space until they were able to send a large number of space crafts to find the evidence for concluded 

theories. Although the calculation was useful, Lorentz did not manage to conclude his hypothesis and write up formula to explain the relativity of light, mass of colliding matters and their power of collision. In the beginning of the 20th,

Einstein concluded all hypothesis and write up the Special Relativity.


4. Einstein's Special Relativity

By the early of 20th century (1900s), scientists knew that gravitational waves were a universal phenomenon.

However, no scientists could prove their existence because no contemporary theories had been taken out from the previous hypothesis about gravitational waves yet. Therefore, Einstein continued the work of Lorentz until he found 

relation between energy(E)mass (m) and speed of light.

Now that the two scientists pioneered the human ambitious to reveal the secret of the sky, two contemporary scientists found the conclusion to the sky mystery— Gravitational Waves.

3. Lorentz Transformation

It could be considered as useless to predict a phenomenon

using mathematical calculation in the modern era when

scientists used sophisticated tools to prove the facts. However,

without Lorentz's calculation using those tools did not make

any sense because seeing was not understanding, especially when the objects, particles, were millions of light years away.

Therefore, the calculation, called Lorentz Transformation, explain the phenomenon experienced through scientists' eyes.

As Gravitational Waves occur when two massive galactic

matters such as neutron stars or black holes collide into each other, emission of light can be detected. This detection

of light was not fully stated by NewtonTherefore, Lorentz

Transformation lets scientists accurately learn about

Gravitational Waves. Lorentz himself found two other

theories of Gravitational Waves: time dilation and Doppler

effect, using the calculation.


Hendrik A. Lorentz (1853-1928) is a Dutch physician.

His specialisation was on electromagnetic theories

which he inspired from Maxwell.

Even though his work from which

he won Nobel Prize in 1902 did

not directly conclude on gravitational waves,

it contributed to

Einstein's hypothesis for his special relativity theory.

©The Nobel Foundation, Stockholm



  • BRITTANICA ENCYCLOPEDIA (2016) Albert Einstein. [e-encyclopedia] Available from :  [Accessed 27/Feb/2017]
  • id., (1999) Hendrik A. Lorentz.
  • LIGO (n.d.) About aLIGO. [website] Available from:  [Accessed 27/Feb/2017]
  • MANCHESTER UNIVRSITY (n.d.) Mass Energy and Interval. [e-book] Available from: [Accessed 26/Feb/2017]
  • NASA (2016) NSF’s LIGO Has Detected Gravitational Waves. [online] Available from: [Accessed 24/Feb/2017]
  • STROBEL, N. (n.d.) Time Warp. [online] Available from: [Accessed 27/Feb/2017]

More for You!


Success in detecting gravitational waves in 2010 proved that the gravitational waves is an existent phenomenon caused by collision between two massive universal matters such as neutron stars or black holes. Recently, iLIGO [Initial LIGO] has innovated to aLIGO [Advanced LIGO] (right). The innovation helps scientists study and record about gravitational waves, based on accurate observation. 

The theory is laid out, as follows:

E=mc^2, meaning energy produced by

a moving particle having nonzero velocity

proportionates with its mass and 

speed of light emitted from it. This theory

helps LIGO detect gravitational waves

and prove their existence. 


.It took about 4 centuries to approve the fact about gravitational waves. Even though gravitational waves finding makes physics enthusiastic, more findings about the universe  remain uncovered and more enthusiastic physics will be. Let's be reminded that gravitational waves is caused by collision between two neutron stars or  two black holes. Wondering who are the physicians behind them and which physic theories is used to prove it, find out more in the next monthly issues.

Hulton Archive/Getty Images


Albert Einstein (1879-1955)

is a German-born American physician.

His Special Relativity theory opened new 

era for science in the 20th century or

modern science.