Tag Archives: General Relativity

100 years of General Relativity part 7: Gravitational Waves, a New Window to the Universe

Friends,

This is the seventh and last part of the VERITAS series on General Relativity. Just to remind our readers: We are doing this series on Einstein’s Theory of Relativity to celebrate the 100th Anniversary of General Theory of Relativity. If you have missed any of the first six parts, you can read them here:
https://unvarnishedveritas.wordpress.com/tag/100-years-of-general-relativity/

Continue reading 100 years of General Relativity part 7: Gravitational Waves, a New Window to the Universe

100 years of General Relativity part 6: Origin and Evolution of the Universe

This is the sixth part of the VERITAS series on General Relativity. Just to remind our readers: We are doing this series on Einstein’s Theory of Relativity to celebrate the 100th Anniversary of General Theory of Relativity. If you have missed any of the first five parts, you can read them here:
https://unvarnishedveritas.wordpress.com/tag/100-years-of-general-relativity/

In the previous parts we have studied the basic ideas behind special and general relativity. We have discussed how gravity bends space time and slows down time. We have also explored one of the most interesting and astonishing results of relativity: black holes. If you have not read the previous parts, I suggest you read them before reading this one.

In this article we will apply General Relativity to the biggest possible problem that can be thought of: the whole universe. We will understand the current theory of how the universe originated and how it evolved after that. We will also see how the universe will evolve into the future. We will also learn about dark energy and dark matter. But before we move further, think about the magnitude of what modern physics allows us to do: we, tiny creatures living on a small planet revolving around a small star in one corner of a medium sized galaxy( which contains over 100 billion stars) have developed the ability to ask and try to answer questions about the whole universe which contains billions of galaxies like our own!

Continue reading 100 years of General Relativity part 6: Origin and Evolution of the Universe

100 years of General Relativity Part 4: Gravity causes time to slow down

 

Friends,

This is the fourth part of the VERITAS series on General Relativity. Just to remind our readers: We are doing this series on Einstein’s Theory of Relativity to celebrate the 100th Anniversary of General Theory of Relativity. If you have missed any of the first three parts, you can read them here:
https://unvarnishedveritas.wordpress.com/tag/100-years-of-general-relativity/

In the previous part we discussed the fundamental idea behind General Relativity- The Equivalence Principle. We used the equivalence principle to show that light is bent by gravity. And then we reasoned that gravity bends space-time and that objects moving along this distorted space-time seem to be moving under the influence of a force. If you have not read that part( or the previous ones), I suggest you read them before reading this one.

In this episode of this VERITAS series we will show how gravity causes time to slow down. We will also consider a practical application of this phenomenon.

Continue reading 100 years of General Relativity Part 4: Gravity causes time to slow down

100 years of General Relativity Part 3: Gravity bends Space-Time

Friends,

This is the third part of the VERITAS series on General Relativity. Just to remind our readers: We are doing this series on Einstein’s Theory of Relativity to celebrate the 100th Anniversary of General Theory of Relativity. If you have missed any of the first two parts, you can read them here:
https://unvarnishedveritas.wordpress.com/tag/100-years-of-general-relativity/

In the previous part we reviewed the Special Theory of Relativity that Einstein proposed in 1905. That theory combined space and time into a single concept, space-time and showed us that time does not flow equally for every object in the universe- time is a relative concept and its flow can vary based on the observer’s frame of reference. We also learnt that if an observer finds that two observations are simultaneous, a different observer in a different reference frame may not find those events simultaneous. We also learnt about some amazing and fantastic consequences of Special Relativity- time dilation, length contraction, twin paradox etc. If you have not read the VERITAS on Special Relativity, I suggest you read it before you start reading this one.

Around 1907 Einstein started think about expanding Special Theory of Relativity to include non-inertial( accelerating) frames. As we have already discussed, Special Relativity only considered uniformly moving frames. In 1907 Einstein was still working as a clerk in the Swiss patent office. His 1905 papers had created quite a stir in the scientific community. But he was still unknown outside the scientific community.

Continue reading 100 years of General Relativity Part 3: Gravity bends Space-Time

100 years of General Relativity Part 2: Introduction to Special Relativity

Friends,

As you know, in this series we are celebrating 100th anniversary of General Theory of Relativity. This is the second part of this series. You can read the first part at : https://unvarnishedveritas.wordpress.com/
Before we discuss General Theory of Relativity, we need to understand the concepts of Special Theory of Relativity. In this VERITAS article, I will give you an introduction to the Special Theory of Relativity.

1905 was a very important year for Einstein and his scientific pursuits. Einstein turned 26 years old in March of that year. He was employed as a clerk in the Swiss patent office in Bern, he was already married and had two sons. His work at the Swiss patent office was neither creative nor did it involve much science. Einstein balanced his work in office, his family life and his real interest, Physics. Like today’s age, the greatest scientific breakthroughs in those days came from universities and laboratories. Einstein was far away from these institutions and was working completely alone( he did discuss his ideas with his friends but none of them were professional scientists). And he had limited access to scientific journals. But he still published 4 papers that year and each one of those papers was a breakthrough in the world of physics. The first of these papers explained the photoelectric effect and laid the foundations of quantum physics, the second paper dealt with Brownian motion, the third paper proposed the Special Theory of Relativity and in the fourth paper Einstein derived the most famous equation of Physics: E= mc^2. It is amazing that a 26 year old clerk could come up with 4 amazing ideas that would change the course of physics in a single year. This year( 1905) is often referred to as Einstein’s Annus Mirabilis ( Miracle year). If you want to read Einstein’s biography, I would recommend “Einstein: The Life and Times” by Ronald Clark and “Einstein: His life and Universe” by Walter Isaacson.

Continue reading 100 years of General Relativity Part 2: Introduction to Special Relativity

100 years of General Relativity Part 1 : Introduction

einstein

Friends,

Exactly a hundred years back, in November 1915, Albert Einstein published a paper that would change the way we look at the universe. He called this theory, “The General Theory of Relativity”. Ten years earlier Einstein had published the Special Theory of Relativity which for the first time combined space and time into a single inseparable “fabric” known as space-time. That was a revolution too but at a slightly smaller scale. The Special Theory applied only to objects moving at a uniform rate. The General Theory of Relativity included accelerating objects and explored the relationship between acceleration and gravity.

Continue reading 100 years of General Relativity Part 1 : Introduction