Understanding the Fabric of Reality
The origin of modern astrophysics — Einstein’s Theory of Relativity explained in a multi-part series.
The late 1800s was a period of immense scientific and technological progress. J.C. Maxwell had recently provided new insights into the nature of electric and magnetic fields and the discovery of electromagnetic waves sought to revolutionize the way we communicate ever after. Overall, it seemed the world was on the cusp of transformation. Isaac Newton’s laws of motion and gravity had reigned supreme for over two centuries, providing a robust framework to understand the universe's mechanics. However, cracks began to appear as scientists delved deeper into the nature of light and the behavior of objects at incredibly high speeds.
As physicists began to unify mechanics and electrodynamics into a single strand of concepts, new problems started arising in mechanics that pointed out that something wasn’t completely right. Then, Michelson and Morley performed their famous experiment in 1887 hoping to search for the medium through which electromagnetic waves travel following the classical view of physics — ‘luminiferous ether’ (I̶ k̶n̶o̶w̶ i̶t̶ s̶o̶u̶n̶d̶s̶ l̶i̶k̶e̶ a̶ n̶a̶m̶e̶ s̶t̶r̶a̶i̶g̶h̶t̶ o̶u̶t̶ o̶f̶ a̶ s̶c̶i̶-̶f̶i̶ m̶o̶v̶i̶e̶, i̶t̶’s̶ n̶o̶t̶ :̶(̶) … which gave a negative result. This single stroke of experimentation challenged the way physicists sought to view and understand nature. The experiment’s results brought a major blow to physicists and created a hole in the subject that would not be filled until the next 15 years.
The Genius of Einstein
It was during these times that a young officer in the patent office in Bern rolled out a series of papers that changed the course of physics forever. Among the four breakthrough papers published by Einstein in 1905, the Annus Mirabilis, was one entitled ‘Zur Elektrodynamik bewegter Körper’ or ‘On the Electrodynamics of Moving Objects’, the paper that showed the world a new image of the universe — one in which space and time merged to create a new ‘spacetime’. This was the paper that introduced the world to the concept of ‘special relativity’. Einstein’s genius lay not only in his mathematical prowess but also in his ability to perceive the universe in a fundamentally different way. His journey towards Special Relativity began with quite a simple question: What would happen if the speed of light were constant for all observers, regardless of their motion? Using this one postulate, he was able to shatter the withstanding notions of physics right from the very basics. Newtonian mechanics came to appear as a mere approximation — a special case of the more general relativistic mechanics.
10 years later, in another landmark result in 1915, Albert Einstein introduced the world to a new view of gravity — one based on general relativity through four texts in November. This theory furthered the Newtonian view of the gravitational force by merging it with one consistent with special relativity. The theory’s success is apparent from the fact that it stands still as one of our most accurate theories to date. The theory has passed every experimental test and has led to the emergence of various other concepts through the specific solutions of what is called the ‘Einstein Field Equation’ of general relativity.
Special relativity solved a large number of outstanding and eventual problems in physics:
- discarded the need for the presence of ‘ether’ thereby providing a coherent explanation of the results of the Michelson-Morley Experiment.
- explained the results of the Fizeau Experiment — the discrepancy observed in the speed of light through a moving optically dense medium such as water; and stellar aberration.
- Subsequent experiments, such as the measurement of the decay rates of particles moving at high speeds (cosmic rays), confirmed predictions of time dilation and relativistic effects.
You may have noticed details were omitted for this experiment, this was done because the concepts behind them have not been covered yet in the series. But do not worry, we will talk about them later on!
The precision of modern technology, from particle accelerators to GPS satellites, relies on Einstein’s insights into how time and space are interwoven, ensuring accurate measurements and predictions in today’s age of information.
Relativity — Explained
The concept of relativity is often seen as one beyond the scope of imagination. It can often come off as intimidating to the layman. Yes, relativity is counter-intuitive for it is general, i.e. not limited in its scope to approximable speeds; and technically, not many of us spend our day speeding off at ninety percent the speed of light. Through this series, I wish to introduce this specific field of mechanics in a way that comes as easy to understand and possibly helps to deepen the understanding of the reader in a visualizable way.
In this introductory article, we have barely scratched the surface of Einstein’s revolutionary insights into Special Relativity. Throughout the series, we will explore in greater depth the mathematics, implications, and broader impact of Einstein’s theory. From the twin paradox to the nature of spacetime, part by part, we will delve into how this theory came into existence and explore various possibilities of what could have been or why couldn't it have been in another way.
We will tread on in a historical manner — for this would be as much a story of the era in itself as an explanatory series. Starting with the period just after the conception of Maxwell's electrodynamics, we will first discuss the story of luminiferous ether — its birth, the problems faced, and its eventual downfall. We will then move on to Special Relativity and spend some time building an understanding of the same. Our series will eventually end with General Relativity which would take well, quite some time, being exceptionally math-heavy.
A few key notes before continuing with the series:
- The readers are encouraged to read and explore relativity further than these articles. These articles provide a basic understanding of the theory. Though we will often take detours to discuss related concepts throughout, however, the burden of text and communication limits us in this process. Suggested readings and sources would be provided at the end of every article for the active involvement of the reader.
- During the series, a few mathematical and physical concepts will be used directly and not be talked about later, for such concepts also, it is suggested to view the links provided in the ‘Texts and References’ section. The reader is encouraged to read them for more conceptual clarity of the concept.
Join us as we embark on a journey into the mind of Albert Einstein and his contemporaries— one that will reveal not just the mysteries of the cosmos, but also the lasting impact of an era whose ideas still shape how we understand our ‘Fabric of Reality’.
And as always, t̶h̶a̶n̶k̶s̶ f̶o̶r̶ w̶a̶t̶c̶h̶i̶n̶g̶ signing off with an xkcd:
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