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Agence France-Presse

When Albert Einstein forged the bedrock theory of modern physics 100 years ago, he had no computer, no internet, no printer – ballpoint pens and pocket calculators did not exist and few homes had telephones.
Yet it took one of the most sophisticated science tools ever built, at a cost of hundreds of millions of dollars, to prove an idea the scientist had crafted with little more than paper, a fountain pen, hard work and a mind sharper than most.
On Thursday, physicists announced they had detected gravitational waves – hitherto a key unproven element of Einstein’s general theory of relativity.
What are gravitational waves?

READ MORE: ‘Holy grail of science’: Einstein’s gravitational waves are detected in landmark discovery
The thesis was published 100 years ago this year, when the world was a very different place, inhabited by a man way ahead of his time.

Radios had been invented, but not yet entered people’s homes.
The first transcontinental telephone call was made in 1915, from New York City to San Francisco, as was the first transatlantic call between Arlington, Virginia and Paris, France.
Electric refrigerators were not yet a thing, and cars shared the road with horse-drawn carriages.
The Eiffel Tower was the tallest building in the world.

In maths, the height of calculating power was the “comptometer” – a clunky mechanical adding machine that predated the electronic calculator.
In physics, there were already interferometers, but they bore little resemblance to the Laser Interferometer Gravitational-wave Observatory (LIGO) credited with spotting Einstein’s waves.
At the time, rudimentary interferometers were used to search for “aether”, a medium theorised, wrongly, to transmit light like air transmits sound.
“The technology that was available at that time was something like 10 billion times less sensitive than what it is today,” Cardiff University gravitational physics professor B. Sathyaprakash said.
Even if they had been more powerful, it was unlikely anyone would have thought of using interferometers to detect gravitational waves.

“It was only about 50 years after Einstein first proposed [his theory] that we had some understanding of what gravitational waves were,” said Sathyaprakash.
“In fact, after working out his initial solution, even Einstein had a hard time believing gravitational waves are real.”
The quest to detect them started in earnest when American physicist Joseph Weber built the first aluminium cylinder based detectors in the 1960s.
This was followed over subsequent decades by telescopes, satellites, and more recently laser beams – all searching for proof of one man’s idea.

Einstein’s genius, experts say, was probably unrelated to the time he lived in or the technology at hand.
“The elegance of Einstein’s theory of gravity does not rely on computational power, but rather on the elegance of its principles,” said David Cerdeno of Durham University’s Institute for Particle Physics Phenomenology.
Sathyaprakash adds: “Computers are good at crunching numbers, they are not very good at analytical calculations ... imagining things in a way that nobody else could do.
“[Einstein] did what are called ‘thought experiments’. He was very good at doing it. He would think about a situation, and then try to see what the consequence of that will be if the theory goes in one particular direction or another.”

Just 20 years ago, said Sathyaprakash, there was no computer powerful enough to solve the equations that emerged from Einstein’s musings.
A photograph of the physicist’s desk, said to have been taken after his death in 1955, presents an image very far removed from shooting laser beams at high-tech physics labs.
The workspace of the man who solved the mysteries of nuclear power, gravity and the speed of light sported no typewriter, no telephone, no radio – no electronic gadget whatsoever.
READ MORE: Was Einstein wrong? Chinese physicist Wu Yueliang claims universe flat not curved, created by ‘big break’ instead of ‘big bang’
His desk was covered in books and papers, with a tobacco tin and a pipe, and a large black board against the wall, covered in white chalk equations.
“Not everything can be solved with a computer,” said Sathyaprakash.
“He had to do analytical calculations with pencil and paper, and those things took a long time.”


The 100-year journey to prove Einstein’s theory about gravitational waves

The original historical documents related to Albert Einstein's prediction of the existence of gravitational waves are seen at the Hebrew university in Jerusalem, Thursday, Feb. 11, 2016. In a blockbuster announcement, scientists said Thursday that after decades of trying they have detected gravitational waves, the ripples in the fabric of space-time that Einstein predicted a century ago. (AP Photo/Sebastian Scheiner)

Israeli Doctor Roni Grosz, head of The Albert Einstein Archives at the Hebrew University of Jerusalem, shows the original document (R) written by Albert Einstein related to Albert Einstein's prediction of the existence of gravitational waves, on February 11, 2016 in Jerusalem. The Einstein theory was developed by Einstein 100 years ago, but had never been proved. One document is the first in which Einstein ever presented his theory of gravitational waves, the other is a page from the 46-page Theory of Relativity. / AFP / THOMAS COEX

epa05154649 A undated handout graphic, made available 11 February 2016 by NASA / CALTECH-JPL, showing an artist's impression of gravitational waves generated by binary neutron stars. US researchers said 11 February 2016 they have detected gravitational waves, which physicist Albert Einstein first described 100 years ago as 'ripples in the fabric of space-time.' Scientists from Caltech and the Massachusetts Institute of Technology (MIT) made the announcement in Washington and other locations around the world. There were immediate suggestions that the discovery could well win them the Nobel Prize in Physics. The signal detected with LIGO, an observatory with sites on both sides of the United States, was very clear and there was no room for doubt that it was direct evidence of the waves, said Bruce Allen, who is acting director at Germany's Max Planck Institute for Gravitational Physics. He said two scientists with his group in the northern German city of Hanover were the first to notice 

File photo shows theoretical physicist Albert Einstein, who postulated the existence of space-time ripples caused by whirling massive objects in his general theory of relativity. An international team of scientists announced on Feb. 11, 2016 that they have detected gravitational waves, ripples in space-time predicted by Einstein 100 years ago, from colliding black holes. (Kyodo) ==Kyodo

REFILE - ADDING RESTRICTIONS A Laser Interferometer Gravitational-wave Observatory (LIGO) technician performs a Large optic inspection in this undated photo released by Caltech/MIT/LIGO Laboratory on February 8, 2016. The twin detectors, a system of two identical detectors constructed to detect incredibly tiny vibrations from passing gravitational waves, are located in Livingston, Louisiana, and Hanford, Washington. Scientists said on February 11, 2016 they have for the first time detected gravitational waves, ripples in space and time hypothesized by physicist Albert Einstein a century ago, in a landmark discovery that opens a new window for studying the cosmos. REUTERS/Caltech/MIT/LIGO Laboratory/Handout via Reuters FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS NO RESALES. NO ARCHIVE.

A computer simulation shows how our sun and Earth warp space and time, or spacetime, represented here with a green grid in this image released in Washington February 11, 2016. Scientists have for the first time detected gravitational waves, ripples in space and time hypothesized by Albert Einstein a century ago, in a landmark discovery announced on Thursday that opens a new window for studying the cosmos. REUTERS/Caltech/MIT/LIGO Laboratory/Handout via Reuters FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. NO RESALES. NO ARCHIVE. TPX IMAGES OF THE DAY

The Albert Einstein Memorial is seen at the National Academy of Science in Washington, D.C. February 11, 2016. Scientists have for the first time detected gravitational waves, ripples in space and time hypothesized by Albert Einstein a century ago, in a landmark discovery announced on Thursday that opens a new window for studying the cosmos. The researchers said they detected gravitational waves coming from two distant black holes - extraordinarily dense objects whose existence also was foreseen by Einstein - that orbited one another, spiraled inward and smashed together. They said the waves were the product of a collision between two black holes roughly 30 times the mass of the Sun, located 1.3 billion light years from Earth. REUTERS/Carlos Barria EDITORIAL USE ONLY. NO RESALES. NO ARCHIVE.

One of the original documents showing Albert Einstein’s calculations predicting the existence of gravitational waves. Photo: AP

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