Einstein predicted this 100 years earlier!!.

 Very First detection of gravitational Waves. 

Image Credit: LIGO LAB

A window into the Universe. 

• On September 14, 2015, something incredible occurred. For the first time, scientists on Earth discovered gravitational waves, which Albert Einstein predicted about 100 years ago. 

• NASA's Jet Propulsion Laboratory (JPL) These were not normal waves. They were ripples in space and time—the very fabric of the universe. For over a century, people suspected these waves existed but had no idea how to detect them. Einstein discussed them in his General Theory of Relativity in 1915, but he also believed they would be too small to measure. According to ScienceDaily, we may now "listen to" the universe in a new sense, beyond just knowing it exists. This finding ushered in a new era in science.

What are Gravitational waves?

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• To comprehend gravitational waves, consider this scene: You throw a stone into a peaceful pond. The water ripples outward in circles. 

• Consider space and time as a massive, unseen pond. When enormous objects such as stars or black holes move or collide, they cause ripples in space and time. These ripples are known as gravitational waves. They are not made of light or sound, but of disturbances in the fabric of the universe itself.

• Einstein's theory of general relativity demonstrated how large objects bend space and time around them. When those things move quickly or collide, they generate energy that flows outward as waves, similar to ripples on a pond. Einstein anticipated these waves in 1916, shortly after publishing his theory of general relativity. However, he also stated that they will be so little that humans may never be able to detect them.

Why Detection was so hard?

Image Credit: NASA 

• For a long time, scientists assumed gravitational waves existed in principle, but no one could quantify them since they are so small when they reach Earth. To see how tiny: Gravitational waves shift distances by less than the width of an atom. 

•Imagine attempting to measure a change that is thousands of times smaller than an atom. That level of precision seemed virtually unattainable — which is why Einstein believed discovering them would be exceedingly difficult.

The Big breakthrough - LIGO.

Image Credit: ESA

• The Laser Interferometer Gravitational-Wave Observatory, also known as LIGO, was responsible for the breakthrough.2 LIGO consists of two massive detectors in the United States: one in Louisiana and one in Washington state. 

• Here's how it works, in basic terms: 

✔ The detectors are shaped like long "L"s, with two arms each 4 km long. 

✔ A powerful laser is sent down both arms. 

✔ When a gravitational wave passes, one arm stretches slightly and the other shrinks slightly. 

✔ The laser light changes its path down the arms, which is measured.

• Even though the effect is less than the size of an atom, LIGO's extraordinarily precise instruments allow it to be detected.

The First detection - A Cosmic collision.

Image Credit: NASA

• On September 14, 2015, at approximately 09:51 UTC, both LIGO detectors recorded a signal. Scientists later established that this signal originated from two massive black holes swirling into each other and merging. 

• These dark holes were really huge. One was around 29 times the mass of our sun, while the other was 36 times the sun's mass. They were so heavy and rapid that when they collided, they emitted massive amounts of energy in the form of gravitational waves.

• That energy was so massive that it produced more energy in a fraction of a second than all of the observable universe's stars combined. However, when these waves reached Earth 1.3 billion years later, they were so small that only the most precise sensors ever built, such as LIGO, could detect them. This first detection was dubbed GW150914, which stands for Gravitational Wave, and it was discovered on September 14, 2015.

What this means for Science?

Image Credit: NASA

• The first detection of gravitational waves did more than just prove Einstein correct. It provided an entirely new perspective on the universe. Prior to this discovery, we observed the universe mostly through light (visible, infrared, X-rays, and gamma rays). 

• However, many cosmic events, particularly mergers between black holes, produce no light at all. Now, for the first time, we may "listen" to the happenings. We can detect events that are unseen to conventional telescopes.

• Scientists refer to this as a new type of astronomy: not just seeing the universe, but hearing it. This has resulted in intriguing discoveries such as neutron star collisions, which created both gravitational waves and light visible through telescopes. Since the first black hole collision, hundreds more have been identified.

Einstein was right - But he was also unsure .

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• It's critical to recognize anything unique about Einstein's role. Einstein's theory anticipated gravitational waves, but he wasn't sure if they were physically real, and he doubted humans would ever detect them.

•  when scientists ultimately measured these waves almost exactly 100 years later, it was a victory of human skill rather than Einstein's vision. Many scientists around the world regard the discovery with tremendous esteem. 

• In 2017, three scientists were awarded the Nobel Prize in Physics for their contributions to the construction of LIGO and the first detection. They were named Rainer Weiss, Kip Thorne, and Barry Barish.

Why this Discovery still matters?

Image Credit: LIGO LAB

• Gravitational wave astronomy is still in its early stages, yet it is rapidly evolving. 

• Black hole mergers occur often across the universe. Improved detectors allow us to detect gravitational waves on a daily basis. Scientists are developing new detectors, both on Earth and in space, to detect hitherto unknown waves.

• This new research allows us to address big questions: 

How are black holes formed?

How large are they? 

What other types of cosmic collisions exist? 

What else exists in our cosmos that we have never seen before?

The Echoes of the Universe.

• What began as Einstein's prediction over a century ago has evolved into one of modern science's most interesting disciplines. 

• Today, gravitational waves are more than just a scientific truth; they are a new language of the cosmos. They tell us stories of events that occurred long before life appeared on Earth. 

• They portray occurrences that are so tremendous that they shake space and time itself. And, best of all, they remind us that there are still many mysteries in the universe to be explored.

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