Gravitational waves: The 100-year journey finds evidence for Einstein's prediction

Interesting story about the process of scientists finding out the mysterious element of this universe, which somehow understands the difficulties they have to go through, the wonders of creation and the prophetic brain. before the hundreds of years of genius Albert Einstein.

War between black holes: a long time ago, far away in the universe, .

Only a few billion years ago, millions of galaxies were present, a pair of unknown black holes plunged into each other, opening one of the fascinating but challenging stories of physics. modern. At that time they curled up, increasingly getting into each other for about a billion years with the most intense but also romantic dance in the universe. At a time of only a few hundred kilometers apart, they abruptly reversed at almost the speed of light, while "shuddering" to emit attractive energy . The space and time were then distorted in the same way as water bubbles rolling when boiled.

In the moment that they are about to merge, they emit more energy than any other star in the universe. A new black hole has been formed 62 times heavier than our Sun and is almost the same size as a US state of Maine. Then it seems that it can polish itself lubrication, forming a slightly flat sphere and start collecting energy that has escaped. After that, space and time continued to be terribly silent as if nothing had happened.

Rendering simulations of space-bending mass according to Einstein's hypothesis

Attractive ripples are pushed away in all directions and the further away they become weaker. Then on Earth, dinosaurs were born, developed and extinct but then these waves continued to be maintained even though they became weaker and weaker. About 50,000 years ago, these gravitational waves entered our Milky Way galaxy , around the same time, Homo sapiens began to dominate the planet named Earth. And then humans went on developing, building their civilization until about 100 years ago, Albert Einstein , one of the senior members of Homo sapiens, predicted the existence of these gravitational waves. and since then, he has inspired hopeless speculations and searches for decades.

The first time the gravitational waves were discovered, the world shook with the excitement and skepticism of the discoverers themselves

Macro Drago - the first to observe the signal of gravitational waves

Speaking of 22 years ago, people began to build the Interferometer Observatory (LIGO). Later on September 14, 2015, an attractive wave reached Earth and then, Marco Drago, a 32-year-old Italian doctoral student, became the first to announce this. At that time, he was sitting in front of a computer screen at the Albert Einstein Academy in Hannover, Germany and tracking data from LIGO.

The waves then appeared on the screen as waves were compressed, but with the most human-made hearing ears of LIGO, subtle vibrations of less than 1 part trillion of centimeters were heard by scientists. and they call this the faint song of the universe. On February 12, 2016, at a press conference in the US, the LIGO team officially declared that it was indeed a signal of gravitational waves - for the first time in history it was directly observed, heard ear.

When Drago saw this signal, he could not help but be stunned: " It's hard to know what to do next when I see it ." He then informed a colleague, who quickly called the LIGO operating room in Livingston, Louisiana. The scientific community began to spread together and more and more people participated in the project. In California, USA, David Reitze, LIGO's chief executive, said: " I don't remember what I said at that time. Looks like damn, what the hell is it."

Vicky Kalogera, professor of physics and astronomy at Northwestern University, said: " My husband called but I left. I completely ignored it and just ran over to a series of strange emails and thought, what is happened . " Meanwhile, Rainer Weiss, the physicist who first proposed to build LIGO in 1972 while on vacation, received news that was logged into the system, saw the signal and shouted " My God ". . The shout was loud enough for his son and wife to run to ask if something terrible had happened. Really terrible.

An extraordinary finding requires extraordinary evidence

Fun enough, the laboratory team began to conduct an arduous process to check the data, not only once but twice, 3 times, 4 times, . Reitze said: "We often say together we have made measurements with only one-thousandth of the diameter of a proton and that will tell us the story of two black holes merged together billions of years ago. It is extraordinary and it needs extraordinary proof for authenticity . "

At the same time, scientists at LIGO were sworn in absolute secrecy of their research process. However, inevitably the rumors spread out in the scientific world from September last year until recently, the media, scientific newspapers occasionally reported and sometimes, people still attend Guess about a Nobel Prize awarded to the research team. However, the research team continued to work quietly and if anyone asked, the answer was "still analyzing the data, nothing to inform". Even researchers do not speak to their husbands or wives.

A little bit about LIGO

Photo of LIGO observatory from above

LIGO consists of 2 establishments separated by nearly 3000 km, about 3.5 hours flying by passenger plane but for gravitational waves, it is only about 10 parts a few thousand seconds to fly. A detector is located in Livingston, Louisiana, in a swamp area east of Baton Rouge, surrounded by pine forests. The other is located in Hanford, Washington, located on the southwest edge of one of the highest nuclear contaminated desert areas in the United States, although the reactors here have ceased operations.

In both areas, a pair of 3.6-meter-tall concrete pipes extends almost two sides perpendicular to each other, thus looking from above to look like an eke that we often use to draw a right angle. Each pipe is about 4 km long and must be lifted off the ground about 1 meter at each end to keep them lying on the ground inherently curved below. Build such a big and expensive project but the ultimate goal is to discover more evidence of Einstein's general theory of relativity. Einstein's theory was simply given, but he knew the process of proving it so difficult. According to him, spacetime will be bent when the presence of mass and this curvature will create an effect called gravitation.

When two black holes enter each other's orbit, they will stretch and squeeze space-time just like running children play on a spring mattress, forming very strong vibrations and these vibrations are called is the gravitational wave . These waves always travel from the source to the whole universe, even to us and it is basically much weaker than other fundamental forces, so we never feel them. Einstein himself thought that it was almost impossible to detect gravitational waves. Even twice, Einstein said it didn't exist, then changed his mind and assumed it existed. Saying that, only designing and building LIGO also lost of scientists a few decades of hardship, not playing.

Joe Weber's failure and the success of those who followed him

Joe Weber's attractive wave detector

Nearly five decades after Einstein's statement, no one had thought of building a tool to detect gravitational waves. The first person to think about it was Professor Joe Weber at the University of Maryland. He named this device the resonant antenna. It was an aluminum tube, essentially acting as a bell and he believed it would help amplify the weak signal of gravitational waves. When gravitational waves touch this tube, it will vibrate very lightly and by using sensors around it to convert into electrical signals to be observed.

In order to ensure elimination of all other fluctuations such as light vehicles, earthquakes, . that may interfere with the results, Weber developed several protective measures: he placed the antennae in a vacuum, copper Time out 2 to work together in 2 separate locations. If both have the same reaction in almost the same time, he will conclude that it could be gravitational waves. In June 1969, Weber claimed that his antenna had a discovery. At that time, physicists and journalists seemed to be successful. Time jerk "a new chapter in the human space observation process has opened ".

After that, Weber announced the signals he collected. However, suspicions began to appear when other laboratories also built detectors like Weber but failed to achieve the same results. In 1974, many concluded that Weber was wrong. Despite this, he believed that he was still right and continued his experiments until his death in 2000. Despite his failure, Weber left behind a legacy of research behind him. It provides a warning for later " gravitational hunters " that "all is a lie, be careful and only God knows what happened ."

And forget to tell you that although scientists did not get results when trying to build devices like Weber's, they were stimulated to do something better. One of them is the MIT physicist Rainer Weiss and he was the one who started designing what we now call LIGO. He said: " I can't understand what Weber has achieved. I don't think it's right. Therefore I decided to make another one myself ."

The way LIGO works - the giant L-shaped device

Structure profile of LIGO detector

According to researcher Fred Raab, the lab leader at LIGO in Hanford, in the process of searching for gravitational waves " most activities take place by phone ." Every week there is a meeting to discuss the data and every 2 weeks there is an additional meeting to coordinate data collected from 2 detectors in collaboration with researchers from Australia, India, Germany and England. , . Raab said: " When we wake up at midnight, what we dream about is a detector. You can understand its familiarity with us ."

And Weiss's proposed approach is completely different from Weber's way and is basically an L-shaped observatory . One could imagine that it was like two people lying on the floor, their heads pinched and the body part open to form a corner. When gravitational waves touch, one person will be raised and the other will be pressed down. A moment later, the opposite will happen. And based on this idea, Weiss developed an extremely large device to monitor the height difference between two branches of the L.

To ensure the accuracy of LIGO, Weiss used light as a ruler. Weiss has put the laser set in the bend of the L and it will emit a laser running along the length of each tube. This laser will shine into a mirror placed at the end of the tube, then reflect back to the detector. The speed of light moving in the tube is fixed, so no matter how long it is, just make sure that no air gets inside. Under normal conditions, the two reflected rays will fold together. When the gravitational waves come in, the mirror and the laser will be deflected slightly, leading to a loss of synchronization when reflected and this is the signal that people seek.

However, the above is just an idea that Weiss wrote in a report in the spring of 1972 and it was never really published. However, according to Kip Thorne, emeritus professor at Caltech, this is one of the greatest papers ever written. However, Thorne initially underestimated Weiss' design and even had his student work out, asking to prove that the gravitational gravitational wave measurement is absurd.

2 men in the same hotel room - the fateful conversation in the middle of the night

Physicist Rainer Weiss and Professor Kip Thorne, 2 people have great merits in developing LIGO

Even so, Thorne quickly changed his mind when he met Weiss in 1975, when the two men got together for an exchange organized by NASA . On that night, two men talked to each other. Weiss remembers: " I don't remember how it happened but we shared a room that night. We sat together on a small table, writing sketches and ways together. There aren't many people in the world who can talk like Thorne, talking about what they both think for years . "

And after that fateful conversation, Weiss returned to MIT and built a small version of the detector with each 1.5 meter long pipe for testing. However, the leadership at MIT and some of his colleagues did not appreciate his research. These include Phillip Morrison, a major influential astronomer in the world who thinks black holes do not exist, but also do not pay attention to Weiss. In fact, at the time, most of the opinions did not believe that black holes existed because they were just a hypothetical phenomenon. At the same time, if the waves were very attractive, Morrison did not believe that. Weiss's device is detectable.

However, Thorne was successfully lured by Weiss. In 1981, a prototype of Thorne's detector was built at Caltech with two detector tubes up to 40 meters long. At the same time, a Scottish physicist watched the whole process and he proceeded to improve Weiss' original design.

In 1990, after a year of research, the three-man team Weiss, Thorne and Drever jointly persuaded the National Science Foundation (NSF) to finance the construction of LIGO. The total estimated cost of the project is about 272 million dollars, more than any research funded by this fund. And this continues to be a battle when many scientists believe that the LIGO project is nowhere to go and ultimately just a waste of money. Then the NSF director, Rich Isaacson, was very suspicious to see if he should sponsor the project.

Rich Isaacson said: " It should not be built. Some crazy devices ran around but no signals were detected, and it had to use vacuum-forming devices, canceling impulses. seismic, feedback system . and there are things that have never been invented . " Fortunately, however, Isaacson once wrote a study of gravitational radiation and he believed that LIGO could be the key to the problem. After a good day of persuasion, the project was finally accepted and started in 1994.

Build LIGO: the world's purest vacuum tube, the most sensitive measuring device in the world and many more, .

Scientists are working inside LIGO's pipeline

In fact, it has not stopped there and it took many years to fully develop the most sensitive detectors in human history with the possibility of not catching anything other than gravitational waves. The application to remove air from the tube took 40 days and the result was the purest vacuum tube ever created on Earth. And yet, people have to find ways to eliminate the effects of wind, waves, fluctuations in the grid, jitter noise of the atoms, storms, thunder themselves from far away, . inherent can distort measurement results, causing confusion with gravitational waves.

The devices are carefully inspected in absolute sterile conditions

Everything is completely removed or controlled. An extremely sensitive shock absorber system is equipped for reflective mirrors to suppress seismic vibrations. Sensing systems that identify jamming movements of vehicles, airplanes, animals, etc. are also equipped to create the purest thing on the planet. If selected, perhaps this is one of the quietest places on our planet .

Weiss shared: "There are tens of thousands of things, I emphasize that tens of thousands of things need to be controlled. Everything must be done perfectly so that nothing can interfere with the signal. When needed. In order to refine, we have to work in an extremely clean room, disinfect everything, wear 100% tight-fitting suits, whether a skin cell or a small dust particle accidentally breaks down. cancel the experiment . "

Inside the operating area of ​​LIGO

Finally in 2001, the first version of LIGO was officially put into operation. And for the next 9 years, scientists continuously monitor the performance of devices, and constantly improve their data analysis algorithms. In addition, two laboratories at Caltech and a facility in Germany are constantly developing new devices, improving the sensitivity of mirrors, lasers, seismic removal technologies, reducing noise, . to increasingly Perfect LIGO. By 2010, LIGO suspended its operations to upgrade in 5 years with a total cost of 200 million dollars. After this upgrade, LIGO's ability has been raised thousands of times more than before.

Check the optical quality of lenses in LIGO, the price is only half a million dollars each

The mirror alone is very successful. Each mirror unit is only about 30 cm wide, weighs nearly 40 kg and each square inch on it is polished hundreds of millions of times to ensure a perfect bridge mirror. Small disclosure, each cost about half a million dollars to complete. Initially, these mirrors were hung up with steel wires, so although they were treated with dampers, they were not perfect. After the update, people attach it to a pendulum system to completely isolate it from the tremors.

Success

On September 13, scientists still spent a whole day conducting device tests in LIGO. Nearly all tests were completed but later than expected, there was still a test simulating a truck that hit a brake near the detector, but at 4 am, the operator decided to close the engine. Go on, let LIGO continue to collect data on your own. Not long after that, at 4:50 local time, a signal ran through two detectors in less than 7 milliseconds each. It was only 4 days after LIGO officially operated again.

Professor Reitze said: " Actually, the result coming so early will lead to a lot of skepticism because the new device has just been operated again soon. I have told people that we will not find anything. until 2017 or 2018. " But then after checking again, that result is really true. Janna Levin, an astrophysicist at Columbia University, who is not part of the LIGO group but was surprised to share: "When rumors started spreading, I told them to Come on. The signal is almost over. Most of us believe that it is perfect when there are so many, many computers, a lot of calculations are done to separate it from noise . "

However, researchers at LIGO have set up an objective team to verify this result. Although they believe in the results, the 4-member team must be blind, independently check many times the results and finally, they confirm that these gravitational waves come from somewhere in Canis Major (Canis Major). However, they have not published yet and continue to reinforce the evidence. They even ask themselves, "Is there someone in the group that has fake the signal that we don't know? ". And the proof goes on until scientists believe that no one can bypass the calculations made by powerful systems and the world's most accurate algorithms.

The group decided to document the outcome statement, including stating how they aligned the device, shared the software source they used, made a list of disturbances and how to remove them, including attacks. storms in the Pacific, fluctuations in the ionosphere, a great lightning storm in Africa, . Finally, they claimed that eliminating the confounding elements discovered this time reached 5 sigma threshold. (a gold standard when declaring a physical discovery).

More importantly, they claim that this is the gravitational wave coming from a pair of black holes colliding . By exploiting more information from gravitational waves, they learn more about the size, mass of the black hole, its orbital speed, the exact time they hit each other and again, confirming that Black holes exist 100%, there is no longer any doubt. This discovery proved that Einstein was right when it came to the physical aspect of the universe.

Although Einstein's theory talks about gravity, it is now possible to test it in the framework of the Solar System , now extending its correctness across the entire universe. Weiss said: " You think that Earth's gravity is what makes you tired when climbing stairs. Not yet! When physics is growing, it's just a small, extremely small effect, extremely small of gravity only . " So how could 1916 Einstein come up with this, something that 100 years later people could actually observe? Imagine what Einstein's face would look like when he realized he was right after 100 years? Perhaps he was smiling under the grave.

Physics will not die, the future of modern physics has begun today

Since the time of Galileo, people have so far relied on light to explore the universe. However, this success of LIGO has provided a new tool, still ensuring hand-to-hand, listening to the ears, seeing the eyes of science and bringing people further into the mysteries of the universe . People will be less afraid of the universe, many other discoveries will be made in the future. This time, one thing that this discovery has led to is time travel .