One of the most renowned scientists, whose name everyone has at least heard once in their lifetime, is Albert Einstein. It is common knowledge that he is one of the greatest minds in Physics, known primarily for his special and general theories of gravity and Nobel Prize for Physics ("Albert Einstein"). However, most people probably have no idea what some of his work explains. To understand a fraction of his work a little, let’s try to comprehend the basis of the general theory of gravity, and scrutinize gravitational waves.
Everything that occupies a space also has a mass. And consequently, a gravitational force exists between every object that has mass according to Newton’s Law of Universal Gravitation. And as mass increases, the attraction between objects with masses increases, considering the distance is constant(”Newton's Law of Gravity”). However, this law was insufficient since it was insufficient to explain some cases.
Einstein suggested a different approach. According to him, masses, instead of exerting forces, alter and curve their surrounding space and time (NBC). A common metaphor is a fabric. Imagine space as a fabric, and mass as a ball dropped onto the fabric held by its four corners (considering the fabric is not stretched and is loose enough to be impacted by the ball). The ball will be in the center and cause the surrounding fabric to be lowered to create a curve surrounding the wall. Thus, instead of attractive forces between masses, those interactions between masses happen because of the curvature of space and time (UCLA) and cause gravitational waves. These waves are the distortions made in the geometry of space and time that travel with the speed of light, and they are called ripples in spacetime (“Introduction to General Relativity.”) However, to be able to detect those ripples in spacetime, the masses have to be enormous. For example, consider ripples on a pond after throwing an object in it. The greater the object, the greater the ripples it will cause. Therefore, the ripples will be easier to detect. To observe ripples, light is used. Since the time light has to travel will be determined by the distance.
The aforementioned quality is used in the LIGO experiment. LIGO, short for Laser Interferometer Gravitational-Wave Observatory, has 4 kilometers long tunnels that are perpendicular to each other. Moreover, lasers are used to measure the distance of the tunnels, giving the observatory its name. A difference in the distance created by gravitational waves is observed and gives information about the effects of the ripples on distance(“Gravitational Waves Explained.”).
LIGO had various eras, considering the changes and processes it went through. During the “Initial LIGO” period, no detections were made. Yet, in the meantime, various breakthroughs in the engineering of the mechanism were made. After the altercations following those breakthroughs, the “Advanced LIGO” project was launched, and the first detection of a wave, which was generated by a merger of two black holes that are 1.3 billion light years away(“LIGO: About”), was observed (“LIGO: About”.).
Following the detection of the first waves, more calibration and precision is sought currently. In 2023, Laser Interferometer Gravitational-Wave Observatory is to operate a new run(“Ligo Resumes Work in 2023 and Will Catch Gravitational Wave Signals Fainter than Ever.”), which will amount to the fourth overall. In this run, collaboration with other observatories around the world will be done; hopefully, providing even more information about the cosmic events the waves originated from and explanations for gravity itself. (“What Are Gravitational Waves?”)
Works Cited
Kaku, Michio. "Albert Einstein". Encyclopedia Britannica, 18 Oct. 2022, https://www.britannica.com/biography/Albert-Einstein. Accessed 18 November 2022.
“2.13 Newton's Law of Gravity:” Newton's Law of Gravity: https://web.fscj.edu/Milczanowski/psc/lect/Ch2/sl13.htm#:~:text=Gravitational force -an attractive force,distance between the two objects.).
“Einstein Showed Newton Was Wrong about Gravity. Now Scientists Are Coming for Einstein.” NBCNews.com, NBCUniversal News Group, 3 Aug. 2019, https://www.nbcnews.com/mach/science/einstein-showed-newton-was-wrong-about-gravity-now-scientists-are-ncna1038671.
Wolpert, Stuart. “Einstein's General Relativity Theory Is Questioned but Still Stands 'for Now,' Team Reports.” UCLA, UCLA, 25 July 2019, https://newsroom.ucla.edu/releases/einstein-general-relativity-theory-questioned-ghez.
“Introduction to General Relativity.” Wikipedia, Wikimedia Foundation, 2 Nov. 2022, https://en.wikipedia.org/wiki/Introduction_to_general_relativity#:~:text=General relativity is a theory,from their warping of spacetime.
phdcomics. “Gravitational Waves Explained.” YouTube, YouTube, 1 Feb. 2016, https://www.youtube.com/watch?v=4GbWfNHtHRg.
“LIGO: About”. Caltech, https://www.ligo.caltech.edu/page/about.
Lea, Robert. “Ligo Resumes Work in 2023 and Will Catch Gravitational Wave Signals Fainter than Ever.” Space.com, Space, 5 July 2022, https://www.space.com/gravitational-wave-detectors-ligo-virgo-march-2023.
“What Are Gravitational Waves?” Caltech, https://www.ligo.caltech.edu/page/what-are-gw.
Image Source: https://www.flickr.com/photos/prachatai/24331168214 https://www.ligo.org/multimedia/gallery/lho-images/Aerial5.jpg