Report by Dhruva KC
Scientists from the North American Nanohertz Observatory for Gravitational Waves ((somebody) Physics Frontiers Center have discovered that gravitational waves exist and make a background ‘hum’.
Albert Einstein, a great physicist (somebody who specializes in physics), made this prediction in 1916, more than a hundred years ago.
His theory (idea) described gravity as a distortion of space and time caused by matter (planets, galaxies, stars and other celestial bodies).
What is wavelength?
Have you observed a wave in an ocean? It goes up and then down. That is what makes it a wave. All other waves also do the same thing – they go up and down – again and again – in a repeated rhythm.
Wavelength is, quite simply, the length of a wave. In the picture above, we use the top of the wave as the starting point and measure the distance upto the point where it reaches the top again. The top point reached by a wave is called its crest and the lowest point it reaches is called its trough.
In the sea, one cycle of the wave may be smaller or bigger than the next. But electrical, magnetic, and sound waves, by and large, have a uniform length of wave (wavelength).
A gravitational wave’s wavelength is longer than a light year (the distance light can cover in one year). The red and blue lines are illustrations of frequencies.
What is frequency?
How frequently do you go to your grandmother’s house?
Vishu goes once a year. That is the frequency of his visit to his grandmother’s house. – 1 per year.
Most of us go to the school five days a week. That is our frequency of going to the school per week.
How many times does a wave complete a cycle in a second? That is the frequency of that wave.
For example, in the image below, we see that the blue wave completes more cycles per second than the red wave. So, we say that the blue wave has a higher frequency (and, have you noticed, a shorter length, or wavelength?) than the red wave (which also, as you might notice, has a longer wavelength).
What frequency waves look like, Image credit: WordPress.com
How do these waves occur
Research shows that space is filled with these waves, occurring constantly every second. Hums are heard when large objects move and collide, causing gravitational waves. Another way gravitational waves occur is when two supermassive black holes exert gravity on each other. These gravitational waves have a low frequency and a high wavelength.
What is a black hole?
A black hole is like a vacuum machine, but it exerts so much gravitational force that nothing, not even light, can escape it. Why did scientists have no evidence that gravitational waves existed until now?Scientists could not observe these gravitational waves so far. This is due to the frequency of these waves being one-tenth of those detectable by the Laser Interferometer Gravitational-Wave Observatory (LIGO), the best wave observatory in the world. This means scientists had to take a different approach if they wanted evidence.The current study is based on pulsars, the cores of dead stars that spin very fast. Scientists observed 68 pulsars over 15 years. This research was conducted by over 190 scientists from the U.S. and Canada. They checked if the pulsars sped up or changed direction to observe gravitational waves.
How does this discovery help scientists?
This discovery allows for a better understanding and examination of the universe. Astronomers relied on learning about the cosmos by studying light until now, which has its limitations.