According to Google, Albert Einstein, in his theory of special relativity, determined
that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels.
In a popular science magazine, I read about the ABC of this 'gobbledygook' an article on the Gravity Waves, explained by T R GOPALAKRISHNAN & concluded that the principles of the theory are actually quite easy to understand by learning about gravitational waves in just four simple steps.
I am sharing the superficial elements of the article as what I understood :
1) THE CONCEPT OF SPACE-TIME
-According to Newton, gravity was a force- that a body attracts another body over a distance. But Einstein said that there could be a better explanation for gravity.
-Einstein actually took the concepts of SPACE & TIME (which are related) & wove them together in a single idea, called Space-time.
-Thinking of space-time as fabric, and the universe as a trampoline, Einstein's theory says space-time can be curved, & what we feel as 'gravity' is the "effect" of that curvature.
2) SPACE-TIME & GRAVITY
-Now imagine what would happen to the trampoline, if we place a huge solid Gold ball over it?
-Yes, obviously.. the trampoline would sink & cause a curvature.
-Now, suppose if we drop another solid Silver ball, smaller in size, on the periphery of the trampoline.. what would happen?
-Undoubtedly, it'd roll down towards the huge Gold ball.
-So, the conclusion here is, the earth is the Gold ball, the moon is the silver ball & the curvature or gravity you can say, is what attracts the moon to earth.
-The bigger the mass of an object, the deeper the curvature it causes.
3) GRAVITY & GEODESICS
-In case of trampoline, the silver ball would roll down to the huge gold ball in a straight line. But it doesn't happen so in the real world.
-Throw a ball into the air, & it makes a parabola in space. Similarly, a celestial body follows a path called geodesic (the equivalent of a straight line in the four-dimensional space-time).
-The moon also orbits the earth in a geodesic.
4) GRAVITY AS WAVES
-Firstly, we need to know what are gravitational waves?
-Let's suppose two heavy iron balls circling each other in the trampoline. Their movement causes ripples in the fabric, which spread outward.
In space-time, such ripples are called gravitational waves.
- When dense bodies such as neutron stars & black holes orbit around each other, the ripples in space-time resemble that of the surface of an agitated pond.
-The denser the objects, the more powerful the waves they generate.
-The faster the objects move, the more waves they produce.
-And the waves travel at the speed of light.
-Einstein's Point Of View :
-What at LIGO (Laser Interferometer Gravitational-wave Observatory) detected was the gravitational waves produced by the circling-around & subsequent collision of two black holes, which were 29 & 36 times the mass of the sun.
-The collision resulted in a bigger black hole, which was 62 times the mass of the sun.
-But, 29+36=65. The new black hole had a solar mass of 62. So, here the question arises where did the mass equivalent of three suns go?
-I was unable to guess the answer properly, but my guess was somewhere close to the explanation.
-Wave is a form of energy, and energy is a form of matter. E= mc^2, which means the mass equivalent of three suns went as energy of the gravitational waves.
-There's you have just thought like Einstein. :-)
-But....
-Scientists found that it does not happen so.
-Reason- An unknown energy was deforming the tunnels, changing their length ever so slightly. As a result, the distance travelled by the beams varied, and they were not reaching the beam splitter at the same time.
Bingo, said the scientists as they had finally caught a gravitational wave.
-Thanks to the wave's effect, the lasers were recombining in such a way that it produced a measurable signal at the light detector.
-What I found interesting was - When converted to an audible sound, the waves made an unmistakable 'chirp', the loudness of which helped scientists make a rough estimate of the age of the waves.
In this case, (to my amaze) 1.3 billion years!!
P.S. - Now, I can say that Albert Einstein's theory of Relativity is not completely beyond my brain. :-)
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