Einstein’s Gravitational waves discovered!
Posted on February 12th, 2016
Bodhi Dhanapala Quebec, Canada. [The author is a popular science writer and a science teacher in a Technical College in Quebec.] ( Courtesy Island)
February 12, 2016, 6:51 pm
Most of us have no idea of Einstein’s theory of relativity. Sri Lankans have heard the claim of Nalin de Silva, an ex-Dean of Science at Kelaniya, that Einstein’s theory is just an unmitigated lie (“Patta-Pal-Boruvak”) — a “just so story” dependent on the Judeo-Christian cultural mindset. Truth be told, science had to battle that very Judeo-Christian hegemony at every step, with celebrated scientists burnt at the stake or put under house arrest.
Scientists in Washington announced the observation of waves of the gravitational field, the analogue of electromagnetic waves (radio waves) that are produced when you move a magnet to and fro. Similarly, when massive objects move at high speed, they produce gravitational waves whose strength depends on how massive, and how rapid is the movement. In this case, two giant black holes moving at half the speed of light produced waves strong enough to be detected. Such waves must exist if Einstein’s theory of gravity is correct, but their detection had required a half century of effort because the waves are very weak. This discovery now confirms a major aspect of Einstein’s theory. It opens a new field of astronomy that uses gravitational waves instead of light or radio waves. Such waves can tell us about the beginnings of our own universe, and other possible events in our multiverse which has many other big bangs inaccessible to ordinary telescopes.
The essence of the theory of relativity is that the laws of physics hold true universally, irrespective of how you are moving. That is, your microwave, radio or wristwatch will work perfectly, at home, on a ship, in an airplane, on a rocket or on another planet in exactly the same way as at home. This seems a very innocent statement. It was the main content of Einstein’s celebrated paper of 1905. This is called the principle of relativity. It should cause no surprises, except that one law of physics requires that light to have a speed of nearly 300,000,000 meters per second. So this has to be the same for everyone, at whatever speed he or she is going. If I were on earth, and you were on a space ship going at 1/4 of the speed of light, normally you would see light going away from you at 3/4 of its speed. But no! Relativity says we both see light running away from us at the very same speed!
This can only happen if your clock runs slow relative to mine, although the clocks work perfectly. From your point of view, my clock runs fast compared to yours! Your meter stick shortens compared to mine, while my meter stick lengthens compared to yours. So, all these happen so that the speed of light is always 300,000,000 meters/s, for both of us, as measured by our individual meter sticks and clocks!
Distances and time intervals are quantities relative to your personal “frame of reference”, being different in another frame. There really are only “events”. There are no space-locations or “time” that everyone can agree on! The sum total of all events is “spacetime”, and the only thing everyone can agree on is the space-time separation between events. Space has three dimensions (length, width, and height, labelled x, y, z) and time has just one dimension (t). Hence spacetime has four dimensions (x, y, z, t) entangled together. Your GPS needs four satellite signals to locate you since it uses Einstein’s equations!
In 1915 Einstein launched another big idea. If you put some iron filings near a magnet, you see the “magnetic field” around it. In the same way, every object, be it the earth, or a coconut, or a person, has a “gravitational field around it”, just like the magnetic field around a magnet. Isaac Newton had the genius to realize that objects attracted each other, but could not explain how. Newton formulated astonishingly accurate equations describing the motion of planets in space, tides on earth, and all motions and mechanics used successfully by engineers today. Einstein added what was missing in Newton’s theory by clarifying the nature of the “gravitational field”.
Einstein suggested that the mass of an object is simply a curvature in spacetime. The more massive the object, the more curved the spacetime near it, making a “mound” in the spacetime. So, “gravitational attraction” is simply that of objects responding to the local curvature felt by them. Planets move along the “locally flat” path in the curved spacetime, just as water flows in the valley between the mounds of hills.
This does not mean that”Einstein has done away with gravity”. Such simplistic statements are found in the popular literature to “shock” the reader. Dr. Nalin de Silva criticizes Sri Lankan, as well as, Western academics for “thinking that there is a gravitational attraction, even a century after Einstein showed that gravity is a fiction” (e.g. see Vidusara 18-11-2015 and other such articles). Einstein himself warned against such simplistic errors by saying (see Relativity, The special and General Theory, by Albert Einstein, 1959, p 176): “Now we might easily suppose that the existence of a gravitational field is only an apparent one. … This is by no means true … It is… impossible to choose a body of reference such that … the gravitational field of the earth (in its entirety) vanishes”.
Dr. Silva went to Sussex University to study theoretical physics. He likes to claim (Vidusara, 30-12-2015, and 13-1-2016) that he came back after 1.5 years with a degree certificate, thanks to his supervisor who bent rules to send him back! Gravitation, Quantum Theory, and the mathematics behind them demand a lifetime to “understand” them. The team of scientists who successfully measured gravitational waves had worked on it for many decades. This is more than a great intellectual achievement where a physics theory, the prediction of a black-hole event, and being ready to observe it, all came together. This heralds new precision tools for studying and adapting our environment to fit our needs. It is a great engineering achievement well beyond putting a man on the moon, demanding an accuracy and sensitivity similar to those for seeing a human hair some zillions of miles way. The black holes collided 1.3 billion years ago, and it took that long for the light and gravity waves to come to earth!
[The author is a popular science writer and a science teacher in a Technical College in Quebec.]