Tag Archives: Gravity

Riding The “Waves” – Part 2

So continuing from last blog, I would like to elaborate more on Gravitational waves in this blog; what exactly are they? How useful this current discovery mean? How could they be pioneered to understand the universe? And why it took so long to physically detect them by LIGO?

So let’s start.

As explained previously that Gravitational waves are nothing but ripples in space-time fabric generated through some violent movements or explosions (Which considering the vast span of universe is norm, but to be able to evidence the same is not that common). Einstein has shown the same mathematically in 1916. Also it stated that these waves travel at light speed and carry significant information of the event which has given birth to the waves. These events could be anything like supernova death of star, colliding of black-holes, “brotherly hug” of neutron or white dwarf stars, wobbly rotation of binary stars and also gravitational radiation created by birth of universe itself.

In fact, in 1974, two astronomers working at Arecibo Radio Observatory had successfully observed the binary stars movements in accordance with Einstein’s theory and hence proof of the existence of Gravitational waves. More studies have also been made into successfully predicting similar effects, but all such proof were, in one sense, mathematical and more of an indirect evidences. Scientists around the world were keen on gaining “physical” proof.


So what’s so important about detecting the waves? To understand the deep mysteries of the universe has always been captured the mankind’s attention since the evolution of Homo sapiens sapiens or may be even before that in whatever half-intelligent Genus we all belong to. More astrophysicists and astronomers explore and understand about universe on behalf of entire humankind, more unsolved mysteries are cropping up. As if span of the universe itself is not doubtful enough, scientists don’t have clear picture of the birth of universe also. Gravitational waves are not electro-magnetic radiation. They are in complete different league; whole new phenomena. They carry information which was not measurable before. They have tendency to travel without any interaction with matter and hence retaining the “purity” of the event. Hence it is becoming so much important to take it up the study of the waves to dive deeper into depths of unknown; in search of those brightly shining but hidden pearls of wisdom.

As per theory, any moving object is source of Gravitational waves; even on earth whether it’s ball pitched at high velocity by pitcher or bullet fired or spinning top or newspaper thrown in your verandah with ferocity of the daily boring job; practically everything. But as noted before, considering heavenly objects for which Einstein’s theory specialized for, numbers generated by this relativity equations via such miniscule objects are negligible. Waves are so weak that you can pretend that they are not present at all. And hence scientists all over the world had to rely on massive movements outside our world. Even those waves, while reaching to earth are faded out, needed very precise and efficient carefully built experimental instruments to measure them. One of them is LIGO which stands for Laser Interferometer Gravitational-Wave Observatory. You can find all the information related to LIGO and science behind the architecture at https://www.ligo.caltech.edu/page/ligo-gw-interferometer .


So not going much detail into how exactly LIGO managed to detect gravitational waves after almost 100 years (It will require much detailed scientific setup of LIGO. Refer above given link & a picture), I would like to wrap up the blog with brief mentions of types of gravitational waves. Based on characteristic vibration signature waves are categorized as below:

  1. Continuous Gravitational Waves: It is generated by single spinning object, say Neutron star. They are mostly constant in their properties such as frequency and amplitude.
  2. Compact Binary Inspiral Gravitational Wave: As name suggests, these waves are created by binary stars. Actually it could be either binary Neutron stars or Binary black holes or mixed-doubles like Neutron star-Black hole. Whatever be the source, one fact is observed by scientists that due to losing energy with each spin, both spinning object come closer which again increases the gravity and spin; ultimately make them spiraling into each other with cataclysmic crash at climax.
  3. Stochastic Gravitational Waves: Frankly speaking these waves are nothing but same as your transistor radio tuned to no particular station but just emitting noise. But these noise here could be from the time when time started its existence i.e. Big Bang. They are small, random, ever-present and difficult to distinguish but most desirables.
  4. Burst Gravitational Waves: These waves are ghost. There is no model or signature to define them and hence no particular methodology. It’s like searching something but you cannot name what it is. They have utmost potential to reveal something which has always been “holy grail” of human conscience.

Further Reading reference:



Riding the “Waves”

Being predicted in 1916 as part of General Theory of Relativity by none other than “The one of a kind” brain, Einstein; it took more than a century by world scientist to physically detect Gravitational waves and remove the last hurdle for proposed Theory of Relativity. For all those whose lives burdened by day-to-day job commuting, daily manager tussles, data crunching and deadlines, family and social overabundant wants, whole universe of love interest and crush problems, EMIs and ever alluring investment plans to aid EMIs, drunken Sensex bobbing up and down or same sex decriminalization (for India); you all need to continue without expecting any change. Though space-time fabric and hence gravitational waves are effective enough to all celestial body and governing the universe, they don’t have any control over humankind’s daily chores. So please don’t expect something major of such (actually major) discovery of Gravitational Waves.

As any astrophysicist agree on the view that there is nothing more endearing than to excavate mysteries buried deep down the Universe’s vast, expansive blackness. It is Pandora’s Box. You will never know what you find next which is utterly bewildering and next to impossible if you are not wearing scientific goggles (Though Science manage to explain all these through well-defined rules and mathematical equations which is more superior than magic).

To explain the intricacies of Einstein’s General Theory of Relativity and importance of detection of Gravitational Waves is no small feat. I would suggest well-known books on the same (find few reference links at end). In short, Einstein was not completely “moved” by force presented as Newton’s laws when the same applied on much more larger scale as Universe. He was not convinced specifically by source of gravity which was assumed to be based on objects’ mass in classical physics. Einstein was keen on providing new model for objects which were much bigger as heavenly bodies in Universe. He took the base of Newton’s Laws and proposed General Theory of Relativity in 1916 (He has already proposed Special Theory of Relativity in 1905 fixing the limit for speed of any object i.e. speed of light).

In very simpler terms, theory assumes space as space-time fabric; kind of a stretchable fabric. Let’s conduct a thought experiment where four of your friends tightly held the each four corners of this square fabric so that it gives you smooth surface same as pool table without any table support (you can imagine corners held by anyone you like. It’s thought experiment, so take liberty :).  Now you rolled one solid snooker ball (in this case strip won’t also make any difference, take your pick) across to center. You can observe the “dint” created by ball. You can also observe that if ball travels across, it will carry this “dint” along with it. Now if you put leather ball of cricket or say baseball, you (along with your helpers if they are interested in science) notes that it will have bigger distortion. In the same manner, all universal bodies i.e. stars, planets, pulsars, asteroids, black-holes make impact on the space-time fabric. Only difference is that space-time fabric is 3-D covering entire object rather than 2-D as in our pool table analogy.

Image converted using ifftoany
Space-time fabric and “dints” created by space bodies

Also observe that as we done in our thought experiment, this wrap of space-time fabric travel along with heavenly body as in motion of earth around Sun. Bigger the object, more contorted the fabric is. And just because Sun is so large as compared to earth and other planets in our solar system that their “impacts” are relatively small compared to larger “impact” of Sun. This “impact” is nothing but gravity. And when such bodies collide or move or blast themselves off, than they transmit waves in the space-time fabric same as ripples at other end of swimming pool once that someone large has crashed down on your end. And this waves are nothing but gravitational waves which in turn travel at speed of light (So if Sun destroy itself by something mysterious, it’s gravitational waves will hit Earth after 8.5 minutes, at the same time when earth experience complete blackout).

Latest Gravitational waves detection has inspired this blog series which I will continue with few more articles on Gravitational waves and LIGO. And if it found footing than may want to took up with more of Einstein’s theory and Quantum Physics which in my view are the most magical understanding of the real world in terms of science.


Last Thought: Newton’s laws of gravitation are not applicable at Universe level, but hold with accuracy as daily affair. Einstein’s theory is good for understanding universe but are cumbersome at taking into account at small level such as velocity of car, train etc. In general, Newton’s laws are nothing but adaptable view of Einstein’s theory. When you come down from Universe to earth, object’s mass could be considered for gravitational laws and hold correctly as per Newton’s laws.

Further References:


http://www.desy.de/user/projects/Physics/Administrivia/rel_booklist.html (Really impressive link to find the suitable GTR book)

(Final Note: I am big fan of science but I’m not scientist. When Einstein could be humble enough to accept his “Biggest Folly”, I am just the small fleck in comparison. So any errors/deviations are liable to me and not Science.)