Black Holes are not so Black (Part 3) - Gravitational Waves

The existence of Gravitational Waves have been confirmed. But you probably have heard that. In this post, we will break down this profound discovery into comprehend-able chunks.

This is going to be a amazing journey. Ready ?

Redefining Gravity

When we usually talk of Gravitation we are bound to think like Newton, where objects are assumed to exerting a force upon each other.

Like imaginary arrows of force in space. But this picture, although good for high school crumbled, with the advent of Einstein’s theory of Relativity.

What is the Space-Time Fabric?

Think of space-time fabric as an actual cloth of fabric. ( An analogy )

When you place an object on the fabric, the cloth curves. This is exactly what happens in the solar system as well.

The sun with such a huge mass bends the space-time fabric. And the earth and all the planets are kept in orbit by following this curvature that has been made by the sun.

Attributing to the various masses of objects, the way they bend this fabric also varies.



What are Gravitational Waves?

If you drop an object in a medium such as water, they produce ripples that propagate as waves through the medium.

Similarly, Gravitational waves are ripples in space-time fabric produced when you drag heavy objects through space time.

And the nature of these waves is that they don’t require a medium to propagate.

How do you make one?

Everything with mass/energy can create these waves.

Source

Two persons dancing around each other in space too can create gravitational waves. But the waves would be extremely faint.

You need something big and massive accelerating through space-time in order to even detect them.

And orbiting binary stars/black holes are valuable in this retrospect.

How can you detect them?

Let’s turn to the problem to detecting them assuming you do find binary stars/black-holes in the wondrous space to suite your needs.

Well, for starters you cannot use rocks/ rulers to measure them because as the space expands and contracts, so do the rocks. ( the distances will remain same in both the cases )

Here’s where the high school fact that the speed of Light is a constant no matter what plays an important and pivotal role.

If the space expands, the time taken for light to reach from A to B would be longer. And if it contracts, the time taken for it to reach from A to B would be smaller.

PC: PHDComics

By allowing the light waves from the contraction and expansion to interfere with each other, such as done in any interferometry experiment we can detect the expansion or contraction. Voila!

And this is exactly what they did! ( on a macroscopic level ) at LIGO (Laser Interferometer Gravitational-Wave Observatory)




14 September 2015

Two Black Holes with masses of 29 and 36 solar masses merged together some 1.3 Billion light years away.

Two Black Holes colliding is the header animation of the ‘Black Holes are not so Black Series’, in case if you haven’t noticed.

The merger of these two black holes results in the emission of energy equivalent to 3 solar masses as Gravitational Waves.

This signal was seen by both LIGO detectors, in Livingston and Hanford, with a time difference of 7 milliseconds.

And with the measurement of this time difference, physicists have pronounced the existence of Gravitational Waves.

Source

All this is most certainly easily said than done and requires meticulous and extensive research, not to mention highly sensitive instruments.

Had they not have measured this time difference, we might have had to wait for the merger for more massive black holes to collide and maybe even build more sensitive instruments to detect these waves.

And Einstein predicted this a 100 years back!

Mind Blown!


Note: Hope you are able to understand and appreciate the profundity of the discovery done by mankind.


** All animations used here are merely for Educational purposes. If you have any issues, please write to us at : 153armstrong@gmail.com

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Bonus comic!

Yahoo! Einstein was right again! :D We now have our first detection of gravitational waves! 

http://www.nytimes.com/2016/02/12/science/ligo-gravitational-waves-black-holes-einstein.html?_r=0

http://www.space.com/17661-theory-general-relativity.html

sciencealert.com
Earth is made up of two planets fused together, new research suggests
RIP, planet buddy.
By Fiona MacDonald

Astronomers investigating how the Moon formed have found evidence that it was produced after a small planet smashed headfirst into Earth around 4.5 billion years ago. And research suggests that this collision was so violent that the ‘planetary embryo’ that hit us, called Theia, ended up fusing with both Earth and the Moon as a result.

The idea that the Moon was formed as part of a Solar System crash isn’t new, but scientists in the past have proposed that Theia simply side-swiped Earth, blasting the Moon into orbit and then continuing off into space. Now new research by a team at the University of California, Los Angeles, suggests that Theia actually never left us.

Continue Reading.

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LIGO Gravitational Wave Chirp - Chirp pattern of gravitational waves detected by LIGO on September 14, 2015.
Credit: LIGO http://www.ligo.org/

Then he’d tried believing in the Universe, which seemed sound enough until he’d innocently started reading new books with words like Chaos and Time and Quantum in the titles. He’d found that even the people whose job of work was, so to speak, the Universe, didn’t really believe in it and were actually quite proud of not knowing what it really was or even if it could theoretically exist.
—  Terry Pratchett, Good Omens
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St Peter’’s Church, Monkwearmouth (1,2)

St Paul’’s Monastery, Jarrow (3,4)

The twin monastery of St Peter (Monkwearmouth) and St Paul (Jarrow) lies near the mouths of the rivers Wear and Tyne. It was established in the seventh century by Benedict Biscop and by the early eighth century was an internationally renowned centre of learning with one of the most important libraries and scriptoria of its time.

It was also a home for the famous Venerable Bede (…) a well-educated polymath. He not only wrote the sole contemporary history (as opposed to chronicle) of Anglo-Saxon times, he also wrote tracts on astronomy and mathematics as well as chronology. His use of Anno Domini (AD) was so successful that it overrode all other dating systems to become the one used until this day.

image source x (and more info)