Everything about LIGO and the Gravitational Waves

LIGO detector at Hanford, Washington. Credit : LIGO Laboratory

"Ladies and gentlemen, we have detected gravitational waves. We did it!". 

Yesterday (11 Feb 2016), physicists at LIGO, officially declared the discovery of gravitational waves. Rumours have been spread months before the declaration and medias were going frenzy. Scientific world was eagerly waiting. Words of the notable physicist, Lawrence Krauss, before the official declaration, "New era in Astronomy and Physics could begin". It is said to be the discovery of the century.  

But why this fuss? Why scientists are going crazy about this? Is it going to change our understanding of the Universe?

Credit : sciencenews.org

First let us know what a gravitational wave is. The concept of gravitational wave was put forth by the renowned scientist, Albert Einstein, through his mind numbing, General Theory of Relativity. According to General Relativity, space and time are aspects of a single measurable reality called spacetime. The objects in space can create warps in the fabric of spacetime. More massive the object, more the warping would be. This curves in the fabric of spacetime is the reason behind the gravity. 

Moon does not revolve around earth, as earth pulls it, instead it takes the direct path in four dimensional spacetime. 

If the spacetime can be warped like a fabric, then it can be rippled also. It will ripple when there is a sudden movement of massive objects. If an object, big or small, is sitting still or in constant motion, it's gravitation field will be static and there won't be any gravitational wave. But when it moves suddenly (speeding up, slowing down or changing direction), like in an explosion, then its gravitation filed changes and causes the ripples in spacetime. Such ripples in the fabric of spacetime are called as gravitational waves. Earth too gives off gravitational waves, but its extremely weak and faint.

Credit : Wikimedia

Scientists of LIGO successfully discovered the ripples caused by the collision of two massive Black holes, 1.3 Billion years ago.  But how do they detect it?

When the ripples in the fabric of space time reaches an object, it can make it stretch and squeeze. The ripples from the collision of those Black holes can make entire Earth expand and contract by 1/100,000 of a nanometer, that is about the width of an atomic nucleus. That is absolutely miniscule. For detecting such a minute wave, we need an extra precise device.

Thus we made the LIGO (Laser Interference Gravitational-Wave Observatory). LIGO comprises of 'L' shaped device called interferometers, with arms of 4 kms long and about a little more than a meter wide. Let's see its working.

In LIGO, laser beams are passed through the arms of the device, at the same time. At the end of each arm, there is an ultra precise mirror, which will reflect back the laser. Laser then travels back and the two beams will join at one point and overlaps and creates an interference pattern. This pattern will be the same, every time the laser overlaps, when there is no gravitational wave. When a gravitational wave passes by, one arm will get stretched and the other get squeezed, thus making differences in the length of both the arms. If the beams travel different distances, then while overlapping, it creates a different interference pattern. These changes in patterns are noted to detect gravitational waves. LIGO is capable to detect a minute distance change of 1/10,000 the width of a proton.

Signals seen in Livingston and Hanford detectors. Credit : LIGO

As LIGO is so sensitive, even a movement of truck or distant ocean waves can shake the mirrors, thus causing difference in measurement. The main trouble scientists face was to clear off the noises. The mirrors were hung from quadruple pendulum to isolate the external shaking. And also, the readings of two observatories (at Hanford, Washington and Livingston, Louisiana), which is 2000 miles apart, are taken and analysed to eliminate the local shakes, that are felt by a single observatory, while the authentic cosmic gravitational waves will felt by both.

That's it. That is how scientists discovered the gravitational waves. Now you maybe asking, what is the significance of this discovery? One thing is that, Einstein's Theory of Relativity is again found to be correct. And also it proved Hawking's predictions on Black Holes. Besides that, we got a new form of media to know the Universe. We were searching and knowing the Universe only by using electro magnetic waves till date. Now we have got a new way of 'seeing', that can lead to many stupendous discoveries.

The sensitivity of LIGO will further enhanced until it reaches the design sensitivity on 2021. We can expect many more detections and improve the knowledge on how Universe works.

For more detailed reading, you can download the press release from LIGO here, http://www.ligo.org/news/detection-press-release.pdf

5 Paradoxes That Will Blow Your Mind

If you had watched the movie, Inception, you would have came across a never ending stairs made by Arthur (Joseph Gordon Levitt). In the dream, he creates an endless stairs that goes in circles. It is a Penrose stair, and such a stair can only depicted in two dimension, but cannot exist in three dimension. Strange right? Lets dive into the world of mind twisting paradoxes.

We will start by understanding what a paradox is. Paradox is a statement or proposition that seems to be logical, but becomes self contradictory on further investigation, or the other way around. They can be invalid in certain cases too. Each paradox will create numerous possibilities on critical thinking. There are paradoxes in mathematics, physics, philosophy etc. I handpicked a few that is quite strange and mind boggling.

1. Grandfather Paradox

This paradox comes under time travel paradoxes. It is one among many, that is put forth to prove time travelling to the past is hard to achieve and is logically impossible. The paradox states,

If you time travelled to the past and killed your grandfather before he conceives any of your parent, it will makes you non existent, and therefore, you was not there to go back in time and kill your grandfather.

But you are existing, as you just came out from the time machine. That means your parents existed and your grandfather was not killed before conceiving your parent. 

What just happened? Its a paradox. Modern scientific theories does not prevent any possibilities of time travelling. But still many physicists were convinced by this paradox to say, time travelling to past is impossible. That includes the most famous, Stephen Hawking. He even did an experiment in 2009. He threw a party in the University of Cambridge, with champagnes and balloons. Sadly no one turned up. Because he didn’t sent an invitation to any. Instead he sent the invitation after the party. He was actually expecting a time traveller to attend his party. He thought in future, someone somewhere will comes to know about this party that he conducted and attends it by time travelling. But no one came.

Many scientific theories popped out to solve the mystery of grandfather paradox like, Parallel Universe theory, Novikov self - consistency principle etc. It needs another elaborate post to explain those.

2. Ross-Littlewood Paradox

Ross-Littlewood paradox is a mathematical and logical paradox. It is famous by the names, 'ball vase problem', 'ping pong problem' etc. This problem was described by John E. Littlewood and Sheldon Ross and hence the name. Lets see the problem,

Suppose we have a vase of infinite height and we have infinite supply of balls. The time now is 30 seconds before noon. We are going to perform infinite number of steps before noon. The steps is as follows,

• Add 10 balls to vase from our supply
• Remove one ball

First step is done right now, that is 30 seconds before noon. Next step is done at the halfway time from now to noon. That is 15 seconds before noon. And the next step at the other halfway, that is 7.5 seconds till noon. And goes on. Thus we can do an infinite number of steps before noon, as we can divide the remaining time into half each time.

Now the question is, How many balls will be there in the vase at noon?

Need to think?

Take your time and come back if you gets a solution.

Here you are. The solution you got is absolutely correct. There will be infinite number of balls. But the surprising fact is that there is another solution at the same time that is mathematically correct. The answer is, vase will be empty. Mind blown? This inconsistency in the solution made this problem a paradox. Now let’s see how this weird answer came.

Suppose every Balls are numbered. From 1 to infinite number. 

For the step 1, balls numbered 1 - 10 are placed in the vase and removed the Ball numbered 1. 

In step 2, balls numbered 11 - 20 are placed in the vase and removed the Ball numbered 2. 

In step 3, balls numbered 21 - 30 are placed in the vase and removed the Ball numbered 3. 

.

.

.

And the steps continues to infinity. Now take any number. You can take any number, there will be a step of removing that numbered ball, because there are infinite number of steps. If the vase has n number of balls the step just before noon, there should be a steps to every ball including n within noon. You have to remember infinity + n is infinity and infinity - n is also infinity. 

I know you have several questions in mind saying, its not true and is less intuitive. But mathematics works in mysterious ways. And that is why it became a paradox.

3. Monty Hall Problem

It is a probability paradox. The name was pinned from the presenter of an American television show (Let’s Make a Deal), Monty Hall. And the paradox is loosely based on this game show. The problem is,

In a game show, you are given three doors to select any one of it. Behind the doors, there are a car, and two goats. If you finds the door with the car, you will win. First you have to select a door from the three. The host will then eliminate the remaining door that has goat. And he will give you a chance to switch the doors. So the question is, what gives you more chance of winning? Switching the doors or stay with your first decision?

Think about it and read the remaining after you gets a solution.

Answer is you will be successful if you switch the doors. Are you correct? The chances of winning by swapping is increased when the host eliminate another door that has a goat. In fact the host is helping us.

• If you selects a goat at the first time, then you are sure you will win by swapping the doors, after the host eliminates a door with goat.

• Initially, the probability of selecting the door with car is 1 out of 3. At the same time, the probability of selecting a goat is 2 out of 3.

• So you have most chance of selecting a goat initially. And when the host eliminates the other goat door, you are having a good chance of guessing the other door has the car as it has a probability of 2/3. While staying with the same door has probability of only 1/3.

Problem solved. It was initially thought of as a fifty-fifty chance of winning on swapping or not swapping, and the answer was seemed to be counterintuitive, even though its true. That is the reason this problem became a paradox.

4. Dichotomy Paradox

It is one of the Zeno’s paradoxes which is a set of philosophical problems. It is very similar to the ‘Achilles and Tortoise Paradox’. The problem is as follows,

If you want to catch a bus that is a finite distance away from you, you have to first reach half of the distance, then the other half, and then the other half, and so on to make infinite number of steps. 

This problem deceive us to make a conclusion that you won’t catch the bus, but it is definitely false. So how it is proved mathematically? For that you have to know the Geometric series.

Geometric series, is a series that has a constant ratio between successive terms. An example is,

1/2 + 1/4 + 1/8 + 1/16 . . .

Each of the term is obtained by multiplying 1/2 with the previous one. Geometric series are infinite series with a finite sum. The solution for the above series is 1, which is finite.

Now let’s take the problem. When you are travelling half the distances continuously, you are actually performing a geometric series. Half the distance plus, the other half the distance and so on. That is the same as the geometric series written above. And the answer is a finite number for that series. 

It is certain that you can travel a finite distance and hence proved the problem.

5. Omnipotence Paradox

It is yet another set of paradoxes that comes under philosophical paradoxes. It is based on the term omnipotent. Omnipotent is all powerful and with unlimited power. And this will lead to numerous paradoxes. There are different versions of this paradox. One of it is The Paradox of the Stone, and it states as,

“If God is omnipotent, can he make a stone so heavy that even he can’t lift?”

If he can, the he won’t become omnipotent as he cannot life it. If he cannot, then still he won’t be omnipotent as is not that powerful to make such a stone.

There are many discussions about this paradox. Some says the paradox itself contradicts. It is similar to ask, “What happens when an Unstoppable force meets an Unmovable object?”

That’s it for the paradoxes session. It’s more than enough to have a lot of thinking.

Learn a lot, think a lot.

Ever wondered why we can't see small things?

Why we don’t see bacterias every day? We know microorganisms are everywhere, its in the air we breathe and the water we drink. Its in-front of our eyes. Then why can’t we see them? Why can't we see small things? To understand that, first we have to know how we SEE things.

Everyone knows, we see things when light from an object falls on our eyes. But how that image reach us? Does light carry information of that image? Yes, in the sense, each photon in the light ray have a different wavelength that matches the colour of the object where it is emitted or reflected. Each photon acts like a pixel of an image. When this light ray reaches our eyes, the signals are detected by the cones and rods in the retina.

Cones detect the colour and the rods detect the brightness. The brain will then formulate the image using this information. Now lets see, what’s the problem while viewing smaller objects. 

The photons that can be detected by our eyes has a limit. A typical human eye is capable of detecting the visible light with wavelength ranging, 390nm to 700nm. We are not adapted to see infrared, ultraviolet, radio waves etc. 

The reason we cannot see too smaller objects is that the wavelength of visible light is much bigger than the size of that object. The photons of visible range (390nm to 700nm) when reflected from smaller objects, like an atom, is too weak. Since an atom is very small compared to the wavelength of visible light, the wave equation requires that the light bounce off with a very broad spread of directions, not at all like reflection from a surface. Thus it makes hard to detect an atom.

Even using a conventional microscope, its hard to see objects below the length of the minimum wavelength of visible light, because a conventional microscope uses visible light to detect objects. It simply magnifies the things it detects.

So what should we do to see an atom? We makes use of an Electron microscope. In an electron microscope, the light source is replaced by a beam of fast moving electrons. As the electron's size is too small, it can successfully create image of smaller objects.

There are several types of electron microscopes for various uses. You can find the details and differences from here : http://www.explainthatstuff.com/electronmicroscopes.html

If you are wondering, the tiniest objects we can see is about 0.1mm, it is the size of a hair, lice etc.

The story of Rosetta and Philae - Cartoon series from ESA

Credit : ESA

ESA's mission to the comet 67p (Churyumov-Gerasimenko) is pictured as a kid friendly cartoon animation series. It tells a brief real life story of the Rosetta mission. No doubt, its not only for kids, but for us adults too. So much informative and with a heart warming storyline to make it understandable for all the ages. ESA released the cartoon in 5 languages (English, Italian, French, Spanish and German). Here I'll provide the playlist in English. For other videos you can check out ESA's Youtube channel.

Rosetta Philae cartoon

• Wake up Rosetta
• Are we there yet?
• Comet landing
• Living with a comet

Here is the playlist - ESA Rosetta and Philae Cartoon

The journey is still continuing and we have to wait for the next event to happen in the mission, to watch the next episode.

Why it's better to stay alert against the Zika Virus?

You might have heard about the Zika outbreak in Latin America. WHO (World Health Organisation) declared Zika virus as International public health emergency. Do we need to afraid? Let’s have a closer look.

Zika virus is transmitted through mosquito bites of infected Aedes genus, Aedes aegypti mosquitos. They are found in tropical regions. They can’t survive in cold temperatures as in Britain. It was identified for the first time in Uganda in Rhesus monkeys in the year 1947. Later in 1952 it was identified in humans.

The disease is so hard to find as it is symptomless. Only 20% of the infected people had some symptoms like a mild fever, skin rash and red eyes. This silent infection affects the highly vulnerable individuals, the pregnant women. This leads to small heads and brain damage to babies.

No vaccines found out yet for this disease. There is no specific treatment. People who are affected is advised to get plenty of rest, drink enough fluids and treat the pain and fever with usual medicines. Better way to prevent from affecting is to avoid mosquito bites. During an outbreak, authorities are allowed to use extreme measures like spraying DDT.

Its spreading in more than 20 countries since the outbreak on May 2015. It spreads through tropical belt. And the tropical belt is expanding due to global warming. Better to take precaution before hand. WHO advises to use mosquito repellent, wear clothes (preferably light-coloured) that cover as much of the body, use physical barriers such as screens, closed doors and windows, sleeping under mosquito nets. Avoid the breeding of mosquitos by emptying, cleaning or covering the containers that can hold water, such as buckets, flower pots or tyres.

Be alert, be safe.

Big Bang : The Origin of the Universe

Credit : NASA / WMAP/ Wikimedia Commons

How the universe began? The answer is universe popped out from nothing. Yes. It just came out from nothing. That is what, the great ‘Big Bang’ theory suggests (not the TV show). 'Nothing' means there was absolutely nothing. No space and no time. Time itself started from Big Bang. But what in the world, triggered the Big Bang? 

First thing you should know is, there is no OUTSIDE for our universe. The space and time exists within our universe itself and they came into existence after the Big Bang. So, the question what caused the Big Bang posses a serious issue of causality. There was no BEFORE to the event, Big Bang.

The word Big Bang misleads the public as it was an explosion in space. But it's not true, it was actually the appearance of space everywhere in the universe. It was a rapid expansion of space, analogous to the inflation of a balloon.

Now lets see the events happened in the beginning. The first event, modern physics is capable to understand, happened at hundredth of a billionth of a trillionth of a trillionth of a second after the Big Bang. That is too small. This time is called a Planck Time (10^-43 sec). No one knows what happened before and has less idea during the Plank Time, after the Big Bang. Einstein’s General Relativity suggests, there was Gravitational Singularity before this time.

All the ideas about the very early universe are speculations. We don’t have sufficient insights about those time.

Early Universe

- Plank era (10^-43sec) to Quark era (10^-06sec)

Credit : Cern

At Plank era, the four fundamental forces (electromagnetic force, weak and strong nuclear force and gravity) all had the same strength, and acted like a single fundamental force, held together by a perfect symmetry. At this time the Universe was expanded to a length of only 10^-35 metres (Planck Length) and had a temperature of enormous 10³²°C (Planck Temperature). The universe was an infinitely dense, hot fireball.

10^-43 sec to 10^-36 sec - gravity separated from the fundamental force and leads to creation of the earliest elementary particles (Quark-Gluon plasma or the "quark soup"). 

10^-36 sec to 10^-32 sec - the strong nuclear force separated and triggered the rapid exponential expansion of the universe, which is known as Cosmic Inflation.

10^-32 sec to 10^-12 sec - leads to the formation of Exotic particles like WIMPs (Weakly interacting massive particles, the fundamental particles of Dark Matter), neutrinos, Higgs Bosons etc.

10^-12 sec to 10^-06 sec - all fundamental forces become distinct and took their present form. Quarks, electrons, neutrinos etc were formed. Quarks and antiquarks annihilate each other on contact. But a quark for every billion pair survived from annihilation, thus forming the building block of matter.

Formation of Basic Particles

- Quark era (10^-06sec) to Nucleosynthesis (20 mins)

Credits : uoregon.edu

At this time period, the universe cooled down and became less dense. The elementary particles smashed together leading to the formation of nuclei.

10^-06 sec to 1 sec - quarks smashed each other to form hadrons (protons, neutrons etc). Electrons collided protons to give neutrons and massless neutrinos.

1 sec to 3 mins  - leptons (electrons) and antileptons (positrons) collide each other and annihilate and that lead to release of energy in the form of photons.

3 mins to 20 mins - temperature again fell down. Nuclear fusion started and formed atomic nuclei of hydrogen, helium, lithium etc.

Formation of Atoms and Elements 

- Nucleosynthesis (20 mins) to Dark Age (150 million years)

Credit : naoj.org

The temperature of the universe fell down again to the temperature of the surface of sun. Elements were created but still no activities of star creation occurred. Cosmic Background Radiation, we see today, started to emit.

3 mins to 240,000 years - universe was a breeding ground of nuclei, and was plenty with plasma of atomic nuclei and electrons. The energy of the universe was mainly from photons which interacted with, protons, neutrons and nuclei.

240,000 years to 300,000 years - formed the first atoms after nuclei captured electrons to neutralise. Universe become transparent to light, photons started travelling freely.

300,000 years to 150 million years - this period is called as the dark age, it is time period between the formation of atoms to the formation of first stars. Universe was dominated by Dark matter.

Formation of Stars and Galaxies 

- Dark Age (150 million years) to Present Day (13.8 billion years)

Credit : universoracionalista.org

This was the period of quasars, stars, galaxies, black holes, neutron stars, supernovae and everything we see today. Universe continues to expand rapidly.

150 million years to 1 billion years - quasars began to form due to gravitational collapse and the universe was composed of ionised plasma. Started formation of stars and due to gravity, formed galaxies and clusters and superclusters of galaxies.

8.5 billion years to 9 billion years - Late generation star, sun was formed from the debris of many generations of stars and the solar system around it formed around 4.5 to 5 billion years ago.

Today, 13.8 billion years - to be exact 13.799±0.021 billion years from the Big Bang. The universe is still expanding and a vast breeding ground of celestial objects.

We have no idea how vast the Universe is and still lots of surprises to be found out, that the mighty Universe holds. 

Know the Constellation - Canis Major

Last time we checked out the Orion constellation. Now its time for Canis Major. Canis Major is located in the southern celestial hemisphere. The name literally means, "The big dog". Canis major, beside the much smaller constellation, Little Dog, is commonly portrayed as accompanying the legendary hunter, Orion. It contains largely of young blue stars. The most important stars within the constellation are, Sirius, Adhara, Wezen and VY canis Majoris.

Sirius, the brightest star in the night sky, is a Spectroscopic Binary star. It is twice as bright as Canopus, the next brightest star. It appears bright because of both Sirius's intrinsic luminosity and proximity to Earth. Sirius is twenty five times additional luminous than the Sun, however features a considerably lower brightness than other bright stars like Canopus or Rigel. Sirius system is one of Earth's near neighbours.It is approx. 9 light years from Earth.The sky location for Sirius is : RA 06h 45m 08s, Dec -17°16' 42".

Know the basics of sky gazing, Sky Gazing for Beginners - Part I

Adhara is a star in Double system. It is the second brightest star in the constellation. The name Adhara came from Arabic, meaning "Virgins". It is one of the brightest known extreme ultraviolet sources in the sky. About 4,700,000 years ago, Adhara was only 34 light years from the Sun, and was the brightest star. It is approx. 405 light years from Earth. The sky location for Adhara is : RA 06h 58m 38s, Dec -29°01' 41".

Wezen is a yellow-white supergiant variable star. It is approx. 1607 light years from Earth. The sky location for Wezen is : RA 07h 08m 23s, Dec -27°36' 25".

VY Canis Majoris is a single star categorised as a semi regular variable with an estimated period of 2,000 days. If placed at the position of Sun, VY Canis Majoris's surface would extend on the far side the orbit of Jupiter, though there's still sizeable variation in estimates of the radius. It is approx. 4892 light years from Earth. The sky location for VY Canis Majoris is : RA 07h 22m 58s, Dec -25°46' 03".