The observable universe is larger than you might expect. Much larger.

The observable universe is larger than you might expect.  Much  larger.

The age of the universe is about 13.8 billion years old.  Since nothing can travel through space faster than light, most people would think the universe has a radius of 13.8 billion light years.  But this is not so.

Einstein's speed limit does not apply to the expansion of space itself because space does not possess mass.  Space is expanding faster and faster and it carries the matter contained within it at a rate faster than the speed of light as well because those galaxies are not moving through space but, instead, are riding in it.

The rate of expansion is higher for objects that are farther away from us.  What we call the visible universe is the part of space around us that is expanding more slowly than light speed, but only in relation to us.  That region does appear to have a radius of 13.8 billion light years.  But that's not the whole story.

The matter that looks to be that far is in reality much further now because the expansion of the observable universe has continued while the light was travelling to reach us.

Some might think this means that matter at the visible horizon is disappearing as the space around it breaks light speed and that the light from these distant places can never reach us, ever.  Eventually, all the galaxies we can see now will forever disappear from view.  Space will appear empty. But this is also not true.

Actually, the expansion has always been faster than lightspeed and what we can see is more and more over time. Weird!  Einsteinian cosmology is just as strange as quantum physics.  Watch this video if you dare.

Calculations based on the increasing expansion rate tell us our observable universe is currently about 46.5 billion light years in radius.  Remember that I am describing the observable universe.  The whole universe may well be infinite.

The Big Bang was not like a single explosion.  The Big Bang occurred EVERYWHERE at the same time.  As far as any point in space is concerned, it is the center of the universe because the universe is the expansion of a singularity.  That's right---an infinite and expanding singularity.  Hmm!

EDIT-- Physicists do not think of spatial expansion in terms of the speed of light, but it is convenient here to illustrate the behavior in a way that is easily understood.

What are some of the best road routes in India?

Answer on @Quora by Nargis Ansari to What are some of the best roads/routes in India? https://www.quora.com/What-are-some-of-the-best-roads-routes-in-India/answer/Nargis-Ansari?srid=ndBp&share=99da1891

1. Road Trip from Delhi to Manali to Leh: Every Backpacker Biker’s First Love

Time: 25 hours
Distance: 1,019 km
National Highway: NH 1 & NH 21

A road trip in the Himalayas will always be accompanied by gorgeous landscapes wherever you look. The Delhi-Manali-Leh road trip is one of the best road trips in India and an absolutely enthralling journey to take. Though the roads may get a little treacherous and tricky on your way to Leh, the awesome scenic beauty makes up for it. It is a road trip every daring traveler must take.
Where to eat: Have an early breakfast at Murthal. Eat at Sukhdev’s dhaba on the way for some butter loaded stuffed paranthas or you could stop by McDonald’s, Barista, Subway, or Haveli.
Where to stay: Take a stopover at Bilaspur while travelling from Delhi to Manali. From Manali to Leh, you could spend a night at Circuit houses in Lahaul Valley.

The Physics Refresher You Need To Read To Understand 'Interstellar'

I've seen many posts on the Internet before I actually went to see Interstellar but out of all those posts, I found this post from the Business Insider, the most helpful and reliable.

The Physics Refresher You Need To Read To Understand 'Interstellar'

Christopher Nolan's latest mind-trip "Interstellar" will be premiering in theaters across the country on Friday, Nov. 7. No doubt, the film is the strangest cinematic experience you will have had since Nolan's "Inception." But unlike "Inception," the visually-gripping film "Interstellar" is based on real, scientific concepts like neutron stars, spinning black holes, and time dilation. And if you're not at least semi-familiar with these terms, you might end up feeling a little lost during the movie.
In the movie, a crew of space explorers embark on an extra-galactic journey through a wormhole. What awaits them on the other side is another solar system with a spinning black hole for a sun.
They must race against space and time to complete their mission. All this space travel can get a little confusing, but it relies on some basic physics principles. And if you understand these principles, then you'll spend less time guessing and more time enjoying.
Here's a brief guide to the five physics concepts you need to know in order to understand "Interstellar."

What are some of the cleverest inventions and ideas ever?

Best Locker ever.

Replace your boring doorbell with the Piano-bell

What are some things every Indian should know about Indian history?

This part has been taken from the blog: The greatest Heist in Indian history..How Indian History was changed and we didn’t even notice. Part 1:The lost eon 6th Century B.C to 1174 A.D .Do visit it for the complete article.

The lost eon 6th Century B.C to 1174 A.D
"This is India’s history from an average  Indian 10th grader's point of view

1. Harappans were the first people in India, and they had a fetish for building abnormally large bath-tubs.
2. Their asses were then kicked by the some unknown invading Aryans.
3. Somewhere down the line, Alexander and his badass gang of Greeks came calling.
4. Chandragupta Maurya with his adviser Chanakya, did some awesome 420giri to take over from the Greeks.
5. They were then  succeeded by the Guptas who brought the ‘Golden Age’ with them.
6. Mahmud of Ghazni, however, looted all that gold. He needed a sum total of 17 visits to complete his gold quest.
7. Mohammad Ghauri followed him with similar intentions, but decided to avoid the trouble and simply stay back. And then he died.
8. He left his slave Qutub-ud-din Aibak to do all the ruling. His most significant achievement was to build one pointless tower.
9. Then came a Muslim queen, underlining our credentials in female liberation.
10. It was then the turn of Tughlaq and his gang of idiots. They moved national capitals around because they hated the weather.
11. From somewhere, Babar, a descendant of a lame, one eyed king from Central Asia landed in India.
12. He and his sons, calling themselves Mughals,  ruled India for the next 350 years.
13. Their party came to an end when Englishmen arrived, redcoats and all, and took a strong fancy to our country.

What is the best love story?

Whoever said that every thing is fair in love and war had no idea  that millions of romantics would get inspired by it to push extreme  limits and thus, make memorable love stories.

The love story of Odia painter P. K. Mahanandia and Sweden’s  Charlotte Von Schedvin is one such tale. She belongs to the Swedish  nobility and he, to a family of weavers considered as outcasts in  Odisha. It is a tale of commitment, romance and perseverance with an  happy ending.

What are some of the best travel and exploring places in India which are not overcrowded with tourists?

Being a traveler I have traveled almost 60% of India till date. I would like to mention the places (list is going to be long, you might get bored in the middle) state wise. I have visited many of these & some are yet to visit. Google has helped me a lot to gather these knowledge & I have tried my best to sum up all the information here  :
Being a Bong I would like to start from West Bengal :-)
1. West Bengal
i) Henry Island (visited) :
Henry Island is an island near Bak Khali in South 24 Parganas District.  It is around 130 km (81 mi) from Kolkata. Henry Island is named after a  European who surveyed land in the area in the late 19th Century. This is an underrated tourist spot. Most of the people do not know about this place. Walking through the beach is simply romantic.

​​

What are the best formats for a resume?

Just as the best product is the one that gets the job done, the best resumes are those that communicate your skills and accomplishments in a clear, effective way.
Graphical resumes are, in particular, terrible. Unless you can be one of the lucky few to get a bunch of media attention for a nifty format, you will hurt yourself far more than you'll help yourself if you use a graphical resume. Graphical resumes are typically difficult to read and they sacrifice content -- your hard-earned accomplishments -- in favor of pretty pictures and useless graphics. See: Why Your Awesome, Creative Resume Isn’t Working.
A good resume format has the following attributes:

• Multiple Columns: Multiple columns make it easier for someone to quickly skim your company titles, positions, schools, and other key facts. It also stores this information in a very compact way, allowing more space to list things you've done. (Note: do not use one of those templates where the entire left part of the resume is a column for the categories. They waste a lot of space.)
• Short and Sweet: People only spend about 5 - 30 seconds reading your resume, and this isn't enough to read even a full page of content. When your make your resume too long, it just dilutes the quality of each thing on your resume. Focus on just the highlights. One page is often all you need, but if you have 10+ years of experience and multiple roles, you can justify at most two pages. That's it though.
• The Right Sections: No objectives (they're useless). Summary sections can be okay, but they're usually not (after all, if your resume is short and concise, then you don't really need a summary section).
• Use Tables: Okay, this is really nit picky, but it's a personal pet peeve of mine. The way to make multiple columns in Microsoft Word is with tables (with invisible columns), not by hitting 'space' dozens of times.
• Bulleted -- No Long Text Blobs: Again, you only have about 15 seconds to make an impression. Large blocks of text will not be read. Keep your bullets to 1 - 2 lines (and, ideally, about half or more of those bullets should be one line).
• Appropriate Use of Fonts and Formatting: You don't want to go overboard with fonts and formatting. However, a little bit of formatting (bold, italics, etc) can be useful to organize your resume.

Do photons, the particles of light, have mass?

One might think that light having weight is awkward, but it does exert weight.
Thinking light as photons (thereby taking the advantage of its dual nature), we know that photons are mass-less.
Yes; their rest mass is zero. But when they move (of course, at the speed c), they have momentum (E=mc² and hence, m=Ec²). Photons cannot stay at rest, because that violates relativity.
[The actual relativistic equation is E²=m²c⁴+p²c²]
Maxwell wrote:

In a medium in which waves are propagated there is a pressure in the direction normal to the wave, and numerically equal to the energy contained in unit of volume.

Hence, the pressure exerted by light can be calculated (force exerted over unit area; and this force can be called as the 'weight exerted by' light!)
So, when the light is incident on an object, that object weighs a bit more, owing to the 'pressure' it exerted.
P.S.: The city of Chicago weighs 140 kg (300 lbs) more in a sunny day compared to a normal one!

What are some of the most realistic pencil drawings you have come across?

I came across these amazing pencil drawings by a Russian Artist, Olga Melamory Larionova.

How would you explain the Higgs boson particle to a seven-year old?

Little Jimmy: "Daddy, I heard them talking on the news about a God Particle. What's that?"
Me: "That would be the Higgs Boson."

Little Jimmy: "What's a Higgs?"
Me: "That's Mister Higgs to you. He's the guy who postulated that boson."
Jimmy: "What's a boson?"
Me: "There are two kinds of statistics that particles follow. One discovered by Mr. Fermi and one discovered by Mr. Bose. The ones that do what Mr. Fermi says they do are called fermions and the ones that do what Mr. Bose says they do are called bosons."

Jimmy: "And what do they do?"
Me: "Well, to answer that I'll have to use some big, scary words. But they're actually easy to understand."
Jimmy: "Alright."

What is the hottest object in the universe?

On a typical day, one contender is the white dwarf that is at the heart of the Red Spider Nebula (NGC 6537).  The surface temperature of that star is around 300,000 K (540,000 R).  That's 50 times hotter than our sun.

Or you could go with a quasar, where the center burns 100 times as much energy as the Milky Way.  The gas around a quasar can reach a temperature of 80 million degrees.

What does Einstein's theory of relativity teach us?

Here are things we get to know from theory of relativity: 
1) Empty space (Vacuum) is not actually empty, it is active. Space is 3 dimensional Fabric, which can bend, vibrate, interact.

2) When you keep some heavy object (Sun) on that fabric, you bend this fabric and this causes gravity. Just as a marble starts revolving when thrown in to a bowl, planets revolve around the Sun.

Why is Ramanujan considered one of the great mathematicians?

Because he is. By any definition of greatness, he is there right at the top.

What do you get when you google "greatest mathematicians"?

​

You see that? Among the likes of Gauss, Newton, Euclid, Euler, Archimedes, Descartes, Pythagoras, and Leibniz. If that isn't some glorious company, what is?

Forget the fact that he was born in a poor family, and that he did not have any formal education in Mathematics. Forget the fact that he compiled, in a short life of 32 years, around 4000 proofs, formulae and identities. Or that as a kid, he completed George Shoobridge Carr's Synopsis of Elementary Results in Pure and Applied Mathematics, volume 2. Or that Ramanujan was the one chosen as an example to portray the genius of Will (Matt's character) in Good Will Hunting.

Ramanujan was one of those people who are born special. With a clear advantage over others. It wasn't passion or dedication as much as it was sheer innate ability that allowed him to think and calculate stuff normal mortals can't even begin to comprehend.

Here's something you should give a shot. A 60 minute documentary that came out in 2013, aptly titled, "The Genius of Ramanujan".

Photographs: What are some rare photographs of Indian history?

1. This image of Tagore and Einstein brings geniuses from worlds apart together. 

Pixgood
2. A man climbs up an electric pole to see the last rites of Gandhiji's funeral.

Some Parenting Hacks That Will Make Life with Kids Just a Little Easier

• Bathe your child in a laundry basket so that their toys don’t float away.
  
  
                                                                                                                                             
• A rubber band can keep your child from getting locked in the bathroom.
  
  
• Make a bracelet for your child with your phone number on it.
  
  
  

What do I need to know about WWII?

Listed below is a comprised list of What Everyone Should Know About WWII.

When did World War II begin?
According to what is written and known in current history books, World War II began on September 1,1939 when Germany attacked Poland without a formal declaration of war. In support of their mutual defence treaty obligations with Poland, France and Great Britain issued ultimatums to Hitler for the immediate withdrawal of German forces from Poland. When the deadlines expired, Great Britain and France declared war on Germany on September 2, 1939. Germany had Italy and Japan on its side, and were known as the Axis powers.

Why is December 7, 1941 considered a decisive date in World War II?
Pearl Harbor, on the island of O'ahu, Hawaii, was attacked by the Japanese Imperial Navy, on December 7, 1941. The surprise attack was masterminded by Admiral Isoroku Yamamoto. On December 8, 1941 the United States -- until then neutral in World War II -- formally declared that a state of war existed between the United States and the Japanese empire. Some historians believe the United States presence helped changed the Allies' (as the forces fighting the German, Italian and Japanese armies were known) fortunes.

Ordos, China - A ''Modern Ghost Town''

Meant as home for one million people, the Kangbashi district remains nearly empty five years after construction began in 2010.

All Quiet
The Kangbashi district began as a public-works project in Ordos, a wealthy coal-mining town in Inner Mongolia. The area is filled with office towers, administrative centers, government buildings, museums, theaters and sports fields—not to mention acre on acre of subdivisions overflowing with middle-class duplexes and bungalows. The only problem: the district was originally designed to house, support and entertain 1 million people, yet hardly anyone lives there.

Empty
Though many of the properties in Kangbashi have been sold and a million people were projected to be living in Kangbashi by 2010, the city is still empty.

Sentinels of the Arctic

Trees are engulfed in snow create this landscape.

It appears as though it were a part of some icy alien planet. Temperature here can go even below -40 degree Celsius .

What is the world's weirdest place? - 3

Disclosure: Some of them are creepy.

The Catacombs Of Paris:  Where the Empire of the Dead sleeps.
Not for the faint hearted, this attraction will stay with you forever. The solemn, chilly air can get to pretty much anyone, If it doesn’t get to you, you might be one of the slinking trespassers that so often creep out of the various hidey holes leading to this mass grave.

Recommended Visit: Warning before you go.

Door to Hell (Literally)
The Door to Hell is a natural gas field in Derweze, Turkmenistan that has been burning continuously since it was discovered in 1971.
Wiki: Door to Hell

What is the world's weirdest place? - 2

The Catacombs (Paris): The Parisian catacombs are a giant ossuary and cemetary that are located beneath that city’s streets. There are approximately 6 million bodies put to rest in the catacombs. There is a city of the dead waiting to be explored beneath the city of lights.

The Mütter Museum (Pennsylvania): The Mütter Museum is an institution dedicated to medical anomalies. It houses organs, bones, fetuses and statues that’ll leave you with chills. Its medical oddities, anatomical and pathological specimens, wax models, and antique medical equipment are world-famous.

(Photograph can be too disturbing, you can have a look at the website if you wish to. Home | The Mütter Museum)

The Door to Hell (Turkmenistan): This was once a gas field, but the Soviets set it on fire. Now, it has been burning for over 40 years. It seems that the dangerous pit of fire will never stop burning.

What is the world's weirdest place? - 1

Socotra

Situated in the Indian Ocean 250 km  from Somalia and 340 km from Yemen, Socotra Island (part  of a group of four islands) was geographically isolated from mainland  Africa for many aeons. The island is about 3,650 square km and has a few  smaller islands around it that are mostly uninhabited. On 2008 it was  recognized as a world natural heritage location.

What are some real life hacks?

EFFECTIVE READING HACKS

When I was in fourth grade I was told that I wasn't a great reader. No concern arose until I was told I had to go to a separate room to read. I was labeled as a SPED kid. (Special Education). This went on for 7 years.

Early on this turned me off from school. I would just doodle in class. Drawing sports players. Or the Penn State Logo (I grew up in PA). Or skateboarders (Tony Hawk).

In year 5 my teachers, my parents and I had to make a decision about my future. I was 15. I didn't know what I wanted to do that night let alone for the rest of my life.

"College is not an option" a teacher that taught me 3 classes (Math, Reading and English/Writing).

As an Indian heading to the US what should I keep in mind so that I can blend with the locals?

US is a large country and that means there will be a range of people you would meet. You should not get your experience be impacted by the minority of assholes. I have lived and traveled in a variety of regions in the US - south, east, northeast, northwest, west and have found very warm relationships with Americans of every type. 

Before I went and lived in the US south, many American friends discouraged that there might be racists down there, but I had a blast living in Nashville. I had fun traveling with white families in Arizona, with blacks in Baltimore and New Englanders in Boston. There are enough good people everywhere. Thus, ignore the stereotypes and keep moving on - as you would invariably meet the bad apples along the way. Let the bad apples not stop you from exploring the garden.

What are the best YouTube channels for learning, growth and development?

♦ Education ( All great learning content at one place  )

♦ Kurz Gesagt - In a Nutshell   - (Explain complex things  into simple terms with beautiful illustration )

Is Kashmir an overhyped tourist destination?

I will let you decide if Kashmir is overhyped about tourism or not.
Just go through the answer..

1. Srinagar

Aerial view of the city

The beautiful sunset at Dal Lake

What are some cool facts about the Universe?

Here are some amazing facts about the universe.

1.  Atoms are the building blocks of all the matter in the universe.
But what's interesting is ,it's comprised of a tiny nucleus surrounded by about 99.9% empty space. 
Theoretically if you are able to remove all of that empty space, you could fit the entire human race in about the size of a sugar cube.



2.  There is a planet that scientists discovered in 2004 called Gliese 436b that's entirely covered by burning ice.
The planet has incredibly strong gravity which super compresses the ice allowing it to withstand the 
800 degree Celsius temperature on it's surface.


​3. About 1% of static that you see on your TV is made up of cosmic microwave radiation which is left over from the big bang that happened 
13.7 billion years ago. 


4. In 2011 there was a magnitude 9.0 earthquake that happened in Japan which was so strong that actually shifted the earth's axes and shortened days on earth by 1.8 micro seconds.


5. Every century, the earth's rotation naturally slows by about 17 mili seconds.
That means if you went back to when dianosours roam the earth, the days would only be about 22 hours long.


6. There is a mountain on Mars called Olympus Mons that's 22 kilometres tall.
That's three times the size of mount Everest on earth.
It's the tallest mountain on any planet in our solar system and it is so big that it actually sticks out of the Mars's atmosphere.
​


7. Aerogel also known as frozen smoke, is the lowest density solid that we know of.
Its made up of about 96% air, it can support 8 thousand times its own weight and  can withstand a blast from 2 pounds of dynamite.
It is also the best insulator in existence that's why NASA uses it to insulate space suits.



8. Our solar system takes ​
Two hundred and twenty five million years to rotate around the milky way. 
That means that the last time the earth was in its current position, the dianosours were just beginning to roam the earth.9. Stars are created when cosmic gases collect billions of tons of mass and gravity gets so strong that fusion occurs and the release of energy creates a star.
According to our best estimates, 
Two hundred and seventy five million 
stars are created every single day.


10. Planets are created from the aftermath of star births.
All the remains of material that's left over will either create an astroid, a comet, a moon and if there is enough a planet.


11. Sagittarius B is a massive space cloud that's 26 thousand light years away from earth, that's entirely made of alcohol.
It contains over
a billion, billion, billion litres of alcohol, which is enough for about 
400 trillion pints of beer.


​12. Astrologists theorise that the centre of our galaxy smells like rum and tastes like raspberry.
This is due to the discovery of 
ethyl formate in the milky way which is the chemical responsible for raspberries its flavour and rum its smell.


13. Everything on earth, including earth itself is made of Stardust.
Every single naturally occurring element with the exception of hydrogen and helium is created within stars.
This means as an example that the iron in your blood is actually billions of years old from a star trillions of miles away.


14. 55 CANCRI E is known as the Diamond planet.
Discovered 40 light years away from earth, its so rich in carbon that its believed to hold 3 times our planet's mass in diamonds.
Its also believed to have a solid diamond core with the size of 
10 billion ,trillion,trillion carats.



15. Black holes are one of the most fascinating things in our universe mostly because of our inability to accurately study them. 
Although we don't know too much about them, what we do know is that they form when a star dies and collapses on itself.
The gravitational pull that is created by this is so strong that nothing can escape from it.
NOT EVEN LIGHT.



16. Its hypothesised that 80% of the universe is made up of Dark Matter.
Dark Matter is a matter that cannot be directly seen with telescopes. 
The only reason that we know they exist is  due to its gravitational pull on visible matter.


17. Planet Venus's day is longer than it's year.
This is because of its entire orbit around the sun before it manages to turn ones on its axis.


18. The light hitting earth right now is over thirty thousand years old.
That's because it takes that long for the energy in the sunlight to leave the sun's core and reach its surface.
When it finally reach the sun's surface it only takes about 8 minutes to reach earth.



19. In space, there is something really cool called cold wielding.
If two pieces of metal touch in space, they instantly bond and become one.
This is due to the vaccum that occurs in space and it doesn't happen on earth because our atmosphere puts a layer of oxidized material between the two surfaces.



That's it.

These are some facts about the universe that I found interesting.

If you want to know more,
Just Google- interesting universe facts.
There is a lot of them out there.

Source: 1. Various links on
www.google.com
2. www.wikipedia.com
3. A book by Stephen Hawking-
    A brief history of time.
4. Self search & google images.

What are some unusual features that would be great to add to a new home under construction?

I think about this subject a lot and I pin my thoughts so I have them handy:

Page on Pinterest

Sunken Living Room- this is my dream for entertaining.

Sunken PreFab Wine Cellar

Hideaway Parking Spot that leads to your underground garage and bunker

Sunken Tub 

Backyard Movie Set Up

Fish Tank Bedroom

Halfway Decent Tree House- this will cost nothing if you have your contractor do it while building your house.

Hanging Bed

Multi Purpose Table

Hidden Rooms

Nooks, lots of nooks

I hope some of these things are what you were looking for.

What are the best and most useful websites?

There are numerous websites on the internet that can make you smarter and more intelligent at no cost. Of course, there are websites which can distract you, but if you want to utilize your time on the Internet, here is the list of sites that you must consider.

1. Quora.com
Quora’s mission is to share and grow world Knowledge. It's a question-answer based site where people ask their questions and queries and get responses from experts. In fact, my this post is inspired by one of questions asked on this website. Simply, Quora is the best source of knowledge. The good thing about Quora is that it contains questions are from all fields like lifestyle, technology, travelling, cooking, internet and many more. Ask Anything and you will get the best answers to your questions and you can also read the answers of the questions asked by other users. In short, Quoracontains great information and facts which are rarely available. You can also write blog posts about what you know. I fell in love with this site when I first visited it.

2. Duolingo.com
An awesome language teaching site that teaches over 20 languages from scratch. The good thing about the site is that it starts at beginner level and is completely free. If you put in a little effort and are really interested in learning a new language, in a couple of months you could speak and write a new language. Learning with duolingo is fun and addictive. The Dulingo app is available for both iOS and Android so that you can learn anytime.

3. Justinguitar.com
You are definitely going to thank me for this if you are fond of learning guitar.Justinguitar.com was started by Justin Sandercoe in 2003 and since then his website has been visited by millions of people. His site provides hundreds of free quality guitar lessons. All lessons are in form of video so that you can easily learn playing guitar. This site provides the best way to learn guitar online and thousands music lovers already making the most of it. 

4. Cookingforengineers.com
Not only provides new recipes but also teach the way how to make them tastier. All the recipes are well written, photographed and very easy to understand. If you love cooking, this is the site to visit. 

5. Lumosity.com
A free online application to test your brain and help you achieve its full potential. It provides free brain testing, memory testing and logical reasoning exercises which refresh your brain and make you smarter and sharper. It’s the Web's most popular scientifically designed training program and it is free. 

6. Khanacademy.com
This site deserves a much higher place in this list because of its mission which aims at providing world class education to those who need it but cannot afford it. It is a non-profit organization which provides world class education for everyone everywhere free of cost. It covers a wide variety of subjects like mathematics, science, economics, Arts, humanities and computer science. It also provide lectures for those preparing for various tests like like SAT, GMAT,IIT-JEE, MCAT, etc. 
All of Khan academy’s educational content and material is available to everyone completely free of charge. 

7. Freerice.com
Well, You might living in a developed country and has a modern lifestyle but there are many people out there who are still not getting enough food and suffering from hunger. Freerice helps to end hunger from world by providing rice to hungry people for free. It has multiple-choice type quiz questions on wide variety of subjects and if you answer right, they donate 10 grains of rice through the World Food Programme. So you can improve your knowledge and provide some food to needy people at the same time. 

8. Ted.com
Collection of TED (Technology, Education and Design) talks in which experts address a wide variety of useful topics through small interval videos. It is like attending a world class seminar from home. 

9. Coursera.org
Do you ever dream of studying at world’s top universities? Now you can virtually fulfill this dream. It provides online courses in collaboration with the world’s best universities like University of California, The Hong Kong University of science and technology, Stanford University, University of Pittsburg, University of Tokyo, University of Michigan and many more. 

The approach used by coursera.org is very much similar to real classes. You learn by watching demonstrating videos, perform activities and assignment and then submit the assignments .On the basis of your assignments you get marks. The quality of content and material at this class matches the education quality at world level universities. Here are the some courses I am currently attending :

· An Introduction to Interactive Programming in Python 

· Programming Mobile Applications for Android Handheld Systems 

· Learn to Program: Crafting Quality Code 

All these courses are available free of cost. 

10. Nerdfitness.com
An ultimate site that helps stay in shape and provide valuable health tips. It provides very valuable information and case studies on how you can lose your weight. Feels like getting instructions from a professional sitting at home. 

11. Codecademy.com
As the Internet is expanding each day, there is more demand of web developersand programmers. At codeacademy you can learn the basics of code. You may not become a professional programmer immediately after following the tutorials but this site teaches you the right way to become an expert. Currently it provides classes and courses on web technologies like HTML, Javascript , jQuery, PHP, Ruby, Wordpress, etc. 

12. Openculture.com
This site can be considered the repository of free online educational resourceswhich include videos, tutorials, eBooks and audio books. It does not provide educational content itself but collects all the good learning material from all the sites(including the sites I mentioned above) and collaborate them so that you can access them at single place. 

13. geographyiq.com
A unique site which provides information about the major facts of all countries. Select a country either alphabetically or from map and access information like Geography, People, Military, Communication, currency, Economy and so on.

14. Instructables.com                                 
A huge community which provide how-to-do step by step guides on almost everything - from some basic household tricks to high end tech tricks. 

15. Howstuffworks.com
If your hobby includes reading and you are curious about things, then this is the site for you to visit. How Stuff works – An online source of easy to understand explanations of how certain things actually works. From car engines to search engines, from cell phones to stem cells, and thousands of subjects in between, HowStuffWorks - Learn How Everything Works! has it covered. 

Still there is many. The list of such kind of websites is very long. I tried to cover only those which I found highly productive and useful. Do I Missed a great online resource? Share it with us by commenting below. Please share this post by using the social sharing buttons below so that everyone can know about these sites.

Edit:
Additional useful websites:

ctrlq.org/screenshots – for capturing screenshots of web pages on mobile and desktops.
dictation.io – online voice recognition in the browser itself.
zerodollarmovies.com – find full-length movies on YouTube.
screenr.com – record movies of your desktop and send them straight to YouTube.
Sign in - Google Accounts... – shorten long URLs and convert URLs into QR codes.
unfurlr – find the original URL that’s hiding behind a short URL.
copypastecharacter.com – copy special characters that aren’t on your keyboard.
codeacademy.com – the best place to learn coding online.
lovelycharts.com – create flowcharts, network diagrams, sitemaps, etc.
iconfinder.com – find icons of all sizes.
office.com – download templates, clipart and images for your Office documents.
followupthen.com – the easiest way to setup email reminders.
jotti.org – scan any suspicious file or email attachment for viruses.
wolframalpha.com – gets answers directly without searching   – see more wolfram tips.
printwhatyoulike.com – print web pages without the clutter.
ctrlq.save – save online files to Dropbox or Google Drive directly.
ctrql.rss – a search engine for RSS feeds.
e.ggtimer.com – a simple online timer for your daily needs.
coralcdn.org – if a site is down due to heavy traffic, try accessing it through coral CDN.
random.org – pick random numbers, flip coins, and more.
pdfescape.com – lets you can quickly edit PDFs in the browser itself.
tubemogul.com – simultaneously upload videos to YouTube and other video sites.
scr.im – share you email address online without worrying about spam.
spypig.com – now get read receipts for your email.
myfonts.com/WhatTheFont – quickly determine the font name from an image.
google.com/webfonts – a good collection of open source fonts.
regex.info – find data hidden in your photographs – see more EXIF tools.
livestream.com – broadcast events live over the web, including your desktop screen.
iwantmyname.com – helps you search domains across all TLDs.
homestyler.com – design from scratch or re-model your home in 3d.
join.me – share you screen with anyone over the web.
onlineocr.net – recognize text from scanned PDFs – see other OCR tools.
flightstats.com – Track flight status at airports worldwide.
wetransfer.com – for sharing really big files online.
hundredzeros.com – the site lets you download free Kindle books.
polishmywriting.com – check your writing for spelling or grammatical errors.
marker.to – easily highlight the important parts of a web page for sharing.
typewith.me – work on the same document with multiple people.
whichdateworks.com – planning an event? find a date that works for all.
everytimezone.com – a less confusing view of the world time zones.
gtmetrix.com – the perfect tool for measuring your site performance online.
noteflight.com – print music sheets, write your own music online (review).
imo.im – chat with your buddies on Skype, Facebook, Google Talk, etc. from one place.
translate.google.com – translate web pages, PDFs and Office documents.
kleki.com – create paintings and sketches with a wide variety of brushes.
similarsites.com – discover new sites that are similar to what you like already.
wordle.net – quick summarize long pieces of text with tag clouds.
bubbl.us – create mind-maps, brainstorm ideas in the browser.
kuler.adobe.com – get color ideas, also extract colors from photographs.
liveshare.com – share your photos in an album instantly.
lmgtfy.com – when your friends are too lazy to use Google on their own.
midomi.com – when you need to find the name of a song.
google.com/history – see your past searches, also among most important Google URLs
bing.com/images – automatically find perfectly-sized wallpapers for mobiles.
faxzero.com – send an online fax for free – see more fax services.
feedmyinbox.com – get RSS feeds as an email newsletter.
ge.tt – qiuckly send a file to someone, they can even preview it before downloading.
pipebytes.com – transfer files of any size without uploading to a third-party server.
tinychat.com – setup a private chat room in micro-seconds.
privnote.com – create text notes that will self-destruct after being read.
boxoh.com – track the status of any shipment on Google Maps – alternative.
mondrian.io – create vector drawings in the browser
draw.io – create diagrams and flowcharts in the browser, export your drawings to Google Drive and Dropbox.
downforeveryoneorjustme.com – find if your favorite website is offline or not?
ewhois.com – find the other websites of a person with reverse Analytics lookup.
whoishostingthis.com – find the web host of any website.
labnol.org – software tutorials and how-to guides.
disposablewebpage.com – create a temporary web page that self-destruct.
urbandictionary.com – find definitions of slangs and informal words.
seatguru.com – consult this site before choosing a seat for your next flight.
unsplash.com – download images absolutely free.
zoom.it – view very high-resolution images in your browser without scrolling.
scribblemaps.com – create custom Google Maps easily.
alertful.com – quickly setup email reminders for important events.
picmonkey.com – Picnik is offline but PicMonkey is an even better image editor.
formspring.me – you can ask or answer personal questions here.
sumopaint.com – an excellent layer-based online image editor.
snopes.com – find if that email offer you received is real or just another scam.
typingweb.com – master touch-typing with these practice sessions.
mailvu.com – send video emails to anyone using your web cam.
timerime.com – create timelines with audio, video and images.
stupeflix.com – make a movie out of your images, audio and video clips.
safeweb.norton.com – check the trust level of any website.
teuxdeux.com – a beautiful to-do app that looks like your paper dairy.
deadurl.com – you’ll need this when your bookmarked web pages are deleted.
minutes.io – quickly capture effective notes during meetings.
youtube.com/leanback – Watch YouTube channels in TV mode.
youtube.com/disco – quickly create a video playlist of your favorite artist.
talltweets.com – Send tweets longer than 140 characters.
pancake.io – create a free and simple website using your Dropbox account.
builtwith.com – find the technology stack to know everything about a website.
woorank.com – research a website from the SEO perspective.
mixlr.com – broadcast live audio over the web.
radbox.me – bookmark online videos and watch them later (review).
tagmydoc.com – add QR codes to your documents and presentations (review).
notes.io – the easiest way to write short text notes in the browser.
ctrlq.org/html-mail – send rich-text mails to anyone, anonymously.
fiverr.com – hire people to do little things for $5.
otixo.com – easily manage your online files on Dropbox, Google Docs, etc.
ifttt.com – create a connection between all your online accounts.

The following websites were part of the original list but they are either no longer available or have been replaced with better alternatives.

virustotal.com – scan any suspicious file or email attachment for viruses.
isnsfw.com – when you wish to share a NSFW page but with a warning.
truveo.com – the best place for searching web videos.
tabbloid.com – your favorite blogs delivered as PDFs.
warrick.cs.odu.edu – you’ll need this when your bookmarked web pages are deleted.
tempalias.com – generate temporary email aliases, better than disposable email.
whisperbot.com – send an email without using your own account.
errorlevelanalysis.com – find whether a photo is real or a photoshopped one.
google.com/dictionary – get word meanings, pronunciations and usage examples.
wobzip.org – unzip your compressed files online.
namemytune.com – when you need to find the name of a song.
snapask.com – use email on your phone to find sports scores, read Wikipedia, etc.
pastebin.com – No.1 paste tool since 2002
encrypted.google.com – Google now redirects all logged-in users to the https versionofgoogle.com by default so this is no longer necessary.
bounceapp.com – replace this with a version that works on mobile.
dabbleboard.com – a online virtual whiteboard that will shut down in August 2012.
chipin.com – helps you raise funds online for an event or a cause (closed).