Today I found out about a man who fairly accurately estimated the circumference of the Earth well over 2,000 years ago: Eratosthenes of Cyrene.

Born around 276 B.C. in Cyrene, Libya, Eratosthenes soon became one of the most famous mathematicians of his time. He is best known for making the first recorded measurement of the Earth’s circumference, which was also remarkably accurate.  (And, yes, people at that point had known for some time that the world wasn’t flat, contrary to popular belief.)

Eratosthenes was able to accomplish this in part because of his education in Athens. There, he became known for his achievements in many different fields, including poetry, astronomy, and scientific writing. His activities became so talked about, in fact, that Ptolemy III of Egypt decided to invite him to Alexandria to tutor his son. Later, he would become the head librarian of the Library of Alexandria.

The mathematician must have been thrilled to have this opportunity. The Library of Alexandria was a hub of learning at the time, attracting scholars from across the known world. Eratosthenes was able to rub shoulders with the likes of Archimedes while continuing his own learning.

It was probably in the Library of Alexandria that he read about a curious event that took place in Syene (now Aswan, Egypt) at the summer solstice. Syene sat to the south of Alexandria. At high noon, the sun would shine directly overhead and there would be no shadows stemming from the columns. However, Eratosthenes realized that at the same moment in Alexandria, columns clearly did have shadows. Being a good mathematician, he decided to use this knowledge to do a few calculations to figure out the circumference of the Earth.

To do this, Eratosthenes measured the shadow of an obelisk on June 21 at noon. He discovered that the sun was about 7°14’ from being directly overhead. He realized that, because the Earth is curved, the greater the curve, the longer the shadows would be.

Based on his observations, he hypothesized that Syene must lie 7°14’ along a curve from Alexandria. Furthermore, he knew that a circle contained 360°, which meant that his calculation—7°14’—was roughly one fiftieth of a circle. Therefore, Eratosthenes thought, if he multiplied the distance between Syene and Alexandria by 50, he would have the circumference of the Earth.

The missing information was simply how far away Syene was from Alexandria. He measured the distance in stadia. There isn’t an exact modern day conversion to stadia, and it isn’t perfectly clear which version of the stadia Eratosthenes was using, but regardless, from what is known, his estimation was remarkably accurate.

There are two theories as to how Eratosthenes figured out the distance: first, that he hired a man to walk there and count the steps. Second, that he heard a camel could travel 100 stadia a day, and it took a camel about 50 days to travel to Syene. Whatever the case, he estimated the distance between Syene and Alexandria was 5,000 stadia. If that was the case, then using his formula, the earth was 250,000 stadiaaround.

Due to the uncertain distance that stadia represents (and particularly which stadia he was using), historians believe that Eratosthenes’ conclusion was between .5% and 17% off the mark. Even if the latter case was true, it was astoundingly accurate given the limited technology he was dealing with at the time. But many scholars think it likely that he was using the Egyptian stadia (157.5 m), being in Egypt at the time. This would make his estimate only about 1% too small.

There had been previous attempts at discovering the Earth’s circumference (which don’t count as “first recorded” because their methods didn’t survive, though we have references to them) which resulted in a 400,000 stadia figure, 150,000 more than Eratosthenes’—obviously far from accurate.

While finding the approximate circumference of the Earth was probably Eratosthenes’ largest contribution to scholarship at the time, it was by no means the only one. Eratosthenes is also credited with coming up with a way to map out the known world by drawing lines north-south and east-west—early latitude and longitude lines. However, these lines were irregular and often drawn through known places, meaning they weren’t entirely accurate. Nevertheless, it provided a precursor for maps we know today.

He is also remembered for the Sieve of Eratosthenes, a simple algorithm that makes it easy to find all prime numbers up to a certain limit. Though none of Eratosthenes’ personal work on the sieve survives, he was credited with the creation of the algorithm by Nicomedes in his Introduction to Arithmetic.

Not only that, but Eratosthenes estimated the distance to both the sun and the moon, and measured the tilt of the Earth’s axis all with amazing accuracy.

He also wrote the poem Hermes, correctly sketched the route of the Nile, and even gave a more-or-less accurate account of why the Nile flooded, something that had baffled scholars for centuries. He worked on a calendar that included leap years and he also estimated and corrected the dates of various historical events beginning with the Siege of Troy.

Despite these accomplishments and many more like them, Eratosthenes was often nicknamed “Beta.” Beta is the second letter in the Greek alphabet and referred to Eratosthenes being second-best in everything he did.

Eratosthenes died around 194 B.C. and is thought to have starved himself to death. It is believed that he started going blind in his later years and, unable to continue his work, he simply stopped eating.

Bonus Fact:

  • A man named Posidonius copied Eratosthenes’ basic method about a century later, using the star Canopus, Rhodes, and Alexandria as starting points. However, he didn’t measure the distance between Rhodes and Alexandria correctly, resulting in a circumference that was smaller than Eratosthenes’ estimation. It was this circumference that was recorded by Ptolemy in his geography treatise and later used by explorers looking for a quicker way to the Indies.



12-Year-Old Indian-Origin Boy Becomes an Overnight Sensation….


Do you know the scientific name for apricot?

We didn’t think so.

But a 12-year-old boy Rahul from Barnet in North London does. A contestant on the latest series of Child Genius, the Indian-origin boy became an overnight sensation after correctly answering every question he was asked on the show, including the scientific name for apricot.

The British reality competition series has children aged 8 to 12 battling against one another in intelligence tests.

Rahul, who is competing against 20 contestants, has already become a hero on the show.

He has an IQ of 162, which qualifies him to become a member of Mensa, the largest and oldest high IQ society in the world, reports BBC.

He received full marks in a spelling test, and scored higher than any contestant in a timed memory round. Competing for the ‘Child Genius’ title, Rahul already thinks he’s a genius. “I always want to do the best, and I’ll do that no matter what the cost. I think I’m a genius. I’m good at mental maths, general knowledge and I find it quite easy to memorise stuff,” he told BBC.

Social media was flooded with appreciation from the viewers of the show, with one of them calling Rahul his “new favourite person.”

Rahul’s father, IT manager Minesh, says he’s no less than Einstein. “As a comparison Rahul is as clever as Albert Einstein or Stephen Hawking,” he said.

The finale of the show will be held over the weekend where they will crown UK’s ‘child genius’.

Source….Deepika Bharadwaj in http://www.the betterindia,com


வாரம் ஒரு கவிதை ….” மழை நீர் போல …”


மழை நீர் போல …
வறண்டு கிடக்கும் பூமி …வானம் திறக்குமா கண் ?
மேலும் கீழும் பார்ப்பது உழவன் மட்டுமல்ல இன்று !
அடுக்கு மாடி கட்டிடக் குவியல் கூட்டில் குடி இருக்கும்
நகரத்துப் “பறவைகளும்” மழை தேடி வானிலை
அறிக்கையை காலையும் மாலையும் அலசும் அவலம் இன்று !
மழை நீரை முத்தமிட துடிக்கும்  வறண்ட பூமி நனையுது
மழை நீர் போல பெருகி வரும் உழவன் அவன் கண்ணீரில் !
குடிக்க நீர் இன்றி தவிக்கும் அடுக்கு மாடி “பறவைகள்”
வழி மேல் விழி வைத்து காத்திருக்குது  தினமும் ஒரு
லாரி தண்ணீருக்கு !
தண்ணீரும் பணமாக மாறும் காலம் இது ..மழை
நீர் சேமிப்பின் மதிப்பு உணராத மனிதன் கொடுக்கிறான்
நீருக்கு ஒரு விலை இன்று !
மழை வெள்ளம் வரும் நேரம் “இது என்ன பேய் மழை”
என்று அலறிய மனிதன் குரல் கேட்டு வானமும்
மனம் உடைந்து “கண்ணீர் ” விடவும் மறந்து போனதோ ?
தினம் தினம் தண்ணீர் தண்ணீர்  என்று மனிதன்
கண்ணீர் விட்டு என்ன பயன் இன்று ?
மாற வேண்டும்  மனிதன்… மாற்றி யோசிக்கவும்
வேண்டும் …வானமும் மகிழ்ந்து  தன் ஆனந்தக்
கண்ணீரால்  நனைக்க வேண்டும் இந்த பூமியை !
மனிதனுக்கும் புரிய வேண்டும்  எந்த நீர்
ஆனாலும்  மழை நீர் போல ஆகுமா  என்று !
in dated  13th August 2017

வாரம் ஒரு கவிதை …” கடல் பயணம் “


கடல் பயணம்
தினம் தினம் கடல் பயணம் …திரவியம்
தேட  அல்ல … அலை கடலில் அவன்
அலைவது  அவன் வீட்டு  அடுப்பு எரிய !
மீனவன் அவனுக்கு தேவை கடல் மீன் !
விண்மீனை பிடிக்க பறக்கவில்லை  அவன் !
கடல் மீனை அவன் தேடி பிடிக்கையில்
அவனை துரத்தி மிரட்டி விரட்டுதே  ஒரு கூட்டம் !
இல்லை  இது உன் எல்லையில் என்று
தினம் தினம் அவனுக்கு தொல்லை !
பிழைப்பு தேடி கடல் நாடி ஓடும் அவன்
தினம் தினம் செத்துப் பிழைக்கிறானே !
என்று தீரும் அவன் அவலம் ?
கடல் பயணம் அவனுக்கு ஒரு சொகுசு
சுற்றுலா அல்ல … அவன் வாழ்க்கையின்
பயணமே  அந்த கடல் அலையோடுதான் !
மண்ணை நம்பும் விவசாயி ….கடலை
நம்பும் மீனவன் … இந்த இருவருக்கும்
பிறக்குமா ஒரு விடிவு  காலம் விரைவில் ?
Natarajan in dated 7th August 2017

வாரம் ஒரு கவிதை ….” தூரத்தில் கேட்குது ….”


தூரத்தில்  கேட்குது ..
அம்மா உன் குரல் முதன் முதல் கேட்டேன்   தூரத்தில்…
உன் கருவில்  நான்  மலர்ந்து வளர்ந்த  போது !
இப்போதும்  உன் குரல் நான் கேட்கிறேன்
தினமும் …தூரத்திலிருந்தே !
அயல் நாட்டு மண்ணில் நான் இன்று  இருந்தாலும்
நம் நாட்டு  மண் வாசம் மறக்கவில்லையே அம்மா  நான் !
தூரத்திலிருந்து உன்  குரல்  நான் கேட்டாலும்
அம்மா..பாசமுடன் மண் வாசம் கலந்து ஒலிக்கும்
உன் குரல் நான்  அன்று  கருவில் கேட்ட
அதே குரலாக இன்றும் ஒலிக்கும் மாயம் என்ன அம்மா ?
தூரத்தில் கேட்குது உன் குரல் என்று என்னிடம்
இது வரை நீ சொன்னதில்லையே அம்மா !
எங்கே நீ இருந்தாலும் நீ இருக்குமிடம் என்
இதயத்தில்தான் என்று எனக்கு சொல்லாமல்
சொல்லுகிறாயா  அம்மா ?
Natarajan … dated 24th July 2017

வாரம் ஒரு கவிதை ….” இன்றைய தாலாட்டு “


இன்றைய தாலாட்டு
தொட்டில் கட்டி  தாய் பாடும் தாலாட்டு
கேட்டது ஒரு தலைமுறை !
தொட்டில் என்றால் என்ன என்று
கேட்குது இன்றைய தலை முறை !
தொலைகாட்சி பாட்டுக்கு தலை
ஆட்டும் இந்த தலைமுறைக்கு அன்னையின்
தாலாட்டு ஒரு புதிர் விளையாட்டு !
வேலை வேலை என்று ஆலாய்
பறக்கும் பெண்ணுக்கு  தாலாட்டு
பாட எங்கே நேரம் ?
மடிக்கணினி இசைக்கும் இசையே ஒரு
குழந்தை கேட்கும் இன்றைய தாலாட்டு !
அம்மா அப்பாவின் கைபேசி
மணிஓசைதான்  தாள வாத்திய கச்சேரி
மடியில் தவழும் குழந்தைக்கு !
இன்றைய குழந்தை  கேட்கும்
ஒரே தாலாட்டு  அதன் அம்மா அப்பா
பாடும் ஒரே பாட்டு …”எடுக்க வேண்டும்
எல்லா அடையாள அட்டையும் நம்ம  குழந்தைக்கு “
in dated 17th July 2017

This 30-Year-Old Indian Pilot Is the World’s Youngest Woman to Captain a Boeing 777!

Currently based in Mumbai, the young aviator had always dreamed of becoming a pilot and did so at the age of 19

“Since my childhood, I wanted to be a pilot. Other children used to make fun of me for this. Kids, at that time, were pushed to pursue engineering or become a doctor but not a pilot,” Anny told to HT.

Coming from an army background, one would think Anny must have had it easy. While she had rock-solid support from her parents, dissent often cropped up in form of family friends and relatives.

“Luckily, my parents never forced their choice on me. They were supportive and progressive in their thinking. My mother always used to encourage me. However, my relatives and my family friends were against my decision to become a pilot. Also, at that time, being a pilot was not considered as a profession for woman,” she said.

After her father took voluntary retirement, the family moved to Vijayawada, where Anny did her schooling. Hailing from a modest background, their family had their share of financial shortcomings. “Since I grew up in Vijayawada, I could write and read English but speaking English was a major challenge that I had to overcome,” Anny said.

Post her school education, the 17-year-old Anny made it to Indira Gandhi Rashtriya Uran Akademi (IGRUA), one of the premier flying schools in the country.

The cultural change from a small town to a big city was overwhelming for me. I had difficulty adjusting and speaking English. People used to mock me for my poor English and that hurt me a lot. At times, I had even thought of going back. However, backed with my parents’ support, I worked hard enough to win a scholarship,” she added.

Completing her training by the time she was 19, Anny bagged a job with Air India and since then, there has been no looking back. Post her training, she kickstarted her flying carrier with Boeing 737.

“When I turned 21, I was sent to London for further training. It was then when I started to fly Boeing 777. Since then, my life has changed. It’s been a great experience so far. I’ve got the opportunity to travel to various countries. My journey so far has taught me a lot,” Anny added.

When the going gets tough, the tough get going!

Source….LekshmiPriya .S  in