Sunday, March 23, 2014

Blog Post #75 - Do you know Prime Numbers - God may not play dice with the universe, but something strange is going on with the prime numbers #primenumbers


Babies can ask questions about primes which grown [wo]men cannot answer.
Paul Erdos, quoted in In Code by Sarah Flannery and David Flannery.


1. Demo visualization  of prime numbers and who was Ulam ?
2. Euclid's elements - did you read this book yet?(Math in Greek!)
3. Prime numbers keep us safe and saves life (note not human life!)
4. Zero and 1 are they prime?


1. Demo visualization  of prime numbers

First click here  and click play on the top of the page


This is the first time you are seeing prime numbers!!! You have read them ,written them never seen them draw and generate patterns. When Stanislaw Ulam attended a long and boring lecture he started 'doodling' . Remember before googling there was doodling - where folks used to use a plant based product called paper and a 'lead' pencil / pen. This was when apple was still a fruit and you never held an apple for more than few minutes. Now I see apple(or Samsung) in most people's hand googling!(messaging,facebooking,tweeting.. you know the drill).

So what happened he created this....


He wrote 1 in center and started created spirals.. and observed the diagonals were prime....

2. Euclid's elements - did you read this book yet?(Math in Greek!)

Before 300 Jesus Christ was born Euclid wrote a book that is referred even today .

Euclid's Elements .

This book has sold more copies than any other book in human history and stands at second place in maximum copies of book published.

The first place - most published book goes to - Holy Bible. 

What did Euclid talk about Prime numbers in 300 BC in Alexandria? Something about prime numbers.

Euclid believed there are infinite number of prime numbers. Why? Do you think the answer is simple. we have infinite numbers so I am surprised why he had to discover that there are infinite prime numbers?

To understand that you need to understand something basic about prime numbers and composite numbers.

Define prime numbers - A prime number can be divided, without a remainder, only by itself and by 1.

How can you tell if a number is not prime -

Simple
  • 2 is the only even prime number in number system . Every other even number is divisible by 2. So no other even number can be a prime. 8090908092 is not a prime number. 
  • A number that ends with 5 or 0 are not prime. They can be dived by - yes 5. 979989779885 is not a prime.
  • Take square root of the number and divide from 3(if it is even number you know it when you see it)  to that square root of that number. square root of 103 is close to 11. so divide by 3,4 5,6 7,8,9,10  or 11 (i will tell you soon only to use only primes- wait) and we know 103 is prime.37. Square root of 37 is close to 6 . so divide by 3,4 and if they cannot no one can. Also 4 is not a prime . Use only prime numbers and in case of 103 use only 3,5,7,11 . 5 can also be eliminated .So use this further refined process and just check for 3,7,11. Any tricks for division by 3- see next?
  • If the sum of a number's digits is a multiple of 3, that number can be divided by 3. So Islam's holy number 786 is not prime. 7+8+6 = 21.  "786" is the total value of the letters of "Bismillah al-Rahman al-Rahim" - "In the name of God, most Gracious, most Compassionate".How did characters below which represent this phrase become 786. Google it.

Every other number that is not prime - composite numbers can be written as multiples of prime.

100 = 10*10= 5*2*2*5
2 and 5 are primes.

Euclid used this principle and wrote the following 300 years before Jesus christ was born (do you find this sentence boring - 300BC sounds simple? BC= Before Christ. Most history books now refer to these dates are BCE - Before Common Era and After Common Era whatever it means!!!)

Assume there is a finite number of primes. We then multiply all these primes together. The resulting number will be a number divisible by every single prime. Now add 1. We now have a number that, when you divide it by any prime, will have a remainder of 1. That means we have just discovered another prime number.


3. Prime numbers keep us safe and saves life (note not human life!)

Prime numbers keep us safe when we use computers - In modern world cryptography uses prime numbers. From your computers talking to your bank to your bank talking to government agencies prime numbers are everywhere.


Life as we known it has nothing to do with humans. 8.7 million species inhibit our planet. When I write prime numbers save life - people mistake it for human life. I want to remind the reader that planet earth is home to 8.7 million -1 species if you take away humans. 

In real time the most commonly citied example is of a small insect which knows prime number can save its life Wikipedia has this simple example elaborated 

Inevitably, some of the numbers that occur in nature are prime. There are, however, relatively few examples of numbers that appear in nature because they are prime.
One example of the use of prime numbers in nature is as an evolutionary strategy used by cicadas of the genus Magicicada.
 These insects spend most of their lives as grubs underground. They only pupate and then emerge from their burrows after 13 or 17 years, at which point they fly about, breed, and then die after a few weeks at most. The logic for this is believed to be that the prime number intervals between emergences make it very difficult for predators to evolve that could specialize as predators on Magicicadas.[ If Magicicadas appeared at a non-prime number intervals, say every 12 years, then predators appearing every 2, 3, 4, 6, or 12 years would be sure to meet them. Over a 200-year period, average predator populations during hypothetical outbreaks of 14- and 15-year cicadas would be up to 2% higher than during outbreaks of 13- and 17-year cicadas.[42] Though small, this advantage appears to have been enough to drive natural selection in favour of a prime-numbered life-cycle for these insects.

4. Zero and 1 are they prime?

The reason for my post is thanks to my round rock library book 

The mathematical universe : an alphabetical journey through the great proofs, problems, and personalities / William Dunham.

The author had a knack of introducing me back to arithmetic and i have only read 4 pages and now i write a post..

He rekindled my quest about knowing and understanding prime numbers at the prime of my life!!(if you can consider 38 as a prime age for Asian Male in US)

From http://mathforum.org/library/drmath/view/57036.html

Zero is not a prime or a composite number either. Zero has an infinite
number of divisors (any nonzero whole number divides zero). It cannot
be written as a product of two factors, neither of which is itself, so
zero is also not composite. It falls in a class of numbers called
zero-divisors. These are numbers such that, when multiplied by some
nonzero number, the product is zero

1 is not a prime number. 


By definition a prime number is a number greater than 1 that has no divisors other than 1 and itself.




1 is also not a composite number as 1 cannot be expressed by any prime number (remember Euclid above - of not re-read section 3) .You cannot express 1 as product of any other number that is not 1. Your question might be what about (-1)*(-1).  Yes. Good question . 


I will ask you a question - do you know negative prime numbers?


Prime numbers were discovered first and so negative numbers did not exist at that time. So most text define prime numbers as positive numbers except 0 and 1. 

There is no harm in thinking about negative prime numbers as any prime number both positive and negative will still be governed by the same rules - divide by itself and 1.


1 is not a prime nor a composite number.So what do we call 1 in math. 1 is called a unit.




One is neither a prime nor a composite number. A prime number is one 
with exactly two positive divisors, itself and one. One has only one 
positive divisor. It cannot be written as a product of two factors, 
neither of which is itself, so one is also not composite. It falls 
in a class of numbers called units. These are the numbers whose 
reciprocals are also whole numbers.


So now you know your numbers.
Eat fruit,nuts and Veggies (okra for Math - According to Quora.com Okra is relatively high in nutrients deemed important for brain function like Phosphorus and Vitamin A. It is also relatively high in Omega-3 and Omega-6 and other antioxidants.)

Keep learning
Sivakumar Manikanteswaran

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