Halloween vs Day of all Saints

Halloween has its origins in Celtic culture.

2000 years ago, in the territory now called Ireland, Celts feasted Samhain, this festival happen on the 1th November. This festival marked the end of the year, the winter beginning and the last harvest.
At that time some people believe that in this date the souls had their last and final chance to return to the realm of the living

In this festival people gathered and lit fires and offer sacrifices to the deceased, believing this would stop them to return. Celts also dressed in clothes made from animal skins and offer food to the dead. As time passed by the festival changed and the people started dressing as ghosts, witches and other creatures known to be malevolent, and asking food and drinks. It is thought that this was the origin of the famous "trick-or-treat".

In the Catholic Church November 1st celebrates the day of "All Saints", in Mexico, for example, is celebrated as the day of "los Muertos" (Day of the Dead).

Samhain or All Saints Day?
People celebrate Samhain (Halloween) on the night of 31 October to 1 November, but using new and present rituals adapted to each country.
The All Saints Day comes as an attempt by the Catholic Church to annul the pagan festivals of the Celtic people. This attempt, despite being brilliant (according to some experts), has not had the desired impact, and the reunion of families around the table with the goal of honoring the Saints never managed to replace Samhain with the desired success.
Today we have a kind of fusion between the two parties- the Hallowe'en and All Hallows, or Halloween and All Saints Day (Hollow has its roots in the word sanctified or holy). The current version of Samhain on the evening of October 31 to November 1, and All Saints Day on November 1, are exactly the same, honoring the dead and settle down.
actividades de outono, Halloween, mitos,
sources:
http://www.history.com
http://ancienthistory.about.com

Et voilá!
Trick-or-treat?

Enjoy!

Instant facts- Just add water 77

Black coffee with no sugar contains no calories.
in http://gomestic.com

Instant facts- Just add water 68

There are many ancient religions believe that cats are exalted souls, companions or guides for humans, that they are all-knowing but are mute so they cannot influence decisions made by humans.
in http://www.catfacts.org

Instant facts- Just add water 57

Yin and yang are the two opposing and complementary forces that make up all phenomena of life. Both proceed from the Supreme Ultimate and together they represent the process of the universe and all that is in it.
in http://www.religionfacts.com

Control digits- Portuguese Identification Card case- ISBN numbers

Each Portuguese identification card has a digit to the right of the ID number.
Countless stories have been created around this digit, most of them myths.

Although this article is in "answers to readers" section, there isn't any particular reader asking about this using the normal channels, but it's a question often brought to the conversion.

So, what is this digit?
Jorge Buescu, degree in physics from the FCL, PhD in mathematics from the University of Warwick and Professor of Mathematics at IST (1), explain this in his book "O mistério do bilhete de identidade e outras histórias"- "The mystery of the identity and other stories".

It's important to clarify
This digit isn't the total number of people with exactly same name as you. This is a urban legend, if you don’t believe me just take a moment to think about this:
This is always a 1 digit number, i.e., the range is from 0 to 9, so, if I have 9 people exactly same name as me it's nuts to think there must be someone with 12 or 14 people with exactly same name? The control number for those people should be higher then 9.

So what is this mysterious digit?
On same book Jorge Buescu, explains that "The extra digit is (or would be, if the Portuguese authorities hadn't committed a pathetic mathematical error!) Only a control number that detects if the number of the card is correctly written", and continues to explain that the human brain can't handle with hundreds of number with many digits if they don’t have a link between them, or a pattern. That’s why this method is used, so the computer can detect errors in the numbers. What would happen if a supermarket operator makes a mistake with the barcode numbers and "... charge 200 bucks for a butter package..." it would be unthinkable.

This number, if there wasn't an error, like noted by Buescu, would be used to detect if the Identification Card Number entered in database contained errors or not. 
This system of "digits detectors" is used in several other daily things such as credit cards, the ISSN for periodicals, the ISBN for the books, there are many other cases like those, where we use a control digit.

So how it works?
Buescu uses book ISBN as an example.
This number is usually in the back of the books and each title have a unique 10 digit number. For instance the ISBN for Buescu book "O mistério do bilhete de identidade e outras histórias", Edições Gradiva from collection "Ciência Aberta", is 972-662-792-3.
To check if the sequence is correct the computer applies the following formula:

x1+2x2+3x3+ … +10x10

Where ISBN number is:

x1x2x3x4x5x6x7x8x9x10

The result, explains the author, is divisible by 11.

Try yourself:

ISBN:  972-662-792-3
(1x9+2x7+3x2+4x6+5x6+6x2+7x7+8x9+9x2+10x3)/11=
(9+14+6+24+30+12+49+72+18+30)/11=
264/11=
24

Some of you, restless minds always on alert, would say: Some of the ISBN numbers have X's! Yes you are correct, some control numbers are not digit but letters, in those cases the 10 is represented by an X, that's due to the nature of used algorithm (2).

If you have a Portuguese identification card, you can try it yourself, do the same as the ISBN numbers, but read the number from right o left, like the image.

The pathetic mathematical error is that the number 10 (or the X in ISBN numbers) was replaced by a 0, so half of the people with control digit 0 should have a X.

Sources:
(1) Buescu, Jorge. "O mistério do bilhete de identidade e outras histórias", Lisboa, Gradiva- Pulicações Lda, 2nd ed 2001
(2) motivate.maths.org/content/Calculator-fun/follow-project-suggestions

Et voilá!
Don't believe everything you ear

Enjoy!

University of Princeton email about the magnetic effect on food

Ana received on of those spam emails. The message was about the danger of having magnets on the refrigerator door. The email seemed somewhat exaggerated, this was the message:


"Researchers at Princeton University have discovered a terrible thing. For several months they feed two groups of rats, one group with food stored in a refrigerator, and the other one with food stored in a refrigerator with several decorative magnets on the door. The purpose of study was to see how they affect the electromagnetic radiation in food. Surprisingly, after rigorous clinical studies they concluded that the group of rats that ate irradiated foods by the magnets has 87% more chances of contracting cancer. "

We found several explanations, some more scientific then others. We found some people that swore this was true, others had a cousin, that has an uncle that has a friend in Princeton University.


Some facts:

• Fridge magnets magnetic field is very low.
• In any case the iron from the refrigerator absorb most of radiations, therefore what goes "inside" the refrigerator is not measurable.
• All electric refrigerators are inevitably driven by electrical motors, in those, electric field changes are much stronger than the magnets.
• The earth has a magnetic field, we live surrounded by it.
• Food is not magnetic therefore is not influenced by magnetic fields.

Some logical arguments:


This email says, the researchers at Princeton University with headquarters at USA found out the fridge magnets on the refrigerator doors of many families all over the world should be trashed because they have a adverse effect on the food, and could significantly increase cancer risk.

As we can read on the email: "rigorous clinical studies", using two groups of rats, shown that, the group that consumed "irradiated" food from the fridge with the magnets has 87% more chance of having cancer, then the other group.

First of all, as always my mother taught me, if you are going to lie avoid the  details, there is no reference to such a study at Princeton University.


Besides, there is no credible evidences to say that a fridge magnet can have such a impact on food. A fridge magnet is a  small low power permanent magnet. A permanent magnet is made from magnetized material, and create his own persistent magnetic field.


There is a intensive debate about magnetic radiation and adverse health effects, like the one generated by cellphones.
However, permanent magnets have been used for a variety of proposes, and there is no evidences that allow us to connect them with cancer or any other health problem.


The email seems to ignore the fact the refrigerator use several components that generate magnetic fields. Many modern fridges have door seals with magnets and contain magnetic strips which help to keep the door closed.

Lastly if the message informations were true, the study would be widely publicized in the media, and in the specialized press, the absence of any of these reports is, in itself, sufficient to identify the false alert.

Sources: Hoax- Slayer; Revista Brasileira de Epidemiologia
Universidade de Princeton- Investigação

Et voilá
Don't believe everything you read


Enjoy!