Tag: friends

The Birthday Paradox

By Anupum Pant

Imagine you meet a random person in the street and ask him/her when is their birthday, there’s a huge chance that the person’s birthday will not be the same as your birthday. In fact, the probability of both your birthdays being on the same day is around 0.27%. Fat chance. At the back of our heads, this is something that is very clear to all of us.

Again, if you repeat this by asking about 22 people the same question, the chance of you finding someone having the same birthday as yours is still around 5%. Too less. This is too is a very intuitive piece of information.

But consider this. If I put all of the 22 guys and you in a room, there’s a big chance that 2 people in that room will have the same birthday – a 50% chance. Moreover, if there are 70 people in the room, this chance increases to about 99.99%. This is called the birthday problem or the birthday paradox.

So, what changed when 20 people went into the room? It was just the fact that in the room, we are picking 2 people from a group of 23 people. That is equivalent to this – everyone is asking everyone their birth dates. Everyone doing it simultaneously makes the probability much higher. The probability of two people sharing a birth date among a group of 23 people is far higher than you alone going around and asking all the 22 people, and finding someone having the same birthday as your’s.

Suppose there are 200 people in the room. The probability of 2 people sharing their birthday is massive (and yet not definite). There is in fact a 99.9999999999999999999999999998% chance!

1024px-Birthday_Paradox.svg

Finally, if you had 367 people in a room, at least a pair among these 367 people in the room would definitely have the same birth date. The 99.99% chance shoots up to a definite (100%) probability if there are 367 people in the same room. Think about it for a minute.

Ants and Their Friends

By Anupum Pant

Background

If you consider the habits, social organization, communities, network of roadways, possession of domestic animals, and counting skills of ants, they are not very different from humans. Yes, ants even domesticate animals. And we’ve talked about their counting skills in the past. Then, I came across a very interesting experiment sir John Lubbock decided to do on ants.

Experiment

He had in his captivity a number of varieties of ants living in different colonies. One day he saw a group of ants feeding on honey together. He picked twenty five of them and managed to intoxicate them by some method, others were left there, feeding on honey.

Next, he picked twenty five other ants of the same species, from a different colony and intoxicated them too. He then placed all of these 50 intoxicated ants near the honey, in the path which the ants were using to move to and fro from the honey.

He watched them for hours and it was an amazing thing he found. The twenty five ants which belonged to the same colony of ants that were feeding on honey were treated much differently by them, than the other 25 ants of the same species that belonged to a different nest! Somehow they were able to identify the ants of their own nest – differentiate friends from strangers.

Twenty out of the twenty five friend ants (which belonged the same nest) were carried by the honey feeding ants to their home. While about 18 of the other intoxicated stranger ants were picked up and thrown into water.
There were just 5 friend ants which were thrown into water (probably accidentally) and 6 stranger ants which were carried back to home (probably accidentally, again)

Nevertheless, most ants were correctly identified as friends and strangers. Moreover, I think their reaction to drunk friends and drunk strangers was so much like what human beings would do!

Next Experiments

In an experiment which he did later, the researcher tried separating friend ants (of the same nest) for about 4 months. And when they met after 4 months they were able to clearly identify each other. They caressed each other with their antennae.

In other experiments when he introduced a stranger ants in a nest, the strangers were evicted immediately and sometimes even killed.

There are a couple of other interesting experiments he has mentioned in his article here. Do read it whenever you find time. [link]