# Can someone explain this math JOKE ?

1. May 7, 2013

### wlcgeek

Can someone explain this math "JOKE"?

A Mathematician, a Biologist and a Physicist are sitting in a street cafe
watching people going in and coming out of the house on the other side of
the street.

First they see two people going into the house. Time passes. After a while
they notice three persons coming out of the house.

The Physicist: "The measurement wasn't accurate.".
The Biologists conclusion: "They have reproduced".
The Mathematician: "If now exactly 1 person enters the house then it will
be empty again."

I saw this on a bunch of sites and just didn't get it. :tongue:

2. May 7, 2013

### Vorde

Well, I guess its a scientist's joke. The idea is that if something appears that wasn't there before, a physicist is used to calling this a measurement error, a biologist is used to observing unexpected reproduction and a mathematician doesn't care about the real world, just about the pure math, so there is nothing wrong in his eyes with saying that there is now '-1' people in the house.

Silly joke :P

3. May 7, 2013

### Staff: Mentor

They are all assuming that the house was initially empty of people, so if two go in and three come out, there must be -1 persons in the house.

4. May 7, 2013

### Simon Bridge

The joke relies on familiarity with habitual thought processes in the different disciplines and realizing how they have been misrepresented here.

The Mathematician is easiest to understand - the change in people leaving the house is -1, but the character has mistaken this information to mean there is less than 0 people in there.

Biologists in the field may find a population changes with successive observations.
This is a normal part of life - if the population should increase, it would be common to conclude that births have exceeded deaths between observations. In this case the character has failed to take account of the time between observations re human reproductive times (though we are not told what this time is.) But, at least, the character has not made assumptions about how many people are in the house.

Physicists deal with physical measurement as a matter of routine. Measurement is plagued by statistical uncertainties.

The key to his statement is figuring out what the "measurement" was ... by context, the measurement is of the number of people who have gone into the house. The initial measurement was such that "2 people went into the house". However, since three people come out, that statement is false. The characters comment suggests that this is due to some sort of statistical uncertainty in the measurement when it is more that the data no longer supports the original conclusion.

OTOH: the physicist has not made as many assumptions about the system as the others.

Taken the other way around you get a progression of increasingly silly-sounding observations based in some characteristic thought process for the discipline represented, building emotional pressure, culminating with a conclusion so silly nobody would really think that ... listener who gets it realizes and laughs or groans or something, releasing the pressure.

Usually one of the disciplines comes of "worse" than the others.

Also see the different disciplines considering the proposition: "all odd numbers are prime"

Last edited: May 7, 2013
5. May 7, 2013

### Ezio3.1415

A lot for a 'hahaha'... :D

Simon sure does sound like Sheldon...

6. May 7, 2013

### Simon Bridge

Well ... I am not crazy, though, my mother had me tested!

By the way, I made a number of mildly amusing grammar and spelling errors in the post which you may enjoy discovering. There may be a small prize for the reader who uncovers the most.
I wonder who it will be - I do enjoy a mystery...

7. May 8, 2013

### Danger

I quit counting after the 3rd paragraph. You're evil.

8. May 9, 2013

Hahaha... :D