Calculations to save money on alcohol and great applications in science

Although Kepler's calculation was only intended to reduce the cost of a barrel of wine, mathematicians later relied on his achievement to maximize the efficiency of everything.

The German astronomer Johannes Kepler (1571 - 1630) was famous for his law of planetary motion when he proved that the planets in our Solar System orbit the Sun in an ellipse. Before he got into astronomy, however, he was an accomplished mathematician. Once, he wrote a whole book on how to approximate the volume of a barrel of wine after being pressured by a merchant.

Johannes Kepler.

The story goes that Kepler ordered a barrel of wine for his second wedding in the beautiful Austrian town of Linz. But when it came time to pay, an argument broke out. Kepler disapproved of the method used by wine merchants to price casks of wine. It is worth mentioning that the other merchant also insisted on claiming that his method was correct, as this was a long-standing custom among the wine merchants.

The way to do this is to lay the barrel on its side, and then poke a long stick through a hole in the center of the barrel until it hits the opposite corner. After the stick is removed, the cost of the barrel is calculated based on the percentage of the stick getting wet.

Kepler quickly realized the shortcoming of the method. He asserted that the price of the same amount of wine would vary with the size of the barrel. "A long, thin barrel will cost less than a short, fat barrel," argued Kepler.

Though still paying for the cask later, Kepler became obsessed with the above method, and couldn't get rid of the question of how to construct an exact math so that the wine buyer could pay the right amount. for the barrel of wine they desire.

Kepler invented calculus to save money on alcohol.

After months of tossing and turning, Kepler came up with a new method. This method can calculate the volume of a curved wine barrel, by imagining it as a flat cylinder, or homogenize a circle with an infinite regular polygon. Thus, he calculated the area of ​​a circle by adding infinitely the areas of infinitely small triangles whose base is the side of the regular polygon and the vertex is the center of the circle.

This method was incorporated into an important mathematical treatise called "Nova stereometria doliorum vinariorum", whose main content was about measuring the volume of containers such as wine barrels, published by Kepler in 1615. is considered to be the foundation text of later integral calculus.

Although at the time, Kepler's calculation was only aimed at reducing the cost of a barrel of wine, later on, mathematicians relied on numbers to maximize the efficiency of everything. For example, mathematician Brook Taylor used math to calculate the right dose of cancer drugs to bring about the most effective response, or the amount of fuel a Boeing 747 needs to carry to fly. all the way so as not to be overloaded.