20th Century Education vs. Present-Day Knowledge - 7 Outdated Notions

Students who attended school during the 20th century were taught a variety of concepts that, due to advancements in science and technology, have either been debunked or drastically altered in meaning.

Indeed, as time progresses, even the most firmly held beliefs can transform, given that our understanding of the world is constantly evolving.

To illustrate this point, let's examine seven ideas that would have been perceived differently by a student 50 years ago compared to one in the present day:

1) Before: Pluto is a planet. Today: Pluto is not a planet (or, at least, it is a dwarf planet).

In 1930 amateur astronomer Clyde Tombaugh discovered a moving object beyond the orbit of Uranus that was named after the Roman god of the underworld, Pluto, thus defining the 9-planet solar system that several generations of students learned about in school.

In 2003, the discovery of an object, later named Eris, beyond Pluto's orbit ignited a lively debate in the astronomy community about the characteristics necessary for a celestial body to fall within the group of planets. The conclusion of this debate led to the denial of Eris the status of a planet, which, however, on the basis of the same considerations led to the downgrading of Pluto to a dwarf planet.

2) First: diamond is the hardest substance. Today: cubic boron nitride is the hardest substance

Actually, as of 2009 we know of at least two substances harder than diamond: boron nitride wurtzite and lonsdaleite, according to the classification reported by Scientific American. the former resists impact with 18 percent more strength than a diamond, while the latter, even, would be 58 percent harder than diamond. It must be said, however, that these are two rather rare and unstable substances in nature, which makes the definition of harder than diamond a bit of a stretch.

In 2013, however, it was reported in the January issue of the journal "Nature" that compressed particles of boron nitride to form an "ultrahard nanotwinned cubic boron nitride" become a much harder object than diamond.

We might therefore expect, shortly, that women all over the world will start asking for engagement rings with stones of this unpronounceable substance. Because these yes, would really be forever.

3) Before: the witches of Salem were burned at the stake. Today: they were actually hanged

In Arthur Miller's novel The Crucible, it is reported that the people of Salem burned the witches at the stake. In reality, this never happened. According to Richard Trask, archivist of the town of Danvers (formerly known as Salem Village.) He has written a book on the town's history in which he also discusses the period in which Miller's novel is set, calling it "Salem Village Witch Hysteria " and explains that, at the time of the events, New England still followed English law, which, for the crime of witchcraft, imposed the death penalty by hanging.

4) Before: Israelite slaves built the pyramids. Today: pyramids were built by exploiting Egyptian laborers

Many movies and books tell us that the pyramids were built by enslaved Jews. In fact, the Book par excellence, namely the Bible, nowhere mentions this fact. Recent archaeological discoveries, on the contrary, support the thesis that it was the Egyptians themselves who built the pyramids by recruiting (paid) laborers from poor families in northern and southern Egypt.

Even, crypts containing the remains of workers engaged in the construction have been found near the pyramids. These bodies bore evidence of proper preparation for burial according to ancient Egyptian tradition. We can be reasonably certain that slaves would not have been similarly honored.

5) Before: It is mathematically impossible to fold a piece of paper on itself more than seven times. Today: the current record is 13 times.

In 2012, a group of students at St. Mark's School in Southborough, Massachusetts, succeeded in folding a sheet of toilet paper onto itself 13 times, in spite of all the calculations and equations that, based on the ratio of paper size to thickness, state that the limit is 11 times.

6) Before: The Great Wall of China is the only man-made structure visible from space. Today: There are many man-made places and structures visible from space.

The presence of the international space station and its alternating missions has been able to make it clear that from space, the lights of cities can be seen well at night, as can the outlines of large structures such as airports, roads, bridges and dams. The Great Wall of China is visible only under certain conditions, such as snow on the structure, and when viewed at a particular angle.

7) Before: there are only three classification kingdoms. Today: there could be as many as eight realms.

Initially, the classification of life was divided into 3 kingdoms: animals, plants and bacteria. Later two were added to these three kingdoms: fungi and protists.

Since then the classification of life has been further expanded to as many as eight kingdoms.

The more we discover new species and try to label them, the more complicated the classification becomes. After the five kingdoms already indicated, we discovered the monerae and Archea, while from the eubacteria came the Chromistae.

As can be seen, knowledge is dynamic and nothing remains the same over the years. What is the next notion to be updated?