The Decay of Knowledge

Author:
Rupert Taylor
Updated:
Feb 13, 2024 11:35 AM EST

A repository of knowledge, much of it out of date.
Nino Carè on Pixabay

The Half-Life of Knowledge

In 1963, the Austrian-American economist Fritz Machlup coined the phrase “the half-life of knowledge.” It describes the amount of time it takes for known facts to be superseded by later research and made obsolete. The term “half-life” describes the time it takes for a substance to decline by a half.

Things that we know to be true today may turn out to be untrue, sometimes comically so, in the future. For example, in the 1930s, an ad for Lucky Strikes showed a doctor advising that “Cigarettes are an important part of any healthy lifestyle.”

The Half-Life of Medical Knowledge

It used to be that opening a vein with a sharp instrument and letting a bowlful of blood out was the standard therapy for everything.

That piece of medical wisdom lasted for thousands of years, through to the middle of the 19th century. It took a long time for the idea to be banished onto the pile of medical interventions that didn't work. Today, healthcare knowledge becomes obsolete much more rapidly.

In March 2017, Christine Colacino wrote for Harvard Medical School News that, “Today, the half-life of medical knowledge is currently about 18-24 months, and it is projected that in about four years, that half-life will be only 73 days.”

Most people probably looked the other way.
Public domain

Difficulty Keeping Up

Medical students experience four doublings of their profession's knowledge during the time it takes them to graduate.

Once they are out practicing, doctors face the daunting task of keeping up with the advances in their field that occur at ever-increasing rates. How can they possibly stay current? The answer is that they can't because their knowledge atrophies at an alarming rate.

The solution is to feed the vast quantity of new information into computer databases. The physician then inputs symptoms as described by the patient or those gleaned from blood tests and imaging. The machine then delivers a diagnosis and treatment program based on peer-reviewed scientific studies that it might have ingested just the day before.

A Medical Example

“To suggest giving a heart failure patient a beta blocker prior to the 1970s would have been considered malpractice ... Today, all patients with systolic dysfunction should be considered for beta blockers—a core measure of good clinical practice ... Well, it turns out that this too may not be true. Recently, an observational study of 45,000 patients was reported in the October 2012 issue of the Journal of the American Medical Association ... [that] discovered that beta blockers conferred no benefit in preventing recurrent myocardial infarctions, strokes, or mortality in patients ...”

Dr. Neil Sanghvi

The Half-Life of Engineering Knowledge

In the 1920s, the knowledge gained by a university graduate in engineering had a half-life of about 35 years. By 1960, the half-life of an engineering graduate's knowledge was estimated to be just ten years.

Engineers in the Past

In 1966, Fellow of the Institute of Electrical and Electronics Engineers (IEEE) Thomas Jones calculated that an engineer would need to spend five hours a week studying to stay current in his or her field. That means 9,600 hours of study over a typical 40-year career in engineering. This is equivalent to the time needed to acquire two degrees.

By 1991, the half-life decay of engineering knowledge was estimated to be five years. A decade later, it was two-and-a-half years, much shorter if the engineer was working in information technology.

The answer for many employers is simply to hire newly graduated engineers and to get rid of them when their expertise has fallen behind the demands of their profession. This has prompted Robert N. Charette, Contributing Editor to IEEE Spectrum, to write that “The half-life of an engineer or IT professional’s career is now about 10 to 12 years or even less.”

Now controlled by a seven-year-old with a smartphone.
Gregory Butler on Pixabay

The Half-Life of Astronomical Knowledge

Once upon a time, the Sun was believed to orbit the Earth, and Galileo Galilei was condemned to house arrest in 1633 for suggesting otherwise. In 2008, the Roman Catholic Church, which had passed the sentence on Galileo, acknowledged that he was right and the Earth revolved around the Sun. You don't want to rush these things.

Pluto's Plight

Until 1930, there were eight planets in our solar system, and then the astronomer Clyde Tombaugh discovered Pluto. Following this, a campaign started to downgrade Pluto from its planetary status; it was just a chunk of ice in the Kuiper Belt like many other similar objects.

In 2003, Professor Mike Brown of the California Institute of Technology found Eris, an object with a bit more mass than Pluto. Should Eris be our tenth planet?

Debate swirled around the astronomical community, fuelled, probably, by research grants. “Pluto is a planet.” “No, it's not.” “Yes, it is.” “Nya, nya, nya.”

In 2006, the International Astronomical Union stepped in to resolve the issue; henceforth, Pluto is to be classified as a minor planet.

According to the observations of several astronomers, Mars was believed to be crisscrossed by canals, as drawn here by Percival Lowell.
Public domain

Astronomy Today

Today, thousands of highly skilled and highly trained astrophysicists are searching to unlock the secrets of the universe, and they freely admit that what is known to be true is dwarfed by what is unknown. For example, among astronomers, it's widely accepted that 85 percent of the universe is made up of “dark matter.” But nobody knows what dark matter is.

There are massive discoveries yet to be made that will make what is taken as truth today seem quaint, and all of it will turn out to be of no account.

Collision to Come

Astronomers tell us that in about four billion years, give or take a billion, our galaxy, the Milky Way, will collide with our nearest neighbour, the Andromeda galaxy. When this happens, there will be casualties. Stars will vanish along with their planets, and black holes will merge to form even bigger black holes.

Astrophysicist Chiara Mingarelli told Atlantic magazine, “It’s going to be like, bloop, done.” And with it, all the knowledge, both correct and incorrect, we humans have accumulated will vanish.

“A false conclusion once arrived at and widely accepted is not easily dislodged; and the less it is understood the more tenaciously it is held.”

— Mathematician Georg Cantor

Bonus Factoids

Some knowledge that is now out of date:

Tomatoes, for 200 years known as “poison apples,” were once believed to be toxic.
Radiation was used as a medical therapy.
Women were held to be incapable of properly exercising the vote.
People believed that bathing was injurious to the health.
High-speed train travel, i.e., more than 20 mph, was thought to cause people to burst into flames or become insane.
Spontaneous generation was a hypothesis that non-living things, such as granite or iron, could create living creatures.
People once believed that a single blood vessel connected the heart to the fourth finger of the left hand, so that was where a wedding ring was placed to symbolize love.
Venus fly traps were thought to have been brought to Earth by aliens.
Some fans still believe that the Toronto Maple Leafs ice hockey team will one day win the Stanley Cup.