According to Jones, an engineer would need to devote at least five hours per week, 48 weeks a year, to stay up to date with new advancements. A typical degree requires about hours of work. Within 10 years, the information learned during of those hours would be obsolete.
The five-hour figure does not include the time necessary to revise forgotten information that is still relevant. A year career as an engineer would require hours of independent study. Keep in mind that Jones made his calculations in the s.
Modern estimates place the half-life of an engineering degree at between 2. Unsurprisingly, putting in this kind of time is simply impossible for most people. A partial escape from this time-consuming treadmill that offers little progress is to recognize the continuous need for learning. If you agree with that, it becomes easier to place time and emphasis on developing heuristics and systems to foster learning.
The faster the pace of knowledge change, the more valuable the skill of learning becomes. A study by PayScale found that the median age of workers in most successful technology companies is substantially lower than that of other industries. Of 32 companies, just six had a median worker age above 35, despite the average across all workers being just over Eight of the top companies had a median worker age of 30 or below — 28 for Facebook, 29 for Google, and 26 for Epic Games.
The upshot is that salaries are high for those who can stay current while gaining years of experience. In a similar vein, business models have ever shrinking half-lives. The nature of capitalism is that you have to be better last year than you were this year — not to gain market share but to maintain what you already have. If you want to get ahead, you need asymmetry; otherwise, you get lost in trench warfare.
In the past, models could last for generations. The majority of CEOs oversaw a single business for their entire careers. Business schools taught little about agility or pivoting. Kaplan writes:. During the industrial era once the basic rules for how a company creates, delivers, and captures value were established[,] they became etched in stone, fortified by functional silos, and sustained by reinforcing company cultures.
Companies with nearly identical business models slugged it out for market share within well-defined industry sectors. Those days are over. The industrial era is not coming back. The half-life of a business model is declining.
In the twenty-first century business leaders are unlikely to manage a single business for an entire career. Business leaders are unlikely to hand down their businesses to the next generation of leaders with the same business model they inherited from the generation before. The flip side of a half-life is the time it takes to double something. A useful guideline to calculate the time it takes for something to double is to divide 70 by the rate of growth.
Known as the Rule of 70, it applies only to exponential growth when the relative growth rate remains consistent, such as with compound interest. The higher the rate of growth, the shorter the doubling time. For example, if the population of a city is increasing by 2 percent per year, we divide 70 by 2 to get a doubling time of 35 years. The average newborn baby doubles its birth weight in under four months.
The average doubling time for a tumor is also four months. We can see how information changes in the figures for how long it takes for a body of knowledge to double in size. Arbesman also gives figures for the time taken for the available knowledge in a particular field to double, including:. The doubling of knowledge increases the learning load over time.
As a body of knowledge doubles so does the cost of wrapping your head around what we already know. This cost is the burden of knowledge. To be the best in a general field today requires that you know more than the person who was the best only 20 years ago. Not only do you have to be better to be the best, but you also have to be better just to stay in the game. The corollary is that because there is so much to know, we specialize in very niche areas. This makes it easier to grasp the existing body of facts, keep up to date on changes, and rise to the level of expert.
The problem is that specializing also makes it easier to see the world through the narrow focus of your specialty, makes it harder to work with other people as niches are often dominated by jargon , and makes you prone to overvalue the new and novel. A block of radioactive material will contain many trillions of nuclei and not all nuclei are likely to decay at the same time so it is impossible to tell when a particular nucleus will decay.
It is not possible to say which particular nucleus will decay next, but given that there are so many of them, it is possible to say that a certain number will decay in a certain time. Scientists cannot tell when a particular nucleus will decay, but they can use statistical methods to tell when half the unstable nuclei in a sample will have decayed. This is called the half-life.
The illustration below shows how a radioactive sample is decaying over time. From the start of timing it takes two days for the count to halve from 80 down to It takes another two days for the count rate to halve again, this time from 40 to It still has the original half-life.
Show 4 more comments. Active Oldest Votes. Improve this answer. Ilmari Karonen Ilmari Karonen And just when I was this close to getting a Populist badge Great answer, though. There is also the question physics. My answer gives examples of "partilces" with internal states that do have memory. Add a comment. Here's a graph that shows what I believe you're currently thinking. Now here's a graph of what actually happens.
Also, the lower graph is not exclusive to radioactive decay; it occurs all over the place. The temperature of cooling soup, the loudness of a tuning fork, you name it. It's just how nature works. After 4 half-lifes Jason C 5 5 silver badges 19 19 bronze badges. Alfred Centauri Alfred Centauri Community Bot 1. David Z David Z Charles E. Grant Charles E. Grant 6 6 silver badges 11 11 bronze badges. Vineet Menon Vineet Menon 2, 1 1 gold badge 21 21 silver badges 30 30 bronze badges. If it didn't adjust its probability of decay, one would expect to exponential decay, because: Thought experiment: roll a sided die.
Yiorgos S. Smyrlis Yiorgos S. Smyrlis 5 5 bronze badges. Helbrecht Helbrecht 1 2 2 bronze badges. The decay process has nothing to do with the presence of an ensemble of atoms, so a ratio doesn't really need to be considered. The Rule of compounding increases The "rule of 72" lets you estimate how long it takes your money to double, given a certain interest rate.
Half lives: compounding decreases Half lives are the same idea, but with negative interest imagine fees on a bank account or inflation. Queen Queen 1. Featured on Meta. Now live: A fully responsive profile. Linked 0. As time goes by, the ratio of carbon to carbon in the organism gradually declines, because carbon radioactively decays while carbon is stable. Analysis of this ratio allows archaeologists to estimate the age of organisms that were alive many thousands of years ago.
C dating does have limitations. For example, a sample can be C dating if it is approximately to 50, years old. Before or after this range, there is too little of the isotope to be detected. Substances must have obtained C from the atmosphere. For this reason, aquatic samples cannot be effectively C dated. Lastly, accuracy of C dating has been affected by atmosphere nuclear weapons testing.
Fission bombs ignite to produce more C artificially. Samples tested during and after this period must be checked against another method of dating isotopic or tree rings.
To calculate the age of a substance using isotopic dating, use the equation below:. How long will it take for Ra has a half-life of years.
Radioactive dating can also use other radioactive nuclides with longer half-lives to date older events. For example, uranium which decays in a series of steps into lead can be used for establishing the age of rocks and the approximate age of the oldest rocks on earth.
Since U has a half-life of 4. In a sample of rock that does not contain appreciable amounts of Pb, the most abundant isotope of lead, we can assume that lead was not present when the rock was formed. Therefore, by measuring and analyzing the ratio of UPb, we can determine the age of the rock. This assumes that all of the lead present came from the decay of uranium
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