The goal of this blog is to create a long list of facts that are important, not trivia, and that are known to be true yet are either disputed by large segments of the public or highly surprising or misunderstood by many.
Author: thomasstigwikman
My name is Thomas Wikman. I am a software/robotics engineer with a background in physics. I am currently retired. I took early retirement. I am a dog lover, and especially a Leonberger lover, a home brewer, craft beer enthusiast, I’m learning French, and I am an avid reader. I live in Dallas, Texas, but I am originally from Sweden. I am married to Claudia, and we have three children. I have two blogs. The first feature the crazy adventures of our Leonberger Le Bronco von der Löwenhöhle as well as information on Leonbergers. The second blog, superfactful, feature information and facts I think are very interesting. With this blog I would like to create a list of facts that are accepted as true among the experts of the field and yet disputed amongst the public or highly surprising. These facts are special and in lieu of a better word I call them super-facts.
Superfact 8 : US Violent Crime Nearly Cut in Half Since 1990
Despite all the news reports about rampant crime, the US violent crime rate has fallen to half of what it was in the early 1990’s.
I’ve known for a while that violent crime in the US has been going down substantially since 1990. However, quite often when I mention this people refuse to believe it. When I visit NextDoor, the hyperlocal social networking service for neighborhoods, I see people complaining about rising crime, and especially rising violent crime. The news media and the newspapers are filled with violent crime stories, murders, mass shootings, assaults, rape, and robberies. It seems to be getting worse and worse. We are living in scary times, aren’t we?
The Better Angels of our Nature
A couple of years ago I bought a book by Steven Pinker with the title The Better Angels of our Nature, why violence has declined, which contradicted the violence is getting worse narrative. In the book he claims that violence is trending down worldwide and that includes US violent crime.
In 1987 I received a Christmas present from the parents of a fellow student whom I had been tutoring. I was an exchange student to the United States from Sweden at the time. The Christmas present in question was the World Almanac of 1987. I loved it and ever since I’ve bought the World Almanac every year. If you open the pages for crime statistics in the United States in the World Almanac you see the same thing, violent crime in the US is declining.
The World Almanac and Book of Facts 2023.
Statistics
Below is what the World Almanac 2023 says about the violent crime rate per 100,000 residents in the United States (page 114). The data sources were : Federal Bureau of Investigation, U.S. Department of Justice, Uniform Crime Reporting Program, Crime in the United States 2020. I also included property crimes in the last column to show that non-violent crimes have declined as well.
Year
All violent crime
Murder and nonnegligent manslaughter
Rape
Robbery
Aggravated assault
All property crime (non-violent)
1990
729.6
9.4
41.1
256.3
422.9
5,073.1
1995
684.5
8.2
37.1
220.9
418.3
4,590.5
2000
506.5
5.5
32.0
145.0
324.0
3,618.3
2005
469.0
5.6
31.8
140.8
290.8
3,431.5
2008
458.6
5.4
29.8
145.9
277.5
3,214.6
2011
387.1
4.7
27.0
113.9
241.5
2,905.4
2014
361.6
4.4
26.6
101.3
229.2
2,574.1
2016
386.6
5.4
30.0
102.9
248.3
2,451.6
2017
383.8
5.3
30.7
98.6
249.2
2,362.9
2018
370.4
5.0
31.0
86.1
248.2
2,209.8
2019
368.6
5.1
31.4
81.8
250.4
2,130.6
2020
387.8
6.5
27.6
73.9
279.7
1,958.2
The graph below is taken from this article from the Pew Research Center tells the same story. The graph. It shows that the US violent crime rate has nearly halved since the 1990’s. There is a slight uptick in crime for the years 2020 and 2021 but according to this PBS article the downward trend has continued in 2022 and 2023.
The four graphs show that both violent crime and property crime has declined since 1990. Click on the picture to see the Pew Research article it is taken from.
Since this is a surprising fact that some does not even want to acknowledge (in my experience) I consider this a super fact.
Do you feel it is hard to believe that violent crime in the US has been declining over the last few decades?
This post is not another super fact but a blog note about the blog and a request for opinions. My most recent post included three super facts combined into one post. The three super facts were:
There has been a steep decline in extreme poverty
There has been a steep decline in child mortality
War and violence have declined
The post became very long. It had more than 2,000 words and several graphs filled with additional text and data. In addition, I rushed the third super fact. The discussion of the third super fact was muddy, incomplete, and it lacked references. Therefore, I deleted the third super fact. I think that was the right thing to do, especially since I had planned a separate super fact entry for it anyway with the title “We are living in relatively peaceful times”. I will write that post for it soon.
However, I’ve realized that some of my other posts have problems as well. The second half of the post titled “Two events may be simultaneous for some but not for others” feature equations and complex reasoning that physics nerds may appreciate but not typical readers. I don’t think I need to delete that section but, in the future, I need separate such sections from the rest and make it clear that I don’t expect readers to read that, well unless they are physics or math nerds, etc.
Expand your mind. Smash your old beliefs with new surprising facts, so called super facts. But there’s no need to confuse or bore your mind. Shutterstock ID: 1685660680 by MattL_Images
So, I am wondering what you all think about this and if you have suggestions or opinions on how I can improve my super fact posts. Blog notes are very much welcome.
Superfact 7 :Poverty and child mortality has been sharply reduced worldwide.
Extreme poverty as well as child mortality has been sharply reduced the world over. The countries that are the worst-off today are still better off than the countries that were doing the best at the beginning of the 19th century. Over the last 20 years extreme poverty and child mortality has continued to decline sharply.
In Hans Rosling’s book Factfulness, “Ten Reasons We’re are Wrong About the World – and Why Things Are Better Than You Think”, the author presented a quiz that he wanted the reader to take before reading the book. Below is the third question of the quiz. I should say that Hans Rosling posed this and other questions to thousands of people around the world.
In the last 20 years, the proportion of the World population living in extreme poverty has…
A. Almost doubled
B. Remained more or less the same
C. Almost halved
The correct answer is C. Almost halved. Around 7% of the quiz takers got the right answer. Around 5% in the United States got it right. That the proportion of the World population living in extreme poverty halved in 20 years is a true fact. This is also an important fact about the world. Despite that most people got it wrong. In fact, monkeys randomly picking answers would do better (33%). I did pretty well on this quiz, but since I was reading the book and the book’s title is “Ten Reasons We’re are Wrong About the World – and Why Things Are Better Than You Think”, I got some help just looking at the front cover. In any case, I think this fact qualifies as a super fact, as do the other fact below (There has been a steep decline in child mortality).
These are selected facts from the data.
There has been a steep decline in extreme poverty
According to the World Bank and Our Data World in Data, an organization which makes data in databases easily accessible to public, extreme poverty went from almost 80% 200 years ago, 60% 100 years ago, about 45% 50 years ago, 34.3% 30 years ago, 23.6% 20 years ago, 8.4% in 2019, then it went up to 9% during the covid epidemic but it seems to be back down to a bit above 8% again. See the graph below as well as the two linked articles in this paragraph.
I should say that extreme poverty is (by the UN, World Bank, etc.) “a condition characterized by severe deprivation of basic human needs, including food, safe drinking water, sanitation facilities, health, shelter, education and information” and is currently defined to be below $2.15. In 2011 it was below $1.90.
This graph from Our World In Data shows a steep decline in extreme poverty over time. Click on the picture to visit the original article.
Other related statistics mentioned in Hans Rosling’s book is that the share of undernourished people went from 28% in 1970 to 11% in 2015. That is despite the earth’s growing population. Related to this is that cereal yield per hectare went from 1.4 ton in 1961 to 4 ton in 2014. This is due to modern agricultural techniques. The share of people with water from protected sources went from 58% in 1980 to 88% in 2015. This statistic was taken from WHO, UNICEF, the World Bank and FAO (the UN Food and Agriculture Organization).
There has been a steep decline in child mortality
According to Hans Rosling’s book the percent of children dying before their fifth birthday went from 44% in 1800 to 4% in 2016. To get a more complete picture see these articles from Our World In Data, article1, article2, as well as the graph below. For most of humanities existence virtually all societies suffered a child mortality rate between 40% and 60%, but that changed drastically over the last 100 years.
Child mortality rate worldwide in 1800. Some of the data are estimates and may not be reliable. Data sources are UN IGME and Gapminder (an organization similar to Our World In Data).Child mortality rate worldwide in 2023. Niger has the highest child mortality rate of 11.6% and Iceland the lowest at 0.2%.Child mortality in in the world since 1950. The spike you see around the end of 1950 to 1960 is the great leap forward famine in China. In 1950 the child mortality rate was 22.7% and 2023 the child mortality rate was 3.6%.
Below is the child mortality rate since 1950 for a few selected countries.
Child mortality in China since 1950. The large spike you see around the end of 1950 to 1960 is the great leap forward famine. 15 to 55 million died from starvation. In 2023 the child mortality rate was 0.7%.Child mortality in the United States since 1950 (3.7%). In 2023 the child mortality rate was 0.6%.Child mortality in Sweden since 1950 (2.6%). In 2023 the child mortality rate was 0.2%.
Superfact 6 : Radon Represents our Largest Exposure to Ionizing Radiation
Radon represents our largest exposure to ionizing radiation.It is responsible for the majority of public exposure to harmful radiation. It is not the sun, the sky, nuclear weapons or nuclear power, or medical treatment, other terrestrial sources, it’s radon. Since we don’t talk much about the very deadly radiation emitted by the radon in our basements that may come as a surprise.
If a radioactive isotope has a long half-life, is that bad? I mean it will be around for a long time. Well, it is complicated. It is important to understand that if the decay rate for an isotope is very slow, in other words, it has a long half-life then it will be less radioactive. If the half-life is 1,000,000 shorter for an isotope X compared to an isotope Y (with a slower decay rate) than it is 1,000,000 more radioactive than isotope Y assuming their decay is of the same type. Short half life means more radioactivity. Long half-life means less radioactivity. The negative aspect of an isotope with a long half-life is that it will be around long, but the positive aspect is that it is less radioactive.
Radioactive decay is the emission of energy in the form of ionizing radiation. There are different types of decay and the decay-rate for different isotopes vary a lot. Stock Vector ID: 2417370135 by grayjay.
I should explain that isotopes mean that an atom can have a different number of neutrons. For example, carbon (coal) has a few common isotopes. C-12 has 6 protons and 6 neutrons, C-13 has 6 protons and 7 neutrons, C-14 has 6 protons and 8 neutrons. The isotope we are talking about when we talk about Radon is Radon-222. That is a really bad one. Radon-222 has a half life of 3.8 days which is 432 billion times shorter than Uranium-238, which has a half life of 4.5 billion years. So, if Radon-222 and Uranium-238 had the same type of decay (they don’t) Radon-222 would be 432 billion times more radioactive than Uranium-238.
Admittedly Uranium-238 isn’t very radioactive, you can safely hold it, but let’s take Plutonium-238, a famously radioactive isotope with a half-life of 87.7 years. Radon-222 has a half-life that is 8,424 times shorter yielding a decay rate and radiation intensity 8,424 times larger than Plutonium-238.
Radon
Radon-222 isotope has 86 electrons, 86 protons and 136 neutrons. Stock Vector ID: 1919418095 by saran insawat
So, Radon-222 is indeed extremely radioactive. But that means it should disappear quickly. Unfortunately, the inside of the earth is constantly supplying more Radon-222 from the radioactive decay and fission occurring there. Nuclear fission (nuclear reactions) is happening inside the earth providing about half of earth’s heat and powering the movement of Earth’s continents and crust. Since Radon-222 is extremely radioactive and is being resupplied by our own planet it is a very big source of the radiation we are exposed to.
Among all the different kinds of sources it is the biggest one. Since Radon-222 is a natural phenomenon, and we focus on so many other types of other natural and unnatural radiation sources we tend to underestimate the problem. At least I did when we bought our first house. I was asking Radon, what Radon? I think it is a surprising and important fact and therefore a super fact.
Radon Exposure
Illustration of how radon-222 enters a house. Stock Vector ID: 2128365599 by VectorMine.
The WHO estimates that radon exposure alone was estimated to have caused 84,000 deaths by lung cancer in one year. In 50 years, this would be 4.2 million deaths. The WHO predicted that the eventual total death toll from cancer related deaths from the worst nuclear disaster in history, Chernobyl, was 9,000, which is a lot less than 4.2 million. The numbers given by Greenpeace (which WHO does not accept) are up to a million and the Union of Concerned Scientists estimated 27,000.
Those numbers are all still smaller than the estimated deaths from Radon. Keep in mind that the Chernobyl reactor was a very dangerous reactor (RBMK) that lacked a containment shield, a reactor that could never be built in a western country. I can add that according to WHO the predicted future cancer deaths due to accumulated radiation exposures in the population living near Fukushima was between zero and a 100.
According to the United Nations Scientific Committee on the Effects of Atomic Radiation, more than 40% of the average annual human exposure to ionizing radiation is radon in the air. The other sources (all smaller) are cosmic background radiation, terrestrial radiation from the ground, radiation in food and water, exposure to radiation by medical treatment/exams, nuclear testing, Chernobyl, etc. According to former U.S. Surgeon General Richard H. Carmona, Radon is responsible for the majority of public exposure to ionizing radiation. Radon in our basements is indeed a very big deal compared to other radiation sources.
Superfact 5 : Two events may be simultaneous for some but not for others
Two events may be simultaneous for some but not for others. This means that two events that are simultaneous to an observer may happen at different times to other observers. If two lamps A and B turn on at the same time according to observer #1, lamp A may turn on first for observer #2, and lamp B may turn on first for observer #3. All three observers are correct because time is relative.
Previous Fact:
My previous blog post “The Speed of Light In Vacuum Is a Universal Constant” explained that the speed of light in vacuum compared to yourself is the same regardless of your motion or the origin of the light beam. A beam from a flashlight you are holding is traveling at a specific speed c = 299,792,458 meters per second as compared to you. If your friend is traveling at half the speed of light compared to you, he will still agree that the light beam from your flashlight is traveling at the specific speed c = 299,792,458 meters per second as compared to him, just like his own light beam by the way.
No matter how everyone is traveling everyone agrees that all light beams everywhere, emanating from everyone’s flashlights, all travel at exactly the same speed c = 299,792,458 meters per second. Like I said, the speed of light in vacuum is a universal constant. This is made possible by accepting that space and time are relative, but what does that mean? As mentioned in the other post this leads to the special theory of relativity.
I can add that since we are talking about relativity, or rather special relativity, relativistic effects have been very well tested by thousands of experiments and are not in doubt by the scientific community. Don’t be fooled by the word “theory” in special theory of relativity. “Theory” is not used the same way in science as in everyday language.
In this picture Amy is traveling past Alan in a rocket. Both have a laser. Both measure the speed of both laser beams to be c = 299,792,458 meters per second.
Relativity of simultaneity
Time is relative not only means that clocks are running slower in moving systems or that distances are contracted. It means that observers will disagree on how fast clocks are running and even disagree on whether events are simultaneous or not and in which order events occur.
If you are traveling through space at a very high speed and your wife/husband is back on earth, you can’t really ask yourself, “I wonder what my wife/husband is doing now?”, because what time it is back on earth depends on how it is calculated and by which observer. There is no universal now. Time is not absolute. Time is relative. The speed of light in vacuum is what is absolute.
I should add that if you combine space and time into spacetime you get an entity that is the same for all observers, the spacetime interval. You can say that in four dimensions the relativity disappears, but that is beyond the scope of this blog post.
Amy is traveling at a high speed to the left compared to two lamps A and B. Alan is standing still compared to the lamps. Adam is traveling at a high speed to the right compared to two lamps A and B. Alan turns on the lamps at the same time. After considering the travel time of the light she sees, Amy concludes that lamp B turned on first. After considering the travel time of the light he sees, Adam concludes that lamp A turned on first. I should add this non-simultaneity can only happen if the lamps are separated by a distance.
Below I am going to explain what is going on in more detail. If you don’t want to get into the details you can stop reading here. I am not going to explain the theory of special relativity, but I will explain some of the background and it gets a little bit complicated. Explaining scientific theories is not the goal of this blog. The goal of this blog is to list scientifically/expert accepted facts that are still disputed amongst the public or are highly surprising facts. Let’s look at time dilation first.
Time dilation
That clocks run at different speeds as a result of the constancy of speed of light in vacuum is pretty much well accepted. This is called time dilation. If Amy is passing Alan at a high speed, Alan will see Amy’s clocks running slower than his. This can be illustrated by the light clocks depicted below. The light clocks consist of light beams that are bouncing up and down between the floor and a mirror in the ceiling. Since light in vacuum is a universal constant, this is a very precise and reliable clock.
However, from Alan’s perspective the light beam in Amy’s system/spaceship must go farther than in Alan’s system (but note, from Amy’s perspective it is the opposite). Since the speed of all light beams in vacuum is a universal constant Amy’s clock is slower from Alan’s perspective.
Alan and Amy have identical light clocks. We call the time it takes for the light beam to go from the floor to the ceiling (one clock tick) Dt in Amy’s case and Dt’ (reference frame) for Alan. Amy is speeding past Alan towards the left. From Alan’s perspective Amy’s clock is running slower. Using Pythagoras theorem, it is possible to derive the formula for time dilation shown in the lower left corner.
When you realize that speeds and velocities are relative, a difficulty arises, perhaps even an apparent paradox. Let’s assume that you are flying in a rocket in space, and you meet another rocket, and your relative speed is 10 million miles per hour.
Is the other rocket standing still and you are moving at 10 million miles per hour? Is the other rocket moving towards you at 10 million miles per hour and you are one standing still? Or are both moving at the speed of 5 million per hour towards each other? Who gets to decide? Do we decide what is “standing-still” by tying it to a point on the surface of planet Earth, the center of planet Earth, the center of our solar system, or the center of our galaxy, or maybe another galaxy or an ether that no one can find?
The point is velocities are always compared to something and can be assigned arbitrary numbers. That means that if an observer, Amy, is speeding past another observer, Alan, at a high speed, then Alan thinks that Amy’s clock runs slower, but note, speed is relative, so we can reverse the situation. In fact, Amy thinks that it is Alan’s clock that runs slower.
It is equally correct to say that Amy is standing still and that it is Alan that is moving fast to the right. This time (pun not intended) the clock ticks Dt correspond to Alan’s clock ticks and Amy’s clock ticks are Dt’.
To understand how this works and why this is not a contradiction you need the Lorentz transform. The Lorentz transform is a so-called coordinate transform that incorporates time and space (as variable x), and it determines the specific time and space coordinate for one system based on the time and space coordinate for another and the relative velocity between the two. The Lorentz transform is a way of keeping account of time and space coordinates and using it correctly resolves any apparent paradoxes.
It is a bit more complicated to derive the Lorentz transform, and it is beyond the scope of this blog post. Suffice it to say that it is the vx/c2 term in the equation that both explains how it is possible for both Amy and Alan to consider the other’s clock slower and introduces the non-simultaneity aspect of special relativity. You have to look at both space and time to get the full picture.
The Lorentz transform is a so-called coordinate transform that incorporates time and space (as variable x), and it determines the specific time and space coordinate for one system based on the time and space coordinate for another and the relative velocity between the two.
The Twin Paradox
There is one obvious paradox that I need to address. Let’s say that Amy and Alan are of the same age. Then Amy leaves earth and travels at high speeds toward the star Sirius. From Alan’s perspective Amy’s clocks are running slower and from Amy’s perspective Alan’s clocks are running slower.
What will happen if Amy turns around and returns to earth after visiting Sirius and they meet up again? Will Amy be younger than Alan or will Alan be younger than Amy. Will they both be younger than each other? Well, the latter is not possible. You have to keep count of the time and what happens is that during the decelerations/accelerations necessary for Amy to turn around as well as the speed-up/slow-down around earth, Amy will catch up on the time that she lost with Alan.
In other words, her acceleration will make it so Alan’s clocks will run faster. When she comes back and meets up with Alan back on earth, Alan will be much older than her.
Recommended Reading
Below is some recommended reading on the Special Theory of Relativity.
Relativity Visualized by Lewis Carrol Epstein This does not require much education in physics and very little math, and yet it explains relativity very well. It is written by a high school teacher.
Relativity, The Special and the General Theory, by Albert Einstein. In my opinion, not the best overall, but it is easy reading for the general public and the chapter on the relativity of simultaneity is pretty good.
The Special Theory of Relativity by David Bohm. It is written for people with some physics education, but it is one of the best books on special relativity that I’ve read.
Einstein’s Miraculous Year This book features the translations of the five famous papers that Albert Einstein wrote in 1905 including “On the Electrodynamics of Moving Bodies”, which was his paper on Special Relativity. Not for the faint of heart but very interesting.
Note after copying all the text from my word document to WordPress I realized that wordpress cannot handle symblic characters. Thus all my delta-t were turned into Dt. I am sorry about that.
Super Facts 