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.

Relativity by Albert Einstein

This is not a super fact post but another kind of fact-oriented post. It is a book review for a book that I find interesting, Relativity: The Special and the General Theory by Albert Einstein. Yes, the book was written by Albert Einstein in 1916 and translated into English in 1920. It is written for laymen, average readers, and despite being more than 100 years old (well this reprint is from 1995) it does not feel outdated.

I should say that I wrote my review decades ago and Amazon has hidden about 900 of the oldest reviews including mine. So, you can no longer find it. Luckily, I still had it, but I cannot provide a link to it. The book comes in formats, hardcover (2024), paperback (1995), Kindle (2014), Audio (2009). I bought the paperback version.

  • Publisher : Independently published (July 29, 2024), ASIN : B0DBQVVJVQ, ISBN-13 : 979-8334454118, 109 pages, item weight : 7.8 ounces, dimensions : ‎ 6 x 0.47 x 9 inches, Translator : Robert W. Lawson, it costs $12.33 on US Amazon. Click here to order it from Amazon.com.
  • Paperback –  Publisher : Crown (June 6, 1995), ASIN : 0517884410, ISBN-13 :  978-0517884416, 208 pages, item weight : 8 ounces, dimensions : ‎ 5.2 x 0.5 x 8 inches, it costs $7.89 on US Amazon. Click here to order it from Amazon.com.
  • Kindle –  Publisher : Amazon Kindle Direct Publishing (February 23, 2014), ASIN : B004M8S53U, 126 pages, it costs $0.99 on US Amazon. Click here to order it from Amazon.com.
  • Audiobook –  Publisher : HighBridge, a division of Recorded Books (November 14, 2009), ASIN : B002XGLDAA, Listening Length : 2 hours and 14 minutes, it costs $12.09 on US Amazon. Click here to order it from Amazon.com.
The front cover of the paperback version feature Albert Einstein in front of a black board full of equations, title “Relativity: The Special and the General Theory” and author – Albert Einstein | Relativity by Albert Einstein
Front cover of Relativity: The Special and the General Theory by Albert Einstein. Click on the image to go to the Amazon page for the paperback version of the book.

Amazon’s Description of Relativity by Albert Einstein

This book was originally written in German by Albert Einstein in 1916 and later translated to English by Robert W. Lawson in 1920. In Einstein’s own words, “The present book is intended, as far as possible, to give an exact insight into the theory of Relativity to those readers who, from a general scientific and philosophical point of view, are interested in the theory, but who are not conversant with the mathematical apparatus of theoretical physics. It is an easy-to-understand collection of the ideas of one of the greatest scientists of the twentieth century including the idea he is most known for, the theory of relativity.

Redesigned inside and out to have a fresh, appealing look, this new edition of a classic Crown Trade Paperback is a collection of Einstein’s own popular writings on his work and describes the meaning of his main theories in a way virtually everyone can understand.

Below is my review for Relativity: The Special and the General Theory by Albert Einstein. First, I should mention that the book is divided into two sections, one for the Special Theory of Relativity and another for the General Theory of Relativity. In addition, there are five short appendices. The five appendices are not written for layman and require at least high school mathematics.

Relativity Explained by Einstein himself

I found it very interesting to read an explanation of the theories of relativity by the developer of those theories. However, it is important to remember that the inventors of science theories aren’t always the best ones to explain them. Isaac Newton is a prime example.

Another thing to remember is that today there are a lot of books and online graphics that use clever pedagogic techniques and visualizations to assist you in understanding these theories, and naturally this book does not contain any of that.

This book was originally written in 1916 and updated in 1920 and since then it has been reprinted/edited several times (as this book is an example of). I should say that the General Theory of Relativity had just been published so there weren’t much else out there for laymen at the time.

I’ve already read many good books on relativity, and I believe I understand special relativity pretty well, but my understanding of general relativity is partial. I did not buy this book to understand relativity. The reason I bought this book was to gain another perspective on the subject. If you just want to learn and understand relativity, I recommend Relativity Visualized by Lewis Carroll Epstein instead.

“Relativity: The Special and the General Theory” features no derivations of the formulas in relativity (except in the appendix) and no visualizations demonstrating relativistic effects and phenomena. The book is focused on the conceptual foundations of relativity and physics.

For example, what are Geometrical propositions, what does it mean to measure the length of a rod, or the time of an event, what do we mean by speed, what is simultaneity, what is the difference between what we observe and what we measure, etc? Einstein spends one and a half page explaining addition of velocities in classical-pre-relativistic kinematics (w = v + u) and what assumptions that are inherent with the approach. In that sense the book is quite philosophical, which is what I meant by “another perspective”. The book covers both the Special Theory of Relativity and the General Theory of Relativity. However, the sections on the General Theory of Relativity are quite short and very introductory.

There are some issues with the book. In appendix 1 Einstein (I presume) derives the Lorentz transforms. However, it is not, in my opinion, the best derivation from a pedagogical standpoint and it also had typos in it. As far as I can tell the formula on page 50 is wrong unless what Einstein means with the “m” is “additional relative mass” and not actual “mass” as stated.

The book features an addition written in 1920 where he is discussing an ad hoc modification to his theory that he had previously made but it turned out to be unnecessary (related to cosmology). The language is also very old fashioned. On the other hand, this kind of stuff makes you feel as if you travel back in time to when the theories of relativity were being churned out.

I don’t recommend the book for learning the theories of relativity but overall I liked the book. It focuses very much on basic concepts and near philosophical aspects of time, space and relativity. The book presents a valuable perspective if you already understand what the theories of relativity are about.

The back cover of the paperback features an overview of the background to relativity and to this book as well as ISBN number and publisher | Relativity by Albert Einstein
Back cover of Relativity: The Special and the General Theory by Albert Einstein. Click on the image to go to the Amazon page for the hardback version of the book.

Other Relativity Related Posts

To see the Super Facts click here

Ukraine Gave up Thousands of Nuclear Warheads

Super fact 47 : In 1991, after the dissolution of the Soviet Union, Ukraine became the third largest nuclear power in the world after Russia and the United States. Ukraine held about one third of the former Soviet nuclear weapons and delivery systems. Ukraine agreed to transfer these weapons to Russia for dismantlement in exchange for economic compensation and assurances to respect Ukrainian independence and borders.

After the dissolution of the Soviet Union in 1991, Ukraine inherited an estimated 1,700 to 1,900 strategic nuclear warheads, 130 UR-100N intercontinental ballistic missiles (ICBM) with six warheads each, 46 RT-23 Molodets ICBMs with ten warheads apiece, and an estimated 2,650-4,200 tactical nuclear weapons. It should be noted that these nuclear warheads were not under Ukrainian control.

In 1994, Ukraine agreed to transfer these weapons to Russia for dismantlement in exchange for economic compensation and assurances from Russia, the United States and the United Kingdom to respect Ukrainian independence and sovereignty within its existing borders. These political agreements are referred to as the Budapest Memorandum.

These events are relevant to what is happening in Ukraine today, and yet it is seldom discussed, and many people are unaware of or have forgotten about this history. It also comes as a surprise to many that there are nuclear states who have relinquished their nuclear weapons. This is why I call this fact a super fact.

Atomic bomb explosion in a city - nuclear attack on a crowded city – 3D rendering of a mushroom cloud encompassing a city with skyscrapers.
Nuclear bomb dropped on a big city. Shutterstock, asset id: 2188083835 by CI Photos.

Nine Nuclear States

There are nine nuclear states in the world as of 2025 according to the Federation of Atomic Scientists. There are 12,331 nuclear warheads including 9,600 in active military stockpiles.

  • Russia – 5,449 warheads
  • The United States – 5,277 warheads
  • China – 600 warheads
  • France – 290 warheads
  • United Kingdom – 225 warheads
  • India – 180 warheads
  • Pakistan – 170 warheads
  • Israel – 90 warheads
  • North Korea – 50 warheads

There are also countries that are hosting nuclear warheads owned by other countries.

  • Italy (the United States) – 35 warheads
  • Turkey (the United States) – 20 warheads
  • Belgium (the United States) – 15 warheads
  • Germany (the United States) – 15 warheads
  • Netherlands (the United States) – 15 warheads
  • Belarus (Russia) – ? warheads
Nuclear bomb, chemical weapons, missile defense, a system of salvo fire.
Four missiles aimed at the sky at sunset.  Shutterstock, asset id: 2131803989 by Hamara

Four nations that relinquished their nuclear weapons programs

The four nations that relinquished their nuclear weapons programs are Belarus, Kazakhstan, South Africa, and Ukraine. Belarus, Kazakhstan, and Ukraine returned their inherited nuclear weapons to Russia after the dissolution of the Soviet Union. However, it should be noted that in 2023 Russia began deploying tactical nuclear weapons to Belarus. However, Belarus does not currently possess its own nuclear weapons. South Africa voluntarily dismantled its nuclear weapons program in 1991.

In 2023 Russia began deploying tactical nuclear weapons to Belarus.
Russia and Ukraine as well as the borders of Russia and Ukraine are colored and look different from other countries.
Russia (green) and Ukraine (brown) map on a world map. Ukraine is about the size of Texas. Russia is about twice the area of the United States. Belarus is the country located immediately to the north of Ukraine and Kazakhstan is the big country immediately to the south of Russia and east of Ukraine. Shutterstock Asset id: 2121271067 by buraktumler

How to Build a Nuclear Bomb

This section is just some extra reading that is only somewhat related to the topic. However, since it is an interesting topic somewhat related to the topic I might as well explain how to build a nuclear bomb. Don’t worry I will not present any engineering details, only general principals, which is all I know, and which are already all over internet. Besides if I were to give detailed engineering instructions some peacenik hippie might have a hissing fit and swear in the comment section (that was a joke).

Anyway, the main idea behind a nuclear fission bomb is to achieve a runaway chain reaction. A fusion bomb, or a so-called hydrogen bomb is different. To create a fission bomb you are not looking for the most radioactive materials there are. You are looking for a fuel which you can use to create a runaway chain reaction, and which is also stable enough to make a bomb possible, in other words not too radioactive. Basically, the fuel must be just right. The primary fuels used in fission bombs are uranium-235 and plutonium-239. These isotopes undergo fission when struck by neutrons, releasing a massive amount of energy in a chain reaction.

The image shows a Uranium atom on the left arrows in the middle and an alpha particle, a gamma ray, a proton, a neutron, and an electron on the right | Ukraine Gave up Thousands Nuclear Warheads
Uranium-235 and Uranium-238 are both not very radioactive and can be used for radiometric dating that stretches millions and billions of years. Uranium-235 is also the “just-right” uranium isotope that can be used for bomb making. Shutterstock Vector ID: 2417370135 by grayjay

I should explain, isotopes are different forms of an element. For example, hydrogen comes in three different forms, a nucleus with just a proton, a nucleus with one proton and one neutron (deuterium), and a nucleus with one proton and two neutrons (tritium). Isotopes for the same element are chemically identical but have different atomic weight and they may or may not be radioactive.

The three isotopes of Uranium are uranium-234, uranium-235, and uranium-238. The one we need is uranium-235, which has 92 protons and 143 neutrons in the nucleus. The isotopes of Plutonium include Pu-238, Pu-239, Pu-240, Pu-241, and Pu-242 but there are others. The one we need is plutonium-239, which has 94 protons and 145 neutrons in the nucleus. There are more than 3,500 known isotopes of which 3,000 are radioactive.

During Uranium-235 fission, an average of 2.5 neutrons are released. Specifically, the fission of U-235 typically releases 2 or 3 neutrons, with the average being close to 2.5. During the fission of plutonium-239, an average of 2.9 neutrons are released (depending on the energy of the incident neutron). The important thing for bomb making is that one atom/nucleus releases enough neutrons so that the neutrons from one nucleus cause more than one fission. For example, a nucleus releases three neutrons and two of those neutrons cause two more fission events, which in turn cause four fission events, etc. 2, 4, 8, 16, 32, 64, a trillion…

From left to right : a neutron strikes a uranium nucleus, and it breaks apart into a Krypton and Barium isotope and release three neutrons, which strike three uranium nucleuses, causing three fission events and releasing nine neutrons in total, etc | Ukraine Gave up Thousands Nuclear Warheads
Illustration of nuclear chain reaction. Uranium-235 fission. Unfortunately, the picture has an error in it. It is 92 protons not 95 in a U-235 isotope. – Shutterstock asset id: 73714504 by Mpanchenko.

By putting together enough U-235 you can make it so that one fission event will result in more than one additional fission event. This is called the critical mass. The critical mass for U-235 is 47 kilograms (104 pounds). Theoretically, you can achieve this by taking a 24-kilogram half sphere of U-235 in your right hand and a 24-kilogram half sphere of U-235 in your left hand and bring them together. You will achieve a limited chain reaction for a nano second, but you will just blow the two halves apart and kill yourself, but your city will survive. This is called a fizzle. To make most of the 48-kilogram mass undergo fission you have to force them together long enough for the chain reaction to complete (or almost complete). This requires force and precise calculations. See the illustration below.

A piece of arrow shaped uranium-235 is shot from the left to the right to collide with a larger half-sphere-shaped uranium-235 core thus achieving critical mass forcefully and quickly | Ukraine Gave up Thousands Nuclear Warheads
Components Inside of Uranium Nuclear Fission Bomb illustration – Shutterstock asset id: 2271462995 by BlueRingMedia.

Another difficulty is obtaining nearly 100% U-235 from natural uranium. 99% of the Uranium you find in nature is U-238. U-235 and U-238 chemically identical so extracting U-235 from natural uranium is difficult. However, U-235 is slightly lighter than U-238 so you can use centrifugal separation as you do to separate cream from milk. What is typically done is using a uranium compound, uranium hexafluoride, heat it into gaseous form and then utilize centrifugal separation to extract the uranium hexafluoride with U-235 isotopes. After that you can chemically extract the uranium, which is now U-235.

To see the other Super Facts click here

There are many environmental success stories

Super fact 46 : There are many serious threats to the environment that we need to take seriously. However, there are also many environmental success stories that we tend to forget about.

It is important to remember the environmental success stories because if we forget about them, it breeds despair, which in turn discourages people from acting and doing the right thing. Denial and Despair are two seemingly opposite emotional reactions that both hinder action on problems. I consider the existence of the many important environmental success stories a super fact because even though it is undeniably true that there are many environmental success stories, some truly amazing, it comes as a surprise to many.

Below I am listing six environmental success stories that I previously chose to be super facts. Super facts are important and true facts that are surprising and perhaps even shocking to many, or widely misunderstood, or disputed amongst the public, but not seriously disputed amongst the experts/scientists. Super facts are facts that are very special and that I think we should be aware of these facts. I should add that this is just a sample of environmental success stories. There are many more.

Super Fact 29:

EV Cars Indeed Emit Less Carbon Pollution

EV Cars emit less pollution than Internal Combustion Engine Cars, even considering manufacturing, disposal and many EV Cars being charged by dirty grids. The basic reason for this is the much higher efficiency of EV cars. EV cars emit significantly less greenhouse gases than internal combustion engines even considering construction of fuel production facilities, production of the car, the battery, and the fuel, vehicle operation and disposal. For more information click here.

The histogram graph shows that if you consider construction of facilities, manufacturing of vehicle and battery, production of fuel, vehicle operation as well as disposal the total average greenhouse gas emissions from EV cars is 52% less | There are many environmental success stories
Lifecycle greenhouse gas emissions comparison of average gasoline car and average EV. This graph is taken from the US Department of Energy.

Super Fact 35:

Natural Disasters Kill Less People Now Than 100 Years Ago

Natural disasters kill a lot less people now compared to 100 years ago. That is despite a larger population and despite the fact that climate change has increased the frequency and intensity of many types of natural disasters. Surveys by Gap Minder show that this fact is quite surprising to people and therefore it is a super fact. To read more about this super fact click here.

The reason for the fewer deaths from natural disasters is not that there are fewer natural disasters. It is because we are now much better at predicting, handling and recovering from natural disasters. Our warnings systems, rescue systems and healthcare have improved significantly. The graph below from Gap Minder illustrates the decline in deaths from natural disasters.

The graph shows 300 to 400 thousand annual deaths at the beginning of the 20th century, then 971 thousand annual deaths in the 1930’s, then it continuously gets lower until the annual deaths in the 2010 to 2016 period is 72 thousand deaths per year.
This graph from the Gap Minder article shows the annual deaths from natural disasters.

Super Fact 41:

Emissions of ozone-depleting gases have fallen by 99 Percent

Largely thanks to the Montreal Protocol in 1987 the emissions of ozone-depleting gases have fallen by more than 99%, 99.7% to be exact, according to Our World in Data. This has resulted in the halt of the expansion of the ozone holes. The reduction in emissions of  ozone-depleting gases is saving millions of lives every year. To read more about this astounding success click here.

The NIH estimate that the Montreal Protocol has prevented 443 million cases of skin cancer worldwide, 2.3 million skin cancer deaths, and 63 million cases of cataracts in the United States alone. Globally, it is estimated that the Protocol has saved an estimated 2 million people from dying from skin cancer each year. The graph below is taken from Our World in Data.

Gases visualized in the diagram are CFCs, Halons, HCFCs, Carbon Tetrachloride, Methyl Bromide, Methyl Chloroform. The diagram shows a peak around the end of 1980’s | There are many environmental success stories
The phase out of six ozone depleting gases. Data source UN Environment Program (2023).

Super Fact 42:

Developed nations have successfully reduced carbon emissions

The developed nations (rich countries) have reduced their carbon emissions since the 1990’s despite continued GDP growth, even if we take offshore production into account. In addition, many developing countries have succeeded in reducing their emissions as well. Other fast-growing developing countries have flattened or at least slowed their increase in carbon emissions. Many countries have decoupled economic growth from CO2 emissions.

In other words, we do not need to increase carbon emissions or burn more fossil fuels to grow the economy. To read more about this promising development click here.

The graph shows three plotted graphs, a dark blue one showing GDP per capita, a light blue one showing UK carbon emissions per capita and a red one showing trade adjusted carbon emissions per capita. The GDP graph is increasing by more than 50% over 33 years and the CO2 emissions per capita graph is decreasing by almost 60% and the trade adjusted carbon emissions decline by almost 40%.
Data source: Data compiled from multiple sources by World Bank (2025); Global Carbon Budget (2024); Population based on various sources (2024). Note: GDP per capita is expressed in international dollars at 2021 prices. Graph taken from Our World in Data.

Super Fact 44:

Sulfur dioxide pollution has fallen by 95 percent in the US

Sulfur dioxide pollution has fallen by approximately 95 percent in the US since the 1970s. This significant reduction is primarily due to regulations like the Clean Air Act. Global sulfur dioxide pollution has also fallen but not as much. To read more about this success story click here. If you visit the aforementioned link you will also see that there are many other pollutants that we have successfully curtailed.

The graph shows a steep increase towards the end of the 19th century with a peak in 1973, followed by a steep decline |There are many environmental success stories
US sulfur dioxide pollution since 1800. US Emissions peaked in 1973. Data Source: Hoesly et al (2024) – Community Emissions Data System (CEDS). This graph is taken from this page in Our World In Data.

Super Fact 45:

Deforestation has peaked

Deforestation peaked back in the 1980s, meaning that is when it was worst. Deforestation has not stopped but the rate of deforestation has slowed as a result of government policies, corporate initiatives, and international agreements.

Overall, we are still losing forests. We had a 47-million-hectare loss of forest in the last decade, which is very bad, but that is better than the 151-million-hectare loss of forest in the 1980s. For temperate forests we have succeeded in reversing deforestation, which means that temperate forests are now gaining forest. To read more about this topic and how government policies, corporate initiatives, and international agreements have slowed the rate of deforestation you can click here. This change in deforestation rate is illustrated by the graph below, which is taken from Our World in Data.

The graphs show that during the 1700’s and the first half of the 1800’s the loss of forests was 19 million acres per decade. From the mid-1800’s to 1920 it was roughly 30 million acres per decade and from the 1920 and on it was 115 million acres per decade until the 1980s and the first half of the 1990s when it was 151 million acres per decade. Since then, it has fallen and in the last decade forest loss was 47 million acres | There are many environmental success stories
Decadal losses in global forest over the last three centuries. Decadal forest loss is measured as the average net loss every ten years, in hectares. This deforestation minus increases in forest area through afforestation. There is no single dataset that applies consistent or transparent methodology for deforestation over centuries. Two different datasets are therefore shown: these still shown the overall development and transition of forestation from temperate to tropical areas, but magnitudes should not be combined at the crossover point. Data sources: Pre-1995 data from Williams (2006). The second series is based on data from UN FAO Global Forest Resources.

Note : I am going on a trip with family and will return next Tuesday (5/27). During this time will not do any blogging. I love comments but I will respond to comments when I come back.

To see the other Super Facts click here

Deforestation peaked back in the 1980s

Super fact 45 : Deforestation peaked back in the 1980s, meaning that is when it was worst. Deforestation has not stopped but the rate of deforestation has slowed as a result of government policies, corporate initiatives, and international agreements.

The rate of global deforestation has slowed significantly since the 1980s. Overall we are still losing forests. We had a 47-million-hectare loss of forest in the last decade, which is very bad, but that is better than the 151-million-hectare loss of forest in the 1980s. For temperate forests we have succeeded in reversing deforestation and temperate forests are now gaining forest. To read more about how government policies, corporate initiatives, and international agreements have slowed the rate of deforestation you can click here, or here, or here.

Aerial photo of a forest. The upper left side shows lot of green trees whilst the lower right side is brown
Amazon rainforest illegal deforestation landscape. Aerial view of trees cut and burned to make land for agriculture and cattle pasture in Amazonas, Brazil. Asset id: 2471967219 by PARALAXIS

This is a super fact because we get a lot of bad news about deforestation, and we should, it is still a big problem. However, we are making progress and because of our negativity bias as well as that of the media, we tend to miss the story about the progress. Therefore, the fact that we are making progress comes as a surprise to many people.

The graphs show that during the 1700’s and the first half of the 1800’s the loss of forests was 19 million acres per decade. From the mid-1800’s to 1920 it was roughly 30 million acres per decade and from the 1920 and on it was 115 million acres per decade until the 1980s and the first half of the 1990s when it was 151 million acres per decade. Since then, it has fallen and in the last decade forest loss was 47 million acres | Proof that deforestation peaked back in the 1980s
Decadal losses in global forest over the last three centuries. Decadal forest loss is measured as the average net loss every ten years, in hectares. This deforestation minus increases in forest area through afforestation. There is no single dataset that applies consistent or transparent methodology for deforestation over centuries. Two different datasets are therefore shown: these still shown the overall development and transition of forestation from temperate to tropical areas, but magnitudes should not be combined at the crossover point. Data sources: Pre-1995 data from Williams (2006). The second series is based on data from UN FAO Global Forest Resources Assessments. The graph comes from Our World in Data – Research and data to make progress against the world’s largest problems.

Peak Agricultural Land

There is one aspect to this story which both explains part of the reduction in deforestation but also provides additional hope for the future and that is that even though the world produces more food than ever, the amount of land we use for doing that is falling. Global land use for agriculture has peaked and is now falling. There has been a global decoupling of agricultural land and food production. I should explain that agricultural land is the total amount of arable land that is used to grow crops, and pasture used to raise livestock. That global land use for agriculture has peaked is illustrated in the graph below.

The graph shows a green line chart representing global agricultural land use and an orange line chart representing global agricultural production. The orange line graph keeps rising but the green line chart peaks and then starts going down | Evidence that deforestation peaked back in the 1980s
Global decoupling of agricultural land and food production. Agricultural land is the sum of cropland and pasture for grazing livestock. Production is measured in constant 2015 international dollars, which adjusts for inflation. Includes all crops and livestock. Data source: Food and Agriculture Organization of the United Nations. Our World in Data – Research and data to make progress against the World’s largest problems.

There are more trees now than 35 years ago (there’s a catch)

Another related good news story is that there are more trees in the world today than there were 35 years ago. A lot of the losses of forest in tropical areas have been compensated for by gains in Europe, North America and Asia. For example, tree planting programs in places like China have added a lot of trees as well as forests. In addition to tree planting programs climate change resulting in northern latitudes warming has resulted in temperate forests expanding.

However, this story is not as good as it sounds. There is a huge catch and that is that there is an important distinction between tree cover and forest cover. Tree cover refers to the total area covered by trees, while forest cover specifically refers to areas where trees form a forest ecosystem. Tree cover has increased but as you can guess from the graph above depicting global deforestation, the forest cover continues to decrease.

In addition, a lot of trees were planted for industrial timber plantations, mature oil palm estates and other specifically planted forests. These add to the global tree cover but not necessarily to biodiversity. Not all tree planting is equal.

So even though having more trees compared to 35 years ago is a good thing, it may not be as great as it sounds and does not contradict the fact that deforestation continues. This is important to point out because there are those who attempt to use the fact that we now have more trees to make the case that the talk about deforestation is a hoax. Don’t fall for that.

Summary

The good news is that even though deforestation is still happening the rate of it has slowed down. It peaked in the 1980s. This slowdown is largely due to government policies, corporate initiatives, and international agreements. An additional circumstance that aids in slowing deforestation is that the amount of land we use for agriculture is falling and we have passed peak land use for agriculture. Another positive situation is that we now have more trees than 35 years ago.

However, it is important to point out that does not mean that deforestation has been reversed. Tree cover and forest cover are not the same thing. The benefit of this is limited even though it is still a good thing to have more trees.

Environmental Success Stories

Aside from the success in reducing the rate of deforestation there is additional surprising, as well as good news regarding the environment.

To see the other Super Facts click here

What is Time

Image above by Kevin from The Beginning at Last

Many and strange are the universes that drift like bubbles in the foam upon the River of Time—first sentence of Wall of Darkness by Arthur C. Clarke, 1949.

What is Time? What is the arrow of time? Does entropy define an arrow of time? Is there a past and a future? Has time always existed as, for example, in the eternal inflation cosmological model in which universes continuously pop into existence via Big Bangs like the bubbles on the River of Time in the Arthur C. Clarke quote above. Does time have a beginning as a recent Big Bang model by Stephen Hawking imply. If time came into existence with the universe itself then there is no place for creation, just as in an infinitely existing universe. There cannot be anything north of the north pole, and there cannot be anything before time itself.

In the theories of relativity time is relative. The speed of clocks as well as the order of events differ from observer to observer. The presence of energy or mass will bend time. There is no universal flow of time. There is no universal time.

The goal of this blog is to create a list of what I call super facts. Important facts that we know to be true and yet they are surprising, shocking or disputed among non-experts. It is a type of myth busting. However, I also create posts that are not super facts but that feature other interesting information, such as this book review and book recommendation.

In the picture there are objects from the past as well as futuristic elements and several clocks | What is Time
This picture reminded me of the mysteries of time. This is a submission for Kevin’s No Theme Thursday

About Time: Einstein’s Unfinished Revolution by Paul Davies

The book I am about to present focuses a lot on relativity. This is not strange since the theories of relativity shed a lot of light on time. Yes, pun intended. I’ve come across a lot of people who make various claims about time, and even consider themselves philosophers of time, and yet they do not even understand the special theory of relativity.

Because of this they say a lot of profound sounding things about time that ultimately are nonsensical. There is no way around it. If you want to say profound things about time and expand human knowledge on this topic you need to first have some understanding of relativity as well as other related physics such as thermodynamics and entropy. This book will provide that.

I should say that the book is somewhat outdated, being written in 1995 and 1996. However, most of it is still relevant and I know of no other book that approaches the topic in such an honest and rigorous way. The book comes in two formats hardcover and paperback. I bought the paperback version.

  • Hardcover –  Publisher – Simon & Schuster; First Edition (March 13, 1995), ISBN-10 : 0671799649, ISBN-13 : 978-0671799649, 316 pages, item weight : 1.3 pounds, dimensions : ‎ 6.25 x 1.25 x 9.5 inches, it costs $18.09 on US Amazon. Click here to order it from Amazon.com.
  • Paperback –  Publisher – Simon & Schuster; First Edition (April 9, 1996), ISBN-10 : 0684818221, ISBN-13 : 978-0684818221, 316 pages, item weight : 0.704 ounces according to Amazon but I think that should be 0.704 pounds, dimensions : ‎ 9.21 x 6.14 x 0.8 inches, it costs $12.28 on US Amazon. Click here to order it from Amazon.com.
Front cover of hardback version of the book About Time: Einstein's Unfinished Revolution by Paul Davies
Front cover of hardback version of the book About Time: Einstein’s Unfinished Revolution by Paul Davies. Click on the image to go to the Amazon page for the hardcover version of the book.

Amazon’s Description of About Time: Einstein’s Unfinished Revolution

An elegant, witty, and engaging exploration of the riddle of time, which examines the consequences of Einstein’s theory of relativity and offers startling suggestions about what recent research may reveal.

The eternal questions of science and religion were profoundly recast by Einstein’s theory of relativity and its implications that time can be warped by motion and gravitation, and that it cannot be meaningfully divided into past, present, and future.

In About Time, Paul Davies discusses the big bang theory, chaos theory, and the recent discovery that the universe appears to be younger than some of the objects in it, concluding that Einstein’s theory provides only an incomplete understanding of the nature of time. Davies explores unanswered questions such as:

* Does the universe have a beginning and an end?

* Is the passage of time merely an illusion?

* Is it possible to travel backward — or forward — in time?

About Time weaves physics and metaphysics in a provocative contemplation of time and the universe.

My four-star review for About Time: Einstein’s Unfinished Revolution

The link above will take you to my original review for About Time: Einstein’s Unfinished Revolution. Below is a slightly modified version of the review.

Our Evolving Concept of Time

Science, particularly physics, has revealed to us some profound insights about time, and yet it remains a mysterious topic. In the first chapter of the book “A Very Brief History of Time” the author describes how the concept of time has evolved throughout human history. The ancient philosophers had a very fuzzy notion of time, and they often dismissed both motion and time as illusions. The author tells us about “cyclic time”, and the “linear time” concept from Judeo-Christian thinking, and how it was incorporated into science as a “time variable”. This made it possible to solve the paradoxes created by such Greek thinkers as Zeno, who based on apparent paradoxes concluded that motion and time cannot really exist. Those “false” paradoxes were solved with the concept of linear physical time.

Physical time also made Calculus and Physics possible, and it became clear that there was a difference between physical time, which is a measurable entity used to sequence events, and experienced time, which is the subjective human feeling of a past, present, and a future.

Most of the rest of the book is focused on the Special Theory of Relativity and the General Theory of Relativity. The theories of relativity revolutionized how we view time, and they enabled a much deeper understanding of time. Special relativity refuted the concept of universal absolute time. Not only do clocks in different systems run at different speeds, but there is no universal “Now”.

However, the theories of relativity are not all there is to know about time, and we are not even done drawing conclusions about time based on the theories of relativity. This is why the book is called “About Time Einstein’s Unfinished Revolution”. The book also discusses quantum time, the arrow of time, worm holes, neuroscience and modern psychological experiments.

The book contains a lot of information and yet it scratches only on the surface. Time is a quite complex concept when you start digging into it. Take, for example, the discussion on the arrow of time. The conclusion of the books seems to be that there really is an arrow of time. Time has direction. The author is presenting both “sides” of the issue and to really get a grasp of the issue you need to clarify and look at the physics. Time certainly seems to have a direction if you look at the concept of entropy. The Cosmos is filled with irreversible processes. Our memory, which is essential for our experience of a self, is another example.

However, time has a direction even on the most fundamental level in subatomic particles. Kaon, a type of meson, decays in a way that is not time symmetric. The same may be true for the neutron. These particles “know” the difference between the past and the future. One could easily imagine how this chapter could be turned into a several thousand pages long book by just digging deeper into the related physics.

“About Time Einstein’s Unfinished Revolution” covers a lot of interesting topics related to time and it is often quite informative. The book is also well written, well organized, it has a good pace, and it is very interesting. It strikes a good balance between depth and breadth, and it does not overwhelm its readers. However, I do have some critique of the book, which prompted me to give the book four stars instead of five stars.

To understand some of the discussions in the book you should have a decent understanding of the theories of relativity, in my opinion. The author is explaining the theories of relativity to some degree, but the explanations did not seem to be that good. I did not have a problem with understanding these explanations since I already studied these topics, but I don’t think I would have understood what I needed to understand had I encountered the theories of relativity for the first time while reading this book.

Another criticism I have of the book is that he introduces ugh Everett’s many-worlds interpretation of quantum mechanics and in my opinion promotes it. This interpretation is in my opinion both strange and implausible and is not necessary for the discussions in the book.

In short, it proposes that every quantum measurement creates new universes, each corresponding to a different possible outcome of that measurement. In essence, our Universe is just one of many, and each quantum event splits the universe into multiple versions, where each version experiences a different outcome.

The problem with this interpretation is not so much that you get multiverses, but that you an infinite number of new fully evolved universes every nanosecond, which in turn create an infinite number of universes, which in turn create an infinite number of universes, and so on infinitely, and there is no way to empirically verify their existence. It is a so-called solution to a problem that is fictitious in my opinion and is derived from an old naïve interpretation of quantum waves. It is “hip” and “cool” interpretation, but I don’t see how it is useful. I should add that I have no problem with, for example, the multiverse idea stemming from string theory.

Anyway, except for my two complaints I think this is a pretty good book that I can recommend.

Front cover of paperback version of the book About Time: Einstein's Unfinished Revolution by Paul Davies.
Front cover of paperback version of the book About Time: Einstein’s Unfinished Revolution by Paul Davies. Click on the image to go to the Amazon page for the paperback version of the book.

About Paul Davis

Paul Davies is an internationally acclaimed physicist, cosmologist, and astrobiologist at Arizona State University, where he runs the pioneering Beyond Center for Fundamental Concepts in Science. He also chairs the Search for Extraterrestrial Intelligence Post-Detection Taskgroup, so that if SETI succeeds in finding intelligent life, he will be among the first to know.

The asteroid 1992OG was officially renamed Paul Davies in his honor. In addition to his many scientific awards, Davies is the recipient of the 1995 Templeton Prize–the world’s largest annual prize–for his work on science and religion. He is the author of more than twenty books, including The Mind of God, About Time, How to Build a Time Machine, and The Goldilocks Enigma. He lives in Tempe, Arizona.

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