Super Facts – Page 2 – 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.

Marsupial Planet

Image above by Kevin from The Beginning at Last

This picture reminded me of our trip to Australia and all the kangaroos and other marsupials we encountered. This is a submission for Kevin’s No Theme Thursday.

There Are Three Types of Mammals

Placentals, Monotremes, and Marsupials

All mammals are warm-blooded, have fur, and produce milk. However, there are three main types of mammals, placentals, monotremes, and marsupials, distinguished by how they give birth. Placentals give birth to well-developed young, and they nourish their young in the uterus through the placenta. Examples include gorillas, humans, whales, rodents, tigers, and bats. Monotremes lay soft-shelled eggs. Examples include the platypus and the echidna.

Then we have Marsupials, which give birth to small and underdeveloped young. Most female marsupials have pouches. Examples include kangaroos, wallabies, wombats, possum, opossum, Tasmanian devils, and koalas. Below is a kid friendly overview of the three types of mammals.

Marsupials on Three Continents

Close to 70% of the 334 extant marsupial species are concentrated on the Australian continent, including mainland Australia, Tasmania, New Guinea, and nearby islands. The remaining 30% are distributed across the Americas, primarily in South America. The Virginia opossum is the only marsupial native to the United States, but it is quite common. For example, we have lots of them in our neighborhood in Dallas. It should also be noted that there are a lot of marsupial fossils in Antarctica, which means that marsupials once lived there.

This map shows the distribution of marsupials. Blue indicates places in which marsupials are native and purple where they have been introduced. The image is from Wikipedia commons created by Michal Klajban under https://creativecommons.org/licenses/by/4.0/.

DNA evidence supports a South American origin for marsupials, with Australian marsupials arising from a single Gondwanan migration of marsupials from South America, across Antarctica, to Australia. These continents were connected and part of the supercontinent Gondwana back then. The ancestors of the marsupials, the metatherians split from placentals around 100 million to 120 million years ago during dinosaur times.

Bamboozled by an Opossum

We’ve found opossums in our house, behind our laundry machine. We’ve seen them along the street, on lawns in the neighborhood and we’ve seen them climb trees. They are pretty common in our neighborhood. It should be noted that they are not possums even though they are sometimes called that. Possums is an Australian relative to the Opossum.

A photo of an Opossum. Author Sergey Yarmolyuk. From Wikimedia commons https://creativecommons.org/licenses/by-sa/4.0/

One day when my wife and I were out walking the dogs we saw an opossum lying on the alleyway behind our house. He looked dead. However, when I checked, he was warm and appeared to be alive even though he was unconscious. We put him in a box containing a soft blanket and took him to the veterinary. We were willing to pay for any treatment or surgeries needed. At the veterinarian he woke up and they later placed him in a nature sanctuary. We did not need to pay anything.

Later on, we learned that when an opossum is threatened or harmed, they will “play possum“. They mimic the appearance and smell of a dead animal. This response is involuntary, like fainting, and not a conscious act. That might have been what was going on. So, I might have been bamboozled by an opossum. Bamboozlement seems to be the story of my life. Luckily, he was a male and the veterinary said it looked like he had been hit by a car, so us taking him to the veterinary probably did not do much harm. However, the “playing possum” thing is something to keep in mind with these animals.

Australia and our Photos of Marsupials

When our kids were young, we traveled to Australia where we encountered a lot of marsupials in the wild, in nature preserves and at zoos We encountered a lot of kangaroos but also wombats, koalas, and Tasmanian Devils. I can add that checking out kangaroos and other marsupials was not the only thing we did in Australia. We also spent a week in Great Barrier Reef where we did snorkel and scuba diving.

The first picture below was from our visit to the Blue Mountains. We stopped to have lunch, and I decided to go and take a leak. As I approached a bush, I heard some noise and when I looked behind the bush, I saw that there was a kangaroo behind it. What you see in the picture below is what I saw. The kangaroo was just two yards away. He seemed to be as startled as I was, and we stared at each other for a few seconds. I had my camera hanging around my neck, so I decided to take a photo. Then he hopped away. I am so glad I did not pee on his lunch.

A surprise encounter with a kangaroo in the wild. I am so glad I did not pee on his lunch.

Our oldest son and daughter feeding small kangaroos (or wallabies) at a nature preserve outside Brisbane, Australia.

Our younger son and daughter feeding small kangaroos at a nature preserve outside Brisbane, Australia. They are laughing because one of the kangaroos grabbed the entire bag of food and then spilled it.

A small kangaroo/wallaby is sniffing my camera (at the same nature preserve).

Note : Koalas are often called Koala bears, but they are not bears.

A Koala sleeping in a tree at Brisbane Zoo.

Our daughter holding a Koala at Brisbane Zoo.

One interesting fact about Wombats is that they produce cubic shaped poop. This makes the poop stackable, and the wombats use it to mark their territory and attract mates.

To see the Super Facts click here

Climate Science versus Pseudo Science

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 other interesting information, such as this book review and book recommendation.

Climatology versus Pseudoscience: Exposing the Failed Predictions of Global Warming Skeptics by Dana Nuccitelli

Climatology versus Pseudoscience by Dana Nuccitelli is a book about human-caused Climate Change, or global warming, and how we know that is happening and how we know that we are the cause of it. If you want to see more about why we know this click here.

The book pays a lot of attention to so called climate skeptics; more accurately called climate contrarians. They are not true skeptics but agenda driven contrarians. Even though their science is bad, and their predictions have failed repeatedly many times over, they have had an enormous influence on public discourse. Conservative politicians, and many talk show hosts are blindly devoted to their falsehoods, whilst real scientists are being attacked. Large segments of the population in the United States, and to some extents elsewhere, have been bamboozled by the pseudo-science.

The good news is that people are waking up to the reality that they have been bamboozled. We know that global warming, or if you call it climate change, is not only real, but we also know that the current rapid warming is caused by us, primarily via our carbon emissions. I was bamboozled by the pseudo scientists myself, but then I took a serious look at the science, and I realized that that I had been bamboozled. This book will walk you through the faulty arguments of the climate contrarians, and it does so in a logical and convincing manner. It features hundreds of references. I bought the hardback version of this book.

Hardcover – Publisher – Praeger; Illustrated edition (March 3, 2015), ISBN-10 : 1440832013, ISBN-13 : 978-1440832017, 232 pages, item weight : 1.3 pounds, dimensions : ‎ 6.14 x 0.56 x 9.21 inches, it costs $11.96 – $53.00 on US Amazon. A new copy is $53.00. Click here to order it from Amazon.com.
Kindle – Publisher – Praeger; Illustrated edition (March 3, 2015), ASIN : B0C71FFTQT, 230 pages, it costs $50.35on US Amazon. Click here to order it from Amazon.com.

Front cover of Climatology versus Pseudoscience. Click on the image to go to the Amazon page for the hardcover version of the book.

Amazon’s Description of Climatology versus Pseudoscience

This book explains the science of climate change in plain language and shows that the 2 to 4 percent of climate scientists who are skeptical that humans are the main cause of global warming are a fringe minority—and have a well-established history of being wrong.

Although some politicians, pundits, and members of the public do not believe it, global warming predictions by mainstream climate scientists have been remarkably accurate while those made by climate deniers have not. And if mainstream global warming predictions continue to prove correct, the window of opportunity to prevent a climate catastrophe is quickly closing. This book is the first to illustrate the accuracy—and inaccuracy—of global warming predictions made by mainstream climate scientists and by climate contrarians from the 1970s to the present day. Written in simple, non-technical language that provides an accessible explanation of key climate science concepts, the book will appeal to general audiences without previous knowledge about climate science.

This is my five-star review for Climatology versus Pseudoscience

A Journey into Climate Science and a Debunking of Climate Contrarianism

The author starts out by giving us an overview of climate science starting with the discovery of the greenhouse effect by Jean Baptiste Joseph Fourier in 1820’s. He explains that the planet would be much colder than it is if it wasn’t for the greenhouse effect. The greenhouse effect acts like a blanket. He also explains why we know that the global warming that we have seen in recent decades is a greenhouse effect chiefly caused by our burning of fossil fuels, and not natural causes.

The warming is leaving behind various fingerprints, such as the upper atmosphere cooling while the lower atmosphere is warming (like a blanket would), which wouldn’t happen if it was the sun or an orbital cycle causing the warming. The conclusion is that we know that global warming is real, and we know that we are the ones causing it.

Note : I will use the term “global warming” in this review. Whether you call the phenomenon climate change, climate disruption, or global heating, is not important.

The author also discusses climate models, and he notes the astounding accuracy of the early climate models. He takes us on a journey through the development of modern climate science into the 1950’s, and the rapid growth of climate science in the 1960’s and 1970’s and then into the 1980’s, 1990’s and the 2000’s. He describes the increasingly advanced and increasingly accurate climate models. In addition, he discusses sulfate aerosols and global warmings forgotten evil twin ocean acidification.

This is all very interesting to any science nerd and it makes you understand why we know that we are causing the global warming we are seeing. It also makes it obvious why there is a consensus on the topic. Several studies have shown that at least 97% of climate scientists believe that global warming is real and that we are the cause of it.

However, despite the scientific rigor of peer reviewed mainstream climate science, despite the impressive success of climate models, and despite the scientific consensus, the public is very confused about the topic. Enter a small group of so-called global warming skeptics, or more accurately, global warming contrarians. They are not true skeptics but agenda driven contrarians. Even though their science is bad (pseudoscience) and the fact that their predictions have failed repeatedly many times over, they have an outsized presence in the media and often a large enthusiastic following.

It is not just rightwing media who are using them for their purposes, but mainstream media are giving the contrarians undue attention as well. Sensationalism is one issue. A science contrarian claiming that all the climate scientists are wrong, and he is the only one who finally got it right is a lot more interesting of a story than a repeat of the consensus. Another issue is false balance. As a journalist you should not feel that you must give equal time to evidence based science and nonsense.

The author also discusses various myths and false claims spread by climate science contrarians. He mentions that unfortunately most Republican congressmen stand with the contrarian pseudoscientists rather than with the science. Well, with the exception for a few brave souls. On average the American public believe that 55% of scientists agree that we are the cause behind the global warming while the consensus is more than 97% and growing stronger. The author refers to this as the consensus gap.

It is easy to be confused. I have a degree in physics and a PhD in electrical engineering / robotics and yet I was bamboozled by the climate science contrarians. I read books by the contrarians including some of the ones the author discusses, and I believed them. I also followed pretty much only rightwing media at the time and as a result I became misinformed. It was not until I took a deep dive into the subject and read what the actual science said that I realized that I had been bamboozled. Some of the science articles that initiated my change of heart were written by the author. That was back in 2012 and 2013.

This book is a great start if you want to take a serious look at climate science. The book is well organized, and the author is an expert on the subject, as well as a great communicator. Even though many of the things he discussed in the book were not new to me, I very much enjoyed reading the book and I learned some new things. If you don’t know much about climate science but are interested in science, then this book is a must read.

Back cover of Climatology versus Pseudoscience. Click on the image to go to the Amazon page for the Kindle version of the book.

About the Author of Climatology versus Pseudoscience

Dana Nuccitelli is an environmental scientist and climate blogger for The Guardian and SkepticalScience.com. He’s been researching and writing about climate science since 2006. He has a bachelor’s degree from UC Berkeley in astrophysics, and a master’s degree from UC Davis in physics.

To see the Super Facts click here

Environmental Benefits of Recycling Are Overestimated

Super fact 32: The common perception that recycling is one of the best things you can do for the environment is an exaggeration. Its impact is often not very large and if not done properly it can be counterproductive.

In general recycling is beneficial, because you conserve natural resources, reduce climate change, save energy and reduce waste and pollution. Battery recycling is particularly important since it reduces toxic waste and reduces the risk of a future shortage of certain minerals. Recycling is often viewed as a very important activity that everyone should participate in, and neighbors often shame those who fail to comply.

The shocking news is that even though recycling in general is good for the environment it may not be as beneficial as it is assumed. It turns out to be complicated. As you will see later, most people think that recycling is the most impactful action you can take as an individual to reduce carbon emissions, when in fact it is of very marginal importance. This is what made me consider this a super fact.

This content was generated by an Artificial Intelligence (AI) system. Asset id: 2531547331

Recycling and Greenhouse Gases

According to EPA recycling saves 193 million metric tons of carbon emissions, which sounds a lot until you consider that the US emit 6,343 million metric tons per year according to EPA making it 3%. According to this website consumers can save 732 kilograms of CO2 assuming they do the recycling correctly. This should be compared to the average carbon footprint for an American (US), which is 16 metric tons, making the savings for good recyclers 4.6%.

According to our World in Data (Not the End of the World page 114), based on this research, giving up an average SUV for a sedan would save 3.6 metric ton, or 22.5%. Switching to a plant-based diet would save 2.2 metric ton per person, or 13.8%. Actions saving more greenhouse gases than recycling that we as consumers can take, are for example: give up SUV, go car free, have a plant-based diet, avoid transatlantic flights, buy green energy, switch to electric car, switch from electric car to no car, avoid medium flights, laundry in cold water, and hand dry clothing.

Surveys across 21,000 adults in 30 countries showed that the two actions that people believed saved the most greenhouse gases were recycling (59%) and upgrading lightbulbs (36%). Upgrading lightbulbs have an even smaller effect than recycling. It is of course still a good action to take.

However, what this data demonstrates is that we are bad at guessing which actions are impactful. We need to get better informed and not make assumptions. It should be noted that the efficiency of the recycling efforts varies from country to country. Among the 32 developed countries for which there is data the United States ranks 25.

Recycling and Plastic Waste

Greenhouse gas emissions is certainly not the only issue to consider. What about plastic waste? As it turns out plastic is very difficult to recycle (depending on the kind of plastic) and according to the EPA less than 9% of plastic is recycled. According to Our World in Data and the book “Not the End of the World” by Hannah Ritchie the US and Europe have well managed landfills and good waste management systems that make our plastic problem less of an issue. That’s good news.

But what about the awful problem with plastic in the ocean? Plastic ending up in the ocean is indeed a bad problem. However, 81% of all plastic in the ocean come from Asia, and the rest mostly comes from Latin America. Only 1% come from the United States and 1% from Europe and Oceania. According to Scientific American 93% of plastic in ocean come from just 10 rivers. Eight of them are in Asia: the Yangtze; Indus; Yellow; Hai He; Ganges; Pearl; Amur; Mekong. Two are in Africa – the Nile and the Niger.

None of them are in North America or Europe. Therefore, if we in the developed world greatly improve our recycling of plastic, it would not make much of a difference with respect to the problem of plastic in the ocean. What we need to do is assist China, India and southeast Asia with improving their waste management systems.

Plastic Ocean pollution. Whale Shark filter feeds in polluted ocean, ingesting plastic. Asset id: 1120768061 by Rich Carey

Another issue to keep in mind is that uneducated consumers can do a lot of damage to the recycling process. For example, throwing a greasy pizza box into the recycling bin can ruin the entire batch. You are not just recycling incorrectly you are ruining the recycling efforts of your neighbors too. There are many ways to ruin the recycling process, by throwing items in the recycling that don’t belong there. Recycling requires consumers to pay attention to the instructions. It should also be noted that some companies have been found to ignore the recycling process and throw all recycled items in with the trash. There are also neighborhoods that don’t have recycling.

Conclusion

In summary, recycling may not be as great as it is often made out to be. You should still do it if you care about the environment. Just be aware that there are actions that you can take and that your government can take that are much more impactful.

One of the conclusions you can draw from this discussion is that if you are driving a big SUV or eating red meat every day you should probably abstain from shaming your neighbor for not recycling.

To see the other Super Facts click here

Eating Organic is not Necessarily Ecological

Super fact 31: The common perception that organic food is by default better for the environment or is an ideal way to reduce environmental impact is a misconception. Across several metrics, organic agriculture proves to be more harmful for the world’s environment than conventional agriculture.

There are things you can do as an individual to reduce your carbon footprint, use public transportation instead of driving, fly less, eat less read meat, don’t waste food, reduce your energy usage. There are straightforward actions you can take to reduce your use of water and avoid adding harmful pollution to the environment. However, as with eating locally grown food, eating organic food is often viewed as an environmentally friendly choice even though it often is not.

Organic farming is a method of growing food without using synthetic chemicals or genetically modified organisms (GMOs). Organic farming practices are intended to protect soil fertility, promote ecological balance, and reduce environmental impact. That’s all good. On the other hand, it should be noted that modern farming techniques, for example, using synthetic pesticides, have greatly increased cereal yield per acre and GMOs can reduce the use of toxic pesticides. It is complicated.

I consider this a super fact because it is often incorrectly assumed that eating organic food is the best choice for the environment.

Global Land Use

Before looking at the details of conventional farming versus organic farming lets look at global land use. In the figure below from Our World in Data you can see that agriculture already uses nearly half of all habitable land in the world. We cannot easily enlarge this percentage and therefore crop yield per acre is a very important factor to consider, and this is a great weakness for organic farming.

Also notice that 80% of agricultural land is used for livestock, meat, dairy and textile, but it only provides 17% global calorie supply. This second observation indicates that the type of food you eat may matter a lot more than whether it is produced via organic or conventional farming.

Global land-use graphics. Licensed under CC-BY by authors Hannah Ritchie and Max Roser (September 2023).

As you can see in the graph below, again from Our World in Data, the land used for producing 100 grams of protein varies enormously between different food groups. 100 grams of protein from lamb and mutton require on average 52.8 times as much land as 100 grams of protein from groundnuts. This graph does not make a distinction between organic farming and conventional farming, but it highlights the huge difference between different food sources. I’ll get to the difference between organic farming and conventional farming with respect to land use later in the post.

Additional calculations by Our World in Data. OurWorldinData.org/environmental-impacts-of-food | CC BY

Agriculture and Greenhouse Gas Emissions

The next two graphs focus on the greenhouse gas emissions including those from agriculture. Electricity and Transport dominate both globally and in the United States, but globally agriculture comes in at 6 billion of the 40 billion tons of greenhouse gas emissions for 2021, which is 15%. For the United States agriculture comes in at 10.6% of greenhouse gas emissions for 2021. In other words, agriculture was not the largest contributor of greenhouse gas emissions but still an important factor.

Data source : Climate Watch (2024). Note : Land use emissions can be negative. OurWorldinData.org/co2-and-greenhouse-gas-emissions| CC BY

Finally, the contribution for different types of food. Notice that beef (beef herd) at 49.89kg is 188 times larger than the 0.26kg for nuts. 188 people eating nuts contribute as much to carbon emissions as one person eating beef.

Greenhouse gas emissions per 100 grams of protein. Greenhouse gas emissions are measured in kilograms of carbon dioxide equivalents (see below). Data source: Poore and Nemecek (2018). OurWorldinData.org/co2-and-greenhouse-gas-emissions| CC BY

Carbon dioxide equivalents (CO2eq)

Carbon dioxide is the most important greenhouse gas, but not the only one. To capture all greenhouse gas emissions, researchers express them in “carbon dioxide equivalents” (CO2eq). This takes all greenhouse gases into account, not just CO2. To express all greenhouse gases in carbon dioxide equivalents (CO2eq), each one is weighed by its global warming potential (GWP) value. GWP measures the amount of warming a gas creates compared to CO2. CO2 is given a GWP value of one.

If a gas had a GWP of 10 then one kilogram of that gas would generate ten times the warming effect as one kilogram of CO2. Carbon dioxide equivalents are calculated for each gas by multiplying the mass of emissions of a specific gas by its GWP factor. This warming can be stated over different timescales. To calculate CO2eq over 100 years, we’d multiply each gas by its GWP over a 100-year timescale (GWP100). Total greenhouse gas emissions – measured in CO2eq – are then calculated by summing each gas’ CO2eq value.

Environmental Impact of Organic Versus Conventional Agriculture

At this point it should be clear that eating different types of food, nuts and vegetables versus red meat makes huge difference regarding the environment. How about organic versus conventional farming? Well, it is complicated. You have to take into account land use, greenhouse gas emissions, biodiversity, pesticide application, energy use and more.

Clark and Tilman (2017) published a meta-analysis of results of published organic-conventional comparisons across 742 agricultural systems over 90 unique foods. The food groups consisted of cereals, pulses and oil crops, fruits, vegetables, dairy and eggs, and meats. As you can see in the resulting graph below organic agriculture is worse for the environment for most food groups with regards to land use, eutrophication potential, and acidification potential. The result is mixed with respect to greenhouse gas emissions and energy use.

It appears that it is best to choose organic pulses and fruits and choose non-organic for all other food products (cereals, vegetables, dairy and eggs, and meat). However, if your primary concern is whether the potato accompanying your steak is conventionally or organically produced, then your focus is arguably misplaced. Whether you go organic or non-organic the steak is much worse for the environment.

Shown is the relative environmental impact of organic and conventional agriculture across various ecological and resource indicators based on a meta-analysis of 164 published life-cycle analyses (LCAs) across 742 agricultural systems. Roughly, lower in the graph means organic is better and higher up in the graph means conventional farming is better. Data source: Clark & Tilman (2017) – Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice. In Environmental Research Letters. The data visualization is available at OurWorldinData.org. There you can find research and more visualizations on this topic. Licensed under CC BY-SA by the authors Hannah Ritchie and Max Roser.

Conclusion

In this post I present empirical evidence from reliable sources comparing organic to conventional agriculture in terms of environmental impact. Despite strong public perception of organic agriculture producing better environmental outcomes, conventional agriculture often performs better on environmental measures including land use, greenhouse gas emissions, and pollution of water bodies. There are, however, some contexts where organic agriculture may be better for the environment. In short it is complicated.

What really matters though is the type of food you eat, not whether it is organic or not. Another thing to note is that if you eat 300 steaks per year you will have a 100 times larger environmental impact compared to someone who eats 3 steaks per year. Quantity matters. This post was about environmental impacts. There are other considerations such as health, what you like, whom you want to support, etc.

To see the other Super Facts click here

Freedom to Roam and Concentric Circles

Image above by Kevin from The Beginning at Last

This picture reminded me of the Swedish lakes I used to swim in. This is a submission for Kevin’s No Theme Thursday

Freedom to Roam Everywhere

When I was a kid, I used to roam around a lot, in the forest and on the mountains, and I liked to swim and fish in the rivers and the famous deep lakes in the Swedish countryside. Sweden has 97,500 lakes larger than 2 acres and many of them are deep lakes with clean and clear water surrounded by forests, typically coniferous forests. A small deep clean forest lake is referred to as a “tjärn”. I can add that there are no alligators or venomous water snakes in Swedish lakes.

Sweden offers a type of freedom that is rare in the world, and it does not exist in the United States and certainly not in Texas where I live. It is the freedom to roam or more specifically allemansrätten. Whether the land is public or private you have the right to roam, to hike, to camp, to swim, to pick wild berries, to pick wild mushrooms, to fish, and no one can stop you. Landowners are not allowed to tell you to get off their land and they cannot put up fences to stop you or animals from roaming on their land. Everyone has the right to roam and swim everywhere. It is a freedom Swedes love, and if you one day come to experience it you will know why.

My son is jumping off a tire swing and into a “tjärn” in northern Sweden.

Allemansrätten

The Swedish freedom to roam or allemansrätten, is a right for all people to travel over private land in nature, to temporarily stay there and, for example, pick wild berries, mushrooms, flowers and certain other plants. It is important to point out that you must respect the landowner’s property. You can pick wild berries but not anything the landowner is growing. You cannot destroy or break things or start fires, use ATVs, cut branches off trees, etc. You also need to stay 70 meters or 230 feet away from any dwelling.

As a landowner in Sweden, you can buy land and use it for farming and forestry, and you have the right to prevent people from damaging or stealing your crops. You can buy land for mining, and you have the right to your proceeds and the right to prevent people from stealing from your mines. In addition, people don’t have the right to get close to your house. However, you do not have the right to prevent anyone from roaming on your land.

Other countries with similar laws are Norway, Finland and Iceland. Limited forms of allemansrätten exist in Austria, Germany, Estonia, France, the Czeck Republic, and Switzerland. In the United States, where allemansrätten does not exist, 63% of all land is private and in Texas 93% of all land is private. Since there is no law in the US protecting your freedom to roam there is noticeably something missing, especially if you are an outdoors person.

Concentric Circles

In addition to evoking my memories of Swedish lakes and allemansrätten, Kevin’s picture tickles my mathematical sense, specifically regarding concentric circles. Concentric circles are beautiful, dreamy, and interesting mathematical phenomena. I could watch concentric circles in the water all day long.

When you jump and play in a lake, when raindrops fall on a lake or a pond you’ll see concentric circles. You see concentric circles on a tree stumps, when you cut an onion, some flower petals, spiderwebs, etc. Concentric circles are everywhere in nature. Light can create concentric circles due to diffraction called an airy disk. Gravitational waves originating from, for example, two black holes colliding create 3D gravitational concentric circles/spheres traveling at the speed of light through space.

Concentric circles are very common in nature. You can see them in Kevin’s picture above. You can see them below my son as he falls into the Swedish lake, and you can see them in the pictures of light below. Whenever waves originate at a point and spread outward you get concentric circles.

There are many kinds of waves, water waves, sound waves, surface waves, seismic waves (earthquakes), mechanical waves, light are waves, electromagnetic waves, matter is both particles and waves, gravitational waves, and they can all make concentric circles. If the waves are moving outward with the same velocity in all directions, you will get equidistant concentric circles.