Evidence for God in Physical Design Archives - Page 9 of 59

May 31, 2023May 30, 2023

Misunderstanding the Big Bang

Religionists and atheists alike continue to make statements that indicate that they are misunderstanding the Big Bang. Some religionists ridicule the idea that an explosion could cause the order and design we see in the cosmos. They don’t realize that the scientific theory of the creation event is not a mere explosion. On the other hand, some atheists refer to the enormous explosions we see in space as proof that there have been multiple “bangs,” and one of them could produce what we see around us. They don’t seem to realize these are explosions of existing material. The original creation event involved something coming from nothing.

There is no question that incredible explosions are taking place in space. In October of 2022, astronomers observed a gamma-ray burst that was the most powerful explosion they had seen up to that time. They labeled it “BOAT” for “brightest of all time.” They theorized that the collapse of a black hole produced it. Some atheists suggested that this was proof that the collapse of black holes could produce the creation we see in our universe. That is an example of misunderstanding the Big Bang.

Now the “brightest of all time” has been exceeded by a much more powerful explosion emitting two trillion times the light of our Sun and ten times the energy of the brightest supernova ever observed. Labeled AT2021lwx, this object, eight billion light years away, is 100 times the size of our solar system and is emitting steady radiation 100 times more than our Sun will emit in its entire lifetime. At the time of this report, there is no scientific explanation of what AT2021lwx is.

Whatever AT2021lwx is, it is not the same as the Big Bang, nor is there any connection between creation and objects like AT2021lwx. A wide range of scientific observations support the Big Bang concept, but it was not an object that exploded. The cosmic creation event, whatever you call it, was a point where time, space, and matter/energy came into existence. There was a beginning, as Genesis 1:1 tells us.

In addition to misunderstanding the Big Bang, there is not and will never be a scientific explanation for it because scientific laws do not describe or apply to what took place. Objects like AT2021lwx are simply transformations of matter/energy that continuously produce the elements of our cosmos. What we see as we observe such things as the cosmic background radiation and the red-shift of galaxies moving away from us are the after-effects of God’s creation of time, space, and matter/energy. This is real creation, and no exploding object duplicates the nature or fine-tuning of the creation event.

AT2021lwx is a testimony to the incredible power and energy present in the creation. We get a small glimpse of how powerful God is when we see objects such as this. There will probably be a workable theory as to what caused AT2021lwx, but like all observations in space, it is simply another statement of Psalms 9:1: “The heavens declare the glory of God, and the skies show the work of His hands.

Reference: “Astronomers Explain What Caused the Largest Cosmic Explosion Ever Seen” on TIME.COM for May 12, 2023, at 2:53 PM EDT.

May 19, 2023May 18, 2023

Relativity, Quantum Mechanics, and Complex Electron Orbitals

Yesterday, we said that the simple atomic model shown in older chemistry textbooks leaves many mysteries unanswered. During my 50 years of teaching chemistry, students sometimes asked questions that could not be explained by electrons in circular orbits. In recent years, spectral analysis has shown that electrons travel in various orbital patterns that may be dumbbell or clover-leaf shaped. In addition, quantum mechanics has shown that electrons can act like waves rather than particles. Relativity, quantum mechanics, and complex electron orbitals explain some of the mysteries of chemistry.

For example, oxygen has a first shell with two s-type electrons traveling in circular orbits and four more in dumbbell-shaped p orbits. That second shell can hold six electrons, leaving openings for two more orbitals 90 degrees apart. If a hydrogen atom with one electron comes nearby, it will bond with the oxygen, each of them sharing an electron. If two hydrogens bond with the oxygen atom, you have a perfect, stable combination – a water molecule.

In the water molecule, the hydrogen atoms repel each other, creating a 180-degree angle between them and giving the water an electrical polarity. The result is that water molecules have a positive and negative end, and as they freeze, they repel each other, expanding their volume. Because of that, ice is less dense and floats on top of the water instead of sinking to the bottom. If bodies of water froze from the bottom up, life on Earth would be impossible.

What makes this picture even more interesting is that electrons can orbit at a speed that is 60% of the speed of light or faster. At that speed, their mass increases, and their orbit contracts in conformity with Einstein’s relativity equations. Relativity, quantum mechanics, and complex electron orbitals combine to explain the mysteries of chemistry. For example, the relativity contraction makes it harder for mercury atoms to interact strongly with each other. As a result, mercury is a liquid, while other metals are solids at room temperature.

Relativity and quantum mechanics also explain the difference in color between gold and silver. Relativistic effects in the electron orbitals cause silver to reflect all wavelengths of visible light equally. Because of that, it has no particular color. On the other hand, gold’s electron orbitals cause it to absorb blue light, making the reflected light appear yellow.

Relativity, quantum mechanics, and complex electron orbitals are opening new understandings in chemistry, allowing new techniques to aid in improving life for all humans. For example, doctors use radioactive technetium and rhenium as tracer molecules in medical imaging because of the effects of relativity. Understanding relativity and electron orbitals explains the formation of lead dioxide, which is essential for lead-acid auto batteries. Relativity in electron orbitals even plays a role in “glow-in-the-dark” items such as signs, stickers, and T-shirts.

The complexity of atoms is a testimony to the intelligence and engineering of the Creator. We are continually reminded that we can know there is a God through the things He has made. The challenges and the future of relativistic chemistry are a great testimony to that.

Reference: “Relativity and the World of Molecules” by Abhik Ghosh and Kenneth Ruud in American Scientist magazine for May/June 2023

May 18, 2023May 18, 2023

The Simple Atomic Model and Unanswered Questions

The Simple Atomic Model Leaves Unanswered Questions — This simple atomic model is not accurate

Our understanding of the design of the atom changed radically in the 50 years that I taught chemistry in public school. When I started teaching, scientists thought atoms were made up of a nucleus surrounded by electrons in circular orbits. This simple atomic model was easy to understand, and we had drawings and even plastic models to show it. However, the simple atomic model leaves unanswered questions.

The simple model did not explain the properties of certain atoms. For example, why is mercury a liquid at room temperature while other metals, such as gold, platinum, and lead, are solids, even though they have very similar structures? Why are gold and silver different colors? Why does water expand when it gets colder when all other materials contract?

As an old chemistry teacher, my students frequently asked questions I could not answer. Improvements in spectral analysis made the simple atomic model more complicated while answering some questions. For example, scientists could see that not all electrons travel in circular orbits. Also, electrons are not solid balls or even particles. Instead, electrons can be waves and have orbital paths that are spherical or shaped like dumbbells, clover leaves, or a mixture of those two.

Different orbital shapes cause different spectral patterns. As a result, scientists have coined the names “s” for sharp spectral lines, “p” for principle lines, “d” for diffuse lines, or “f” for fundamental lines. Moving out from the nucleus of an atom, the number of electrons increases, and their paths become more complex.

The more we learn, the more we see the wisdom built into the design of every atom in the universe. The precision of design makes it possible for life to exist. Minor changes would mean that we would not be here. However, the simple atomic model leaves unanswered questions and can’t begin to show the extent of God’s design wisdom. Applying what we know about relativity, quantum mechanics, and electron orbits answers some of the chemistry students’ difficult questions. We will have more on that tomorrow.

Reference: “Relativity and the World of Molecules” by Abhik Ghosh and Kenneth Ruud in American Scientist magazine for May/June 2023

May 11, 2023May 10, 2023

Geological History Lessons

One of my favorite places on Earth is northern Michigan. As a child, I spent many summers on Lake Michigammi in the upper peninsula and grew to love the land of birches and pines. We can learn from the geological history lessons of northern Michigan.

Returning to this area over 70 years later has been a shock. When I was a kid, the people made a living harvesting and using the trees to make wood for construction purposes and to make paper. That industry still exists, but tourism and the construction of elaborate homes have replaced the trees as the basis of the northern Michigan economy. People have been buying large plots of land, building huge houses, and calling their property a “forest preserve.” Unfortunately, this practice includes the shoreline of Lake Michigan, Lake Huron, and the many inland lakes, limiting the general public’s access to this water wonderland.

Michigan’s state rock is the Petoskey stone, a beautiful coral often used to make attractive jewelry. The interesting thing about the Petoskey stone is that it is a tropical coral that only grows in warm water. Obviously, there has been a change in the climate because Michigan is not a tropical paradise. In our time of concern about climate change, we find the geological history lessons of northern Michigan indicating that Earth’s climate has changed in the past.

Another lesson from northern Michigan is the action of ice over time. Everywhere you look, you see huge rocks weighing many tons that could not have been placed by running water. These rocks come from many places and are all different. As a public school earth science teacher in South Bend, Indiana, I would take my students to the local gravel pit to hunt for unusual rocks. One student found a jasper conglomerate from Bruce Mines in Ontario. It had glacial groves and was hundreds of miles from its origin. We also found pieces of raw copper from outcrops in northern Michigan. One student found a diamond from an unknown Klondike area somewhere to the north. The geological history lessons we learn from the enormous rocks, the sand, and the many lakes is that, at one time, glaciers covered the area.

So how much time did these climate changes take? Knowing the geological history has been essential for oil drilling, coal and copper mining, and agriculture in Michigan. These things were part of how God prepared planet Earth for human habitation. Some religious people have tried to explain these things by Noah’s flood, but most ignore any attempt to explain the method and just say, “God did it.” That avoids the question of how and when.

Genesis 1:1 is undated and untimed, and the Genesis account uses the Hebrew words “bara,” meaning to create, and “asah,” meaning to make. Creating from nothing (bara) is used in verse 1, where it applies to space, time, and matter/energy. It is used again in verse 21 for the creation of the first life and in verse 27 for the creation of the first humans. Making (asah) refers to taking what was created and changing it. It is used in verses 7, 16, and 25. Chapter 2 verse 3 summarizes what God had done by using both bara and asah.

The geological history lessons of northern Michigan show us God taking what He had created and molding the Earth to prepare it for human habitation. As we understand more of what God has done, it becomes evident that all we see around us is the work of an intelligent Creator who cares about His creation and the humans He created in His image.

May 10, 2023May 9, 2023

Let There Be Light

The third verse of the first book in the Bible quotes God, saying, “Let there be light.” Most people don’t understand the full meaning and impact of that statement. For the past two days, we have examined how the ability to see invisible light revolutionized astronomy. First, we looked at the forms of light at frequencies below the visible spectrum. Today, let’s look at frequencies above the light we can see.

Higher frequencies mean shorter wavelengths, and electromagnetic energy above the frequency of visible light has wavelengths short enough to penetrate living cells and damage them.

Ultraviolet is the first band of light above the visible spectrum. The Hubble Space Telescope is the leader in observing ultraviolet light coming from the hot and energetic formation of young stars. Auroras on gaseous planets like Jupiter also emit ultraviolet light. The ability to see the invisible UV light helps us understand more of the process God used in creation.

Our Sun is also a source of ultraviolet light, and everyone knows UV light can cause painful sunburns. Because of its short wavelength, UV light can penetrate and damage cells resulting in skin cancer. God has given Earth an upper atmosphere ozone layer that absorbs much of the ultraviolet radiation. While protecting us from health damage, the atmosphere makes ultraviolet astronomy impossible on Earth. That’s why the Hubble Space Telescope leads in UV observation of the universe.

Above ultraviolet light, we find X-rays that are even more harmful to living cells. This band of invisible light energy can penetrate matter. Because of that, they are useful in medicine for doctors to see inside your body. However, medical X-rays must be limited because they can cause DNA mutations leading to cancer.

In astronomy, X-rays allow astronomers to study some of the hottest places in the universe, such as supermassive black holes and neutron stars. Thankfully, God has placed us far from black holes and neutron stars. However, our Sun also produces X-rays, but Earth’s atmosphere blocks X-rays. Therefore, X-ray telescopes, such as NASA’s NuSTAR mission, must be located in space.

Finally, let there be light at the top of the invisible spectrum. Astronomers use the shortest wavelength, gamma rays, to study the creation. Unfortunately, gamma rays have the highest energy and are the most dangerous to living cells. Supernova explosions release gamma rays, and space telescopes such as NASA’s Fermi and Swift can detect them. Fortunately, those gamma-ray-producing events are far from Earth. However, nuclear explosions on Earth also produce gamma rays, and the Sun occasionally produces gamma-ray flashes in solar flares.

By studying all of these forms of light, astronomers today know much more about the universe and the processes God has used to create and sustain it. As we look into the night sky, we are looking back in time and seeing the various frequencies of electromagnetic energy. It is light, both visible and invisible, and it tells us of the power and wisdom of the process that brought our planet and the life upon it into existence. Light is energy, and energy is matter (e=mc²). Knowing that, we realize what a profound statement Genesis 1:3 contains – “Let there be light.”

For more information on this picture, click HERE.

May 9, 2023May 9, 2023

Seeing Invisible Light

In ancient times, people looked up into the night sky in wonder. Without modern light pollution, they could have seen the stars more clearly, but they had only their unaided eyes to see the majestic sky. The first revolutionary change occurred when Galileo made and used an optical telescope. However, he was limited by being able to see only the visible spectrum of light. Today, astronomy involves “seeing” invisible light.

Light is electromagnetic radiation, and our vision can detect only a very narrow range of the electromagnetic spectrum. But astronomers today have instruments that allow them to “see” light frequencies in wavelengths outside the human vision range. Yesterday we discussed two portions of the spectrum invisible to our eyes – radio waves and microwaves. Those frequencies can tell us many things about the universe God created. Today, we will examine more ways of seeing invisible light.

The higher the light frequency, the shorter its wavelength. Microwaves have wavelengths between one meter and one millimeter. The next higher frequency of light has wavelengths below one millimeter, so they are called submillimeter waves. One weakness of optical telescopes is that visible light can’t penetrate clouds of gas and dust in regions where stars are forming, but submillimeter waves can. However, water vapor in our atmosphere absorbs submillimeter waves, so astronomers build observatories for studying them in dry, high-altitude locations such as the mountains in Chile and Hawaii.

We find infrared light at even higher frequencies and, thus, shorter wavelengths. Although we can’t see infrared energy, we can feel it as heat. The James Webb Space Telescope (JWST) leads the revolution in infrared astronomy. Scientists have used infrared sensors to measure the temperature of stars, including our Sun, but the Webb Telescope takes that to a new level. It can detect emerging stars hidden by clouds of dust and gas. The JWST can also observe matter that is only a few degrees above absolute zero. In only its second year, JWST has sent back images that allow us to see space objects we have never seen before.

Just above the infrared frequencies, we find optical light. Optical telescopes have been showing us many features of the universe since Galileo, but they have limitations. Not all objects in space produce optical light. For example, we can only see the planets in our solar system because they reflect the Sun’s light. Also, our atmosphere scatters optical light giving us the blue sky in the daytime and atmospheric blurring of the stars at night. Optical telescopes are usually the only option for amateur sky watchers, but for the sharpest viewing, professional astronomers locate their optical telescopes on tall mountains or in space. The Hubble Space Telescope is the leader in optical astronomy.

Although visible light can tell us much about God’s creation, seeing invisible light has opened a new understanding of how the Creator has produced the elements essential for life. Three types of light have higher frequencies and shorter wavelengths than visible light. Those short wavelengths contain the energy to harm or destroy life, but God has provided the protection we need. We will look at that tomorrow.

Find more information about this picture at Sace.com.

May 8, 2023May 7, 2023

Revolution in Astronomy Shows God’s Handiwork

Before the introduction of electric lights, the darkness of the night allowed people to observe the sky much more clearly. For thousands of years, people looked up at night and marveled at what they saw. Of course, they saw the Moon and stars, but they could also see other objects. Those included the “wandering stars,” which we know as planets, “shooting stars,” which we know as meteors, and occasional stars with tails, known as comets. But understanding the night sky was limited by the resolving power of human vision. Then something happened to create a revolution in astronomy.

The revolution began in 1609 when Galileo put some lenses together and made his first telescope. Still, it was limited to observing visible light. People assumed that the only light was what they could see with their eyes. After all, what other kind of light could there be? Then, in 1800, British astronomer William Herschel accidentally discovered infrared light. After that, scientists discovered ultraviolet, radio waves, microwaves, X-rays, and gamma rays in the following years.

Astronomers today use all of those forms of electromagnetic radiation or “light” to explore the universe. You might wonder why we can see only a tiny portion of the electromagnetic spectrum. There is a good reason for that. Electromagnetic radiation surrounds us. That includes natural radiation and all frequencies transmitted from radio, television, mobile phones, wi-fi, Bluetooth, and other sources. If we could see all of those electromagnetic frequencies, our vision would be more limited than what we experience in a dense fog.

In God’s wisdom, He limited our vision to the rainbow of colors we need to see the world. However, science has given us the ability to “see” the other frequencies of light, and that has opened up a new revolution in astronomy.

Radio waves were the first portion of the invisible spectrum astronomers used. In 1933, Karl Jansky, a young American radio engineer working for Bell Labs, was searching for the source of “hiss” that interfered with radio transmissions. He found that some of it came from sources outside our solar system. That led to using radio telescopes to explore the vast reaches of space through the new science of radio astronomy.

Microwaves are the next frequencies above radio waves, and astronomers first detected them using radio telescopes. When we hear the word “microwave,” we think of a way to cook our meals quickly, but in astronomy, microwaves help us learn about the early universe. In 1965, American astronomers Arno Penzias and Robert Wilson, working for Bell Labs, were trying to find the cause of noise picked up by a radiometer they were using. They thought it was a defect in the system, but they had accidentally discovered what scientists call cosmic background radiation. It’s energy left over from the cosmic creation event, or the “big bang.” The cosmic microwave background proved that the universe had a beginning, as the Bible clearly says in verse 1.

Sometimes “accidental” discoveries lead to our learning more about how God created and sustains the universe. The revolution in astronomy today involves all of the various portions of the electromagnetic spectrum, and we will continue to consider that tomorrow.

May 2, 2023April 28, 2023

How the Elements Were Crafted

One of the great mysteries of science has been the question of how the heavier elements came into existence. Physicists have produced a few heavy elements in particle accelerators, and they have observed them being made in stars. Understanding how the elements were crafted is a solid apologetic for God’s creative power and wisdom. Being able to duplicate in a laboratory what God has done in the vast outreaches of space increases our amazement at what God has done.

As we said yesterday, the ability to produce nuclear fusion may solve our energy needs, but the fact that God did it “in the beginning” has led to a greater appreciation of God’s power and His methods. We know that the nuclear fusion of hydrogen can produce helium. We can duplicate that process in the laboratory on a small scale and see it in operation in the Sun.

Hydrogen (1) was produced first, but forging elements, including carbon (6), nitrogen (7), and oxygen (8), required enormously high pressures and temperatures in the interior of stars. These elements are the four starting points for life—still heavier elements require even greater pressures and temperatures.

In 1987, astronomers watched a star explode, becoming supernova 1987a. After the explosion, astronomers detected neon (10) in the star, which was not there before. Direct and indirect observations of the nuclei of exploding stars has shown how the elements were crafted as God produced the following 28 elements in the periodic table. This group includes copper and phosphorus, which are present in our bodies and are essential to life.

As our cosmic tools have become capable of detecting gravitational waves, we have seen even heavier elements produced when neutron stars collide. For example, computer models have shown that those collisions can produce the elements gallium (31) through bismuth (83). In addition, the merger of two black holes can produce very heavy elements such as thorium (90) and uranium (92). The bottom line is that we can see how the elements were crafted by God. He made the universe and our bodies from elements produced in the core of ancient stars.

Obviously, the Bible doesn’t explain how the elements were crafted. However, it does tell us that God acted “in the beginning” to set the process in motion. As we observe the universe through new tools such as the Webb Telescope with the help of computers, we can see a vivid display of God’s power and wisdom in creating all that we see and are. For most of us, “In the beginning, God created” is all we need to know, but as science learns what it takes to create the building blocks of creation, we have a whole new appreciation of “the heavens declare the glory of God and the expanse proclaims the work of his hands” (Psalms 19:1 CSB).

Reference: “Cosmic Alchemy” by Sanjana Curtis, Scientific American, January 2023, pages 31-37, and “Astronomy Picture of the Day” for January 8, 2023

May 1, 2023May 2, 2023

Nuclear Fusion to Power the Future

People today are concerned about “green energy.” The government is attempting to move the economy away from fossil fuels to protect the environment and reduce climate change. However, all of the alternative power sources have limitations. What we need is nuclear fusion to power the future.

Presently, the favored alternatives to fossil fuels are wind and solar, both of which have drawbacks. They include the expense of installing and maintaining them, plus the fact that sunshine and wind are only sometimes available. In addition, there are few locations where water power is feasible, and building dams on rivers can cause other issues. Nuclear fission is probably the most efficient method of generating electric power without putting carbon in the atmosphere. However, past catastrophes cause people to fear that option. Plus, nuclear fission creates waste that will be radioactive for years, and we have no place to store it.

On the other hand, nuclear fusion can release massive amounts of power. After all, that’s what powers the Sun and other stars. With nuclear fusion, there is no radioactive waste and no carbon to create greenhouse gases. The byproduct produced is helium, a useful resource in short supply.

Nuclear fusion to power the future sounds like the answer to all of our problems, so why aren’t we switching to it now? The problem is that science hasn’t found a practical way to do it. However, in December 2022, scientists at the Lawrence Livermore National Laboratory in California produced nuclear fusion in a lab. The tiny reaction was nowhere near what the Sun does, and it lasted only trillionths of a second. But it was a start. Thirty private fusion companies worldwide are using the Livermore breakthrough as a pattern to promise clean energy that would outpace wind or solar, or anything else we now have. The Fusion Industry Association suggests they could generate fusion electricity sometime in the 2030s.

Is nuclear fusion to power the future just a pipe dream, or could it really happen? God has given us everything we need for an advanced civilization. Intelligent planning of Earth’s history provided the fossil fuels needed to bring us into the modern age. Einstein’s equation e=mc² revealed the enormous power contained within each atom. By releasing some of that power, we have generated electricity by nuclear fission. By applying the intelligence God gave us, we can go a step further and release even more power through nuclear fusion. That could get us away from depending on energy sources that are unreliable or pollute the atmosphere.

The truth is that tiny atoms are held together by incredible power, and releasing that power can solve our energy needs. The power that holds every atom together had to have a source—the One who created everything and holds everything together. “[Jesus Christ] is the image of the invisible God, the firstborn of all creation. For by him all things were created, in heaven and on earth, visible and invisible… And he is before all things, and in him all things hold together” (Colossians 1:16-17 ESV).

Reference: “Homemade Suns” by Virginia Heffernan in Wired magazine, March 1, 2023

April 21, 2023April 19, 2023

What Are the Chances?

Advocates of unguided naturalistic evolution say that evolution could have gone in many directions, and we are lucky to be here. But what are the chances of evolution producing you and me as we are today? Evolutionists would say the changes are 100% since we are already here. But, if we go back to the cosmic creation event, or “big bang,” the chances that we would have evolved are nil. On the other hand, if God planned and guided the creation because He had us in mind, the chances are 100%.

The DNA that makes us who we are physically is a highly complex strand of information. What are the chances that it could have written itself by chance? First of all, information comes from intelligence, not chance. Calculating the likelihood of something after it has happened is a statistical fallacy. After all, DNA is here, and so are we, so the chances are 100%. But what are the chances if we go back before the fact? What are the chances that non-living chemicals could come together in a just-right way to form the first living cell? Then what is the statistical evidence for that first cell multiplying and modifying by random chance mutations and natural selection to create humans?

One imagined scenario involves a billion chimpanzees typing on a billion keyboards for a billion years, accidentally typing one line of Shakespeare. What are the chances of that? Well, the short answer is that it will never happen. Computer keyboards have various numbers of keys, but the old-fashioned typewriters had 58, so let’s go with that number.

Forget Shakespeare. Look for the line “I love you more.” without quotation marks. That is a total of 16 letters, spaces, and a period. With 58 keys and 16 letters, what are the chances of accidentally typing that line? To compute that, you would have to multiply 58 X 58 X 58 X 58 X 58 X 58 X 58 X 58 X 58 X 58 X 58 X 58 X 58 X 58 X 58 X 58. That is a total of 16 times. If you want to try it, go ahead, but it will probably exceed the capacity of your calculator. The answer would be 16.4 trillion quadrillion typing attempts.

Typing continuously at a speed equivalent to 45 words per minute, it would take 2,100 trillion years to have a 50/50 chance that one of those chimps would type that phrase. Absolutely nobody thinks that the Earth is anywhere close to 2,100 trillion years old. Nobody even suggests that the universe is that old. For this thought experiment, we are only looking for one short line of text, “I love you more.” That is nothing compared to the complex system of life on this planet.

The bottom line is that we can’t explain life or the fine-tuned physical constants of the universe by chance alone. But we can explain those things if God planned and guided the creation because He had us in mind. With God, our chances of being here were 100% from the beginning. (See Genesis 1:1.)

Reference: “Chances are…” by Bob Berman on Astronomy.com

For more on this topic see “Arranging Books on a Shelf“