Category Archives: Universe & Cosmology

From Simplicity to Complexity

What makes the existence of life and the universe seem so improbable? Without question, the incredible complexity of all things is at the heart of the improbability dilemma. And it requires some form of explanation. In order to properly examine improbability, we must first address complexity. How can complexity be explained?

The complexity of the universe is staggering, in some ways beyond human understanding. For many, this fact alone can’t be accounted for without a design, particularly when the only alternative considered is chance. With this comparison, design usually wins over chance, and design implies a designer. Ancient civilizations observed a universe that was much simpler—in their eyes—than the universe we know exists today. Nevertheless, it would have appeared complex enough to invoke a designer. Even a number of natural phenomena that are easily explained today were attributed to gods.

Our present understanding of the universe reveals a universe that is far more complex than the ancients could have imagined. We have the opportunity of looking back in time for answers—back to a time when the universe wasn’t nearly as complex. Through a series of scientific discoveries, simple origins were found to be the precursors of the present universe.

Darwin opened our eyes, albeit slowly, with his insights on evolution. As it pertains to life, Darwin showed us a different way of thinking about the emergence of life. His theory of evolution by natural selection broke down the complexity of life into incremental steps. He managed to shift the focus from the finished product (or the present product) to the steps that led to it. According to Darwin, and verified by other more recent discoveries, life has evolved from simple beginnings—simple relative to its present state. It all began with single cell organisms, and perhaps only one. Now we have a world full of diverse and complex life forms, some containing trillions of cells. Darwin showed that from simple origins, complexity could arise over time, and by a natural process.

Even the life that we see today starts simple, and grows in complexity. For example, a tree begins with a single seed, and grows to a complex structure of roots, branches and leaves. When I look at a seed I find it difficult to imagine that a tree can come out of it, and yet it does so naturally. Like the seed of a tree, a human being also has a simple beginning—we were all initially a single cell. You could make the argument that a cell is complex on its own, and it is, however, millions and trillions of cells working in unison is several orders of magnitude more complex. Keep in mind that what we classify as the origin of life—a single cell—is somewhat arbitrary. Even a cell has to be constructed from simpler chemical processes, which at some point we call life. Although life, especially the origin of life, is an amazing and mysterious process, we can clearly see that it moves in a direction from simplicity to complexity.

Now let’s turn our attention to the universe as a whole, and see if the same principle applies. After Darwin had provided an explanation for the evolution of life, it was not automatically assumed that the universe evolves by a similar process. In fact, the idea that the universe was eternal and unchanging was a long-held belief by the general population and scientists alike. This idea took some time to overthrow. But by the mid-twentieth century, new discoveries were pointing directly towards an evolving universe; one which had a beginning.

The big bang is analogous to a cell. Just as a single cell can be viewed as the origin of life, the big bang can be viewed as the origin of the universe. And as I mentioned earlier, a cell can also be thought of as complex, but nowhere near as complex as the life that arose from it. The universe can also be viewed in a similar light. Although the big bang was not necessarily a simple event, it was nonetheless simpler than the universe that emerged from it.

Scientists theorize that a substantial amount of activity occurred at the initial moment of creation. The basic forces of nature emerged (gravity, electromagnetism, and the strong and weak nuclear forces), as well as a host of elementary particles (such as photons, protons, neutrons and electrons). Space and time as we know it were also created.  All that and more happened in a tiny fraction of a second. On the surface, this seems to present a problem as far as a simple beginning is concerned, however, there is more to consider.

In spite of this initial creative activity, for the first 300,000 to 500,000 years the universe was nothing more than an enormous cloud of hot expanding gas. Complexity would then increase gradually over time—in a sort of cosmic natural selection. It took one billion years before stars and galaxies formed. A few more billion years before supernovae explosions (the death of stars) created and distributed the heavier elements necessary for life. Simple life on earth emerged 9.9 billion years after the big bang. And from there it would take over 3 billion years of evolution to arrive at modern humans. From this simplified timeline, we can see that the early universe was much simpler than it is now—the result of 13.7 billion years of cosmic evolution.

There is another point worth noting that relates to the discussion. The big bang theory is a theory that describes the universe a fraction of a second after the universe came into existence. The big bang theory is silent on the cause of the creation event. Although scientists speculate on what the cause may have been, the big bang represents the edge of our present ability to understand the universe, a theoretical time barrier that we have not yet crossed. I like the way Bill Bryson wraps up the discussion regarding the cause of the big bang. In  A Short History of Nearly Everything, he writes:

“… it may be that space and time had some other forms altogether before the Big Bang—forms too alien for us to imagine—and that the Big Bang represents some sort of transition phase, where the universe went from a form we can’t understand to one we almost can.”

Like a cell, which is created by more elementary processes, the big bang could have been a transition phase that was precipitated by a simpler pre-existing cosmos. Some scientists even suggest that the universe may have been created out of nothing. And by nothing, I don’t think they really mean nothing, but perhaps something very small that we don’t completely understand. Physicists now believe that you have to incorporate aspects of the quantum world in order to understand the big bang. And if you go by quantum theory, particles can spontaneously come in and out of existence from nothingness. That is the nothing that scientists are talking about. Bryson writes: “It seems impossible that you could get something from nothing, but the fact that once there was nothing and now there is a universe is evident proof that you can.” Therefore, if the universe was created from nothing or very little, you can’t get much simpler than that. And if this is even remotely correct, the principle of things moving from simplicity to complexity definitely applies to the universe as a whole.

Having said all that about complexity, let’s insert improbability into the equation. Both life and the universe evolved from simple origins, and through incremental steps, have grown in complexity. Although this does not explain how the simple origin came about, it does show that complexity can be achieved by gradual steps, even if the finished product seems improbable—improbable by means other than design. Also, an after the fact approach of looking only at the finished product can be deceiving, that is in terms of what improbability entails. If something is improbable, does it mean that it can’t happen? And because the existence of life and the universe appears improbable, does it mean that it came about by design?

Let’s begin with a simple exercise. Do you remember what you did yesterday? I mean everything you did yesterday. If you went to work, think about the route you took, and the exact location of the cars you passed. What about the people you met and the exact time you met them. Then there are the phone calls or emails you received. Where did you have lunch, what did you eat, and with whom? What tasks did you perform? And what about after work, what else happened? You get the idea. Although you may think you had an ordinary day, the fact is that the exact details of your day will never happen again. Yesterday, just as it occurred, was extremely improbable. And today, tomorrow, and every other day will unfold in a way that is also improbable.

Now let’s look at another example, something more profound than an ordinary day—your own existence. In order for you to have a life, an almost endless series of events had to occur. Think about the coupling of your parents, and their parents, and every ancestor that came before that. In order for you to exist, every combination of ancestors had to mate, and possibly at the exact time that they did. I will spare you the trouble of going any further down the evolutionary line, but the basic idea is that your life is extraordinarily improbable. And so is my life and everybody else’s. Just because something is improbable, does not mean it can’t happen. The fact is that as long as you have a universe, something has to happen, and that just about everything that happens is improbable.

Therefore, if improbable things happen all the time, does it have to come about by design? I am certain that many would say that it does. They could also argue that the existence of life seems so improbable that it implies a higher order to the universe. Although that may be true, it does not necessarily mean that life was designed. The universe’s enormous scales of time and space allows for limitless opportunities to create. Given the mind-boggling numbers that are involved, what seems improbable or impossible does not necessarily apply to the universe.

We know that the universe allows life, because we find ourselves on a planet that allows life. On the other hand, on all the planets that don’t allow life, there is no one to count the failed attempts, or whether any attempts were made—no one to contemplate why it wasn’t designed to allow life to exist, or if it was designed at all. Although we can’t definitely confirm that life exists elsewhere, we know that life is rare relative to the size of the universe. If life was plentiful, we probably would have found some elsewhere by now. This means that vast regions of the cosmos are without life. And if we could closely observe those regions, we wouldn’t think that they were anything special. We would see planets orbiting stars and swirling galaxies, but this would go on for eons, without any conscious experience. Keep in mind that the process that led to life here on earth is essentially the same process that led to the lifeless regions. Of course, there are a few exceptions. One of which is the earth’s special location.

The location of the earth is an example of something that appears improbable, and thus appears designed. The earth’s location has been called the Goldilocks Zone, taken from the fairy tale Goldilocks and the Three Bears. The obvious reason being that its location is just right (just the right distance from the sun to support life). Of all the possible locations that couldn’t support life, why here? Again you could say that it is by design. But it doesn’t have to be, simply because improbable things can happen, especially with large scales like the universe. With a universe as vast as ours, it is inevitable that some planets will be located in Goldilocks Zones. It may be that we just happen to be here. Not necessarily because it was designed that way, and not merely by chance. But rather by an evolutionary process on a cosmic scale, which moves in a direction from simplicity to complexity. It is a process that creates stars, galaxies, and planets. Sometimes when the conditions are just right, it creates life.

Goldilocks Zones are not only applicable to planets, but the same principle is also present in nature. For instance, let’s examine something that is closer to home, such as the life cycle of a tree. A mature tree can produce at least several thousand seeds in a growing season, which are eventually deposited on the ground. The vast majority of these seeds will never become trees. Usually, only a very small percentage will germinate and grow to become trees. They are seeds that fall in Goldilocks Zones. In this context, a Goldilocks Zone would include fertile soil, sufficient water, sunlight, shade, etc. The probability of any one specific seed becoming a tree is very remote; however, when all the seeds are taken into account, probabilities can be viewed in a different light. We know that some seeds will become trees, because they will benefit from conditions that are just right. What we don’t know is which seeds will be selected by this process.

There is another analogy that I have heard a few times, which deals with the improbability question. This analogy has been used in support of design, and it goes something like this: the world’s oceans, with the comings and goings of its tides and waves could never construct a sand castle. The argument being that it requires a design for something constructive to emerge, and this applies to all the complexity we see today. The problem with this view is that it evaluates design against only one other alternative—whether chance alone could construct the sand castle.

There is another way to look at this analogy, which in my opinion, better shows how seemingly improbable things emerge. I agree that the ocean could not directly construct a sand castle, but it could do so indirectly. Life emerged from the ocean, and gradually made its way on land, and over billions of years evolved into more complex forms. One of these forms, a child, walked on the beach and built a sand castle. Consequently, the sandcastle came about from a complicated natural process that can’t be broken down into simplistic explanations, such as the polar opposites of design or chance. If we could go back in time a few billion years, we would think that the likelihood of a sand castle appearing on any of the world’s beaches would be very low. And yet today, sandcastles regularly appear (and disappear). Therefore, whether we are talking about living planets, trees, or sandcastles—and even if the finished product seems improbable—it doesn’t mean it can’t happen.

 

References: Bill Bryson, A Short History of Nearly Everything (London: Black Swan, 2004), 31, 32.


 

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Super-Size it

If you live in a rural area, as I do, outside of the influence of city lights, you can often get a clear view of the night sky. I don’t normally make a special effort to look at the night sky, but on occasion I am drawn to it. I usually notice the stars when I return home on a clear evening. As I get out of my car, and before I enter the house, the night sky often grabs my attention. I pause for a moment, and try to absorb the enormity of it all. There are no words that come to mind, no thoughts, or even a sense of time. I find it difficult to focus on any particular star or any region of the sky. It’s as if I am staring into infinity—it really is an awesome sight.

The feeling of wonder that one gets when looking at the night sky is as much about the sheer amount of space, as it is about the stars that occupy that space. However, the experience doesn’t even begin to encapsulate the actual size of the universe. The size of the universe is difficult to grasp, as there is no experience in everyday life that can relate to the numbers that are required to measure the universe. The measurements of time and distance, along with the number of stars and galaxies are hard to get your head around. Nevertheless, I will try to put it in some kind of perspective.

We can all relate to a thousand, so let’s begin there. Imagine having one thousand dollars. We can do that without too much trouble, but as the numbers get larger and larger, it may not be quite as intuitive. Millions, billions and even trillions can begin to sound alike, as if there isn’t much difference between them, but there is a huge difference. One thousand, a thousand times is a million. One million, a thousand times is a billion. And one billion a thousand times is a trillion. That’s a lot of money. But it is stars and galaxies that concern us at this time. So keep these numbers in mind as we move forward.

How big is the universe? The fact is that scientists don’t know, and here is why. Light travels at 300,000 km per second, which is the fastest speed in the universe. We can never hope to see a galaxy that is farther away in light travel time than the universe is old—the light emitted hasn’t had the time to reach us yet. This cosmic speed limit prevents us from seeing anything that is farther away from us than 13.7 billion light years (the age of the universe is 13.7 billion years).

Now here is where it gets a little tricky. The most distant galaxies we can actually see are about 10 to 12 billion light years away, however, we are seeing the light that was emitted 10 to 12 billion years ago. Keep in mind a light year is a measure of distance—the distance that light travels in one year. We know that the universe is expanding. Galaxies are moving away from each other on average. Those galaxies are presently much farther away than 10 to 12 billion light years. We know at least that much. That being said, scientists can still estimate the actual size of the universe by factoring in the expansion rate since the birth of the universe.

Estimates for the rate of expansion can vary widely, and are debatable. If some of the larger estimates are taken into account, much of the light emitted from the universe will not reach us until the sun and earth have died out. To put these distances into perspective, it takes only 8.3 minutes for the sun’s light to reach the earth. If the size of the earth is used to represent the entire cosmos, the part we could see, even with the best telescopes available, would be less than a grain of sand. Wow! Although it is possible that these larger estimates are wrong, even some much more conservative estimates would still reveal a cosmos that is unimaginably large. As vast as our universe might be, we can’t rule out the possibility that there could be other universes—perhaps an infinite number of universes. The possibilities are mind boggling, but before we get carried away, let’s get back to what we know.

The speed of light and the expansion rate of the universe give us an idea of distances. Now let’s take a different perspective and look at content: the number of planets, stars and galaxies. The earth and our solar system are a small part of the Milky Way galaxy, which could be described as a stellar disk about 100 thousand light years in diameter. Our sun is located about 1/2 to 2/3 away from the center of the Milky Way. Galaxies are plentiful, as there are well over 100 billion galaxies in the observable universe alone. In an image known as the Hubble Deep Field, the Hubble Space Telescope was focused on a dark spot in the sky for a period of ten days. The spot was about the size of the opening of a drinking straw, and it covered only two parts in a million of the whole sky. In this very tiny spot 10 thousand galaxies were observed.

When numbers get significantly large they start to run together and become difficult to digest. That’s where analogies can be helpful, and when it comes to the total number of galaxies in the universe we almost need something we can visualize. How much is 100 billion galaxies? If galaxies were scaled down to the size of frozen peas, they would fill the old Boston Garden (this has actually been computed). For those of you who are not sports fans, the old Boston Garden is where the Celtics and Bruins previously played professional basketball and hockey respectively. If you don’t like peas, let’s try hamburgers. If we used hamburgers to represent galaxies, and lined them up end to end, there would be enough burgers to circle the earth fifty-two times. That’s not all. You would still have enough burgers left over to stack them to the moon and back. You may think that’s a lot of peas, burgers or galaxies. But hold on to your hats, we’re just getting started.

Galaxies are not individual objects, but vast groupings of stars. The amount of stars contained in galaxies varies by a large extent. The Milky Way contains at least 200 billion stars. The nearby Andromeda Galaxy—relatively speaking, about 2.5 million light years away from earth—is much larger than the Milky Way, and contains 1 trillion stars. From there, the numbers can get even bigger; the largest galaxy ever discovered consists of 100 trillion stars. Once again, only analogies can put these kinds of numbers into perspective; however, the sheer number of stars is so staggering that even an analogy is somewhat limiting. According to the 2010 NOVA (PBS) documentary Hunting the Edge of Space, there are more stars in the observable universe than grains of sand on all the beaches and all the deserts on earth. Yes, that’s not a misprint—all the beaches and all the deserts on earth. As difficult as that is to grasp, there is more. Imagine if you can, how many planets could be orbiting these stars—and of course you probably can’t. Out of the unimaginable number of possible planets (hundreds have already been discovered), how many of them may be able to support life? The potential is truly enormous.

I have omitted one important fact in all of this, and that is the vast amount of space that separates galaxies. Typical galaxies are usually separated by millions of light years of space, and due to the expansion of the universe the space between galaxies is increasing. Everything we can see, stars, galaxies and clusters of galaxies, make up only a tiny fraction of the entire universe. Although scientists are discovering that space may not be empty after all, in the conventional sense we could say that the universe is dominated by empty space.

When I look up at the night sky, in a way, it is the emptiness that is striking, emptiness sprinkled with twinkling yellow dots. And speaking of dots, one is suddenly reminded of just how insignificant the earth seems to be. In the immense scale of the cosmos, we make our home on a pale blue dot in an ocean of tranquility. Everything we treasure, everyone we love, our hopes and dreams, and all of human history has transpired on what is essentially a dot. And most people spend their entire lives on only a fraction of a dot. With the number of stars out there, I wonder if somewhere in a far away galaxy, someone else is also contemplating a similar situation. Due to the distances that are involved, we may never know for sure. But I think it is likely that there is intelligent life somewhere else in the universe. After all, the basic chemistry and physics is believed to be essentially the same throughout the universe. And given the number of planets that likely exist, the opportunities for life to evolve seem plentiful.  Nevertheless, in the grand scheme of things, the earth appears to be a small and lonely place, but it is all that we have—our only home.

 

References: 2010 NOVA (PBS) Hunting the Edge of Space


 

The Universe Revealed Through Modern Science

Physical laws have existed since the beginning of time, but they had to be discovered for science to become relevant. Scientific knowledge was built mainly by a series of small advances and adjustments, however, a few major discoveries by a few scientists have altered the course of the scientific endeavor. The age of modern science was pioneered by men like Copernicus, Galileo and Kepler. They began to examine the patterns in nature, and discovered that in some situations the workings of nature could be explained, and even predicted. They found that nature’s harmony was governed by physical laws, which were at least partly accessible to human comprehension. They studied the motion of objects on earth, and then turned their attention to the heavens. They charted the movement of the celestial bodies in great detail, and discovered that the motion of the celestial bodies could also be predicted. The gateway to scientific discovery had been opened—the universe would soon begin to reveal its most profound secrets.

In the early years, it was Isaac Newton’s insight that stood above all others. He discovered gravity as the force responsible for the motion of the moon and the planets. And as the story goes, the same force responsible for an apple falling from a tree. In 1687, he published the Principia Mathematica, where he disclosed his law of universal gravitation and the three laws of motion. It was a major breakthrough in advancing the scientific cause. Newton’s laws provided the foundation for what has become known as classical physics. For more than 300 years his equations have stood the test of time. In fact, Newton’s equations were all that was needed to plot the course that placed men on the moon. Although his equations provided an accurate mathematical framework (actually a very close approximation that was later revised by Einstein), Newton had no idea what mechanism was responsible for the effects of gravity. It is also believed that he regarded space, the arena of motion, to be absolute and unchangeable. He viewed time in much the same way.

It was not until the early 1900s when the mysteries of space and time, as well as the underlying causes of gravity, were addressed. Albert Einstein changed the course of history when he published his theories of special relativity (in 1905) and general relativity (in 1915). Einstein formulated that space and time are not absolutes, but have dynamic qualities associated with mass and motion. In fact, he described space and time as a unified whole, which later became known as space-time.

With special relativity, Einstein showed that measurements of time (and even distance) could differ for two observers, based on their relative motion. Time will elapse slower for someone in motion than it does for someone at rest. And the discrepancy in elapsed time will increase as the difference in the speed increases. In a sense, observers carry their own clock with them. This realization signifies another important point—that the observers would also disagree on what constitutes a given moment in time. One person’s now would be different from the other person’s now, yet both perspectives would be equally valid. Keep in mind, that it’s only when dealing with speeds approaching the speed of light or extreme distances that disagreements in time become significant. The effects of special relativity are not visibly apparent in the temperate conditions that exist here on earth; however, the earth is somewhat of an anomaly in comparison to the universe as a whole. With the universe, where extreme distances and speeds are commonplace, special relativity becomes important.

With general relativity, he showed that the effects of gravity are caused by the warping or curving of space (or space-time, but for simplicity I will use the term space). Heavy objects like planets and stars warp the fabric of space, thus creating the effects of gravity. It is similar to placing a heavy ball in the center of a trampoline. Any smaller balls placed on the surface will be drawn to the center, due to the surface being warped by the heavier ball. Bear in mind that a trampoline is a two dimensional representation of what is actually a three dimensional spatial fabric. It does, however, give us a clear visual analogy of how curved space participates in the motion of celestial bodies. In the case of planets and stars, orbits will develop when a stable balance is achieved. The earth can be thought of as moving in a straight line along a curved surface of space. Or as taking the path of least resistance along the distorted spatial fabric, which is created by the sun’s presence.

Another consequence of general relativity is that just as gravity curves space, it also curves time. But what does curved time mean? Similar to special relativity, where motion alters time, general relativity claims that gravity also alters time. When gravity exerts its influence time slows down. For instance, time passes a little slower on the surface of the earth than it does for objects high above the earth. A practical example of this effect is in the technology behind global positioning systems (GPS). The satellites that guide GPS devices have to account for both special and general relativity (general relativity producing the largest effect). The internal clocks of the satellites account for the fact that clocks on the earth’s surface run slower. If not for these adjustments, GPS devices would quickly become inaccurate; the coordinates on the ground would drift off by several kilometers each day.

Einstein’s relativity goes against our common sense perceptions, but apparently this is the reality of the universe. Einstein’s insights led to modern cosmology (the study of the origin and evolution of the universe), and our current view of the universe. Both classical physics (Newton’s view) and relativity (Einstein’s view) provide a deterministic framework. That is, if the present conditions are known, the past and future conditions can also be determined. That’s assuming that you have all the present data and the mathematical ability to do the calculations.

The next scientific breakthrough would be of a very different nature. In the mid-1930s a group of scientists were unlocking the secrets of the atom. In so doing, it led to the development of quantum mechanics. They found that the atomic and subatomic realms behave in ways that are very different from the world experienced at the larger scales. A whole new set of laws had to be developed to deal with the bizarre nature of the atom—laws that are partly governed by randomness and probabilities. Physicist Brian Greene describes the nature of quantum mechanics. He writes in The Fabric of the Cosmos:

 “…according to the quantum laws, even if you make the most perfect measurements possible of how things are today, the best you can ever hope to do is predict the probability that things will be one way or another at some chosen time in the future, or that things were one way or another at some chosen time in the past.”

The probabilities that are used in quantum mechanics are more fundamental than the probabilities that are assigned to everyday events. When we assign a probability to a game of dice or blackjack, it is based on our inability to calculate the precise conditions that will determine the outcome of the event—specifically, each roll of the dice or flip of the card. With quantum mechanics, however, even if we know all the present information possible, we still can not predict a future outcome with absolute certainty. Quantum physics describes a reality that is fundamentally uncertain, in which objects have no definite position, take no definite path, and even have no definite past or future.

Some experiments (known as the double-slit experiment and variations of it) have actually shown that a single particle, such as a light photon, can behave as if it simultaneously takes a number of different paths from a source to a target. It is debatable whether this really happens; nonetheless, outcomes are determined by the number of possible paths of the photon, whether or not they are all realized. The photon takes a definite position only when it is observed or measured (when it strikes the target). In between the source and the target, it can be thought of existing as a haze of possibilities.

This is partially explained by the idea that subatomic objects, like photons and electrons, exhibit both wave-like and particle-like properties. At times, a photon or electron can be described as occupying a wide region in space, and at other times described as occupying a single point in space. Depending on the variation of the double-slit experiment, a photon can sometimes behave like a wave and sometimes behave like a particle. Although it is not entirely clear how these results should be interpreted, physicists agree that our conventional sense of reality does not apply at the quantum level—even to a larger degree than Einstein’s relativity.

I know this all sounds absurd. Nevertheless, the predictions of quantum mechanics have produced results that are extraordinarily accurate. Quantum mechanical predictions are accurate in the sense that if a sufficient number of identical experiments are carried out, the totality of the outcomes will reflect the assigned probabilities. Yet each single experiment will generate a random and unpredictable outcome. Therefore, even with the most precise calculations possible, there is an unavoidable degree of uncertainty in quantum mechanics.

It has been said that nobody understands quantum mechanics, that even scientists that work with quantum mechanics don’t understand it. So if it’s not sinking in, don’t lose any sleep over it. In summing up: the renowned physicist Richard Feynman once wrote in The Strange Theory of Light and Matter “[Quantum mechanics] describes nature as absurd from the point of view of common sense. And it fully agrees with experiment.”

Once again our common sense is challenged by the laws of physics. From classical physics to the updating of relativity, and the weirdness of quantum mechanics, reality is proving to be difficult to grasp, as these theories give us very different views of reality. For this reason, there is a consensus among some physicists that there exists a deeper level of reality to the universe that remains undiscovered. They propose that there should be one theoretical framework that describes the universe, and not a fragmented view based on several partial theories. Einstein called this hypothetical theory a unified theory (also called the theory of everything). The quest for a unified theory became one of Einstein’s passions during his later years; however, it was not realized during his lifetime.

Today, physicists are still seeking the elusive unified theory. Our present understanding of the universe is based on the two major breakthroughs of the 20th century. 1) General relativity, which describes the large scale structures of the universe, like stars and galaxies. 2) Quantum mechanics, which describes the small scale structures, like molecules and atoms. These two theories have been very successful in their own right, but in some extreme situations they cannot be applied successfully. In some situations where large densities are compressed into a tiny region of space, an understanding of both the large and the small is required. But when general relativity is applied together with quantum mechanics, the theories fall apart. This becomes a major obstacle when trying to understand conditions such as the center of black holes and the origin of the universe where these conditions need to be considered. The big bang theory describes the events a fraction of a second after the beginning, but says nothing about the beginning or before. Without a unified theory, or a new theory altogether that can deal with this situation the cause for the origin of the universe will remain a mystery.

As we have seen, each new discovery has added a piece to the puzzle and our understanding of the universe has increased dramatically over the years. The ultimate goal of science can be nothing other than a complete understanding of the laws of nature, though it may be that mystery will forever be a part of the picture. In his 1988 book, A Brief History of Time, Stephen Hawking weighs in on the subject:

“But can there really be such a unified theory? Or are we perhaps just chasing a mirage?

There seems to be three possibilities:

1) There really is a complete unified theory, which we will someday discover if we are smart enough.

2) There is no ultimate theory of the universe, just an infinite sequence of theories that describe the universe more and more accurately.

3) There is no theory of the universe; events cannot be predicted beyond a certain extent but occur in a random and arbitrary manner.”

There may very well be limits to what humans are able to understand, but this should not limit our quest for knowledge. Where would we be today if some people hadn’t questioned conventional thinking and opened the door to greater discovery? It is due to the few who dared to challenge the beliefs of their time that many benefited. Not only in science, but in other domains as well, it is the quest for knowledge that paves the way for progress. This is the case for our lives, as well as humanity as a whole. No one knows how far we can go, and only time will tell. On this note, we can at least rest assured that the modern age of science has brought humanity out of the darkness of ignorance, and into the light of knowledge.

References: Brian R. Greene, The Fabric of the Cosmos (New York: Alfred A. Knopf, 2004), 10-11.

Richard Feynman, QED: The Strange Theory of Light and Matter (Princeton: Princeton University Press, 1988).

Stephen W. Hawking, A Brief History of Time (New York: Bantam Books, 1988), 165-166.


 

Horizons Out of Reach

Imagine you are walking on a terrain of rolling hills; in the distance you can see the horizon. Beyond that point you don’t know what you’ll find. When you arrive at the crest of a hill a whole new landscape appears with its own horizon. This is a common metaphor used to show how knowledge is usually acquired. Each horizon reached often presents another horizon (or question) in the distance.

The story of science is one of impressive discoveries. Many horizons have been reached, but many more are yet to be encountered. No one knows how far we can go and what we will find. I hesitate to limit what might be possible, because science has surprised us time and time again. If the human race survives long enough, is there anything we can’t find out? I would think that there are some questions we will not be able to answer, but which ones? One should think long and hard before ruling anything out, which I have done. For what it’s worth, I am left with two questions which appear out of reach. I’ll get back to this later but first a little context.

Horizons Reached

At present the knowledge base is immense, but it had to be acquired. Imagine going back 100, 500 or 1,000 years and contemplating the future. It’s possible that some future discoveries could have been predicted. However, there are other findings that few saw coming. It is practically impossible to provide a full account of impressive scientific discoveries. However, there are some that immediately stand out. What follows has been mentioned in prior blogs of mine; think of it as a short list of scientific highlights:

  1. The Idea of Natural laws: At around 500 BC the ancient Greeks documented the concept of natural laws. They suggested that patterns in nature could be recognized and attributed to natural laws. This was a major breakthrough in scientific thought.
  2. The Copernican Revolution: In 1543 Nicolaus Copernicus published his theory of the heliocentric model of the universe. He removed the Earth from the center of the known universe and replaced it with the Sun. This was a significant reality check, which would influence human philosophy for years to come.
  3.   Newton’s Laws: In 1687 Isaac Newton disclosed his law of universal gravitation and his three laws of motion. Newton laid the foundation for what later became known as classical physics. Now over 300 years later, Newton’s equations still apply (except for extreme circumstances).
  4. Einstein’s Relativity: With special relativity (in 1905) and general relativity (in 1915), Albert Einstein filed in the gaps in Newton’s laws. Einstein accounted for those extreme circumstances. His contribution led to a greater understanding of the large-scale universe.
  5. Darwin’s Theory of Evolution: Charles Darwin provided an explanation for how all life evolves with his famous publication in 1859. This one basically speaks for itself; few if any discovery is more impressive.
  6. Revealing the Atomic and Subatomic Realm: Beginning in the early 1900s, several people worked on theories such as quantum mechanics and the standard model of partial physics. A realm previously inaccessible was shown to be real and would unwittingly have a significant impact on human affairs.
  7. The Big Bang: In the 1931 George Lemaitre suggested that the universe began in a single geometric point. He arrived at this by applying general relativity to the observations of William Hubble. Lemaitre`s idea would eventually provide us with a truly universal origin story. 
  8. DNA: In 1962 James Watson, Francis Crick and Maurice Wilkins won a Nobel Prize in medicine for the discovery of the structure of DNA. This opened up a whole new science, which will undoubtedly impact us for generations.

Of course the list above could be significantly longer and still fall short. However, I present it just to give you a feel for how knowledge, particularly scientific knowledge, alters our perception of the world. It is debatable how many past discoveries could have been foreseen; nonetheless one can imagine some horizons in the distance which may be attainable. For example: figuring out how life on Earth got started, or the discovery of life elsewhere in the universe. Closer to home, perhaps finding a cure for cancer (or most cancers), and maybe even weather forecasting weeks or months in advance. No one knows for sure which findings are coming, but I feel fairly certain that at least two questions will remain unanswered.

Contemplating the Unanswerable

The two questions I am referring to are as follows: 1) Why is there a universe in the first place?  2) Why is the universe the way it is and not some other way? Another question which I feel I must address before moving on to question 1, is this: Why is there something rather than nothing? You’ve probably heard this one before, and it is similar to question 1. However, I find this to be a peculiar question and here’s why. First let’s define what is meant by nothing. If by nothing, one assumes the absence of everything, then nothing is a non-entity. In other words, how can nothing be a reality if by definition nothing has no existence. The question gives us two options, something or nothing and it seems to me that something is real and nothing is not. By this logic one could conclude that there has to be something, but why a universe?

For some, the existence of the universe doesn’t seem to be a big problem to solve. The standard answer is that God created the universe and that’s it. However, I can’t help but ask two simple follow-up questions: a) Why is there a God in the first place? b) Why is God the way he (she, it) is and not some other way? Do you see how this works, by inserting God as the explanation for the universe we’ve circled back to where we started. In essence the questions are identical. We have merely moved the starting point from the universe to God.

Another approach is to examine the possibility of a multiverse. There are scientific reasons that suggest that other universes may exist, but that is as far as it goes.  Although the multiverse is theoretical, it may shed light on question 2. Why is the universe the way it is and not some other way? If multiple universes actually exist, it could be that all possible universes exist, therefore it is not surprising that at least one universe is like ours. Although the multiverse idea is somewhat satisfying on the surface, it has its problems. For starters, it does not address question 1. Why is there a universe in the first place? It says nothing on why there would be a multiverse in the first place.

There is also the problem of testing the multiverse idea scientifically. How can we ever verify something outside the boundaries of our vast universe? Hypothetically, even if our science advanced to a point where universes outside our own could be detected, how could we know the full-scale of a multiverse? We would likely be unable to determine how many universes exist in total. Ultimately that’s where I think the multiverse idea falls short in terms of answering question 2. Why is the universe the way it is and not some other way? If we can’t know how many universes exist in total, we can’t explain why our universe is the way it is and not some other way. All possible universes have to exist in order for the multiverse to the job. Or at the very least, it would take an extremely high number of universes.

Why is there a universe in the first place and why is the universe the way it is and not some other way? I have thought about these two questions philosophically, religiously and scientifically and have made little progress. Each approach gains momentum only to fall short. There are undoubtedly still many horizons within our reach and it will be interesting to see what lies ahead. That being said, I have to conclude that there are at least two horizons that seem to be hopelessly out of reach.

References:http://www.bbc.co.uk/schools/gcsebitesize/science/add_edexcel/cells/dnarev3.shtml

https://www.quora.com/What-is-the-relationship-between-the-Standard-model-and-Quantum-field-theory


 

The Physics of Time?

Our conception of time as moving in one direction, from past to present to future, is so commonplace that we accept it as fact. But what if our experience of time is misleading us, and perhaps hiding the true reality of the universe? Can we rely on our senses to accurately perceive something as abstract as time? Is time real, or just an illusion caused by other physical effects? Can science provide any clues into understanding time?

It was once thought that time existed as absolute and unchanging, flowing at a constant rate and moving in one direction. This was true for scientists and the public alike. Isaac Newton considered time in much the same way as space; time and space providing the arena in which the universe unfolds. Newton’s famous laws of gravity and motion assumed absolute space and time. His laws work extremely well for our corner of the universe, that which is accessible to human senses. They are still used today to calculate the gravitational forces of the sun, moon and planets, as well as the motion of spacecrafts and objects close to earth.

There is a catch, however; Newton’s laws are not 100% accurate. Absolute space and time is not an acceptable assumption when dealing with extreme scales of the universe, a reality that was hidden from Newton in his time. The modern laws of physics question our everyday concept of time. In the early 1900s, Einstein devised the theories of special relativity and general relativity, and the idea that space and time could be flexible was born.

Einstein’s Revision of Newtonian Time

More than 300 years ago Isaac Newton wrote that, “He did not need to define time because it is something well known to all.” For obvious reasons our common sense perception of time has been called Newtonian time. The concept of absolute time had gone unchallenged until Einstein came along.

With Einstein’s revision of Newton’s ideas we have to envision a universe where each celestial body and each observer (what concerns us) carries their own clock with them. With relativity, the passage of time is relative to influences of mass and motion. In short, massive objects like stars and planets cause space and time to warp, resulting in gravitational effects and slowing down time. Also, time elapses slower for an object in motion than for an object at rest; the discrepancy in the passage of time gets proportionally larger as the speed increases. Even though it can be said that time runs at different rates (or two observers disagree on the passage of time), each perspective is equally valid. When one observer moves relative to another observer, clocks will not agree.

Flexible time is a property that applies everywhere in universe, however, the effects are minuscule in everyday life. Although the effects of relativity are not visibly apparent to us, observations have confirmed that this is how the universe really works. The scientific evidence is conclusive; time is relative, not absolute. Just as one can move through space, one can also move through time. No longer could space and time be considered as two separate entities; a new term called spacetime was brought into use to better account for the relationship between the two.

A hypothetical situation of an alien in a distant galaxy shows how bizarre relative time can be. If you are stationary here on earth and the alien moves away from you, the alien’s now coincides with a moment in your past. If the alien turns around and moves towards you, then the alien’s now coincides with a moment in your future. Just as extremes in speed and gravity alter the passage of time, extreme distance has a similar effect on what constitutes a given moment of time for two observers. This is the kind of universe that Einstein described.

I cannot think of a better everyday example of flexible time than GPS devices. The clocks in the satellites in orbit need to account for the fact that clocks on the Earth run a little bit slower. This is due to the combined effects of the motion of the satellites and the gravity on earth (the Earth’s gravity having the largest effect). If not for the application of relativity, GPS devices would quickly become inaccurate.

The Laws of Physics, Entropy and The Arrow of Time

Whether we examine small physical systems or the universe as a whole, there is no arrow of time found in the laws of physics. For example, if a scientist knows all the current conditions, he can determine precisely what happened in the past or predict a future outcome. This can be achieved by applying the same laws either backward or forward in time.

Is there anything in science that indicates an arrow of time? There is a concept in physics called entropy, which may give us an arrow of time. Simply stated, entropy is the measure of disorder, and the implication of entropy is that physical systems move towards a direction of increasing disorder. The reason being, that there are many ways in which disorder can come about. Conversely, there are few ways that order can be achieved.

Let’s take the example of the pages of a book (all numbered in order). If we were to randomly mix up the pages (and re-stack them) the chances are extremely high that the pages will end up disordered. In only one configuration will the pages be ordered, while many arrangements will be disordered. In almost all cases it takes a special effort to create order and no effort at all to create disorder.

The puzzle is: how has the universe created stars, galaxies, planets and life on earth? If entropy rules, you would think that the universe would be in chaos forever. To get an answer we may have to go back to the birth of the universe. The Big Bang is believed to have been a highly ordered event (perhaps the most ordered state of the universe). From that point on the universe has evolved into greater disorder. Entropy may give us an arrow of time. From the point of most order (in the past) towards increasing disorder (in the future).

This should make us pause and consider our present conditions on earth. Conditions favorable for life are extremely difficult to come by, and entropy is bound to rule in the end. In the grand scales of the universe, in both time and space, life is a newcomer and rare (as far as we know). Life on earth is destined to be extinguished, at least at some time in the far future.

Our experience shows us that many things only happen in one direction, and usually in the direction of more disorder. For example: A glass can fall to the ground and break, but a glass can’t reassemble by itself. A drop of ink can mix in water, but the ink can’t come back together into a drop. An egg can be broken, but can’t reassemble back into the shell. This is entropy at work, and possibly the scientific reason behind our common-sense experience of an arrow of time.

The River of Time

Clearly, there is a sense that time moves from past to present to future, like a river, which flows in one direction from one moment to another. From the present perspective the past is gone forever and the future is yet to be realized. However, for physicists it is not as clear cut. From Einstein’s perspective, what constitutes a given moment of time is dependent on the observer. Because time is relative to each observer, my now could coincide with a past or future experience of someone else in a far-away galaxy. There is no sense that the whole universe progresses at the same rate. There is no now that everyone can agree on.

How could this be? As long as there are discrepancies in time for different locations and observers, there can be no universal now for all. Equally, there can be no past or future moment that all can agree on. If this is true the implications are unsettling: All moments of the universe exist. From a physicist point of view Brian Greene concludes in The Fabric of the Cosmos:

” … if you agree that your now is no more valid than the now of someone located far away in space who can move freely, then reality encompasses all of the events in spacetime… Just as we envision all of space as really being out there, as really existing, we should also envision all of time as really being out there, as really existing, too.”

Einstein also saw the paradox between physics and experience: “For we convinced physicists, the distinction between past, present, and future is only an illusion, however persistent.”

Does time really flow like a river? Even from a common sense perspective the distinction of past, present and future is relative to the individual. For me, someone who lived many years ago existed in the past. Someone that will live 100 years from now will exist in the future. That’s all from my perceptive or from my point of reference. From the perspective of a historical figure, like Einstein, he lives in the present and I will exist only in the future. With each moment there is no essential difference, no temporal absolute, just the relative perspective of each individual.

Change as The Scorekeeper of  Time

If I haven’t created enough doubt as to your assumed notion of time, I will conclude with one more observation. This has to do with change. Is it possible that the only real aspect of time is change? At least could change be the only way that time is perceived?

We notice time has elapsed because something has changed. It is reinforced by our mind. Our memories tell us that an event was in the past, and our imagination projects that something could happen in the future. In essence, we experience the passage of time or that time flows because of continual change. If there were no change at all, would time even exist? Imagine a universe with every object being still or no objects at all. Every moment would be identical.

A reality with no change is not our experience, nor is it how the universe presently works. However, a particular question about the Big Bang Theory may shed some light: That is, what happened before the bang? Science can’t take us back any further, as the Big Bang represents a theoretical barrier. Perhaps we don’t need to look further. Physicists believe that time and space as we know it were created at the Big Bang. This may be highly speculative, yet it could be that there was no change before the Big Bang; or conditions were so chaotic that there would have been no discernible events. Thus, that would mean that nothing really happened before.

At the other end of the spectrum, one current model of the universe predicts that space will continue to expand at an increasing rate. This expansion will drag every galaxy farther apart with no end in sight. Far, far into the future everything in the universe will become diluted. In the end, if we can call it that, everything will decay, leaving only random particles drifting in space. The universe will be cold, dark and practically empty. We could even conclude there will be no change and time will also come to an end.

Coming up with an explanation for time is challenging. You could even make a case that time does not exist. What we experience as time may be something else altogether. With each perspective of time I have mentioned there is something intriguing, and still something seems to be missing. How could something as familiar as time be explained differently, with each explanation having some merit? That’s how it appears to me.

Newtonian time aligns very well with our daily experience of time. Einstein’s relativity is in agreement with modern observations of the universe. Entropy gives us an arrow of time not found in the laws of physics. The river of time points to everyone’s unique frame of reference. And finally, change gives us a physical component that marks the passage of time.

 

References: Brian R. Greene, The Fabric of the Cosmos (New York: Alfred A. Knopf, 2004), 139.

The Fabric of the Cosmos: The Illusion of Time, Life Sciences, Published on Apr 12, 2016. https://www.youtube.com/watch?v=pPA83Ap0Xsg.


 

Evidence for the Big Bang Theory

We are all aware of the Big Bang Theory, but how much is known about the strength of the theory. For some the Big Bang is a vague and far-out idea, for others it is a T. V. sitcom. Nonetheless, it requires some background to appreciate how the Big Bang Theory became what it is today.

The Story Begins

Isaac Newton is credited for saying: “If I have seen further than others, it is by standing upon the shoulders of giants.” Newton was implying that his discoveries would not have been possible, without the brilliant people (giants) which preceded him. The Big Bang is such a theory, it was pieced together by several individuals spanning decades of work. Or perhaps a few centuries of work, it all depends on when one chooses to begin the story.

I will arbitrarily begin in 1687 when Newton published his Principia Mathematica unveiling his law of universal gravitation and his three laws of motion. Newton was the first to provide a mathematical framework to account for the effects of gravity, thus he could calculate the motion of the moon and planets. Gravity was also the force responsible for keeping objects firmly on the Earth or causing an object (such as an apple) to fall to the ground.

Newton’s laws have stood the test of time; however, they are not 100% exact and serve as a very close approximation. They are, however, practically exact for our experience of everyday events. Only in some extreme situations do they fall short. Also, Newton was forced to concede that he did not know the mechanism behind the force of gravity. In simple terms, Newton was able to calculate the effects of gravity even thought he was unable to provide a complete explanation for how gravity worked. Nevertheless, Newton’s laws were a major scientific breakthrough for its time and started the ball rolling in the right direction.

Dynamic Space

Image converted using ifftoanyIt wasn’t until 1915 when Albert Einstein came up with his Theory of General Relativity, which addressed some of the gaps in Newton’s understanding of gravity. Einstein was able to explain gravity in detail, as a consequence of curved space. The mass of bodies (such as planets and stars) bend the fabric of space, thus generating the attraction. The fact that space has dynamic qualities, which can expand and curve would later become important to the big bang concept.

Also significant, is that General Relativity predicts that the universe should be either contracting or expanding. However, in Einstein’s time the prevailing wisdom was that the universe was static and eternal. Einstein gave way to convention, and after the fact, arbitrarily added a figure in his equations known as the cosmological constant. This was a repulsive force with just the right value to counter the effects of gravity, thus keeping the universe stable. As it turned out, Einstein’s original prediction of a non-static universe was later proven correct. He then dropped the cosmological constant from his theory.

Measuring the Night Sky

After Einstein’s General Relativity it was left to astronomer Vesto Slipher, who worked at the Lowell Observatory in Arizona. Slipher took spectrograph readings of distant stars and discovered that the light emitted was moving away from us. The starlight was shifted to the red end of the spectrum. Slipher was the first to realize that receding light is red shifted and in coming light is blue shifted. This was an indication that the universe was not static after all; however, his work went unnoticed at the time. Slipher was not aware of General Relativity and his findings would only have an impact a few years later.

henrietta-swan-leavittAnother breakthrough came from a woman named Henrietta Swan Leavitt. She worked at the Harvard College Observatory as a computer, as they were known in those days. These women studied photographic plates of stars and made computations. Leavitt was able to establish Cepheid variables as standard candles; a method to determine the intrinsic brightness of a star. Cepheids are elderly stars which pulsate at regular intervals; these stars brighten and dime in a very reliable pattern. Leavitt worked out that these stars could be used to calculate distances. For the first time, there was a method of measuring the large-scale universe. Today, Type 1A supernovae are also used as standard candles. Similar to Cepheids, Type 1A supernovae are said to have intrinsic brightness, making them reliable measuring tools.

Building a Case

edwin-hubbleThe story now shifts to the Mount Wilson Observatory in California. Equipped with a new telescope Edwin Hubble was able to make use of Slipher’s red shifts and Leavitt’s standard candles. In the early 1920s Hubble discovered that some of the starlight he observed was coming from distant galaxies. Before this finding the only known galaxy was our own. Today we know that there are well over 100 billion galaxies in the visible universe alone. In an instant, Hubble had shown that the universe was much bigger than anyone had theorized.

Roughly a decade later, Hubble made an equally stunning discovery. By observing distant galaxies, he determined that they were all moving away from us. The only exception to this was our own local cluster (close enough in proximity to be held together by gravity). All galaxies were moving away from us on average. In short, the universe was expanding in all directions! Furthermore, the distance between galaxies and the speed at which they were moving were proportional. For instance, galaxies twice as far away were moving twice as fast, three times as far away, three times as fast. Interestingly, debris from an explosion shares a similar signature. This is because the further away from the epicenter the debris comes to rest, the faster it has to travel.

george-lemaitreJust as Slipher before him, Hubble had little understanding of General Relativity and failed to recognize the full significance of his discovery. It took a Belgian priest and scholar named Georges Lemaitre to put it all together. He applied General Relativity to Hubble’s findings, wound the clock backwards, and in 1931 he suggested that the universe began in a single geometric point. This was the original idea, which later became known as the Big Bang. Nevertheless, the world was not yet ready for Lemaitre’s bold idea. It took a few more decades before Lemaitre’s idea became an established scientific theory.

In 1964 the Big Bang Theory was finally confirmed by observation. Two Bell Laboratory scientists named Arno Penzias and Robert Wilson were testing a microwave detector. They were receiving interference coming from all directions. After ruling out a number of possibilities, it was determined that the signal was coming from outer space. In fact, they had discovered the cosmic microwave background radiation. They had accidentally stumbled upon the echo of the Big Bang.

The cosmic microwave background (CMB) is the remnant of light from the Big Bang. It had been predicted earlier, but now it was confirmed by observation. Due to the expansion of space, this light has been stretched to the microwave part of the spectrum. From its extremely hot beginning, the temperature of the CMB has now cooled to 2.7 degrees above absolute zero (nothing can be colder than absolute zero). No matter where we look the temperature of the CMB varies by less than a thousandth of a degree. These temperature measurements imply a common origin. How else could microwave radiation, separated by vast distances, have practically the same temperature (everywhere) unless it originated from a common event?

Evidence for the Big Bang (Recap)

  • Receding Starlight- By measuring the red shift of distant stars Vesto Slipher discovers that distant stars are moving away from us, suggesting that the universe is not static.
  • Establishing Cepheid Variables- Henrietta Swan Leavitt finds a way to make use of pulsating stars to measure distances in the large-scale universe.
  • Expanding Universe- Edwin Hubble discovers that the universe is expanding proportionally in all directions.
  • Compatible with General Relativity- Albert Einstein’s famous theory predicts a non-static universe and allows for space to bend and expand (necessary for the big bang concept).
  • The Smoking Gun- Arno Penzias and Robert Wilson stumble upon the cosmic microwave background radiation (the echo of the big bang). The Temperature of the CMB varies by less than a thousandth of a degree.

Note: There are also other pieces of evidence which point to a Big Bang that requires a background in particle physics to appreciate (which I do not have), so I have left it out here.

Interesting Facts About the Big Bang

  1. The Theory begins a tiny fraction of a second after the bang. The known laws of physics cannot be applied prior to the theoretical beginning of time. What happened before is uncertain.
  2. The Big Bang created time and space as we know it, calling into question the idea of a before.
  3. At the Big Bang the universe was at its hottest; it has been cooling ever since.
  4. At the beginning, the universe was in its most orderly state. From the moment of its origin, it has been moving towards higher disorder.
  5. The universe was in its simplest form at the Big Bang; it has been growing in greater complexity since its birth.
  6. There is no such thing as the center of the universe. From any given galaxy an observer would see the same thing; all galaxies would be moving away on average.
  7. Galaxies don’t move through space, it is the space itself which is expanding and carrying the galaxies along.
  8. The term ‘Big Bang’ was coined by astrophysicist Fred Hoyle. It was meant as a put down for a theory he never accepted and the term stuck.
  9. Arno Penzias and Robert Wilson won a Nobel Prize for their discovery of the CMB; something they were not even looking for.
  10. If you tune a T. V. to a channel that is not broadcasting, 1% of the snow on the screen is due to the cosmic microwave background. So if you ever complain that there is nothing to watch on T. V., you can always disconnect the cable and watch the Big Bang.

 

References: Bill Bryson, A Short History of Nearly Everything (London: Black Swan, 2004).

Mark Henderson, Joanne Baker, Tony Crilly, 100 Most Important Science Ideas (United States: Firefly Books, 2011).

Dec. 30, 1924: Hubble Reveals We Are Not Alone, Randy Alfred, 12.30.09, https://www.wired.com/2009/12/1230hubble-first-galaxy-outside-milky-way/

Scientific America, What is the Cosmic Microwave Background Radiation? October 13, 2003, https://www.scientificamerican.com/article/what-is-the-cosmic-microw/


 

The Moon: Our First Satellite

moonWhen one thinks of a satellite it is usually in the form of a man-made object orbiting the Earth. However, by definition a satellite is a moon, planet or machine which orbits a planet or a star. From our vantage point here on Earth, the Moon is the predominant satellite. Long before Sputnik 1 (the first man-made satellite launched by the Soviet Union) the Moon was our one and only satellite.   

Long, Long Ago

When the Solar System first formed it consisted of a star surrounded by a disk of gas. Eventually this gas gathered into dust, rocks, asteroids and finally planets. Each planet also had its own disk of gas, which in turn would follow a similar process. Some of the debris was pulled into the planets, but not all. Over time some of the gas eventually turned into moons. Some moons could have formed independently from their host planet, and later were captured by gravity as they drifted through space.

Our Moon is believed to have been created by a different manner. The early Solar System was a very violent and chaotic place. As planets and moons were born, they were bombarded by asteroids and small planets. The Moon’s many craters is clear evidence of this early chaotic period. In the 1970s a theory was proposed: about 4.5 billion years ago the Moon was formed by a gigantic collision between the early Earth and another planet. Recently a new theory has surfaced which tweaks the original 70s theory. I’ll begin with the established theory first, then get back to the revised theory later.

earth moon collisionThe original theory states that a mars-size planet on a similar orbit as Earth struck the Earth on an angle. The collision created the Moon and quite possibly the tilt of the Earth’s axis of 23 degrees. This rouge planet is sometimes referred to as Theia, named after the mother of the ancient Greek moon goddess, Selene. The impact generated intense heat in both planets. The Earth absorbed part of Theia along with her heavy iron core, the lighter rocky material ended up in a ring around Earth’s orbit. From this debris our first satellite would from. Interestingly, the Moon may have been intact after only several decades. Over billions of years both bodies cooled, but not entirely; the Earth still has a largely molten core. The smaller Moon may have completely cooled or perhaps still retains a tiny molten core.

 Evidence for the ‘Giant Impact Theory’ (70s theory)

  • The Moon is large for a satellite in comparison to the size of the Earth. Most moons are much smaller in ratio to the planet they orbit. Models for how moons are usually formed place a limit on how big a moon can be in relation to its host planet. Our Moon appears to be too big to have formed by surrounding gas in the early solar system or captured by the Earth’s gravity.
  • By examining the surfaces of both Mercury and Mars we are able to see what the early solar system must have been like. Virtually unchanged for about 4 billion years, these planets are dotted with craters. Some of which are as large as six hundred miles wide. The Earth has no such markers due to climate and erosion, but by deduction, we can assume that the early Earth was also hit by large objects (such as Theia).
  • In six trips to the Moon the Apollo astronauts collected rock samples and for the first time they were able to see what the Moon was made of. Remarkably, the Moon samples were found to have a similar chemistry to Earth. This discovery is in line with a Theia and Earth collision. Such an event would have blasted parts of the Earth into space which coalesced with bits of Theia to form the Moon.
  • The impact hypothesis was also put to the test with computer simulations. The impact suggested, was applied to software that recreated the conditions of the early Solar System. After running several simulations of a Mars-size object colliding with the Earth at the angle predicted, everything worked. The end result was the Earth/Moon system we have today.

The ‘big Whack’ (new theory)

This is where the new revised theory comes in; modern computer simulations suggest a much more intense collision at a significantly sharper angle. Such an intense impact would have vaporized Theia and much of the Earth. This  accounts for why the Earth and Moon are so similar in their chemistry. In fact, new research is finding increasing chemical similarity. This points to a much more violent impact which would have thoroughly mixed both bodies before they separated.

Also, the impact forced the Earth to spin much faster (about once every 2 hours) and tilt as much 60 to 80 degrees on its rotational axis. The Earth’s present rotational tilt of 23 degrees is though to have been arrived at later by complex interactions with the Moon and the Sun. Another interesting fact, which the original theory left unexplained, is the 5 degree tilt of the Moon’s orbital plane. The Moon’s orbit is tilted 5 degrees in relation to the Earth’s orbit around the Sun. The Earth orbits the Sun on what is called the ecliptic plane; this plane is where most bodies orbit the sun. The early Moon’s orbit is though to have matched the severe tilt of the Earth and did not transition smoothly to match the ecliptic plane. The revised theory proposes that the 5 degree orbital tilt of the Moon is but a relic of a much steeper orbital tilt from the distant past.

A Match Made in Heaven?

earth and moonThe two prominent heavenly bodies are the Sun and the Moon. Much of the Sun’s influence on the Earth is clearly recognizable; the Moon, however, affects us in more subtle ways. The warmth of the Sun (or lack of it on some days) is an everyday experience. In ancient times the Sun was worshiped by some cultures as godlike. It would have been clear then, as it is now, that without the Sun the Earth would be void of heat and most likely without life.

As it turns out the Moon’s presence might also be fundamental to life. However, for a large part of human history the Moon remained mysterious. Today scientists speculate that the Moon may have contributed to life in various ways. What follows are plausible explanations for how our Moon influenced life:

  • When the Moon was first formed it was much closer to the Earth than it is today. It is still receding by a minuscule amount every year. Over 4 billion years ago the Moon exerted a greater gravitational pull on the Earth, which may have set plate tectonics in motion. Plate tectonics are believed to be necessary for a living planet.
  • Shortly after the Earth’s post impact formation it rotated about once every 5 hours (70’s theory) or once every 2 hours (new theory). Either way, the Moon’s presents gradually slowed down the Earth’s rotation, diminishing the severity of the weather. The Moon may also have stabilized the earth’s rotation on its axis.
  • Nocturnal animals behave differently at various times during the monthly lunar circle, depending on the brightness of the Moon. If not for the influence from varying moon light, who knows how the course of evolution would have been altered.
  •   The greatest influence the Moon has on the earth is in generating tides. This would have allowed life from the ocean (where life began) to spend short intervals of time on land. This may have provided the ideal training ground for life to gradually adapt to the land.

ocean tidesThe Earth and the Moon have been united by gravity for over 4 billion years. It is hard to know for sure what the Earth would be like without the Moon. Would there be life? If so, what would it look like? Nevertheless, if there was no Moon and life did manage to evolve, it would almost certainly be different.

 

References: Jim LeBans, The Quirks & Quarks Guide to Space.

Did We Need The Moon For Life? Fraser Cain, Published on Nov 20, 2015, https://www.youtube.com/watch?v=KulEmr7X1HM

Origin of the Moon, tonyweston9, Uploaded on Nov 27, 2008, https://www.youtube.com/watch?v=m8P5ujNwEwM

What is a Satellite? Dan Stillman, Feb 12, 2014, http://www.nasa.gov/audience/forstudents/k-4/stories/nasa-knows/what-is-a-satellite-k4.html

Scientists propose new theory about how Earth got its moon, By Sheena Goodyear, CBC news, Posted: Nov 1, 2016. http://www.cbc.ca/news/technology/moon-theory-1.3830623

Violent Impact That Created Moon Mixed Lunar and Earth Rocks, By Charles Q. Choi, Space.com Contributor | January 28, 2016 02:28pm ET. http://www.space.com/31763-moon-creating-impact-mixed-lunar-earth-rocks.html

Did Early Earth Spin On Its Side? Monday, October 31 2016. http://www.seti.org/seti-institute/press-release/did-early-earth-spin-its-side

New Model Explains the Moon’s Weird Orbit, October 31, 2016, http://cmns.umd.edu/news-events/features/3680


 

The Anthropic Principle

the astronomerWhy are we here? This is perhaps the most fundamental philosophical question. One can imagine contemplating this question at any time in human history. Many stories have been inspired by this question, usually taking the form of myths, or religious and spiritual traditions. Today, ‘why are we here’ is also a scientific question. The anthropic principle arose as a response to the question of human existence. The idea was first proposed in 1973 by theoretical astrophysicist Brandon Carter. Since then it has been expanded and stated in several forms.

What is the Anthropic Principle?

The word anthropic is defined by the Merriam-Webster online dictionary as: “Of or relating to human beings or the period of their existence on Earth.” That’s a start. For simplicity I will stick close to Brandon Carter’s original formulation, which he expressed as two variants. I will paraphrase based on the description from a few sources:

  1. The Weak Anthropic Principle refers to our special location in the universe (both in time and space), which is conducive to our existence. The fact that we can observe the universe means that planet Earth must have the conditions necessary for our existence.
  2. The Strong Anthropic Principle refers to the fundamental laws of physics, which are precisely set for our existence. The strong principle takes into account the properties of the universe as a whole.

The Burden of Proof

habitable zoneIn a vast universe it is not surprising that a planet, like the Earth, has a special location (usually called a habitable zone or a Goldilocks zone). The specific laws of the universe needed for human life are more difficult to explain (usually called fine tuning). Using a legal metaphor, the strong anthropic principle has a greater burden of proof than the weak anthropic principle. In this case, burden of proof is a figure of speech, because the anthropic principle is as much a philosophical idea as a scientific one. 

In The Grand Design, Stephen Hawking and Leonard Mlodinow describe the weak anthropic principle as an environmental factor. They write:

“Environmental coincidences are easy to understand because ours is only one cosmic habitat among many that exist in the universe, and we obviously must exist in a habitat that supports life”

The strong anthropic principle is all-encompassing and generally more controversial. Hawkings and Mlodinow go on:

“The strong anthropic principle suggests that the fact that we exist imposes constraints not just on our environment but on the possible form and content of the laws of nature themselves”

Stating the Obvious or a Profound Insight

Is the anthropic principle a satisfying explanation? On the surface, it seems like an obvious statement that explains very little. But as I reflect on the idea, I am not so sure. Maybe it is suggesting something profound. Perhaps the answer to why we are here is simple: it could not be otherwise.

Lawrence KraussFor example, Lawrence Krauss provides an anthropic interpretation to one of the universe’s properties. In the book, A Universe from Nothing, he examines the relationship between the energy density of matter and the energy density of empty space. Yes, space has energy and it can be measured. The density of matter in the universe can also be measured. It turns out that now is the only time in cosmic history that both values are comparable. That’s a curious result.

The universe has been expanding since the big bang, and as it expands the density of matter decreases. Matter gets diluted as galaxies get farther apart from each other. Meanwhile the energy in empty space remains constant (there is nothing to dilute or increase in empty space). Therefore at the time galaxies formed the density of matter was greater than the energy in empty space. That’s a good thing, because the gravitational effect of matter was dominant, which allowed matter to come together.

However, if the values for matter and energy had been comparable at the epoch of galaxy formation, galaxies would not have formed. Empty space exerts a repulsive force, which would have canceled out normal attractive gravity. Matter would not have clumped together. Krauss writes in A Universe from Nothing:

“But if galaxies hadn’t formed, then stars wouldn’t have formed. And if stars hadn’t formed, planets wouldn’t have formed. And if planets hadn’t formed, then astronomers wouldn’t have formed!”

It seems highly coincidental that the energy values for matter and space are roughly equal now, but they could not have equalized too much earlier. Otherwise, no one would be here to observe it. Similarly, if one of a number of physical properties were slightly different, we would also not be here. That’s when anthropic reasoning steps in: An observer must observe the conditions of the universe that allows the observer to exist.

astronomersMaybe a change of perspective is needed: Instead of focusing on our present circumstances and looking back, we can look at the evolution of the universe. Life is a latecomer to the process, of which an incalculable series of events occurred. Our existence is the result of all that came before. Although it does appear that the universe was made for us, it is in fact, the universe that made us. We were formed from the conditions that were set long before conscious beings could observe any of it.

Is Physics an Environmental Science?

The traditional approach of physics is to discover and understand the universe we live in. The fundamental laws and the values for the constants of nature are consistent throughout the observable universe. The physical laws discovered on Earth can be applied to the universe as a whole. But there can only be one exact set of laws and history that allow for our existence. That’s unless our universe is not the only one.

For some, recent scientific evidence is suggesting that there are many universes (a multiverse). Others point out that inferring a multiverse is not science; because by definition other universes cannot be observed directly (they would exist outside our observable universe). If we apply the strong anthropic principle to the multiverse theme, it does partly explain the exact parameters of our universe.

If the cosmos is populated with many universes, possibly infinite universes, then the laws of physics could be purely random. They would simply emerge as an environmental consequence. Some physicists have compared the multiverse to a foam of bubbles (each bubble representing a universe). The laws could be different in every bubble of an endless cosmic foam. Some bubble universes could be similar to ours, others vastly different.

Of course, this is a hypothetical argument. Nevertheless, if we could observe every universe in a multiverse, every single one would be finely tuned for its own existence. Anthropic reasoning would state that there is nothing special about our universe. In all the non-life generating universes there is no one to observe them, in ours there is. It’s that simple. Obviously, the anthropic principle (inferring a multiverse or not) is not a proven argument, but it’s one of many possible answers to the question: Why are we here?

 

References: Stephen W. Hawking and Leonard Mlodinow, The Grand Design (New York: Bantam Books, 2010), 155.

Lawrence M. Krauss, A Universe from Nothing (New York: Free Press, 2012).


 

How Could We Discover Alien Life in The Universe?

exoplanetOf all the so-called big questions, perhaps none inspires more curiosity than the following: Is there life elsewhere in the universe? The question leads to many other questions, speculations, possibilities and impossibilities. In recent years science has made tremendous progress towards understanding the universe, both in what is out there and how it came to be. The number of stars and galaxies is enormous, and we now know that many stars have planetary systems (nearly 2000 exoplanets have been discovered). Some planets outside our solar system are believed to be earth-like, in size, composition and location in relation to their host star.

Recent discoveries have shown that other locations in the universe may have conditions similar to Earth. Our galaxy, the Sun and the Earth are not unique. That said, the Earth supports life due to a series of coincidences that may be unique. Still an unimaginably large cosmos presents many opportunities for life-giving conditions to align. This means that the possibility for alien life may be greater than once thought. There seems to be 3 ways in which humans could discover extraterrestrials: 1) Searching the universe for life. 2) Sending signals in outer space so aliens could intercept them. 3) Aliens discovering us. Let us examine these possibilities a little further:

Searching the Universe for Life

mars roverNumerous unmanned space probes have explored our Solar System. The firsts space probes to visit other planets were launched in the sixties, even before the first lunar landing. By the seventies probes were reaching the outer planets, and in 2015, New Horizons made its historic Pluto flyby (the farthest planet when I was in school). Several rovers have landed on Mars, transmitting images and analyzing soil samples (the first successful mission was in 1976). Presently, the rovers Opportunity and Curiosity are still operating on Mars.

Scientists have discovered much about the composition of the planets and their moons, including evidence for liquid water. A few moons of Jupiter and Saturn are believed to contain oceans of liquid water beneath their icy surfaces. And in October 2015, NASA made the announcement that liquid water flows on Mars. A number of conditions are necessary for life to exist, but liquid water is a must for all known life on Earth (the starting line in the search for life). At least if life exists somewhere without water, it would be to foreign for us to imagine.

If there is alien life in our Solar System, it would be simple life and probably microbial; but what about intelligent life? How far do we have to look? The Solar System is merely our cosmic neighborhood.

In 1995, the first exoplanet was discovered and many more followed. The existence of the planets is inferred by studying minor changes in starlight, which are caused by the presence of planets; however, the distances involved are immense. The closet star system is Alpha Centauri (a 3 star system), which is 4.25 light years away. By comparison it takes about 8 minutes for the Sun’s light to reach the earth. The Milky Way alone is 100,000 to 120,000 light years in diameter, and contains over 200 billion stars. Beyond our home galaxy, there are over 100 billion galaxies in the observable universe.

By numbers alone, it seems that the opportunities for extraterrestrial life are endless. But the odds against discovering alien life seem equally as great. At this time indirect evidence is all we have. For example: exoplanets that may be located in habitable zones or distant regions that have chemical compositions similar to our Solar System. Maybe all we will find is information or signals which have to be decoded, and conclusive evidence may never be found.

Sending Signals in Outer Space

Humans have been inadvertently sending signals to the universe since the first radio and television broadcasts. By now the signals have reached thousands of star systems. However, they travel as electromagnetic waves and will go undetected unless someone has an appropriate receiver at the other end. Even if the signals have crossed advanced civilizations, what are the chances that they have built earth-like technology? There is also the evolutionary timeline to consider. Could some civilizations be too early in their development, or could others have long gone extinct?

Attempts were made to purposefully send messages to outer space. In 2008, the Beatles song “Across the Universe” was broadcasted towards Polaris (the North Star). But even traveling at light speed the signal will take over 300 years to reach its destination. And if we get a reply, it will take another 300 years.

voyager 1The space probes Pioneer 10, Pioneer 11, Voyager 1 and Voyager 2 have completed their missions exploring the planets, and have left the Solar System (speeding away indefinitely). They all contain time capsules, with information about humans and our location in the universe. Incidentally, the well-known image of the pale blue dot was taken by Voyager 1 as it left our Solar System; a snapshot of the earth from 6 billion miles away.

Sending space probes into interstellar space solves one problem, but creates another. On the one hand they are concrete objects (not like radio waves), on the other hand they travel much slower than radio waves. For example, the nearest star system is 4 light years away (that’s 4 years for a radio signal). By comparison, it will take 70,000 years for the space probes to travel the same distance. Either way, the odds appear slim that our messages will ever be noticed.

Aliens Discovering Us

alienIt is possible that aliens have already discovered the Earth; they may even have tried to communicate with us. Some people believe that aliens have visited the Earth, but for a logically minded person the stories are far-fetched. From a scientific perspective, there is no evidence to support such claims. Everything scientists know about space travel makes alien visitations practically impossible. The distances are simply too great; it would take hundreds of generations to make the voyage (unless aliens have lifespans of a 1,000 years or use teleportation and wormholes, though we shouldn’t believe everything we see in Star Trek).

The most likely form of alien contact would be indirect, such as something moving at light speed, like an electromagnetic wave. An alien space probe sent many years ago would be a possibility, however, it would be a tremendous stroke of luck to pass anywhere near the Earth. Then again, it depends on how many probes are out there. The odds of being found or finding something is proportional to how many are looking. Therefore, we don’t know if humans are the only species looking to the stars for life.

A Numbers Game

By studying the light spectrum of distant galaxies, astronomers have discovered that the chemistry of the universe is similar throughout. In addition, at the largest of scales the universe has evolved basically the same everywhere. The Earth has intelligent life because of a series of fortunate events (fortunate for us); it could also have occurred elsewhere. Or maybe a very different form of life evolved due to totally different circumstances.

For example, take the Earth’s distance from the Sun as one of many specific variables. The Earth is about 93 million miles from the sun, just the right distance to allow for liquid water. To appreciate how precise the location is, the change from summer to winter is caused by a 23.5 degree tilt of the earth’s axis. As the Earth orbits the sun it either tilts towards (in summer) or away (in winter) from the sun. That’s it. Of course the northern and southern hemispheres have their seasons in reverse relation to each other.

So is the existence of life simply a numbers game? Given the unimaginable size of the universe, is it inevitable that conditions will be just right somewhere else? With the number of planets that likely exist, even if the odds for life were a billion to one, there would still be life on a billion planets. If I had to make a call, I think the odds are good that there is life elsewhere in the universe. However, the odds are slim that we will ever discover it. The distances involved present challenges that may be too much to overcome.

 

References: Big Picture Science: Life in Space, April 20, 2015.

Big Picture Science: How to Talk to Aliens, January 12, 2015.

Universe Today: 10 Facts About the Milky Way, by Matt Williams, http://www.universetoday.com/22285/facts-about-the-milky-way/ December 3, 2014.

Universe Today: What is the Closest Star, by Fraser Cain, http://www.universetoday.com/102920/what-is-the-closest-star/ June 14, 2013.


 

Nature’s Fine Tuning and the Multiverse

numbersThere are a number of fundamental physical constants of nature, in which their values seem to be finely tuned. Examples of  such constants are: the speed of light, the strength of gravity, the mass of the elementary particles, and the strength of the atomic forces. The fine-tuning angle comes into play when one considers the exact parameters of the constants. Hypothetically, if one were to adjust the values just a little bit, the universe would be vastly different. This fact alone does not present a problem. However, physicists have noted that minor changes to the values of the constants would not allow life to develop. It is as if the universe knew we were coming, or is it?

The values of the physical constants are critical for giving our universe the structure that it has. For example: the precise strength needed to hold the atomic particles together in stable arrangements, and the gravitational force needed to clump matter into stars and planets. If the strength of gravity was slightly weaker, matter in the early universe would have spread apart too quickly; thus preventing stars from forming. Conversely, if the gravitational force was a little stronger, matter would have come together too quickly and everything would have collapsed. It is clear to scientists that gravity, as well as other values, could not be adjusted very much without erasing the possibility for life.

The Most Extreme Fine Tuning

Although the apparent fine tuning of the constants demand an explanation, nothing compares to the level of fine tuning of one particular constant. This is called the cosmological constant (also called dark energy), and it represents the value of the energy in empty space. The cosmological constant is believed to exert an outward force, which is causing the universe to expand at an accelerated rate. In 1998, the value of the cosmological constant was measured by two teams of astronomers. The number they came up with is extremely small, a decimal point followed by 122 zeros and a one (measured in Planck units).

The energy in empty space, represented by the cosmological constant, is only relevant at the largest of scales. As the universe expands the amount of space is also increasing, thus increasing the effect of the dark energy. But in the distant past when the universe was much smaller, the total energy in space would have produced a far lesser effect. And here is the catch. If the outward push of the cosmological constant was slightly larger by a few decimal points, it would have counteracted the pull of gravity too quickly. This would have prevented stars, planets and galaxies from forming. In this scenario life would not exist.

By removing just a few zeros from an already small value, a universe suitable for life would disappear. Physicists are at a loss to explain why the number is so small and so finely tuned for our existence. In addition, the value of the cosmological constant revealed by observations is far less that what theory predicts. That is, the theory of the microscopic realm (quantum mechanics) predicts that the energy in empty space should be much larger. The mismatch between theory and observation does not sit well with physicists, as it shows that there is something missing with this picture.

Possible Solutions

The specific values of the physical constants require an explanation. Some people will look for a metaphysical solution. This will usually imply a creator for the universe who setup the constants for a purpose. The word God is the preferred choice, and it suggests that the universe was planned for our existence. Yet for others, crediting God for designing the universe in a special way is a non-explanation. One would still have to explain where God came from and why he was there in the first place.

Another line of reasoning would be to accept that mere chance accounts for the constants. But given the amount of fine tuning, this seems akin to winning a lottery with an infinite number of combinations. Chance alone is not a very satisfying solution. There is also the possibility that we don’t have enough information to solve the problem. Maybe a deeper understanding of the laws of physics is needed, and someday physicists will find the answer.

 The Multiple Universe Proposal

multiverseThe word universe has traditionally been used to describe all that exists. However, cutting-edge physics is requiring that a change of perspective is needed. Through a variety of physical discoveries the idea of multiple universes is being considered. The words parallel universes, parallel worlds, alternate universes, multiverse and others are being used. In the multiple-universe theme, the word universe has a slightly different meaning. Universe no longer means all there is, but rather means a region of a larger cosmos that is separated from other regions.

Physicist and science writer Brian Greene states, in The Hidden Reality, why the concept of multiple universes is compelling:

” The subject of parallel universes is highly speculative. No experiment or observation has established that any version of the idea is realized in nature… That said, I find it both curious and compelling that numerous developments in physics, if followed sufficiently far, bump into some variation on the parallel-universe theme.”

Although not yet experimentally tested, having large numbers of universes (possibly infinite) could explain the fine tuning of the physical constants. The logic is simple. With many universes, with different possible values for the constants, it is likely that one has the values we observe. Therefore, it is not surprising that we find ourselves in a universe that allows life. In the universes that have conditions that don’t allow life, there is no one to observe them, no one to say that they are not finely tuned for life.

As Brian Greene suggested, there are several theories in physics that imply a multiverse. The reasoning is technical, though I will list a few examples, which point to the possibility of a multiverse:

  • Eternal Cosmological Inflation: The extreme burst of spatial expansion at the early moments of the universe is known as inflation. Inflation is a cosmological principle, which in theory could happen anywhere, thus giving rise to multiple big bangs.
  •  A Spatially Infinite Cosmos: By inferring an infinite expanse of space-time, there is a limit to ways particles of matter can be arranged. Conditions in one location would eventually have to repeat somewhere else, creating parallel universes.
  •  The Extra Dimensions of String Theory: String theory proposes that at the tiniest of scales there exist extra spatial dimensions. It also states that there are many possible shapes for the extra dimensions of space. However, string theory cannot determine which of the shapes corresponds to our universe. If string theory is correct, the different possible shapes for these extra dimensions could be realized in different universes.
  • The Many-Worlds Interpretation of Quantum Mechanics: The atomic/subatomic realm is governed by randomness and understood using probabilities. Interpretations can vary. The many-worlds interpretation states that all the possible outcomes associated with quantum mechanical probabilities really happen, resulting in parallel worlds.

parrallel universeNot all the multiple universe proposals would yield different values for the constants. Some would produce exact replicas of our universe, or very close copies. Hence the term parallel universe. Yet other proposals would allow for different laws of physics or different values for the constants. These could be universes that are totally foreign and barely recognizable to us.

Whether we live in one of multiple universes is anyone’s guess. Presently, there is no known method that could observe them. Nevertheless, there are plenty of cases where physical theories or mathematics have pointed toward a phenomenon in nature, even before it was observed. And then at some later date, observations confirmed the theory. Therefore, if modern physics is suggesting the existence of a multiverse, it provides an interesting argument for the fine tuning of the physical constants of nature.

 

References: Brian Greene, The Hidden Reality (New York: Alfred A. Knopf, 2011), 8, 9.

Leonard Susskind – Is the Universe Fine-Tuned for Life and Mind? (Closer to Truth), Published on Jan 8, 2013. https://www.youtube.com/watch?v=2cT4zZIHR3s

 The Fabric of the Cosmos – Universe or Multiverse (Published on July 16, 2014) https://www.youtube.com/watch?v=ib0RNqVusoU