Tag Archives: Physics

Living in a Medium-Size World

The human experience is limited by the range of our senses. We can only see, hear, touch, smell and taste so much. Our sensory input is the result of the world directly around us, and that is what we perceive as reality. Humans have evolved to intuitively deal with the medium-size world. Hidden from us are the microscopic realm and the large-scale universe. In addition, we are not well equipped to deal with things moving at light speed and extreme time scales (sometimes called deep time).

universe-telescopeTo a large extent modern science has advanced due to decoding the small-size world and the large-size world. The current picture of the universe is defined by technologies that probe realities beyond the human senses. Scientists have come to the realization that human intuition is deceptive in understanding how the universe works. For example: the behavior of atoms, the formation of stars and galaxies, the speed of light, and the evolutionary timeline. This creates a gap between knowledge and perception, which demands a stretch of imagination to bridge the gap. It may even be wise to expect that new scientific discoveries will be counter-intuitive, just like many significant discoveries from the past.

 Some People Can’t Go There

Why are some people able to digest objective scientific information, while others can’t get beyond their subjective experience? In other words, to expand our world view we need to look outside ourselves. An individual’s life experience is by far too small a sample size to make any meaningful conclusions, particularly when examining some of life’s big questions. There is tremendous variety in life experiences, both in time and geography.

Before modern science the earth was viewed as the center of existence; humans were the focal point of all life and the universe. Now the message is clear that humans occupy a planet that is a tiny part of a much grander scheme. Human life is also a brief existence in an epic evolutionary tale of innumerable life forms. An appreciation of the modern scientific view requires we look beyond our direct experience and consider a reality foreign to ourselves. It is a challenging mental and emotional exercise to honestly look at life from a truly universal perspective.

Albert Einstein was a revolutionary thinker and well-known for his thought experiments. It was by first imagining physical scenarios that he came up with his great insights. He is quoted as saying:

“The true sign of intelligence is not knowledge but imagination.” and “Logic will get you from A to B. Imagination will take you everywhere.”

A Miss-Match Between Intuition and Reality

If we had to find candidates for the most influential and revolutionary scientific theory of all time, at a minimum the list would include: Newton, Darwin, Einstein and the quantum theory scientists. These three individuals and the group of scientists that formulated quantum theory have created the foundation of modern science. Newton’s ideas describe the physics of our everyday reality. Einstein worked out the precise laws of space, time and the large-scale universe. Quantum physics describes the atomic and subatomic realm. And Darwin’s theory of evolution is the cornerstone for studying all life.

quantum-universeAn interesting angle with these landmark ideas is that they are all counter-intuitive. These theories are defined by hidden realities that required great minds and creative techniques to uncover. It is not clear whether others could have come up with similar discoveries; however, I think that few thought along those lines. In the early years of science, knowledge of the world was limited to the human senses. The idea that to accurately describe our world required a leap beyond the sensory experience of the medium-size world must have been revolutionary. Today, scientists and philosophers have come to accept theories based on evidence, even if it goes against common sense.

Before Newton no one had considered that the same force was responsible for controlling the orbits of the planets and falling objects on earth. Space and time were believed to be absolute and unchanging before Einstein showed that they were flexible. Life was clearly designed by God (each species set apart in its present form) before Darwin unveiled the mechanism of natural selection as a powerful creator. And in several ways quantum theory is the most bizarre of scientific theories; For instance, even those that work with quantum mechanics can’t explain why light behaves as both a particle and a wave.

If these examples are too abstract for you, consider the deceptive everyday observation of the sun traveling across the sky. In medieval times it was thought to be heretical to suggest anything other than the sun moving around a stationary earth. And today, if we go by our senses alone we would reach the same conclusion. The earth moves, it spins and orbits the sun, but we don’t feel it. To take it a step further, if the sun actually orbited the earth, it would still look exactly the same. How many other things about our world do we get wrong by overlooking scientific facts? This could be due to ignorance, oversight, or possibly by over rating subjective experience.

Evolution is the Big One

charles-darwinDarwin clearly knew the implications of his theory of evolution; perhaps that is why he waited a couple of decades to publish. Evolution, properly understood, solved the great mystery of life’s propagation and overthrew centuries of beliefs. In terms of its philosophical implications, evolution is the most life-altering scientific idea. Yet, it is still not universally accepted or understood. If I was only exposed to one scientific idea, I would pick evolution; it has the farthest reach and most deeply influences us.

We don’t need to know how atoms work or how galaxies form to function in everyday life. Common sense and intuition will serve us well enough in most situations. Understanding evolution is debatable; I think it is very valuable in understanding human behavior and how our lives unfold (not to mention the natural world).

If we neglect thinking in evolutionary terms we can easily be led astray. Take for example the vibrant colors of flowers: We could assume that the flowers are meant for the enjoyment of human observers (designed for our benefit). But we are only bystanders, which have stumbled upon a deeper truth. The colorful flowers have attracted pollinators over long periods of time, allowing seeds to spread. Nature favors brightly colored flowers over duller colors, because they are more noticeable to birds and insects. Generation after generation the colorful flowers have the advantage. It is not about us, it’s about the insects and the flowers. Nevertheless, we are here and can still enjoy the flowers.

The point I am trying to make is that the deeper questions of our lives need a deeper view. We can’t tackle profound questions with the same reasoning that we use to bake a cake or change a tire; a leap of imagination is required. Although we can’t think about the mysteries of life and the universe all of the time, for those that are philosophically inclined, we cannot help but think about it some of the time. Be forewarned that surface impressions are usually not the whole story.

 

References: Brainy Quote, 2001-2016. http://www.brainyquote.com/quotes/authors/a/albert_einstein.html


 

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Is Anything Possible?

You’ve heard it before: ‘anything is possible.’ I have also, but how much truth is there in this statement? On the surface it sounds OK; it’s usually used in a positive tone (but not always) and it’s open to seemingly unlimited possibilities. What could be wrong with that? Hold on just a minute until we look a little deeper.

highway-at-nightIs anything really possible? And can we determine when something becomes impossible? If a person losses a hand, it won’t grow back. A conventional air plane will not fly without wings. Pure water will not freeze if the temperature is above 0 degrees Celsius. So there you have it, anything is not possible. I don’t think this is a big revelation. People who say that ‘anything is possible’ know that it isn’t true. So why do they say it? We all go through life with insufficient knowledge, it’s just part of being human. I believe what people are really thinking is: many things are possible, or they don’t know what’s possible.

Nature’s Regularities

‘I don’t know what’s possible’ doesn’t sound quite as positive as ‘anything is possible.’ So maybe that’s why the word anything is so often used. Despite our limited knowledge, there lies one fundamental truth which determines what is possible and what isn’t. This truth is related to the following question: What does the loss of a hand, an airplane not being able to fly and water not freezing have in common? On the surface they seem totally unrelated; however, they share a subtle and profound relationship. I’ll get back to this later but first a little back ground.

There are reasons why some things are possible and others impossible and they are fundamentally the same reasons. It has to do with the way the world works (in fact the entire universe). There exist regularities in nature, both seen and unseen. Some of these regularities would have been known in ancient times simply by observing nature. For example, the ancients were aware of the conditions needed to make fire and how to put it out. They learned how to grow food by observing how crops responded to the seasons and so on. Early humans had a rudimentary understanding of what might be possible. They achieved this with varying degrees of success by observing nature’s regularities. However, they lacked an appreciation of what was behind the observed regularities. A deeper understanding would come about later.

The Scientific Revolution of the 15th and 16th hundreds is the unofficial line of demarcation of modern science. This is when scientists began deciphering the laws that govern nature. The laws of nature are fundamental to the regularities we observe. For the first time nature could be explained by a series of scientific laws rather than superstition, conjecture or a few rules of thumb. For instance, seen phenomena such as the motion of objects were explained by Newton’s laws of motion. Perhaps even more ground breaking is that eventually parts of the unseen world could also be explained by scientific laws. For Example, quantum laws of the early 19th hundreds, of which several scientists were involved, explained the workings of atomic and sub-atomic particles.

Out of the Ordinary

In everyday experience people often use the ‘anything is possible’ line as a positive projection into the future. They are usually thinking about the trajectory of one’s life and the numerous untapped possibilities. In this context they are referring to ordinary events in human affairs. Ordinary in the sense that one doesn’t had to believe in anything outside the established laws of nature to account for what might unfold.

ghostSome people consider other ideas, which fall into a totally different category. These ideas are sometimes called paranormal or supernatural, but personally I dislike both those terms. The reason being, that some of these concepts diminish the established laws of nature. The simplest way I can convey what kind of ideas I mean is to begin with a list. The following is just from the top of my head and much more could apply: alien visitations, ghost stories, miraculous healings, near-death experiences, psychic readings and so on. With this list, one should ask: how do the laws of nature fit in these schemes?

Let’s look into one of the possibilities listed above. With alien visitations for instance, one has to consider such things as a life-sustaining planet and the distance the aliens would have to travel. A little understanding of the laws of nature can give us clues as to how seriously we should consider a claim. We know that other than Earth, there is no complex life in our Solar System. So our star system is out.

The nearest star system is a three star system call Alpha Centauri, of which Proxima is the closest (about 4.24 light years away). On the surface this doesn’t sound all that far away. However, if we consider present technologies, it would take anywhere from 19,000 to 76,000 years to make the trip. The wide range in estimates has to do with which technologies would ultimately prove viable for such a trip. We should also consider the possibility that the proposed aliens would have to come from much farther away.

rocketIn short, in an absolute best case scenario, there would have to exist a life-sustaining planet where intelligent life evolved and its inhabitants developed far superior technology. Not an impossibility, but a long shot. The determining factor is the limits imposed by the laws of physics. The limits in this case are distance and how fast a spaceship can travel. Keep in mind that no matter how advanced a technology may be it cannot overcome the laws of physics. Considering the distances involved, it seems unlikely that we have been visited by aliens.

Pure and Simple

Now back to my earlier question: about the loss of a hand, an airplane unable to fly and water not freezing. All three are determined by the laws of nature; specifically, the limits of biology, physics and chemistry. And that’s not only true for these three scenarios but for any proposed idea. That’s right, any proposed idea. That being said, it needs to be mentioned that our understanding of the laws of nature are likely incomplete and currently serve as our best representation of reality. Nevertheless, whether we are talking about everyday experience or the fantastic, the laws of nature run the show. Whether the answer lies within the scope of our knowledge or not; it all boils down to one simple truth: anything which is in principle allowed by the laws of nature is possible and anything which is not allowed by the laws of nature is impossible!

 

References: Universe Today, How Long Would it Take to Travel to the Nearest Star?, Sept 6, 2016 by Matt Williams. http://www.universetoday.com/15403/how-long-would-it-take-to-travel-to-the-nearest-star/


 

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


 

Discovering the Nature of Gravity

Of course we all know what gravity is. It’s the force responsible for making objects fall, keeping our feet firmly planting on the ground, and maintaining the moon’s orbit around the earth. But by what mechanism does gravity accomplish these tasks? Surely there are no invisible strings of a master puppeteer. The full story behind understanding the force of gravity spans at least 400 years. Three giant steps have led to modern physics’ current picture.

Heliocentric Modle

 Step 1: The Copernican Revolution, Galileo and Kepler

Just before he died, in 1543, Nicolaus Copernicus published his famous work describing the heliocentric model of the universe. Although he had formulated his theory years earlier, he delayed publishing until the end of his life. This was probably because he feared criticism from contemporaries or retribution from the church. Placing the sun at the center of the known universe (as opposed to the earth) was a revolutionary idea for its time. This was a monumental leap in the early scientific age.

The idea that the earth moved went against common sense and intuition. In reality, whether the sun moved or the earth moved could not be determined by visual means. Sometimes science has to rely on other methods; in this case, the daily/monthly movements of the planets had to be charted and analyzed.

An object can only be said to be in motion in reference to something else. For example, if you are on a boat that is departing from a large dock, and you look to your side, you will see the dock moving. For an instant you will think that the dock is moving. Then you realize this can’t be true. You may feel the boat rocking or accelerating, but from a visual point of view you can’t tell which is moving.

Years later, Galileo adamantly supported Copernicus’ view and took the brunt of the attack from the church. He was sentenced to house arrest, where he spent the last decade of his life. Nevertheless, Galileo’s contribution to science extended much further than the celestial model. He was instrumental in establishing observation and experimentation as pillars of scientific reasoning. It was becoming clearly that there was order and predictability in nature, which was accessible to human analysis.

Johannes Kepler also lived in Galileo’s time, and he was able to calculate the motion of the planets using mathematics. His most famous work is known as the laws of planetary motion, a precursor to Newton’s laws. In the process he calculated that the orbits of the planets were not perfect circles as originally thought. But rather moved in elongated circles called ellipses. Although the movement of the celestial bodies were being charted in great detail, there was still no comprehensive theory of gravity.

 Step 2: Newton’s Insights

Newton's Cannon

Newton’s Cannon

Isaac Newton imagined a cannon perched on a mountain top and asked himself the following question: what would happen if cannon balls were fired at steadily increasing speeds? The first few balls would start out in a straight line and then fall to the earth in a curved trajectory. However, if he kept going, something peculiar would happen. The curved path of the cannon ball would eventually match the curvature of the earth. The cannon ball would be in perpetual free fall, and orbiting the earth.

This was the key insight. The same force that was responsible for maintaining the orbits of the moon and planets also caused an apple to fall from a tree. No one had thought of this before. At least if someone had, it did not become public knowledge.

Therefore, the story that Newton got his idea of gravity when an apple fell on his head may not be true. He could have been thinking about cannon balls. But having a cannon ball fall on his head does not make for an inspiring story. What followed was a mathematical unity of both the heavens and earth, his laws of motion and universal gravitation. In spite of Newton’s great achievements, he still had no clue what gravity actually was. It would take more than 200 years for someone to come up with the answer.

 Step 3: Einstein’s Imagination

Among many things, Albert Einstein was famous for his thought experiments. He imagined physical scenarios, which he tried to figure out what would happen and how it could be explained. Perhaps this is how he came up with his picture of gravity.

In 1915, ten years after his theory of special relativity, he published the theory of general relativity. As it relates to the actual cause of gravity, the answer is as counter intuitive as the earth moving through space. The gravitational effects are caused by the properties of space itself; just as Einstein had shown that time was flexible (in special relativity), space was also flexible.

It is the warping or curving of the fabric of space that make objects fall and maintain the orbits of celestial bodies. It is similar to the effect of a large rubber sheet (like a trampoline). If one were to place a large heavy ball at the center of the sheet, any smaller balls would be drawn to it by the warping of the sheet (caused by the heavy ball).

Warps in Space

Warps in Space

Orbits will be created when a balance is established between the motion of a body and the distortion of the spatial fabric. That’s it, distortions in space caused by massive bodies, not a pull or push is responsible for gravity. This theory goes beyond Einstein’s imagination; it has been confirmed by scientific observations. It took 400 years of investigation to understand the basic property of one of the most familiar forces on earth.

 

References: Richard Dawkins, The Magic of Reality

The Elegant Universe 1 of 3 Einstein’s Dream (Published on Jun 21, 2012) https://www.youtube.com/watch?v=UV_X2B5OK1I

Stephen Hawking’s Universe -101- Seeing is Believing (June 14, 2013) https://www.youtube.com/watch?v=5kgPxvJqvEA