Category Archives: Physics

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Is Time Real Or Just a Construct of Our Mind?

Categories, Physics, Time Travel, Universe Mysteries, , , , , , ,

Philosophers have debated the nature of time for over 2500 years, and have left us with three principal theories, listed below in no particular order:

1) Presentists Theory of Time—The “presentists” philosophers argue that present objects and experiences are real. The past and future do not exist. This would argue that time is an emerging concept, and exists in our minds.

2) Growing-Universe Theory of Time—The “growing-universe” philosophers argue that the past and present are real, but the future is not. Their reasoning is the future has not occurred. Therefore, they reason the future is indeterminate, and not real.

3) Eternalism Theory of Time—The “eternalism” philosophers believe that there are no significant differences among present, past, and future because the differences are purely subjective. Observers at vastly different distances from an event would observe it differently because the speed of light is finite and constant. The farthest-away observer may be seeing the birth of a star while the closest observer may be seeing the death of the same star. In effect, the closest observer is seeing what will be the future for the farthest-away observer.

Now let us ask what does science have to say about time and start by discussing the “arrow of time.” The flow of time, sometimes referred to as the “arrow of time,” is a source of debate, especially among physicists. Most physicists argue that time can only move in one direction based on “causality” (i.e., the relationship between cause and effect). The causality argument goes something like this: every event in the future is the result of some cause, another event, in the past. This appears to make perfect sense, and it squares with our everyday experience. However, experiments within the last several years appear to argue reverse causality is possible. Reverse causality means the future can and does influence the past. For example, in reverse causality, the outcome of an experiment is determined by something that occurs after the experiment is done. The future is somehow able to reach into the past and affect it. Are you skeptical? Skepticism is healthy, especially in science. Let us discuss this reverse causality experiment.

In 2009, physicist John Howell of the University of Rochester and his colleagues devised an experiment that involved passing a laser beam through a prism. The experiment also involved a mirror that moved in extremely small increments via its attachment to a motor. When the laser beam was turned on, part of the beam passed through the prism, and part of the beam bounced off the mirror. After the beam was reflected by the mirror, the Howell team used “weak measurements” (i.e., measurement where the measured system is weakly affected by the measurement device) to measure the angle of deflection. With these measurements, the team was able to determine how much the mirror had moved. This part of the experiment is normal, and in no way suggests reverse causality. However, the Howell team took it to the next level, and this changed history, literally. Here is what they did. They set up two gates to make the reflected mirror measurements. After passing the beam through the first gate, the experimenters always made a measurement. After passing it through the second gate, the experimenters measured the beam only a portion of the time. If they chose not to make the measurement at the second gate, the amplitude of the deflected angle initially measured at the first gate was extremely small. If they chose to make the measurement at the second gate, the deflected angle initially measured at the first gate was amplified by a factor of 100. Somehow, the future measurement influenced the amplitude of the initial measurement. Your first instinct may be to consider this an experimental fluke, but it is not. Physicists Onur Hosten and Paul Kwiat, University of Illinois at Urbana-Champaign, using a beam of polarized light, repeated the experiment. Their results indicated an even larger amplification factor, in the order of 10,000.

Although the above experimental results are relatively new, the classic double slit experiment implies exactly the same conclusion, namely future measurements can influence past behavior. For those of you not familiar with the double slit experiment, a brief synopsis is provided below.

There are numerous versions of the double-slit experiment. In its classic version, a coherent light source, for example a laser, illuminates a thin plate containing two open parallel slits. The light passing through the slits causes a series of light and dark bands on a screen behind the thin plate. The brightest bands are at the center, and the bands become dimmer the farther they are from the center. The series of light and dark bands on the screen would not occur if light were only a particle. If light consisted of only particles, we would expect to see only two slits of light on the screen, and the two slits of light would replicate the slits in the thin plate. Instead, we see a series of light and dark patterns, with the brightest band of light in the center, and tapering to the dimmest bands of light at either side of the center. This is an interference pattern and suggests that light exhibits the properties of a wave. We know from other experiments, for example the photoelectric effect, that light also exhibits the properties of a particle. Thus, light exhibits both particle- and wavelike properties. This is termed the dual nature of light. This portion of the double-slit experiment simply exhibits the wave nature of light. Perhaps a number of readers have seen this experiment firsthand in a high school science class.

The above double-slit experiment demonstrates only one element of the paradoxical nature of light, the wave properties. The next part of the double-slit experiment continues to puzzle scientists. There are five aspects to the next part.

1. Both individual photons of light and individual atoms have been projected at the slits one at a time. This means that one photon or one atom is projected, like a bullet from a gun, toward the slits. Surely, our judgment would suggest that we would only get two slits of light or atoms at the screen behind the slits. However, we still get an interference pattern, a series of light and dark lines, similar to the interference pattern described above. Two inferences are possible:

a. The individual photon light acted as a wave and went through both slits, interfering with itself to cause an interference pattern.
b. Atoms also exhibit a wave-particle duality, similar to light, and act similarly to the behavior of an individual photon light described (in part a) above.

2. Scientists have placed detectors in close proximity to the screen to observe what is happening, and they find something even stranger occurs. The interference pattern disappears, and only two slits of light or atoms appear on the screen. What causes this? Quantum physicists argue that as soon as we attempt to observe the wavefunction of the photon or atom, it collapses. Please note, in quantum mechanics, the wavefunction describes the propagation of the wave associated with any particle or group of particles. When the wavefunction collapses, the photon acts only as a particle.

3. If the detector (in number 2 immediately above) stays in place but is turned off (i.e., no observation or recording of data occurs), the interference pattern returns and is observed on the screen. We have no way of explaining how the photons or atoms know the detector is off, but somehow they know. This is part of the puzzling aspect of the double-slit experiment. This also appears to support the arguments of quantum physicists, namely, that observing the wavefunction will cause it to collapse.

4. The quantum eraser experiment—Quantum physicists argue the double-slit experiment demonstrates another unusual property of quantum mechanics, namely, an effect termed the quantum eraser experiment. Essentially, it has two parts:

a. Detectors record the path of a photon regarding which slit it goes through. As described above, the act of measuring “which path” destroys the interference pattern.
b. If the “which path” information is erased, the interference pattern returns. It does not matter in which order the “which path” information is erased. It can be erased before or after the detection of the photons.

This appears to support the wavefunction collapse theory, namely, observing the photon causes its wavefunction to collapse and assume a single value.

5. If the detector replaces the screen and only views the atoms or photons after they have passed through the slits, once again, the interference pattern vanishes and we get only two slits of light or atoms. How can we explain this? In 1978, American theoretical physicist John Wheeler (1911–2008) proposed that observing the photon or atom after it passes through the slit would ultimately determine if the photon or atom acts like a wave or particle. If you attempt to observe the photon or atom, or in any way collect data regarding either one’s behavior, the interference pattern vanishes, and you only get two slits of photons or atoms. In 1984, Carroll Alley, Oleg Jakubowicz, and William Wickes proved this experimentally at the University of Maryland. This is the “delayed-choice experiment.” Somehow, in measuring the future state of the photon, the results were able to influence their behavior at the slits. In effect, we are twisting the arrow of time, causing the future to influence the past. Numerous additional experiments confirm this result.

Let us pause here and be perfectly clear. Measuring the future state of the photon after it has gone through the slits causes the interference pattern to vanish. Somehow, a measurement in the future is able to reach back into the past and cause the photons to behave differently. In this case, the measurement of the photon causes its wave nature to vanish (i.e., collapse) even after it has gone through the slit. The photon now acts like a particle, not a wave. This paradox is clear evidence that a future action can reach back and change the past.

To date, no quantum mechanical or other explanation has gained widespread acceptance in the scientific community. We are dealing with a time travel paradox that illustrates reverse causality (i.e., effect precedes cause), where the effect of measuring a photon affects its past behavior. This simple high-school-level experiment continues to baffle modern science. Although quantum physicists explain it as wavefunction collapse, the explanation tends not to satisfy many in the scientific community. Irrefutably, the delayed-choice experiments suggest the arrow of time is reversible and the future can influence the past.

The above experimental results raise questions about the “arrow of time.” It appears that under certain circumstances, the arrow of time can point in either direction, and time can flow in either direction, forward or backward. If that is true, we can argue time has a physical reality. In other words, it is not a construct of our mind. The reality of time implies that actions in the past can influence the future and actions in the future can influence the past. If time were simply a mental construct, it would not be possible for future events to influence the past.

One last point, none of the above negates Einstein’s view of reality consisting of four-dimensional space-time. All aspects of relativity continue to apply. The above article is intended to substantiate that nature of time itself is a physical reality and not a mental or mathematical construct.

Nature of Light

Can Anything Travel Faster Than the Speed of Light?

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Can anything travel faster than the speed of light? To answer this question, let us understand the nature of light. Here are three salient facts about light:

1. First, light can exhibit both the properties of a wave and a particle. For all of the Nineteenth Century, and for the early part of the Twentieth Century, most scientists considered light “a wave,” and most of the experimental data supported that “theory.” However, classical physics could not explain black-body radiation (the emission of light due to an object’s heat). A light bulb is a perfect example of black-body radiation. The wave theory of light failed to describe the energy (frequency) of light emitted from a black body. The energy of light is directly proportional to its frequency. To understand the concept of frequency, consider the number of ocean waves that reach the shore in a given length of time. The number of ocean waves than reach the shore, divided by the length of time you measure them, is their frequency. If we consider the wave nature of light, the higher the frequency, the higher the energy.

In 1900, Max Planck hypothesized that the energy (frequency) of light emitted by the black body, depended on the temperature of the black body. When the black body was heated to a given temperature, it emitted a “quantum” of light (light with a specific frequency). This was the beginning of Quantum Mechanics. Max Planck had intentionally proposed a quantum theory to deal with black-body radiation. To Planck’s dismay, this implied that light was a particle (the quantum of light later became known as the photon in 1925). Planck rejected the particle theory of light, and dismissed his own theory as a limited approximation that did not represent the reality of light. At the time, most of the scientific community agreed with him.

If not for Albert Einstein, the wave theory of light would have prevailed. In 1905, Einstein used Max Planck’s black-body model to solve a scientific problem known as the photoelectric effect. In 1905, the photoelectric effect was one of the great unsolved mysteries of science. First discovered in 1887 by Heinrich Hertz, the photoelectric effect referred to the phenomena that electrons are emitted from metals and non-metallic solids, as well as liquids or gases, when they absorb energy from light. The mystery was that the energy of the ejected electrons did not depend on the intensity of the light, but on its frequency. If a small amount of low-frequency light shines on a metal, the metal ejects a few low-energy electrons. If an intense beam of low-frequency light shines on the same metal, the metal ejects even more electrons. However, although there are more of them, they possess the same low energy. To get high-energy electrons, we need to shine high-frequency light on the metal. Einstein used Max Planck’s black-body model of energy, and postulated that light, at a given frequency, could solely transfer energy to matter in integer (discrete number) multiples of energy. In other words, light transferred energy to matter in discrete packets of energy. The energy of the packet determines the energy of the electron that the metal emits. This revolutionary suggestion of quantized light solved the photoelectric mystery, and won Einstein the Nobel Prize in 1921. You may be surprised to learn that Albert Einstein won the Nobel Prize for his work on quantizing light—and not on his more famous theory of relativity.

2. Second, the speed of light in a vacuum sets the speed limit in the universe. Nothing with a (rest) mass travels faster than light in a vacuum. In addition, this is a constant, independent of the speed of the source emitting the light. This means that the light source can be at rest or moving, and the speed of light will always be the same in a vacuum. This is counterintuitive. If you are in an open-top convertible car speeding down the highway, and your hat flies off, it begins to move at the same speed as the car. It typically will fall behind the car due to wind resistance that slows down its speed. If you are in the same car, and throw a ball ahead of the car, its velocity will be equal to the speed of the car, plus the velocity at which you throw it. For example, if you can throw a ball sixty miles per hour and the car is going sixty miles per hour, the velocity of the ball will be one hundred twenty miles per hour. This is faster than any major league pitcher can throw a fastball. Next, imagine you are in the same car and have a flashlight. Whether the car is speeding down the highway or parked, the speed of light from the flashlight remains constant (if we pretend the car is in a vacuum). The most elegant theory of all time, Einstein’s special theory of relativity, uses this property of light as a fundamental pillar in its formulation.

3. Third, the quanta of light have no rest mass. This last property of light may explain why light in a vacuum sets the upper limit of speed in the universe. According to Einstein’s theory of special relativity, any object with (rest) mass becomes infinitely massive as it approaches the speed of light. By inference we can argue that it would take infinite energy to accelerate a mass to the speed of light.

However, there are other physical entities that have speeds that may equal or even exceed the speed of light. For example, the universe is considered to be expanding faster than the speed of light by numerous cosmologists. Another physical process known as quantum entanglement may also take place at or even faster than the speed of light. Quantum entanglement refers to two particles (photons, for example) which interact and become entangled, such that even when separated the quantum state of one particle will dictate the quantum state of the other particle. For example, if one photon has an angular momentum defined as spin up, the other particle will have an angular momentum of spin down, to conserve spin. If you change the angular momentum of either particle, the other particle appears to instantaneously change, such that they continue to conserve spin. The effects of gravity also appear to propagate at the speed of light. Today, science still questions the nature of gravity. In classic physics, gravity was thought of as an invisible field between two or more masses. However, some physicists speculate the existence of a particle called a graviton, which is a hypothetical elementary particle that mediates the force of gravitation. If gravitons exist, physicists speculate that they travel at the speed of light.

What does all this mean? Basically, it means that light (photons) may not be the only entities that travel at the speed of light in a vacuum.

A Holy Bible placed next to a microscope on a wooden surface, symbolizing the intersection of science and faith.

Can Science Replace Religion?

Categories, Physics, Universe Mysteries, ,

Stephen Hawking, the world’s most famous scientist, made a startling statement on September 2, 2010, one week prior to the release of his new book, The Grand Design. He declared the “Almighty” irrelevant. Dr. Hawking believes that M-theory may hold the ultimate key to understanding everything, even the birth of the universe. Therefore, the need for religion becomes unnecessary. Of course, critics ask where M-theory came from. This is surprising since Dr. Hawking is on record saying, “Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?” To my mind, this is the right question.

Dr. Hawking is just one scientist, albeit highly famous. In general, what do scientists believe? Numerous studies, regarding scientists in the United States, indicate about a third are atheists, a third agnostic, and a third believe in God or a higher power. Similar studies of the general population suggest that three-fourths of the population believes in God or a higher power. (Survey 2005-2007 by Elaine Howard Ecklund of University at Buffalo, The State University of New York). What does this mean? A majority in the scientific community no longer look to religion for answers, but to their science.

The elegance and orderliness of scientific theories and mathematics becomes seductive and, in effect, replaces a need for a higher deity. However, this is not to say there is any unified conspiracy on the part of the scientific community to replace religion with science. In fact, without intention, science and religious ethics appear to have much in common. Einstein wrote in “Essays in Physics” (1950), “However, all scientific statements and laws have one characteristic in common: they are “true or false” (adequate or inadequate). Roughly speaking, our reaction to them is “yes” or “no.” The scientific way of thinking has a further characteristic. The concepts which it uses to build up its coherent systems are not expressing emotions. For the scientist, there is only “being,” but no wishing, no valuing, no good, no evil; no goal. As long as we remain within the realm of science proper, we can never meet with a sentence of the type: “Thou shalt not lie.” There is something like a Puritan’s restraint in the scientist who seeks truth: he keeps away from everything voluntaristic or emotional.”

However, regardless of the inherent ethics, shared by science and religion, one thing that stands in the center of this passionate debate is the existence of miracles. For something to be a true miracle, it must be outside the natural laws of science. In effect, natural law is suspended, and a miracle happens. A majority of scientists have difficulty believing this. Einstein summed this up in the following statement, “Development of Western science is based on two great achievements: the invention of the formal logical system (in Euclidean geometry) by the Greek philosophers, and the discovery of the possibility to find out causal relationships by systematic experiment (during the Renaissance).” To illustrate the difficulty of suspending natural laws, consider this example. If I told you apples fall up instead of down, would you believe me? Probably not. You probably would not even argue with me. My guess is that you would likely be dismissive, and ignore me. Yet, at the heart of various religions is the belief in miracles.

Is it possible to suspend natural laws? I suspect most scientists would answer a resounding “No!” However,what may have been considered a miracle just a hundred years ago is easily explained by today’s science. Television would be an example. In 1914, it would have appeared miraculous to watch television. It involved principles of science and engineering that were not understood at that time. I point this out because I don’t think that miracles can be used to prove or disprove the existence of a deity. Consider this example: Advanced aliens may have a science that appears to suspend natural laws. Perhaps they know how to create “worm holes” and travel vast distances, faster than the speed of light. To our observations, they may be violating another pillar of modern physics, namely the speed of light in a vacuum is the upper limit of velocity in the universe. However, simply because we do not understand their science does not mean that they have suspended natural law. They simply have learned secrets about nature we have not discovered. They know how to harness more energy than we do, which allows them to apparently violate nature laws and create miracles. This may make them appear god-like, but they are not the deity worshiped by the major religions of the world.

I judge that many in the scientific community believe that science will ultimately be able to answer all questions, and they are willing to replace religion with science. I do not share this view. Often, it appears that every significant scientific breakthrough results in an equally profound mystery. I have termed this irony of scientific discovery the Del Monte Paradox, namely:

Each significant scientific discovery results in at least one profound scientific mystery.

Here is an example to illustrate this paradox. Consider the discovery of the Big Bang theory. For this discussion, please view it as a scientific framework of how the universe evolved from a highly dense energy point to the universe we experience today. While the scientific community generally accepts the Big Bang theory, it is widely acknowledged that it does not explain the origin of the energy that was required to create the universe. Therefore, the discovery of the Big Bang theory left science with a profound mystery. Where did the energy originate to create a Big Bang? This is arguably the greatest mystery in science, and currently an area of high scientific focus.

In the final analysis, I don’t think it will come down to science proving or disproving a deity exists. I don’t think it will come down to science discovering a theory of everything. I think it will come down to what it has always come down to over the centuries, namely, faith. To answer the title question, can science replace religion, I offer these thoughts. If you believe that science will ultimately be able to answer every question and enable humans to become god-like, then it is logical to assume science can replace religion. If you believe that science will never be able to answer all questions and ultimately we will   be left with a profound mysteries, then I think its possible to make a case that science will not be able to replace religion. Whatever your believe, I respect your right to formulate your own beliefs.

 

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Is String Theory Pseudoscience?

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Is string theory pseudoscience? To address this questions, let’s start by understanding what constitutes science and distinguishes it from pseudoscience.

Let’s start by defining science. Science is the intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment. The important words in this definition are “observation” and “experiment.” In other words, real science, and scientific theories, requires its hypotheses and associated predictions to be observable and/or be experimentally verified. One example of a solid scientific theory is Einstein’s special theory of relativity. It has withstood over one hundred years of observation and experimental scrutiny. In fact, it is generally held as the “gold standard” that all theories of science should be measured against.

With the above understanding, if I were to propose a new theory that by its inherent nature had at its core hypotheses that we are unable to experimentally verify and yielded predictions we would not be able to observe or measure, I believe many would consider such a theory to be pseudoscience. Pseudoscience is a system of theories, assumptions, and methods erroneously regarded as scientific, but are not verified, or verifiable, by experiment or  observation.

Now let’s examine string theory. String theory is built on the idea that elementary particles are not point-like objects, but are the vibration modes of one-dimensional “string-like” entities of energy. Proponents of string theory generally argue that it offers a theory of gravity and may provide a solution to the problem of reconciling Einstein’s general relativity with quantum mechanics. Therefore, if it were a valid theory, it would represent a leap in the physical sciences. However, there in lies the key question. Is it a valid theory?

Let start with its hypotheses. Can we measure or observe the one-dimensional vibrating strings of energy that form the core hypotheses of string theory? The answer is no, and that is an emphatic no. We cannot measure them with today’s science, and it is unlikely that we will ever be able to measure them. According string theorist the one-dimensional vibrating strings of energy are about equal to the Planck length, which is the smallest length science theorizes to exist. It is equal to 1.616199(97)×10^−35 meters and is defined from three fundamental physical constants, which I won’t to into here for the sake of brevity. The problem is that today’s science is unable to measure anything smaller than 10^-18 meters, which is billions of times larger than a Planck length. Many in the science community do not think we will ever be able to measure a Planck length, regardless of improvements in measurement technology. Therefore, the first significant problem with string theory is that its hypotheses are not verifiable.

Let’s next look at a significant predictions of string theory. In its current form, M-theory (i.e., membrane-theory, the most comprehensive form of string theory), it predicts there are 11 space-time dimensions, in serious disagreement with our senses and the most recent observations using particle accelerators. There is no experimental evidence of additional dimensions beyond the 4 space-time dimensions of Einstein’s general relativity.

There are arguably other issues with string theory, but the above two points, the lack of experimental verification of its hypotheses and its most fundamental prediction of 11 dimensions, serve to make an important point. It fails to pass the definition of science. String theory doesn’t  provide an intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment. It is not only unverified, but appears to be unverifiable at its core.

It’s natural to ask, why has string theory gained such a following in the scientific community. First, modern theoretical physics is based on two incompatible theories, Einstein’s theories of relativity and quantum mechanics. As I mentioned in a previous post, some progress has been made to reconcile them, but no progress has been made with regard to a unified theory of gravity. This has caused serious issues in the scientific community and it is only human to seek a theory that offers to resolve the issue. However, in this case, we are taking a theory that is flawed and unverifiable to attempt to reconcile relativity and quantum mechanics, both of which have been widely successful as theories within their specific context. Next, numerous formidable physicists, like Stephen Hawking and Brian Greene, have written best selling books based on string theory. To the average popular science reader, their books are exciting and their standing in the scientific community suggests their books are science fact. How is it possible that Dr. Hawking and Dr. Greene are in such strong support of a questionable theory. I think this has to do with the mathematical elegance of M-theory. It is relatively easy to become enamored with the mathematical formulations and loose sight of the fundamentals. Unfortunately, I think this has happened. Dr. Hawking has gone as far as saying we no longer need a God since we now have M-theory. Opponents rightly ask, where did M-theory come from? I am not going to get into the religious aspects. I only point this out to delineate how deeply some of today’s most respected physicists have embraced string theory.

Where do I stand? Obviously, today’s theoretical physics is based on two incompatible theories, Einstein’s relativity and quantum mechanics. Although, both theories work extremely well in the specific contexts, relativity at the macro level and quantum mechanics at the micro or quantum level (i.e., the level of atoms and subatomic particles), they do not come together to provide cogent theory of gravity. Even though string theory offers a speculative path to resolve the incompatibilities, at its core it appears to be pseudoscience. At best, it is a conjecture, which means it falls into the category of opinion.

I offer this sober warning to those that plan on making a career in science. Before you decide to become a string theorist and spend your career working to understand M-theory mathematics, be sure that you agree with the fundamental hypotheses and predictions of string theory. Don’t fall hopelessly in love with the elegant mathematics. Just because you can publish your theoretical string theory results in respectable scientific journals and participate in professional conferences doesn’t legitimize string theory. Much like a recovering alcoholic, science must admit there is a problem and not grasp at the current fad of string theory. It is better to admit we don’t have a solution than to forward what is likely the most legitimized pseudoscience of modern times, string theory.

A glowing sign with the word 'TRUTH' illuminated against a sunset backdrop.

Science Versus Truth

Categories, Physics, Universe Mysteries,

Many people, even some scientists, believe science equates with truth, especially with regard to the behavior of nature. Let’s examine whether this hypothesis is correct.

Modern physics is based on Einstein’s special and general theories of relativity and quantum mechanics. Each theory models and predicts the behavior of reality within specified contexts. The theories of relativity work well in explaining and predicting the behavior of reality at the macro level (i.e., typically the level of our everyday world), even as objects approach the speed of light. Quantum mechanics works well in explaining and predicting the behavior of reality at the micro level, often termed the quantum level (i.e., the level of atoms and subatomic particles). However, the two theories are incompatible. For example, the theories of relativity describe the behavior of reality at the macro level with certainty, but are unable to  explain reality on the quantum level. Quantum mechanics is able to describe the behavior of reality at the micro level in terms of probabilities, but again is unable to provide an adequate model of how gravity works at the quantum level.

Physicists have been working to reconcile relativity and quantum mechanics for over a century. To date, some progress has been made. For example, special relativity was merged with electromagnetism. This resulted in the theory of quantum electrodynamics (QED) or relativistic quantum field theory. QED is widely considered to be the most precise theory of natural phenomena ever developed. In the 1960s and 1970s, physicists attempted to unify the weak, the strong, and the gravitational forces. This resulted in another set of theories that merged the strong and weak forces called quantum chromodynamics (QCD) and quantum electroweak theory. However, no theory has successfully reconciled quantum mechanics and general relativity with regard to gravity. This incompatibility and the vastly different models of reality posed by the theories of relativity and quantum mechanics forces many in the scientific community to question their overall validity. In response, some physicists have forwarded a completely different model of reality based on string theory. In essence, string theory is a a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects of vibrating energy called strings. The most comprehensive string theory is termed M-theory, which stands for membrane theory. While many highly esteemed physicists, like Stephen Hawking, have championed M-theory, there is no experimental proof that it correctly models nature.

What does all this say about science and it relationship to truth? Science attempts to explain (i.e., model) and predict reality, but the best theories of modern physics are either inconsistent or not experimentally verified. In science, we have models, laws and mathematics that strive to explain and predict reality. However, our view of reality continues to evolve as our understanding of science evolves. For example, Newtonian mechanics works well for most problems in our everyday world, but fails to work when objects move close to the speed of light. Einstein’s theories of relativity evolved to solve relativistic problems (i.e., objects moving at speeds close to the speed of light). In principle, we can replace Newtonian mechanics with the theories of relativity, but reality has not changed. The only thing that has changed is our model of reality and the mathematical equations we use to predict nature’s behavior.

In conclusion, what can we say about science versus truth. If we define truth as the actual way nature behaves, then we must  admit that science does not equate with truth. Science is continually evolving to more closely model what nature is actually doing. The mathematics of science are continuously being refined to more closely predict how nature will behave. What is true in science? Scientific facts are true. For example, we can scientifically measure the gravitational attraction between two masses. However, scientific theories that explain this attraction may be wrong. For example, Newtonian mechanics explains gravity in terms of a gravitational field. General relativity, which superseded Newtonian mechanics, explains gravity as the distortion of space caused by a mass. Although the facts of science are indisputable, the theories used to explain them are not.