Tag Archives: how to time travel

M-theory

Are There Any Real Time Machines? Part 2/2 (Conclusion)

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Are there any real time machines?

In my opinion, we are in about the same place space travel was at the beginning of the twentieth century. At the beginning of the twentieth century, all we knew about space travel came from science fiction. We knew that birds could fly, and this observation provided hope that human air flight would eventually be possible. However, at this point we could only fly using balloons, which was a long way from controlled air flight. We knew about projectiles, such as cannonballs and simple rockets, and this provided hope that one day humankind would be able to travel into space. However, at the beginning of the twentieth century we were still three years away from building the first successful airplane. The first successful airplane did not come from a well-respected theory or formal scientific investigation. Most early attempts at air flight tended to focus on building powerful engines, or they attempted to imitate birds. The early attempts at air flight were dismal failures. The first successful heavier-than-air machine, the airplane, was invented in 1903 by two brothers, Orville and Wilbur Wright. They were not scientists, nor did they publish a scholarly paper in a scientific journal delineating their plans. Quite the contrary, the two brothers had a background in printing presses, bicycles, motors, and other machinery. Clearly, their background would not suggest they would invent the first airplane and lead humankind into space. However, their experience in machinery enabled them to build a small wind tunnel and collect the data necessary to sustain controlled air flight. From the beginning, the Wright brothers believed that the solution to controlled air flight lay hidden in pilot controls, rather than powerful engines. Based on their wind tunnel work, they invented what is now the standard method of all airplane controls, the three-axis control. They also invented efficient wing and propeller designs. It is likely that many in the scientific community in the beginning of the twentieth century would have considered aeronautics similar to the way the scientific community in the early part of the twenty-first century considers time travel—still something outside the fold of legitimate science. However, on December 17, 1903, at a small, remote airfield in Kitty Hawk, North Carolina, the two brothers made the first controlled, powered, and sustained heavier-than-air human flight. They invented the airplane. It was, of course, humankind’s first step into the heavens.

I believe the invention of the airplane is a good analogy to where we are regarding time travel. We have some examples, namely, time dilation data, and a theoretical basis that suggests time travel is potentially real. However, we have not reached the “Kitty Hawk” moment. If Dr. Mallett makes his time machine work, and that is a big “if,” numerous physicists will provide the theoretical foundation for its success, essentially erasing any errors that Dr. Mallett may have made in his calculations. He will walk as another great into the history of scientific achievement.

My point is a simple one. The line between scientific genius and scientific “crank” is a fine one. When Einstein initially introduced his special theory of relativity in 1905, he was either criticized or ignored. Few in the scientific community appreciated and understood Einstein’s special theory of relativity in 1905. It took about fifteen years for the scientific community to begin to accept it. Einstein was aware of the atmosphere that surrounded him. In 1919, he stated in the Times of London, “By an application of the theory of relativity to the taste of readers, today in Germany I am called a German man of science, and in England I am represented as a Swiss Jew. If I come to be represented as a bête noire, the descriptions will be reversed, and I shall become a Swiss Jew for the Germans and a German man of science for the English!”

Dr. Mallett is on record predicting a breakthrough in backward time travel within a decade. Only time and experimental evidence will prove if his prediction becomes reality. Even if the Mallett time machine works, it would still represent only a baby step. We would still be a long way from human time travel, but we would be one step closer.

Source: How to Time Travel (2013), Louis A. Del Monte

science of time & time dilation

Are There Any Real Time Machines? Part 1/2

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There are no existing time machines capable of sending humans forward or backward in time. The closest we have come to time travel is using particle accelerators to cause subatomic particles to experience time dilation (i.e., forward time travel). There is a significant amount of time dilation data available. Particle accelerators succeed in achieving time dilation by accelerating subatomic particles close to the speed of light. Unfortunately, though, backward time travel has no similar body of experimental data. The major problems with creating backward time travel appear to fall into three categories:

  1. Backward time travel appears to require negative energy, based on arguments made by American theoretical physicist Kip Thorne and British theoretical physicist/cosmologist Stephen Hawking. Many in the scientific community acknowledge that negative energy likely exists, and point to the Casimir effect, discussed previously, as an example in nature. However, today’s science is unable to harness negative energy in any meaningful way to make a time machine.
  2. Many in the scientific community, like physicists Dr. Olum and Dr. Everett, believe the amount of energy required to twist space sufficiently for spacetime manipulation and enable Dr. Mallett’s time machine to work is enormous. Conceptually, we may be talking about the amount of energy provided by a star, similar to our own sun. Harnessing this level of energy is far beyond today’s science. Science’s best efforts to study high-energy physics has to date been confined to particle accelerators, such as the Large Hadron Collider. There is no experimental evidence that Dr. Mallett has succeeded in manipulating spacetime.
  3. Many in the scientific community are concerned with causality violations, especially regarding backward time travel. However, as we learned in the section titled “Twisting the arrow of time,” there can also be causality violations regarding forward time travel. The causality violations are generally termed “time travel paradoxes,” which we will discuss in detail in the next chapter.

Having made the above points, I think it is important to point out that some physicists believe subatomic antimatter particles travel in the opposite direction in time (i.e., backward in time) versus their matter counterparts. For example, some physicists assert that positrons, the antimatter equivalent of electrons, travel backward in time, while electrons travel forward in time. In solid-state physics, if we consider a current flowing in a semiconductor, electrons in a semiconductor move as a current in one direction, while the “holes” (i.e., the position the electron occupied in the semiconductor, which becomes vacant when the electron moves as a current) move in the opposite direction. Physicists differ on whether the “holes” represent positrons (i.e., actual physical antimatter particles). I mention this for completeness. There is no scientific consensus that antimatter travels backward in time.

Where does this leave us? I think this question deserves a complete answer. Stay tuned for part 2.

Source: How to Time Travel (2013), Louis A. Del Monte

Multiple overlapping clock faces with various times, creating a surreal and abstract time concept in blue tones.

Do Time Travel Paradoxes Negate the Possibility of Time Travel?

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Do time travel paradoxes spell doom to time travel? The short answer is no. Many in the scientific community do not think time travel paradoxes present an insurmountable barrier to time travel. Many physicists have suggested solutions to time travel paradoxes. In fact, discussing them all would result in a book. I will discuss the major ones. For the sake of convenience, I have divided them into four categories:

  1. Multiverse hypothesis—The multiverse hypothesis argues that time travel paradoxes are real, but they lead to alternate realities. The most famous theory in this category is American physicist Hugh Everett’s many-worlds interpretation (MWI) of quantum mechanics. According to Everett (1930–1982), certain observations in reality are not predictable absolutely by quantum mechanics. Instead, there is a range of possible observations associated with physical phenomena, and each is associated with a different probability. Everett’s interpretation is that each possible observation corresponds to a different universe, hence the name “many-worlds.”  Let us consider a simple example. If you toss a coin in the air, it can come down heads or tails. The probability of getting heads is equal to the probability of getting tails. If you toss the coin, and it comes down heads, then there is another you, in another universe, who observes tails. This sounds like science fiction. However, according to a poll published in The Physics of Immortality (1994), 58% of scientists believe the many-world interpretation of quantum mechanics is true, 13% are on the fence (undecided), 11% have no opinion, and 18% do not believe it. Among the believers are Nobel laureates Murray Gell-Mann and Richard Feynman, and world-famous physicist/cosmologist Stephen Hawking. In our everyday reality, many of us would reject the many-world interpretation of quantum mechanics because we do not experience it directly. However, let me point out, we do not experience the individual atoms of a book when we hold it. Yet, we know from sophisticated experimental analysis that the book is a collection of atoms. Unfortunately, in the strange world of quantum mechanics, our intuition and experience rarely serve us. I leave it to you to formulate your own conclusions.
  2. Timeline-protection hypothesis—The timeline-protection hypothesis asserts that it is impossible to create a time travel paradox. For example, if you travel back in time and attempt to prevent your grandfather from meeting your grandmother, you fail every time. If you attempt to shoot yourself through a wormhole, the gun jams, or something else happens, which prevents you from changing the past. Several other paradox resolutions fit under this category. They are:
    • The Novikov self-consistency principle, suggested by Russian physicist Igor Dmitriyevich Novikov in the mid-1980s, which asserts anything a time traveler does remains consistent with history. For example, if you travel to the past and attempt to keep your grandfather from meeting your grandmother, something interferes with any attempt you make, causing you to fail in the attempt. In other words, the time traveler is unable to change history.
    • The self-healing hypothesis theory, which states that whatever a time traveler does to alter the present by traveling to the past sets off another set of events to cause the present to remain unchanged. For example, if you attempt to prevent Abraham Lincoln’s assassination, you may succeed in preventing John Wilkes Booth from carrying out the assassination only to find someone else assassinated Lincoln. In essence, time heals itself.
  3. Timeline-corruption hypothesis—The timeline-corruption hypothesis suggests that time paradoxes are inevitable and unavoidable. Any time travel to the past creates minute effects that inevitably alter the timeline and cause the future to change. For example, if you inadvertently step on an ant in the past, it changes the future. Popular science fiction literature calls this the “butterfly effect,” namely, that the flutter of a butterfly’s wings in Africa can cause a hurricane in North America. Under this theory, anything you do will have a consequence. It may be small and benign. Alternatively, it may be large and disastrous. The destruction-resolution hypothesis fits in this category. It holds that anything a time traveler does resulting in a paradox destroys the timeline, and even the universe. Obviously, if the destruction-resolution hypothesis is true, any time travel would be disastrous. However, I doubt the validity of the destruction-resolution hypothesis, since we are able to perform time dilation (i.e., forward time travel) experiments with subatomic particles using particle accelerators.
  4. Choice timeline hypothesis—The choice timeline hypothesis holds that if you choose to travel in time, it is predestined, and history instantly changes. This implies you can time travel to the future and leave an item there that you will need sometime in the future. It will be there for you when the future becomes the present. For example, assume you are in New York City, and someone is about to assault you. You have no escape or means of protection. According to the choice timeline hypothesis, you can use your time machine to travel to the future. You hide a gun near the place where the assault is about to occur. When the assault occurs, you retrieve the hidden gun and scare off the attacker.

There are numerous other time-paradox resolution hypotheses. Most fall under one of the above categories, or are not as popular as the above. I left them out in the interest of clarity and brevity. The four categories above give us a reasonable framework to understand the major time-paradox resolution theories, and the current thinking regarding their impact on the timeline.

The majority of the scientific community does not think time paradoxes inhibit time travel. For example, Kip Thorne, an American theoretical physicist and professor of theoretical physics at the California Institute of Technology until 2009, argues that time paradoxes are imprecise thought experiments which can be resolved by numerous consistent solutions. The scientific consensus appears to be that time paradoxes may or may not occur, but they do not exclude the possibility of time travel. This position appears validated by the time dilation (i.e., forward time travel) experiments routinely performed using particle accelerators.

This post is based on my book, How to Time Travel (2013)

Aliens and UFOs

Warp Drive – Time Travel to the Future – Science or Science Fiction?

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Is a warp drive spaceship feasible? Mexican theoretical physicist Miguel Alcubierre thinks it is.

In 1994, Dr. Alcubierre published a 1994 paper, “The Warp Drive: Hyper-Fast Travel Within General Relativity,” in the science journal Classical and Quantum Gravity.

The Alcubierre drive appears to allow a spaceship to travel faster than light, but it requires the existence of negative mass to make the Alcubierre drive work. In principle, the drive works by contracting the space in front of the spaceship and expanding the space behind the spaceship faster than the speed of light. In this fashion, the spaceship rides like a surfer on a wave. As the space behind the spaceship expands faster than the speed of light, the spaceship appears to move faster than the speed of light. However, it does not. Only the space behind the ship is expanding faster than the speed of light. In this way, Dr. Alcubierre avoids violating the laws of special relativity, namely, that no mass can exceed the speed of light.

There is no law in physics that prohibits space from expanding faster than the speed of light. From this viewpoint, the Alcubierre drive has merit. The Alcubierre drive is a mathematically valid solution to Einstein’s field equations. However, requiring negative mass as part of the mechanism for the Alcubierre drive makes the theory highly speculative and, once again, beyond the reach of today’s science. As a side note, Dr. Alcubierre got this idea by watching Star Trek and its use of the warp drive.

Often today’s science fiction becomes tomorrow’s science fact.

This post is based on my new book, How to Time Travel (2013), Louis A. Del Monte.

A website homepage featuring a book titled How to Time Travel by Louis A. Del Monte with a clock image on the cover.

Kirkus Book Review of How to Time Travel

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Kirkus Book Review of How to Time Travel

Kirkus Reviews (or Kirkus Media) is an American book review magazine founded in 1933 by Virginia Kirkus (1893–1980). Kirkus Reviews is published on the 1st and 15th of each month. Kirkus reviews over 7,000 titles per year, and their reviews are widely regarded by librarians and bookstores, which regularly peruse their lists for the “best” books to order. Therefore, a Kirkus review can significantly influence book sales. Recently, my new book, How to Time Travel, was reviewed by Kirkus and is live on their Website at http://bit.ly/1eTpFAv. If you are considering purchasing and reading How to Time Travel, I thought you would be interested in their review, which is is presented below in its entirety:

“Time travel—its possibilities, potential and primary obstacles—gets a levelheaded review from a physicist in this lucid, optimistic book.

Throughout Del Monte’s book, which focuses on how time travel might be accomplished and the major issues that stand in the way of its realization, he takes care to emphasize the scientific method, not just for time travel but in evaluating the theories and evidence behind it. By necessity, much of the book discusses various theories and speculations, beginning with Einstein’s Theory of Relativity and extending forward to modern formulations, ranging from Alcubierre’s space-warp proposal to Mallet’s space-time twist theory. Given that many in the scientific community believe time travel is at least theoretically possible, Del Monte focuses in later chapters on the engineering challenges, discussing what would be needed to achieve it and how civilization might go about reaching those milestones. While some of the ideas along the way are the stuff of conspiracy theorists and late-night talk radio—UFOs, the Philadelphia Experiment, etc.—Del Monte never condescends in his examinations, taking a rational, methodical approach to evaluating the possibilities and explaining why he thinks they do or don’t merit further examination. In his refreshingly even-keeled, forthright approach—particularly in his discussion of scientific and anecdotal evidence and the place of both in any thought process—Del Monte does an excellent job of exemplifying the scientific method in action. He clearly favors certain conclusions, but he takes pains to allow room for readers to develop their own interpretations, and he includes appendixes with further information to assist readers in digging deeper.

This articulate, principled use of scientific methodology offers a clear, rational examination of an intriguing concept.”

 

A black and white image of a clock face with a spiral effect distorting the numbers and hands.

Explore Two Famous Time Travel Paradoxes – The Grandfather Paradox & Twin Paradox

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Time Travel Paradoxes – The Grandfather Paradox & Twin Paradox

What is a time travel paradox? It is an occurrence that apparently violates some aspect of causality (i.e., cause precedes effect) typically associated with time travel. Although there are numerous time travel paradoxes, let us explore two famous ones: The grandfather paradox and the twin paradox.

  • The grandfather paradox—Science fiction writer René Barjavel, in his 1943 book, Le Voyageur Imprudent (Future Times Three), originally proposed the grandfather paradox. It goes something like this. A person goes back in time and meets his grandfather before his grandfather meets his grandmother. The person in some way interferes with his grandfather meeting his grandmother. Consequently, the grandfather and grandmother never meet. The question becomes, what happens to the person? In theory, the person will never be born.  Is this just some illogical premise, similar to asserting that a square circle exists? Most of the scientific community considers it a valid concern regarding causality violations due to time travel. Some physicists believe that it actually presents a barrier to time travel. However, numerous theories exist to resolve time travel paradoxes. We will discuss those theories in the next section, but first let us explore another famous paradox.
  • The twin paradox—The is one of the most famous time travel paradoxes. It goes something like this: On Earth live a pair of twins. They are almost the same age, differing only by the order in which they were born. One twin boards a spacecraft capable of traveling near the speed of light. In the spacecraft, the twin embarks on a one-year journey, measured by the clock within the spacecraft. During the one-year journey, the spacecraft travels at 99.94% the speed of light. When the spacecraft returns to Earth, the twin on the spacecraft has aged one year, but learns his twin has aged almost thirty years. Although the example is fictitious, the science is real. The twin paradox has been experimentally verified using highly accurate atomic clocks, one on a jet plane and the other at the airport. There have been many variations of the twin paradox. The scientific community considers it a valid effect of Einstein’s special theory of relativity regarding time dilation.

There is a laundry list of time travel paradoxes. I discuss many of them in my critically acclaimed best selling new book, How to Time Travel. The paradoxes above are sufficient to illustrate causality issues. It is important to note that the time travel paradoxes are not simply in the category of thought experiments. Numerous time travel paradoxes, like the twin paradox and the double-slit delayed-choice paradox (discussed in a previous post), are experimental facts. They are real. The important question is: Do time travel paradoxes form a barrier to time travel? We will address this question in an up coming post.

 

Multiple overlapping clock faces with various times, creating a surreal and abstract time concept in blue tones.

What Is the Science of Time Travel?

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The science of time travel is real. There is experimental evidence that proves time travel is real. Yet, with but a few exceptions, most of my colleagues in the scientific community avoid discussing or doing serious time travel research. Why is this?

The theory regarding time travel is relatively easy to understand on a technical basis if you have or are pursuing a degree in the physical sciences, or on a conceptual basis, for the layperson. For example, professors teach time dilation (i.e., forward time travel) in undergraduate physics classes. Professors also teach general relativity in both undergraduate and graduate physics classes. The general theory of relativity embodies, along with Einstein’s theory of gravity, the science of time travel to the past. Both the special and general theories of relativity are easy to grasp for a person with the proper scientific background. However, designing and engineering experiments to demonstrate time travel is an extremely difficult task. In fact, building particle accelerators capable of demonstrating even the simplest form of time travel, time dilation, requires the participation of numerous institutions, numerous nations, and a huge financial investment. An example of this is the Large Hadron Collider (LHC), which is the world’s largest high-energy particle accelerator. The European Organization for Nuclear Research (CERN), a collaboration of ten thousand scientists and engineers from over one hundred countries, built the LHC over a ten-year period, 1998 to 2008, at an estimated cost of $9 billion. Scientists hail it as one of the greatest scientific achievements. It is able to perform time dilation experiments, among many other important scientific tasks. However, even with highly sophisticated scientific instruments, research regarding particle acceleration and detection is a difficult endeavor. For example, in 2011, scientists using the Oscillation Project with Emulsion-tRacking Apparatus (OPERA) reported accelerating neutrinos faster than the speed of light, which later proved incorrect and due to faulty cable connections.  The main point is that the apparatus proposed to perform time travel research, even using subatomic particles, is extraordinarily expensive, difficult to build, and difficult to use. The energy required, even when dealing with subatomic particles, is enormous.

In summary, here are the salient elements of the science of time travel:

  • Einstein’s special theory of relativity provides a strong theoretical foundation for forward time travel, which is termed “time dilation.”
  • There is a wealth of scientific data proving time dilation is real and can occur when a frame of reference accelerates near the speed of light, or when a frame of reference is in a strong gravitational field.
  • Even though there is general agreement regarding time dilation, no one has built a machine that enables a human to experience significant time dilation. It is true, however, that people traveling at high speeds, like astronauts, experience some time dilation. To date, the amount of time dilation experienced by any humans is only a small fraction of a second, and not noticeable to the humans involved.
  • Particle accelerators, such as the Large Hadron Collider, are able to accelerate subatomic particles near the speed of light, and time dilation is a measurable effect.
  • Einstein’s general theory of relativity predicts gravitational time dilation. The scientific community generally agrees time dilation occurs in strong gravitational fields.
  • Some solutions to Einstein’s equation of general relativity result in closed timelike curves, which theoretically suggest backward time travel.
  • The scientific community is not in agreement regarding the practicality and reality of backward time travel. In fact, the entire subject of backward time travel is contentious.

The above material is based on my critically acclaimed new book, How to Time Travel, available at Amazon.com.

 

A black hole in space surrounded by stars and a glowing gravitational lensing effect.

Using a Black Hole to Time Travel!

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Using a black hole to time travel!

What is a black hole? A black hole is a point in space where gravity pulls so much that not even light can escape. We cannot see black holes, but we can infer their existence by how they influence stars around them.

There are numerous types of black holes. Some are small, about the size of an atom. Yet, they can have a mass equal to a mountain. Some are supermassive, like the black hole theorized to exist at the center of our galaxy, a mere twenty-six thousand light-years from us. It is the single heaviest object in our galaxy. In between the atom-size black holes and the supermassive black holes are the “stellar” black holes. They are roughly up to twenty times the mass of our sun.

You may wonder: How do black holes form? Physicists think that the atom-size black holes formed during the early stages of the big bang, and that the supermassive black holes formed when the galaxies formed. Physicists also think the stellar black holes form when a star dies and collapses on itself.

What makes a black hole interesting from the standpoint of time travel is that the gravitational attraction is so great that time dilation due to gravity (as predicted by Einstein’s general theory of relativity) would be enormous. In fact, a supermassive black hole, like the one at the center of our galaxy, would slow down time far more than anything else in the galaxy would. This makes a black hole a natural type of time machine.

You may worry that a black hole may swallow the Earth. However, I have good news for you. Black holes do not move around, and there are none close to the Earth. In short, we do not have to worry about being swallowed by a black hole.

Is there any practical way to use a black hole as a time machine? The answer is no, not via today’s science. The scientists at CERN using the Large Hadron Collider are attempting to make small black holes. Perhaps, in time, they will succeed, and we will be able to use its properties as a time machine. This, however, is speculation.

This material is from my new book, How to time Travel (2013).

Diagram of a double-slit experiment setup with light source, thin opaque plate, double slits, and screen.

A Classic Time Travel Paradox – Double-Slit Experiment Demonstrates Reverse Causality!

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Almost the entire scientific community has held for hundreds of years that for every effect, there must have been a cause. Another way of saying this is cause precedes effect. For example, if you hit a nail with a hammer (the cause), you can drive it deeper into the wood (the effect). However, some recent experiments are challenging that belief. We are discovering that what you do after an experiment can influence what occurred at the beginning of the experiment. This would be the equivalent of the nail going deeper into the wood prior to it being hit by the hammer. This is termed reversed causality. Although, there are numerous new experiments that illustrate reverse causality, science has been struggling with a classical experiment called the “double-slit” that illustrates reverse causality for well over half a century.

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. See image below to visually understand this.

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 (see glossary), which I discussed in my first book, Unraveling the Universe’s Mysteries—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:
    1. The individual photon light acted as a wave and went through both slits, interfering with itself to cause an interference pattern.
    2. 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:
    1. 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.
    2. 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.

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.

This post is based on material from my new book, How to Time Travel, available at Amazon in both paperback and Kindle editions.

Image: Figure 3, from How to Time Travel (2013)

A black and white image of a clock face with a spiral effect distorting the numbers and hands.

The Mallett Time Machine – Time Travel to the Past May Become Possible!

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Thanks to particle accelerators, like the Large Hadron Collider (LCH) 175 meters (574 ft) beneath the Franco-Swiss border near Geneva, Switzerland, physicist have been able to routinely demonstrate forward time travel (i.e., time dilation) using subatomic particles. In a sense, you can think of the Large Hadron Collider as a time machine. It is capable of sending subatomic particles to the future. Unfortunately, we do not have a similar machine that can send subatomic particles to the past. However, Dr. Ronald Mallett is attempting to change that.

Dr. Ronald Mallett is an American theoretical physicist and the author of Time Traveler: A Scientist’s Personal Mission to Make Time Travel a Reality (2007). Dr. Mallett is a full professor at the University of Connecticut, where he has taught physics since 1975.

Dr. Mallett is attempting to twist spacetime using a ring laser (i.e., a laser that rotates in a circle) by passing it through a through a photonic crystal (i.e., a crystal that only allows photons of a specific wavelength to pass through it). The concept behind spacetime twisting by light (STL) is that by twisting space via the laser, closed timelike curves will result (i.e., time will also be twisted). In this way, Dr. Mallett hopes to observe a violation of causality when a neutron is passed through the twisted spacetime. Dr. Mallett also believes he will be able to send communication by sending subatomic particles that have spin up and spin down. Note, the spin of a subatomic particle is part of the particle’s quantum description. As a simple example, we can consider spin up equal to 1 and spin down equal to 0. Using this technique, Dr. Mallett can send a binary code, similar to the binary codes used in computing.

Few scientists openly discuss their work on time machines. They fear ridicule. In this regard, Dr. Mallett is a pioneer. When Dr. Mallett was ten years old, his father died at age thirty-three from a heart attack. Dr. Mallett has shared that his initial drive to invent a time machine was to go back in time and visit with his father. Unfortunately, the science of time travel only allows a person to go back in time to the point when the time machine is first turned on. Dr. Mallett acknowledges this, but continues his quest.

Dr. Mallett’s concept of twisting space is close to the concept of creating a wormhole, as discussed in my last post. Dr. Mallett is using laser light as means of creating the mouth of the wormhole. In a publication (R. L. Mallett, “The Gravitational Field of a Circulating Light Beam,” Foundations of Physics 33, 1307–2003), Dr. Mallett argued that with sufficient energies, the circulating light beam might produce closed timelike lines (i.e., time travel to the past).

Is Dr. Mallett’s theoretical foundation solid? According to physicists Dr. Olum and Dr. Everett, it is fatally flawed. In a paper published in 2005 (Ken D. Olum and Allen Everett, 2005, “Can a Circulating Light Beam Produce a Time Machine?”, Foundations of Physics Letters 18 (4): 379–385), they argue three points:

  1. Dr. Mallett’s analysis contains unusual spacetime (i.e., mathematical) issues, even when the power to the machine is off.
  2. The energy required to twist spacetime would need to be much greater than lasers available to today’s science.
  3. They note a theorem proven by Stephen Hawking (chronology protection conjecture—1992), namely, it is impossible to create closed timelike curves in a finite region without using negative energy.

Although Dr. Mallett did not address their criticism in a formal publication, he did argue in his book, Time Traveler, that he was forced to simplify the analysis due to difficulties in modeling the photonic crystal. This, however, is far from a complete response.

Who is right? In the physical sciences, we are judged by the weakest link in our theories. If I use this criterion, I would say the argument favors Dr. Mallett, since the chronology protection conjecture, which we will discuss in the next chapter, has come under serious criticism, and it is not clear that it presents a valid challenge. Nonetheless, Dr. Olum and Dr. Everett are highly regarded physicists. Therefore, at this point, it is hard to know who is right, and right about what. Perhaps the mathematical analysis is flawed, and the approach published by Dr. Mallett requires more energy than is available via today’s technology. However, we are witnessing a significant event in science. A respected physicist, Dr. Mallett, is openly publishing his work on building a backward time travel machine. Other respected physicists, Dr. Olum and Dr. Everett, are entering into a scientific debate regarding Dr. Mallett’s theoretical basis. From my point of view, this is how it should be in science. The debate is healthy. As a theoretical physicist, I know that the debate will end only when either:

  1. The Mallett time machine works, or
  2. The Mallett time machine enters the rubbish pile of scientific failures, along with astronomer Ptolemy’s Earth-centered model of the solar system and the flat Earth theories.

This material is based on my new book, How to Time Travel.