Category Archives: Time Travel

A diagram showing a black rod in space with concentric circles and arrows, labeled with time (x) and space (y) axes.

Tipler cylinder time travel – Is It Possible?

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The Tipler cylinder is a cylinder of dense matter and infinite length. Historically, Dutch mathematician Willem Jacob van Stockum (1910–1944) found Tipler cylinder solutions to Einstein’s equations of general relativity in 1924. Hungarian mathematician/physicist Cornel Lanczos (1893–1974) found similar Tipler cylinder solutions in 1936. Unfortunately, neither Stockum nor Lanczos made any observations that their solutions implied closed timelike curves (i.e., time travel to the past).

In 1974, American mathematical physicist/cosmologist Frank Tipler’s analysis of the above solutions uncovered that a massive cylinder of infinite length spinning at high speed around its long axis could enable time travel. Essentially, if you walk around the cylinder in a spiral path in one direction, you can move back in time, and if you walk in the opposite direction, you can move forward in time. This solution to Einstein’s equations of general relativity is known as the Tipler cylinder. The Tipler cylinder is not a practical time machine, since it needs to be infinitely long. Tipler suggests that a finite cylinder may accomplish the same effect if its speed of rotation increases significantly. However, the practicality of building a Tipler cylinder was discredited by Stephen Hawking, who provided a mathematical proof that according to general relativity it is impossible to build a time machine in any finite region that contains no exotic matter with negative energy. The Tipler cylinder does not involve any negative energy. Tipler’s original solution involved a cylinder of infinite length, which is easier to analyze mathematically, and although Tipler suggested that a finite cylinder might produce closed timelike curves if the rotation rate were fast enough, Hawking’s proof appears to rule this out. According to  Hawking, “it can’t be done with positive energy density everywhere! I can prove that to build a finite time machine, you need negative energy.”

One caveat, Hawking’s proof appears in his 1992 paper on the “chronology protection conjecture,” which has come under serious criticism by numerous physicists. Their main objection to the Hawking’s conjecture is that he did not employ quantum gravity to make his case. On the other hand, Hawking and others have not been able to develop a widely accepted theory of quantum gravity. Hawking did just about the only thing he could do under the circumstances. He used Einstein’s formulation of gravity as found in the general theory of relativity. Another fact, Hawking’s proof regarding the Tipler cylinder is somewhat divorced from the main aspects of his paper and could be viewed to stand on its own. However, in science we are always judged by the weakest link in our theory. Thus, with a broad brush, the chronology protection conjecture has been discredited, and even Hawking has acknowledged some of its short comings.

Where does that leave us with a finite Tipler cylinder time machine? In limbo! There is no widely accepted proof that a finite Tipler cylinder spinning at any rate would be capable of time travel. There is also another problem. We lack any experimental evidence of a spinning Tipler cylinder influencing time.

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

Diagram of a double slit experiment setup showing a monochromatic light source, double slit, and interference pattern on a screen.

The Classic Double Slit Experiment Is a 100 Year Old Time Travel Paradox that Continues to Baffles Modern Science

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First, let’s define a time travel paradox. It is an occurrence that apparently violates some aspect of causality typically associated with time travel. Many science students are introduced to the oddities of the double slit experiment in an advanced high school science class or in an entry level college science class. The double slit experiment is a paradox that has to do with the the future changing the present or the past. The effect has been known for well over a hundred years. It continues to this day to baffle science.

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 the figure below:

3-17-2014 3-08-41 AM Double Slit Fig 1 small

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.

  1. 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.

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

Aliens and UFOs

Are UFOs Time Travelers from the Future?

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Internet searches for the keyword acronym “UFO” (unidentified flying object) are among the most popular on the Internet. According to Google, there are five million global searches per month for the keyword acronym “UFO” (without the quotes).

Let us start with a little background. Surprisingly, the United States Air Force (USAF) officially created the acronym “UFO” in 1953. Their intent was to replace the more popular phrases such as “flying saucers” and “flying discs” because of the variety of shapes reported. In their official statement, the United States Air Force defined the term UFO as “any airborne object which, by performance, aerodynamic characteristics, or unusual features, does not conform to any presently known aircraft or missile type, or which cannot be positively identified as a familiar object.”

The phenomena, namely UFO sightings, are worldwide. Various governments and civilian committees have studied them. The conclusions reached by the various organizations that have studied them vary significantly. Some conclude UFOs do not represent a threat and are of no scientific value (see, e.g., 1953 CIA Robertson Panel, USAF Project Blue Book, Condon Committee). Others conclude the exact opposite (see, e.g., 1999 French COMETA study, 1948 USAF Estimate of the Situation, Sturrock Panel).

Given the sheer volume of unexplained sightings by credible witnesses, including military, police, and civilian witnesses, there is little doubt that the UFO phenomenon is real and worldwide, and for the most part, there is no widely accepted public or scientific explanation of what they are or what their intentions might be.

Three popular speculations regarding UFOs are:

  1. They are future generations of humans who have mastered the science of time travel, and they are coming back either to observe us or to carry out other intentions.
  2. They are technologically advanced aliens from another planet who have mastered the science of time travel, and they are coming here either to observe us or to carry out other intentions.
  3. They are secret government (United States or any government) experimental spacecraft, and by some accounts they are reverse engineered from advanced alien spacecraft in the government’s possession.

In my estimation, the ninety-page 1999 French COMETA study (the English translation stands for “Committee for In-Depth Studies”) is the most authoritative source of UFO information and provides a thoughtful, balanced view. Here are the facts that led me to this position:

  • The COMETA membership consisted of an independent group of mostly former “auditors” (i.e., defense and intelligence analysts) at the Institute of Advanced Studies for National Defense, or IHEDN, a high-level French military think tank, and by various other highly qualified experts. The independence of the group lends credence that the findings and conclusions would not be censored.
  • The French government did not sponsor it. This lends credence that the COMETA members were objective and not politically guided.
  • The COMETA study was carried out over several years. This lends credence that the COMETA study is a thorough account of UFO phenomena, not a hastily put out government press release.

The 1999 COMETA study concluded:

  1. About 5% of the UFO cases studied were inexplicable.
  2. The best hypothesis to explain them was the extraterrestrial hypothesis (ETH), but they acknowledged this is not the only possible hypothesis.
  3. The authors accused the US government of engaging in a massive cover-up of UFO evidence.

According to the 1999 COMETA study, a small but significant percentage of UFOs are likely of extraterrestrial origin. Does this rule out that they are future generations of humans, visiting the past? In my opinion, it does not. Even the conclusions of the 1999 COMETA study did not rule out this possibility. However, there is no conclusive evidence either way.

You will find an English translation of the 1999 COMETA study at this website address: http://www.ufoevidence.org/newsite/files/COMETA_part2.pdf.

The main questions regarding time travel and UFOs are:

  • Are the UFOs future generations of humans, time traveling back to our past and present?
  • Are the UFOs alien spacecraft, or secret government experimental spacecraft, able to traverse great distances using technologies essential to time travel, like a matter-antimatter propulsion system?

I suggest you read the complete 1999 COMETA study and draw your own conclusions.

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

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

Twisting the Arrow of Time

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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.

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. This is a scientific result, and I am not going to speculate about religious connotations, free will, and the like. Obviously, there are numerous religious connotations possible and a plethora of associated questions.

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

M-theory

Using Wormholes as a Time Machine

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Scientists have proposed using “wormholes” as a time machine. A wormhole is a theoretical entity in which space-time curvature connects two distant locations (or times). Although we do not have any concrete evidence that wormholes exist, we can infer their existence from Einstein’s general theory of relativity. However, we need more than a wormhole. We need a traversable wormhole. A traversable wormhole is exactly what the name implies. We can move through or send information through it.

If you would like to visualize what a wormhole does, imagine having a piece of paper whose two-dimensional surface represents four-dimensional space-time. Imagine folding the paper so that two points on the surface are connected. I understand that this is a highly simplified representation. In reality, we cannot visualize an actual wormhole. It might even exist in more than four dimensions.

How do we create a traversable wormhole? No one knows, but most scientists believe it would require enormous negative energy. This is interesting, since the Existence Equation Conjecture, discussed in previous posts, implies moving in time requires negative energy. A number of scientists believe the creation of negative energy is possible, based on the study of virtual particles and the Casimir effect.

Assuming we learn how to create a traversable wormhole, how would we use it to travel in time? The traversable wormhole theoretically connects two points in space-time, which implies we could use it to travel in time, as well as space. However, according to the theory of general relativity, it would not be possible to go back in time prior to the creation of the traversable wormhole. This is how physicists like Stephen Hawking explain why we do not see visitors from the future. The reason: the traversable wormhole does not exist yet.

Stephen Hawking did a fascinating time-traveler experiment in his popular TV series, “Into the Universe with Stephen Hawking.” He held a reception for time travelers from the future. He sent the invitations out after the reception had already occurred. His hope was that someone in the far-distant future would come across the invitation, and travel back in time to attend the reception. In the TV series, you see the reception room and Stephen Hawking, but no time travelers. He was disappointed.

However, we have four possible explanations why no time travelers attended:

1.    The invitation did not survive into the far-distant future, a future whose science enabled time travel to the past.

2.    Time travel into the past is not possible in the future, regardless of how far into the future the invitations survive.

3.    The human race does not exist in the distant future, destroyed by our own hand, or a cosmic calamity.

4.    Time travelers showed up at the party, but it was in another universe (an alternate reality suggested by the “Many-Worlds of Quantum Mechanics” theory). Perhaps in that reality, the TV series broadcasts a reception room filled with time travelers.

Although, we are discussing time travel, it is essential to note that wormholes imply connections between different points in space. This means that they may provide a faster-than-light connection between two planets, for example. Although faster-than-light travel is not possible, the wormhole may represent a shortcut. Travel inside the wormhole may remain below the speed of light, but be faster than the time it would take light to traverse the same two points outside the wormhole. Think of this simple picture.

You are on one side of the mountain. If you want to travel to the other side of the mountain by traversing its circumference, the journey will take longer than using a tunnel that connects to the other side of the mountain. The speed you travel is the same, but the tunnel allows a shortcut, and it appears that you traveled faster.

Will we ever be able to create traversable wormholes? Theoretically, it appears possible. Experiments are being conducted, as I write, using the Large Hadron Collider to create small wormholes, small black holes, and dark matter. The next decade holds considerable promise to address these questions.

Source: Unraveling the Universe’s Mysteries (2013), Louis A. Del Monte

Image: iStockPhoto (licensed)