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Is Time Travel Possible?

After 32 years working as a chemist for a major pharmaceutical company, Melvin has finally retired. He is an avid reader.

Stephen Hawking refers to time as the fourth dimension.

Stephen Hawking refers to time as the fourth dimension.

How many times have you said, “If I could do that again, I would do it differently"? From time to time, when something does not go according to plan, I wish I had said or done something differently. When mistakes happen, I often wonder: "What if I could build a time machine to go back in time and change a decision I made to cause it to go right instead of wrong?"

The late Stephen Hawking, a world-renowned cosmologist, believed time travel (or temporal displacement) to be possible. Many other physicists agree, but the main problem with moving through time is that it requires a lot of energy, especially if one wants to send something big, such as a human. It is, however, very possible to do this with subatomic particles in an accelerator, as we will learn later.

A Timely Definition

Thanks to Einstein’s papers on relativity, which focused on particle physics and black holes, today's physicists can explain how it is possible to go through time. From a physicist’s viewpoint, time is defined as one of the four dimensions in our physical world. In essence, everything in the universe exists in four dimensions—length, width, height, and time. When we are moving around in the world, we always move within these four dimensions, and everything in the universe moves with us, down to the atoms and subatomic particles that comprise matter.

Time is, in essence, the existence of something in the universe. Time is basically another dimension in length. Look at it this way: Each one of us will be around for 70 to 100 years, the pyramids have existed for about a couple thousand years or more, and the Earth and sun will exist for a few billion years more. In this case, we are measuring a type of length by using time.

The Connection Between Mass and Time

Physicists have known for a while that time slows down near massive objects. It was clarified in Einstein’s 1916 paper on special relativity that mass put a drag on the flow of time. This is called the time dilation effect. Think of time as water flowing in a river. The speed of the flowing water slows down around large boulders in the river.

Time Slows Down Near the Pyramid of Giza

This phenomenon happens every time tourists stand near the Pyramid of Giza in Egypt. This pyramid is one of the most massive structures on the planet, with an estimated mass of 40 million tons. Time slows down near the monument due to its large mass, but the effect is very small.

To put the effect into perspective, we can exaggerate it by using an observer looking at the pyramid. This individual would see people moving slower near the pyramid, whereas if they were to look out toward the desert, they would see people moving at a faster pace. In this exaggerated scenario, depending on how long the individual stood by the monument, they would emerge a few minutes, hours, or even a day into the future. The time dilation is taking effect as the time away from the pyramid is zooming by faster than the time near the pyramid.

The Pyramid of Giza

The Pyramid of Giza

Time Also Slows Down Near the Surface of the Earth

This drag on time also occurs near the Earth's surface. Time moves slower on the surface of Earth compared to the flow of time measured at a distance of 100 or even 200 miles outside of its atmosphere. This is because Earth is a massive object and causes the space near it to curve. This theory (discovered by Einstein) was proven many years ago with a specially designed gyroscope-equipped satellite.

Satellites Are Programmed to Correct Time Dilation

In fact, there is even more proof of this dilation effect taking place literally every second of the day just above our heads. The precise clocks on the 31 global positioning satellites (GPSes) circling the Earth experience the dilation effect. Time moves faster in space with respect to time on Earth because the satellites are further away from the massive body of the Earth. The distance between the satellites and Earth's surface causes a time dilation effect.

The effect is very small, but it is enough to throw the clocks on each satellite off by about one billionth of a second every day. Due to the dilation effect, the positions measured on the Earth’s surface may be thrown off by six miles a day from the perspective of the satellite. Fortunately, there is a built-in correction program on each satellite to account for this time error.

Time Moves Very Slowly Near Black Holes

Physicists know that the effect of time dilation near a massive object could be significantly amplified if we could fly a spacecraft near the most immense object in the universe—a black hole (Mother Nature’s time machine).

For a spacecraft to approach a black hole, everything must be done correctly. Astronauts in the spacecraft must move toward the black hole at the right speed and trajectory to avoid being drawn into it. If done correctly, the astronauts in the spacecraft circling the black hole would experience this slower passing of time. Those away from the black hole would experience time moving at twice the speed compared to the astronauts in the spacecraft.

If the astronauts stayed near the black hole for one year, people back on Earth would have already experienced two years. Obviously, traveling to a black hole would not be a practical way to travel into the future because too much time and energy are needed to achieve any significant time travel into the future. However, there is a more straightforward approach to traveling into the future, and it involves speed.

Black holes are said to be capable of making physical information disappear permanently, known as the "black hole information paradox."

Black holes are said to be capable of making physical information disappear permanently, known as the "black hole information paradox."

The Connection Between Speed and Time

Another aspect from Einstein’s paper on special relativity states that time slows down to an observer approaching the speed of light. Particle physicists have proven this theory at the CERN particle accelerator facility in Geneva, Switzerland. It is there that subatomic particles are accelerated to velocities near the speed of light in an underground tube in a 16.8-mile circular tunnel.

The CERN Particle Accelerator Increases the Lifespan of Particles

To study a very short-lived subatomic particle called a pi-meson (which has a lifespan lasting only 25 billionths of a second), the particles in the CERN particle accelerator are accelerated to 99.99% the speed of light. About a trillion of these particles are placed in the circular accelerator and are accelerated from 0 to 60,000 miles per hour in a few seconds with powerful magnets. The particles continue to accelerate until they are traveling at 99.99% the speed of light. At this speed, the particles move around the 16.8-mile circular accelerator 10,000 times per second, and thanks to the time dilation effect, the lifespan of the particles lasts 30 times longer than it normally does.

Train Traveling at the Speed of Light

This same scenario can be imagined with a train traveling close to the speed of light on Earth. This would be a challenging task to accomplish. If it were possible, imagine about 200 to 300 passengers board a train for a trip into the future. This is a one-way trip from which you cannot return.

The doors close and the train begins to accelerate slowly on a 25,000-mile track circling the Earth. The train continues to accelerate until it reaches a speed close to the speed of light. Once there, the train will be orbiting the Earth seven times a second. To an observer outside the train (granted he is able to see the passengers), the passengers will appear to be moving very slowly due to the time dilation effect.

If this train continued at this speed going around and around and finally coming to a stop after one week, 100 years would have gone by for the people who are not on the train, whereas the passengers on the train will only see one week go by. They will be 100 years into the future once they step off the train.

The problem with this scenario is that it would require a lot of power, energy, advanced technology, and manpower to accomplish, but it would work if it could be done.

A Trip to Space

This scenario could be done in space, as well, with the use of an enormous spaceship. The problem here is that the ship would once again require a lot of fuel and manpower. Also, the ship would have to travel out of the galaxy to achieve the same effect because it would take the ship almost four years just to reach 90% of the speed of light. By that time, it would just be passing the nearest star, Alpha Centauri (about four light years from Earth). The other obvious problem is that flying a ship at the speed of light would be a one-way trip. Passengers would not come back from this trip.

Finally, the Time Paradox

Cosmologists and physicists believe there is one thing you cannot do in time travel, and that is travel back to the past. Yet, this seems to be what everybody would want to do with a time machine (if they had one). Traveling back in time is impossible, and I will explain why.

You cannot have "effect" before "cause." In other words, you cannot see the effect before its cause—it simply doesn’t make sense. Here is an example: Imagine a scientist had assembled a gun to shoot himself in the past. Now, let’s say he invented a time machine to open a portal that allows him to travel approximately one minute back in time to shoot himself before he assembles the gun. Therefore, the scientist shoots his past self and his past self dies before he assembles the gun. Who fired the shot? It doesn’t make sense; it's a paradox.

This is an example of the way all events progress in the universe: cause, then effect—not the other way around. Another way of understanding the cause and effect is that the future is the “effect” and the present and past is the “cause." Unfortunately, you will never be able to go back in time to witness the Wright brothers taking off at Kitty Hawk, North Carolina, for their first flight, nor experience when the pyramids were built.

An example of the time paradox.

An example of the time paradox.

Time Travel in Science Fiction Movies

There are many shows and movies that depict time travel, such as the sci-fi classic, Time Machine, or the '60s TV series, "The Time Tunnel." More recent movies include The Time Traveler’s Wife and the Back to the Future trilogy. These shows and films were all wonderful, but they never quite accomplished explaining the significant amount of power needed to send something back and forth across the time continuum.

The sets in sci-fi movies and television shows will often use fancy pieces of equipment such as lights, dials, and gauges to dramatize the power of time travel. Often, the actor or actress who is time traveling will "disappear" in the blink of an eye. While it looks quite cool, that simply isn't how it works.

In the popular sci-fi movie, "Back to the Future", the DeLorean is a time-traveling car.

In the popular sci-fi movie, "Back to the Future", the DeLorean is a time-traveling car.

The Time Machine (1960)

The Time Machine (1960)

© 2011 Melvin Porter


Melvin Porter (author) from New Jersey, USA on November 13, 2015:

Glenn, thanks for reading my hub. Time slows down near massive objects. That is why time comes to a complete stop near a black hole because of its immense mass which affects the curvature of space near it. Stephen Hawkins also mentioned this effect in his tv series while explaining the possibility of time travel. The pyramids are very massive objects and their mass are affecting the curvature of space near them. That is why time slows down near them. The effect is extremely small but that is what is happening near massive objects. Time flows slower on earth compare to objects away from earth in space. However, the clocks on the GPS satellites run a little slower because they are moving at a speed close to 17, 000 mph. This tiny effect on the flow of time on the satellites cause the location of on points on the earth to be off by a few miles due to a calculation error. The error is corrected by introducing a correction factor for time dilation in the calculation to determine positions on earth.

Glenn Stok from Long Island, NY on November 12, 2015:

Generally interesting hub. But time dilation is caused by motion, not by mass. You correctly explain that near the end of your hub where you talked about the CERN particle accelerator in Geneva. But earlier in your hub you mentioned that time goes slower when near a large mass and you called that time dilation too. Can you give a reference to where you found proof of that? I'd like to read it to see if I missed something.

Abbi Clarke from Bangalore on August 18, 2015:

Very excellent Hub. Time is matters a lot when it comes to perfect travel....

Rami Sabeer from Egypt on July 22, 2015:

Great hub with value information thank you for sharing this hub in

Chaos from Providence on December 15, 2014:

rulixa on September 12, 2013:

time travel may be possible, but if not tied together with movement travel is has no sense

Look to

Melvin Porter (author) from New Jersey, USA on March 23, 2013:

RonElFran, thanks for your comment. The "Cause and Effect" law is a well established law in the physics community. Every event in our natural world proceeds from a cause before you see the effect. For example, the process of nuclear fusion in the our Sun produces the heat and light we see from the Sun. The light from the Sun causes the water in the earth's ocean to evaporate into the air to produce clouds. The water vapors in the clouds eventually cool down to produce rain, etc. This is the way all events in the universe progresses in time and not the other way around. Again thanks for your comment.

Ronald E Franklin from Mechanicsburg, PA on March 22, 2013:

Great hub. I do wonder if your conclusion that cause and effect preclude travel back in time is airtight. I seem to dimly remember that some discoveries in sub-atomic physics bring the principle that effect cannot precede cause into question. Would it be on more sure footing based on conservation of matter and energy, which would seem to forbid removing matter from one time and injecting it into another. Anyway, I enjoyed reading.

Melvin Porter (author) from New Jersey, USA on June 21, 2012:

Diliptech, thanks for your comment.

Dilip from INDIA on June 20, 2012:

Of course Time travelling in past for matter states is never possible and you could't just meet your ancestors, but i think we should't loose our hope in not geeting any feel of that.

Melvin Porter (author) from New Jersey, USA on December 27, 2011:

Dipless, thanks for your comment and for stopping by to read my hub.

dipless from Manchester on December 27, 2011:

An interesting hub, nicely written.

Melvin Porter (author) from New Jersey, USA on June 28, 2011:

TheWorldNow, thanks for your comment and for stopping by. I hope you enjoy reading my other hubs.

TheWorldNow from Washington DC on June 28, 2011:

Wow, I'm definitely following you. I look forward to reading all your other hubs!

Melvin Porter (author) from New Jersey, USA on March 09, 2011:

crystolite, thanks for the comment and for stopping by to read my hub.

Emma from Houston TX on March 09, 2011:

Interesting hub,thanks for sharing.

Melvin Porter (author) from New Jersey, USA on March 02, 2011:

Thanks Montecristo. Thanks for stopping by to read my hub.

Angel Caleb Santos from Hampton Roads, Virginia on March 01, 2011:

Great hub. I enjoyed it.

Melvin Porter (author) from New Jersey, USA on February 22, 2011:

Chinemeremz, thanks for your comment. Time travel is possible, the problem is that it requires a lot of energy to make it happen. Massive amount of energy is needed to push something much larger than the sub-atomic particles in an accelerator to near the speed of light. Currently scientists are able to push short-lived sub-atomic particles near the speed of light to make it possible to observe them since time slow down near the speed of light thus slowing the decay process of sub-atomic particles down. Also time does slow down near massive objects such as the pyramid of Giza.The effect is so small. This is proven by the fact that time moves faster when objects are further away from earth as proven from the GPS satellites circling the earth.

Chinemere onuekwusi on February 22, 2011:

Time travelling as seen from the physicist point of view cannot be feasible due to some irreconcilable facts like mass, error and human inconsistencies.

Time is unfortunately irreversible-that even the optical illusion at the pyramid Giza is over-hyped.

Oh I wish this was true (time travelling), as I wish to go back in time and reverse all the silly mistakes I made in the past.

However, the only way we can time travel is making the best of the moment we currently exist.

Thanks for this wonderful academic discourse, really pro scholarship.

Got my vote up!

sligobay from east of the equator on February 14, 2011:

Yesterday is only a dream and tomorrow is only a vision, but today well -lived, is the goal.

Melvin Porter (author) from New Jersey, USA on February 14, 2011:

Sligobay, thanks for your comment. As you can see the time paradox pretty much says we cannot change what already happened because the effects of the event continues forward in time.

sligobay from east of the equator on February 13, 2011:

melpor, greetings from the future, past and present. Time is of the essence and I learned something new about cause and effect. I am now following. Thank you.

Melvin Porter (author) from New Jersey, USA on February 12, 2011:

Time4Travel, thanks for your comment. I also enjoy this topic and generally tried to watch most movies on this subject. It is a fascinating subject.

Time4Travel from Canada on February 12, 2011:

A neat hub that is well written. I must say-- I do love this topic!

Melvin Porter (author) from New Jersey, USA on February 12, 2011:

Henry, All the pictures are in photo capsules and each photo were obtained through google search in the image tab of google.

henry1robertson from Los Angeles, CA 90013 on February 12, 2011:

This page attractive for other users. How are you decorate it?

Melvin Porter (author) from New Jersey, USA on February 11, 2011:

2besure, thanks for stopping by and thanks for the comment. Time travel would be fun if we could done it.

Pamela Lipscomb from Charlotte, North Carolina on February 11, 2011:

Great hub on time travel. Well done! If it were possible, I would be one of the first to sign up to go back and forward in time. Voted up!

Melvin Porter (author) from New Jersey, USA on February 06, 2011:

Genna East, thanks for your comment. I agree with you. If I had a choice I would choose to go back in time but all you will be able to do is observe the events. You will not be able to change anything due to the time paradox problem.

Genna East from Massachusetts, USA on February 05, 2011:

Fascinating hub...especially, the Time Paradox. Should we be given a choice to embark on a little time travel, I'm fairly certain that most people would choose to go back in time. A vote up and thank you1

Melvin Porter (author) from New Jersey, USA on February 05, 2011:

Agvulpes, I read an article where scientists have successfully teleported a small quantity of matter from one point to another using a beam of light to make it occur. But I believe it will be a while if it is ever possible to teleport something as complex as a living organism from one point to another. Thanks for reading my hub.

Peter from Australia on February 05, 2011:

melpor your explanations for time travel are very plausible and I very much enjoyed reading your Hub. I am wondering what your thoughts are on 'matter' transportation such as the 'Beam me up Scottie' machine ?

Rated up and bookmarked!

Melvin Porter (author) from New Jersey, USA on January 30, 2011:

Joyus, thanks for your comment. That is a good point. I forgot about adding multiverse into the picture but like you say travel between universes is highly impossible right now.

Joyus Crynoid from Eden on January 30, 2011:

Great hub melpor. I would say that the the irreversibility of time is explained by the second law of thermodynamics.

In his book "The Fabric of Reality" quantum physicist David Deutsch speculates that time travel into the 'past' might be possible in a multiverse, if it were possible to 'sidestep' from one universe to another: in which case the paradox you described is resolved by the fact that cause and effect actually occur in different (parallel) universes. Of course, not everyone accepts the many-universes interpretation of quantum mechanics; and even if it is correct, it is difficult to envision how one might travel between alternate universes!

Melvin Porter (author) from New Jersey, USA on January 29, 2011:

A M Werner, thanks for your comment. The possibility of time travel is here but we just don't have the technology, resources, and manpower to make it happen on a larger scale.

Allen Werner from West Allis on January 29, 2011:

Great hub - much to think about - much to ponder. Glad my life is moving just fast enough to do that. Any faster and I'd get dizzy. Peace

Melvin Porter (author) from New Jersey, USA on January 29, 2011:

Docmo, Thanks for your comment. I also find time travel to be a fascinating subject for many years. I always enjoyed various ways it was presented in movies and TV shows and my favorite movie on this subject is the classic one "The Time Machine".

Mohan Kumar from UK on January 28, 2011:

Brilliant ! Something that fascinated me for a long-time. the very first story I wrote when I was at school involved the grandfather paradox. I have since red a lot of sci-fi and theory around these concepts. I find this hub a very effective summation.voted up!

Melvin Porter (author) from New Jersey, USA on January 28, 2011:

Jeffrey, thanks for your comment. Time tunnel was one of my favorite sci-fi show back in the day. I enjoyed watching it because it educated me on some very historical events.

Jeffrey Talbot on January 27, 2011:

It is nice to see that THE TIME TUNNEL (ABC 1966-67) tv series is still remembered!

And it is an exciting prospect that time travel may one day be a scientific reality-achievement.

Let's hope that it happens in our lifetime.

Melvin Porter (author) from New Jersey, USA on January 26, 2011:

Ssaul, thanks for your comment. Yes it would be nice if you could flip a switch and go back in time to correct mistakes that you made. But remember going back in time may not be possible since you violates the "Cause" and "Effect" principle. It would be a paradox if you could do that.

Melvin Porter (author) from New Jersey, USA on January 26, 2011:

Dahoglund, once again thanks for the your comment. Movies involving time travel were always my favorite in the Sci-Fi genre. After watching them they always left me thinking and wondering.

ssaul on January 26, 2011:

hey how about we make a time machine, with technology enhancing everyday, its possible, lol! then when you want to correct something we just flip the switch. I would really like to change something really bad only knows.

Don A. Hoglund from Wisconsin Rapids on January 26, 2011:

Time stories have been my favorite form of Science fiction, although I don't much care for most of movie and TV treatment of it.

Melvin Porter (author) from New Jersey, USA on January 26, 2011:

TahoeDoc, I hope the above comment clears up the confusion about black holes. They are not that small. They are small relative to the size of everything else in the universe. Thanks for your comment.

Melvin Porter (author) from New Jersey, USA on January 26, 2011:

Gordon, black holes are large based on what Stephen Hawking said in his "Into the Universe" series. If I remembered correctly they are dense but they are millions of miles in diameter and that is small compared to most things in the universe. They are large enough for stars and other objects in space to fall in. That is what is happening at the center of our galaxy and there is proof of this. Thanks for bringing that point up and thanks for your comment.

TahoeDoc from Lake Tahoe, California on January 25, 2011:

Melpor - excellent hub! You have a gift for explaining complicated matters very well.

But now I'm confused by the above post...why can't something be both dense and large? I don't see how that's a contradiction. In any case, I understood it as a theoretical explanation in the hub.

Gordon Hamilton from Wishaw, Lanarkshire, United Kingdom on January 25, 2011:

I think that your Hub is absolutely wonderful and extremely informative in a great many ways - so why make it scientifically inaccurate??? "Large," black hole? How can the most dense matter theoretically possible be deemed to be, "Large...???" in what is effectively human comparitive terms? I respectfully refer you, Sir, to the works of Professor Stephen Hawking and the theory that, "Black holes," are configurations of collapsed matter so dense that light itself can not reflect from their substance...

Please be assured that I am genuinely interested and not being critical for its own sake.

Yours sincerely and genuinely,


Melvin Porter (author) from New Jersey, USA on January 25, 2011:

Suziecat7, thanks for comment. But remember you can not go back to the past. You are the effect and the past is the cause. Cause comes before the effect.

suziecat7 from Asheville, NC on January 25, 2011:

Very interesting Hub. If it was possible to time travel, I'd travel back to the 19th century. Great Hub.