It's a well-known fact that our universe is, as far as we know today, a four-dimensional space-time continuum with three spatial coordinates and the time playing a role of the fourth one. We are perfectly capable of traveling backwards and forwards within the first three spatial coordinates, but is it possible to do the same on the fourth one? I am sure you would agree that it is not too exciting going up or down or left or right, but traveling through time could be something special. But is it possible? Let's explore all the theories, share some stories, and read about one connected hoax.
Ok, ok, I know how ridiculous this sounds, so I will stop now and try to get back to the main topic. Let's try to summarize what we scientifically know about time and how to bend it. Throughout Einstein's theories, we now definitely know that the universe is built from the fabric that is bendable. It was first proven by a famous experiment during a solar eclipse, which showed the curvature of light from a star as the light rays passed by the sun. Arthur Eddington led an expedition to west Africa back in 1919 in order to take pictures of a solar eclipse with definite proof of dislocated stars located next to the sun's disc, caused by a curved universe caused by the sun's large mass. In other words, we definitively know that spacetime is bendable, but the physics of how and why it bends is a completely different story. According to Einstein, in lack of better knowledge of the universe fabric itself and lack of discovery that would prove existence of gravitons, we can't say for sure even that gravity is a force at all! It could be just a property of the space-time fabric that bends easily by mass. In other words, the universe could be just a large system of perforated roads for traveling particles with mass and energy waves. Maybe to describe it better with a metaphor, if we are a large mass traveling throughout space and we don't have enough speed and encounter a curved space around a giant star, we are doomed and will be simply captured into circular motion around the large star. The question is, of course, is it possible to curve the space that much so we can travel the curved path back or forth in time? Thanks to Einstein, we now have a great understanding of the physics of the big. There are mathematical equations that describe and predict all known and still not observed objects in our universe. We are also aware of boundaries like the ultimate speed of light for any particle with a mass, and even the physics of the wormholes and warp drives are mathematically plausible. The only problem is that we are too small to comprehend the great amount of (negative) energy required to establish a wormhole or a drive capable of curving the space instead of propelling itself. In many theoretical studies of wormholes, it is still unknown whether or not it is possible to create a stable tunnel through the fabric.
It seems that building large shortcuts in the universe is still out of our reach, probably because of the great energy needed and our lack of understanding the space fabric itself. The solution is probably waiting to be discovered within a quantum level of existence. Comparing to enormous space and large objects, ironically speaking, studying the science of small particles and energy waves is difficult because we are too big! Simply put, we are unable to monitor and understand small objects because our monitoring tools are too large in size. For example, if we are using an electron microscope, we would only be able to monitor objects much larger than the electrons we are beaming into; otherwise, we would be adding additional disturbance to objects we want to see. Studying the quantum world is only possible indirectly, like in giant accelerators where we are beaming two small particles and forcing them to collide and then learning from the snapshots taken from the clash. However, quantum mechanics is a scientific discipline we have been researching for a century or so, and while there are many things waiting to be understood, we have already learned a great deal about particle physics, electromagnetic waves, and the quantum microworld.
So, what do we quantumly know in regards to time travel? This is the story of searching for the ultimate theory that could be able to connect the microworld with the fabric of the universe itself and explain both the physics of micro and macro objects and their relations. We are still out of luck, but a couple of leading theories arrived in the previous century in the form of string theory and it's variations. What is common for all of them is that they compete with old particle physics either to replace it or to be built on it similarly to what theory of relativity did for Newton's gravity theory. String theory in the form of a membrane or M-theory suggests multiple dimensions and also the creation of multiple universes caused by collisions of membranes. The microworld in this theory would be capable of living and traveling through multiple dimensions and perhaps even universes. Now, how is this connected to time travel? It is important because of our efforts to find a solution to a so-called time travel paradox where traveling backwards in time would be potentially dangerous because of the butterfly effect, where a time traveler, by changing something even as small as killing a butterfly, would end in fatal disturbance of the future already happening events. So the additional question arises: if time travel backwards in time is possible by bending space, how has nature solved this paradox? Two solutions are proposed, wherein one the universe is blocking inconsistent events by it's nature, so it is simply impossible for you to go in the past and kidnap Hitler or kill somebody's ancestors in order to change history. If a future version of you visits a younger you, then it is simply impossible to prevent you later in the future not to make the visit in the first place, as this already happened, and it is nothing but a closed, inconsistent loop that is very hard to imagine. To complicated? Maybe, but check then the other solution where time travel actually places you in a different timeline or parallel universe with copies of you and others. The quantum world recognizes a so-called quantum entanglement where two particles share the same properties even located in two different locations in space, maybe in time, and perhaps even separated by two dimensions or branes. Does it look like 'Fringe' science to you?
Either way, traveling back in time seems to be impossible, blocked, or extremely hard. If you ask Stephen Hawking, the only proof we need is a lack of tourists from the future visiting us. Of course if you exclude my encounter with the Oktoberfest and gray alien from the beginning of this story.
Like you probably noticed, this post is more about traveling backwards in time, but it would be unfair not to mention the ease of traveling forward in time. We are doing it on a daily basis, and since you started reading this post, you traveled forward in time for a couple of minutes by now. However, jumping forward into some future destination in time is a different story, but thanks to the theory of relativity during fast flight of say 95% of the speed of light, traveling into the future is more than possible. So to speak. In theory, that is. Namely, it is a well-known thought experiment where a train is circling the Earth with a near to light speed for a period of 100 years. Time in the train could be slowed down by ratio of 1/5000, and their passengers would be older only one week compared to their fellow Earthlings, who got older one full century or so.
Like I said, easy. :-)
Time travel is not only popular in scientific circles or sci-fi stories. It is also popular among internet hoaxes. Back then, during 2000 and 2001, a guy named John Titor ruffled the internet audience of the time within bulletin boards and forums, claiming that he came from the year 2036 of his own universe into ours as a guinea pig of the government time travel experiment in his own future time. He was sent to retrieve some old computers they lost in their timeline. He even posted various images and schematics of his time machine based on contained micro singularities installed in the car capable of bending the laser beam toy and therefore the space-time itself. It was enjoyable how detailed it was, along with predictions of future nuclear wars, the CERN LHC experiment, the war in Iraq, etc. Don't miss this story in the below links. I am looking forward to the movie.
* Image credit
http://www.imdb.com/title/tt1092026/
Refs:
http://www.dailymail.co.uk/.../STEPHEN-HAWKING-How-build-time-machine.html
http://science.howstuffworks.com/science-vs-myth/everyday-myths/parallel-universe.htm
http://www.npr.org/2011/01/24/132932268/a-physicist-explains-why-parallel
http://www.quantumjumping.com/articles/parallel-universe/parallel-universes-theory/
http://www.dailymail.co.uk/home/moslive/article-1269288/STEPHEN-HAWKING
http://library.thinkquest.org/27930/wormhole.htm
http://www.h2g2.com/approved_entry/A6345407
http://en.wikipedia.org/wiki/John_Titor
Well yes, like many of you, I also love reading sci-fi stories and watching great movies about time travel, but before I start upgrading my DeLorean with a brand new flux capacitor kit I can find online, let me tell you a story that inspired me to start reading articles and buying popular scientific books regarding the famous fourth dimension of our universe. It happened about 12 years ago when I was telecommuting with a Munich-based company developing software for interactive conferences for pharmaceutical companies. We did a great job, and I was asked to visit Munich for some software tuning and also for some socializing with my partners during the famous Oktoberfest festival. This is kind of a "conference" where instead of software driving the event, the only tool needed is, you guess, a great Bavarian beer. So, one night we went there and had a great time. I remember my visit didn't hit the main Oktoberfest night, but still the feeling was all the same. We were sitting in the big hall filled with lots of wooden tables, and I estimated up to 500 people in there. In one brief moment of insanity, I spotted a man enjoining his friends about 50, maybe 70 meters away from us. They were doing the same as we, drinking beer and having a good time, but what impressed me the most was his appearance, which hammered my head for a couple of moments or more. He looked amazingly like gray aliens portrayed in Fox Mulder X files aired at the time. He had a large head compared to his body, large black eyes slightly curved, a small nose and mouth, and not much of ears on the top of his head. Probably because of the large amount of beer, I didn't remember clearly what happened after, but I was probably in the center of loud laughter when I pointed my finger and said, "Look, there's an alien drinking beer!". I am sure the amount of beer I drank was responsible for the whole thing, but still, ever since then, I can't stop thinking that gray aliens are nothing more than just our future descendants traveling through time, visiting the past and enjoying good shows, like in this case the best quality of Bavarian beer, especially brewed for Oktoberfest.
Let's face it, we surely don't know how humans will evolve within the next millennium or more, but I am confident that one particular outcome could be just like grays! It's not far from reason that our body would evolve down while our head will be 'heading' in the opposite direction in the future, directly caused by fewer physical activities and more brain evolution toward rationality. Anyway, if I am a future human in possession of a DeLorean with a working flux capacitor from "Back to the Future", after visiting a couple of main historical events, I would definitely visit some great entertainments of the past.
Ok, ok, I know how ridiculous this sounds, so I will stop now and try to get back to the main topic. Let's try to summarize what we scientifically know about time and how to bend it. Throughout Einstein's theories, we now definitely know that the universe is built from the fabric that is bendable. It was first proven by a famous experiment during a solar eclipse, which showed the curvature of light from a star as the light rays passed by the sun. Arthur Eddington led an expedition to west Africa back in 1919 in order to take pictures of a solar eclipse with definite proof of dislocated stars located next to the sun's disc, caused by a curved universe caused by the sun's large mass. In other words, we definitively know that spacetime is bendable, but the physics of how and why it bends is a completely different story. According to Einstein, in lack of better knowledge of the universe fabric itself and lack of discovery that would prove existence of gravitons, we can't say for sure even that gravity is a force at all! It could be just a property of the space-time fabric that bends easily by mass. In other words, the universe could be just a large system of perforated roads for traveling particles with mass and energy waves. Maybe to describe it better with a metaphor, if we are a large mass traveling throughout space and we don't have enough speed and encounter a curved space around a giant star, we are doomed and will be simply captured into circular motion around the large star. The question is, of course, is it possible to curve the space that much so we can travel the curved path back or forth in time? Thanks to Einstein, we now have a great understanding of the physics of the big. There are mathematical equations that describe and predict all known and still not observed objects in our universe. We are also aware of boundaries like the ultimate speed of light for any particle with a mass, and even the physics of the wormholes and warp drives are mathematically plausible. The only problem is that we are too small to comprehend the great amount of (negative) energy required to establish a wormhole or a drive capable of curving the space instead of propelling itself. In many theoretical studies of wormholes, it is still unknown whether or not it is possible to create a stable tunnel through the fabric.
It seems that building large shortcuts in the universe is still out of our reach, probably because of the great energy needed and our lack of understanding the space fabric itself. The solution is probably waiting to be discovered within a quantum level of existence. Comparing to enormous space and large objects, ironically speaking, studying the science of small particles and energy waves is difficult because we are too big! Simply put, we are unable to monitor and understand small objects because our monitoring tools are too large in size. For example, if we are using an electron microscope, we would only be able to monitor objects much larger than the electrons we are beaming into; otherwise, we would be adding additional disturbance to objects we want to see. Studying the quantum world is only possible indirectly, like in giant accelerators where we are beaming two small particles and forcing them to collide and then learning from the snapshots taken from the clash. However, quantum mechanics is a scientific discipline we have been researching for a century or so, and while there are many things waiting to be understood, we have already learned a great deal about particle physics, electromagnetic waves, and the quantum microworld.
So, what do we quantumly know in regards to time travel? This is the story of searching for the ultimate theory that could be able to connect the microworld with the fabric of the universe itself and explain both the physics of micro and macro objects and their relations. We are still out of luck, but a couple of leading theories arrived in the previous century in the form of string theory and it's variations. What is common for all of them is that they compete with old particle physics either to replace it or to be built on it similarly to what theory of relativity did for Newton's gravity theory. String theory in the form of a membrane or M-theory suggests multiple dimensions and also the creation of multiple universes caused by collisions of membranes. The microworld in this theory would be capable of living and traveling through multiple dimensions and perhaps even universes. Now, how is this connected to time travel? It is important because of our efforts to find a solution to a so-called time travel paradox where traveling backwards in time would be potentially dangerous because of the butterfly effect, where a time traveler, by changing something even as small as killing a butterfly, would end in fatal disturbance of the future already happening events. So the additional question arises: if time travel backwards in time is possible by bending space, how has nature solved this paradox? Two solutions are proposed, wherein one the universe is blocking inconsistent events by it's nature, so it is simply impossible for you to go in the past and kidnap Hitler or kill somebody's ancestors in order to change history. If a future version of you visits a younger you, then it is simply impossible to prevent you later in the future not to make the visit in the first place, as this already happened, and it is nothing but a closed, inconsistent loop that is very hard to imagine. To complicated? Maybe, but check then the other solution where time travel actually places you in a different timeline or parallel universe with copies of you and others. The quantum world recognizes a so-called quantum entanglement where two particles share the same properties even located in two different locations in space, maybe in time, and perhaps even separated by two dimensions or branes. Does it look like 'Fringe' science to you?
Either way, traveling back in time seems to be impossible, blocked, or extremely hard. If you ask Stephen Hawking, the only proof we need is a lack of tourists from the future visiting us. Of course if you exclude my encounter with the Oktoberfest and gray alien from the beginning of this story.
Like you probably noticed, this post is more about traveling backwards in time, but it would be unfair not to mention the ease of traveling forward in time. We are doing it on a daily basis, and since you started reading this post, you traveled forward in time for a couple of minutes by now. However, jumping forward into some future destination in time is a different story, but thanks to the theory of relativity during fast flight of say 95% of the speed of light, traveling into the future is more than possible. So to speak. In theory, that is. Namely, it is a well-known thought experiment where a train is circling the Earth with a near to light speed for a period of 100 years. Time in the train could be slowed down by ratio of 1/5000, and their passengers would be older only one week compared to their fellow Earthlings, who got older one full century or so.
Like I said, easy. :-)
Time travel is not only popular in scientific circles or sci-fi stories. It is also popular among internet hoaxes. Back then, during 2000 and 2001, a guy named John Titor ruffled the internet audience of the time within bulletin boards and forums, claiming that he came from the year 2036 of his own universe into ours as a guinea pig of the government time travel experiment in his own future time. He was sent to retrieve some old computers they lost in their timeline. He even posted various images and schematics of his time machine based on contained micro singularities installed in the car capable of bending the laser beam toy and therefore the space-time itself. It was enjoyable how detailed it was, along with predictions of future nuclear wars, the CERN LHC experiment, the war in Iraq, etc. Don't miss this story in the below links. I am looking forward to the movie.
* Image credit
http://www.imdb.com/title/tt1092026/
Refs:
http://www.dailymail.co.uk/.../STEPHEN-HAWKING-How-build-time-machine.html
http://science.howstuffworks.com/science-vs-myth/everyday-myths/parallel-universe.htm
http://www.npr.org/2011/01/24/132932268/a-physicist-explains-why-parallel
http://www.quantumjumping.com/articles/parallel-universe/parallel-universes-theory/
http://www.dailymail.co.uk/home/moslive/article-1269288/STEPHEN-HAWKING
http://library.thinkquest.org/27930/wormhole.htm
http://www.h2g2.com/approved_entry/A6345407
http://en.wikipedia.org/wiki/John_Titor