Time Travel: Theories, Possibilities, and Paradoxes

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Time Travel is great, right? Being able to cut through the accumulated lies of history, to see the truth of the past, or being a tourist in a strange world of the future.

For years despite science says no stop it. You can’t, people have tried to prove once and for all that the time travel exists. In addition, the theories ranged from compelling to stupid and are often both.

I’m a man of many loves, and what kind of nerd would I be without loving Doctor Who.

A concept-driven sci-fi epic, super brick, pottering around space, being clever and seeing interesting things, and traveling through time.

What is Time?

Time is something that everyone is familiar with 60 seconds is one minute; 60 minutes is one hour, 24 hours is one day, and so on. This implies that time is linear, and it’s something that everyone is familiar with an agrees upon. But if someone came up to you and asked you to draw time, what would you draw? You might draw a clock or a watch ticking every second. But that’s all those drawings would be just physical representations of the passing of time. Those drawings would just scrape the surface of the Enigma that is time.

Think time as an arrow that moves only in one direction forward. This arrow of time started form big bang and moved in one direction since then.

Einstein’s Theory of Relativity

Einstein's Theory of Relativity

Well, we need to start with the basics of Einstein’s theory of relativity. Let’s say we have two individuals, Bob and Joe, who both have a watch on their wrist.

Let’s say Bob got into a spaceship, which could travel at a pretty good fraction of the speed of light. Well, when Bob gets back down from the spaceship, he’s gonna find that his watch is ticking much slower than Joe’s. That’s because motion through space affects our motion through time. As you move faster through space, you move slower through time. This phenomenon is called time dilation. It’s pretty hard for us to notice the effects of time dilation on our everyday lives, but it still occurs.

For example, when you’re driving time actually passes a few quadrillions of a second slower for you than someone outside. Speed isn’t the only thing that can affect how fast you move through time as well. Went back to older blogs we all know by now that gravity can also dilate time. Since, the presence of matter warp space and time, the more matter present in an object. The more that object warp space and time around it. In addition, the stronger gravitational field means time actually runs slower within that field.

Gravitational time dilation

It is present in our everyday life. For example, your feet actually age a few femtoseconds slower than your head. Since the Earth’s gravitational tug on your feet is stronger than the tug on your head.

Satellites that orbit Earth actually experienced time at a significantly faster pace and they do on earth surface due to the weaker gravity at such a high orbit and have to take this into account when providing GPS locations. These are still everyday scenarios. When we approach a gravitational field of immense strength such as a black hole or approach light speed, we noticed that time dilation becomes more intense.

Time Travel Possibilities

Contrary to what may think, Time Travel is Possible. Here’s how…

Time Travel through Wormholes

Time Travel through Wormholes

Imagine if you wanted to travel to the Andromeda galaxy, which is about 2.5 million light-years away. Even with our fastest rockets, we still couldn’t get there within a human lifetime. Enter the wormhole. A wormhole makes an impossibly long trip to the Andromeda much shorter by an going to take a sort of shortcut through the space required to get to the Andromeda galaxy.

But it turns out that wormholes can be used as more than just a quick gateway. They could be the key to our past and future, quite literally, How so? As we discussed Einstein’s Theory of Relativity.

How could we apply this principle to wormholes? Well, it’s simple, we put one man to the wormhole in a spacecraft and accelerate that spacecraft to a good fraction of lightspeed and keep the other mouth in a stationary position back here on Earth. When we decide to go through the fixed mouth here on Earth, and exit through the starship man, we essentially are time traveling to the past since the starship man is experiencing time at a much slower rate than us back here on Earth.

So essentially, it’s at a different point in time than we are.

Now obviously, the technology which involves near light speed travel, and creating wormholes is something we haven’t invented yet and probably won’t for a good amount of time. But in theory, assuming that we did, this is how it could likely work.

Also Read: Asteroids Vs Meteoroids Vs Meteor Vs Meteorites

Black Holes: Natural Time Machines

Black Holes: Natural Time Machines

Natural time machines, black holes can only used to travel into the future as Stephen Hawking described.

The idea would not be to go inside them but rather to orbit around them, as black holes are so dense that they are not only distorting space around them but also time itself, slowing it down more than anything else in Universe. As a matter of fact, if a spaceship was orbiting a black hole while another was floating in space a bit further the crew in orbit to the black hole would age half less than those onboard on the other ship.

If these spacemen stay for 10 years in orbit around it, 20 years will have passed when they’d be back on earth, therefore, allowing them to experience what appears like the future for them, including no possible return.

Tripler Cylinder

American physicist Frank J. Tripler invented another valid way to think about time travel. Who stated that any object rotating around a hypothetical cylinder of infinite length would go backward in time.

NASA engineer has even though o the cylinder as a way to host life during the endless journey around it but the “Tipler time machine”, though a viable solution for time travel, seems like a hardly practical method because the very notion of infinity means that it is out of reach of human perception, and then unfeasible.

Rotating Universe

In 1949, Einstein’s friend and confrere, Kurt Godel, one of the most brilliant mathematicians of the 20th century introduced a new solution to Einstein’s equations that allowed for time travel, which did no please his fellow.

Godel found that if the Universe itself was rotating, and if a spaceship traveled around it fast enough it would go back in time, and arrive before it left.

In spite of being one of the most foolproof solutions to travel through time, it’s also one of the less achievable as it might be an impossible challenge only to get out of the Milky Way, our galaxy, and one of 100 billion of other galaxies in the observable universe alone.

We, may in fact never know how gigantic the Universe is, so getting out of it just sounds like an unrealistic project.

Cosmic Strings

Cosmic Strings

Cosmic strings are hypothetical defects in the fabric of space-time, leftover from the birth of the Universe. These odd structures are one-dimensional objects, meaning they have length, but no height nor width and are suspected to have spread in large numbers throughout the Universe, like thin cracks over a frozen lake.

Comparing their imperfections within crystals, We thought that two strings side by side would be so dense that they would have a dramatic impact on surrounding space-time, allowing a spaceship spinning around them to emerge anywhere, anytime!

Since the discovery of the “Twin Quasar” in 1979 these strings might not be hypothetical any longer, which was revealed to be a double image of the same object claimed by scientists to be the result of a cosmic string that passed between Earth and the quasar, causing it to be seen at two different time periods on the same image.

Speed of Light

Speed of Light

During a faster-than-light journey, you would first experience time going slower and slower around as you would approach the speed of light until theoretically stopping time when reaching the speed of light, and finally going backward in time as you would travel faster than light.

If some astronauts made a round trip to the closest star system near the speed of light, 8 years would pass on Earth but to them, the trip would only last 8 minutes and someone watching them coming back at that speed from Earth would see them arriving in slow motion.

Yet it considered that nothing can go faster than the 300,000 kilometers per second of light(186,00 mi/s) because it would need an infinite amount of energy but recent studies have shed doubts about it, revealing a particle that might breach the holy laws of relativity.

These particles, called tachyons, have not only been demonstrated to go faster than light but also to have the mind-boggling characteristic of imaginary mass, meaning that they actually speed up as they lose energy.

It is possible to move at infinite speed with no energy at all the discovery would prove that, and maybe change the way scientists think of travel.

Warp Drive

Warp Drive

Just like black holes and other gravitational objects like planets ad stars distort space and time around them the Alcubierre Drive is based on the idea that a ship manipulating negative energy could have a similar impact on space-time.

NASA has already started to work on a model of real-life Star Trek-style spacecraft called IXS Enterprise, that will use the Alcubierre Warp Drive and even if it is designed to create shortcuts in space and not in time, it will inherently do both at a time, and may then be the most advance time machine to this day.

The IXS Enterprise would be able to generate a warp bubble around it, stretching space-time in a wave on which the spacecraft could ride, with time ahead of it being contracted, and time behind it being expanded.

Time Machine

Time Machine

We all travel in time, we travel at a rate of one hour per hour. But if we can travel in time faster or slower than one hour per hour or maybe traveled back in time, say at the rate of 10 hours per hour. Theoretically, a time machine can make that possible for us. Einstein’s general theory of relativity allows for the possibility of bending space-time so far that it actually folds upon itself to form a loop, technically known as a closed timelike curve, and popularly referred to as the time machine.

If you were able to travel along this loop, you would end up at a moment in the past and be again experiencing the same moment since all over again. But to create this type of Time Machine, scientists say we would need an exotic form of matter that has a negative mass, and which has yet to be discovered. Such exotic matter has bizarre properties, including moving in the opposite direction of normal matter when pushed.

Such matter could theoretically exist, but even if it did, it could be present only in quantities too small for the construction of a time machine.

Excotic Matter.

However, another time travel research suggests time machines are possible without exotic matter. The work proposes creating a doughnut-shaped hole enveloped within a sphere of normal matter, which carries whatever’s incited through space and time along the large circular path.

Inside this doughnut-shaped vacuum, using focus gravitational fields spacetime could bend upon itself to form a closed timelike curve. To go back in time, a traveler would race around inside the donut going further back into the past with each lap.

However, this theory is unimaginably hard to become a reality. But we are never going to stop wondering about the possibilities of time travel, and the future is going to be exciting.

Paradoxes

According to Wikipedia,” paradox, also known as an antinomy, is a logically self-contradictory statement or a statement that runs contrary to one’s expectation. It is a statement that, despite apparently valid reasoning from true premises, leads to a seemingly self-contradictory or a logically unacceptable conclusion. A paradox usually involves contradictory-yet-interrelated elements—that exist simultaneously and persist over time.

The Bootstrap Paradox

Imagine one day you receive a mysterious package. There is no note saying who sent the package or why it’s been sent to you. Confused but curious, you open the package and find a book, “how to build a time machine”. At first, you think it as some kind of joke. But after reading through the book, you start to believe that it might actually be real. You decided to give it a go and start collecting all the materials and items you need. It takes a long time, but after 10 years and several failed attempts, you finally build a working Time Machine.

In all this time, you never find out where the book came from, or why it was sent to you. But then it suddenly hits you. You grab the book and jump into your Time Machine.

Traveled back in time, 10 years leaving the book for your younger self to discover, but where did the book originally come from? You can only build the time machine if you discover the book. But you can only discover the book. If you build a time machine. It appears that the book has not been created by anyone, and it’s stuck in an endless causal loop. This is known as The Bootstrap Paradox.

The bootstrap paradox works with an object like the book, a piece of information, or a person.

Imagine you go further back in time and meet a young Albert Einstein before he was famous. Tell him about the Theory of Relativity, which he later publishes, and many years later you learn about in school. So who here came up with the theory?

The bootstrap paradox goes against our understanding of cause and effect.

An event A in the past causes event B in the present, which will cause events C to happen in the future. Time passes in a straight line from A to C, with the future always uncertain and dependent on our actions in the past and present. In the paradox, event C causes event A, which would mean that the future event has already happened.

We only subjectively experience the present moment. Therefore, this has big implications, does our time traveler have the choice to build the time machine, or it is already determined. Otherwise, how else could he have received the book?

Multiverse.

Multiverse
Source Google | Image by Forbes

One possible solution is the idea of multiverse time travel. When a time traveler goes back in time. They arrive in a different universe, a duplicate of the one they left, which is identical up to the time they arrive, then free to act in this new universe without affecting the original. However, this would not be a true causal loop but could explain how it will be possible to travel back in time and change past events.

A further problem with the bootstrap paradox is that it appears to violate the second law of Thermodynamics. An object stuck in a timeline, such as a book will age and eventually wear down, its entropy will increase to the point where it can no longer be used to build the time machine. We could suppose that entropy is somehow reversed by time travel So, that the book is restored to its original state. However, it’s not clear what an object’s original state is. When it doesn’t have a clear origin, to begin with, and would this also apply to the time traveler, restoring him to his original state of 10 years ago?

This would make time travel back further to the 1500s. Impossible.

The Grandfather Paradox

If you traveled back in time and killed your grandfather before he made your father, would you still be born? not possible, then how did you manage to travel back in the first place? If the killing of your grandfather were to happen. For instance, some physicists say he would not be born in one parallel universe, but you’d still be born and another.

Mind blowing

Based on quantum mechanics, the universe doesn’t have one history, but rather an infinite number of parallel histories. This theory is called the many-worlds interpretation.

It suggests that for every observation or decision on Earth, new world history is created. Based on this theory, a new universe with a different feature would branch into creation where you have killed your grandfather, while the universe from where you traveled would exist as it did before. The science behind time travel is full of uncertainty, and humans may not be able to withstand time travel at all.

Jeff Tolson, a professor of physics at Chapman University, said traveling nearly the speed of light would only take a centrifuge, but that would be lethal.

Predestination Paradox

Imagine, that you have a date today and you are waiting for your girlfriend at the cafe. After some time you get the news that your girlfriend died in a car accident. You were so attached to your girlfriend that you decided to build a Time Machine. It takes you a long time, but after 10 years and several failed attempts, you finally build a working Time Machine.

You traveled back in time to the exact date, when your Girlfriend died. In a hurry, you get in the car to save your girlfriend, and you drive fast and hit a car in which you see a girl who is dead, and also your girlfriend. It is a classic example of the Predestination Paradox.

The predestination paradox in time travel paradoxes is a causal loop paradox. Which tells every event is predestine and you cannot change it by going back in time. If someone tries to change events in the past. He will rather become part of that event.

Predestintion(2014) movies is based on this paradox.

This is of course, all hypothetical. paradoxes like this demonstrate why some scientists, such as Stephen Hawking, believe that time travel to the past is impossible. But what do you think? Will we one day be able to travel back in time? And if so, how can we account for these paradoxes?

Possibilities of Time Travel

We have already discussed many theories through which we can think that the time travel is possible.

One final method that could potentially allow an individual to more or less travel through time is cryopreservation. Preserving humans is called cryonics and since the 1960s the practice has continued. Cryonics is on the speculative edge of medicine, as its proponents suggest that death is not a singular event, but a process. Freezing humans before they die is currently illegal, but the practice needs to succeed.

When a person has opted to be cryopreserved their bodies prepared minutes after official death. The theory is that by reducing the patient’s body temperature to around negative 130 degrees Celsius. Enough brain information will be retained for doctors and scientists of the far future to revive the patient. Temperatures that low inevitably cause significant damage to the human body regardless of prior preservation safeguards. Today’s doctors are relying on future development that will allow the brain to be repaired at the molecular level and restored to functioning conditions.

If someday technology has advanced far enough to revive cryopreserved humans, they will have essentially time travel to the future

Is Time Travel Really Possible?

Is Time Travel Really Possible?

It’s not quite as easy as shows like futurama make it seem, but it is theoretically possible, and that’s time travel, in a nutshell, you really can move forward through time by traveling at immense speeds or through cryopreservation. But travel to the past is likely impossible.

The science of quantum physics and time travel is incredibly vast and well beyond the grasp of most normal people. So you know, we may be missing just one crucial element to understanding exactly how space-time works. After all, who knows, maybe someone from the far future will show up in our time and give us the key to the mystery, or would that cause a paradox?

Also Read: What is the big bang theory?


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