It is very important that you keep in mind that when discussing time travel, often spacetime will come up. The reason for this is that it connects to several different areas of how time itself passes. For example, GPS systems are not connected technically to on-ground sources. They connect to satellites in low orbit. They’re roughly 12,500 miles above the Earth’s surface.
Due to being outside of the Earth and rotating around with it, one would assume that time-wise they are connected to the same time as our own. However, they’re actually off by 1 second per second. Since Albert Einstein was able to accurately find that gravity actually curves space and time, scientists knew how to calculate this time difference.
Since gravity is weaker in low-orbit, time is altered. In this area, they even run faster in time. Yet Spacetime overall is important to keep in mind. Gravity dictates how spacetime operates, in that, the more gravity something has, the slower time will pass.
Gravitational Time Dilation is present to help us make assumptions about how time will pass for us. Meaning, if we did visit a new planet with different forms of gravity to our own, we can make an accurate assumption of how this gravity will impact our species. Einstein came up with this under his Special Relativity concept.
Gravitational Time Dilation is essentially a comparison model where we bring in two things or events and give them different forms of gravity. The time dilation will be how the time is altered between the two. Einstein found that when the potential for gravity lowers, time will pass slower. However, as gravity increases, the faster time will be.
In fact, we were even able to find that the Earth’s core is roughly 2.5 years younger than its surface due to this model. This proved to us that larger effects will require a bigger distance or a larger source of gravity.
How space & gravity affected humans intrigued NASA, so they wanted to do a comparison experiment with twins. Therefore, they used Mark & Scott Kelly. They were perfect because they were identical and did not have any major differences. In fact, both men were checked for everything known to man and seemed to match up in every major category pre-flight.
Scott went into space while Mark remained on Earth. The testing NASA wanted to do was immense. They wanted to test how the immune system responded as well as information on epigenetic changes, gut bacteria, body weight, serum metabolites, and much more.
Scott spent a year in space and upon returning, he showed positive numbers that gave scientists a lot of hope when it comes to possible long-term space travel. Some numbers were even considered shocking. However, compared to his brother Mark, Scott was a bit taller, had less facial aging, and much more. If you want to read a full summary of the study, click here.
While it might not seem to be hard to comprehend the speed of light is fast, we need you to grasp how fast it actually is. In terms of speed, the number of miles that light travels per second are 182,282. In terms of kilometers per second, that translates to 299,792. Yet in MPH terms, or how we normally judge speed, one could travel 670,616,629 miles in a given hour.
Nothing can quite move this quickly other than the light itself. If we were able to capture the ability to do this in a machine…it could be the secret to long-term space travel and even teleportation. This is also key when understanding how lightyears operate too. When you hear that a planet is roughly 10 lightyears away, this does not mean it takes 10 years to get to.
Rather, it would take 10 Earth Years to get there when moving at “the speed of light.” The fastest a manned vehicle has ever been able to go was done by the Apollo 10 when it moved at 24,791 MPH. At this rate, to get to something 10 light years away, it would take us 270,000 Earth Years!
When something moves faster in terms of speed, the slower one will experience time. If you move fast, you will experience time along with the fast-moving manned craft you’re in. Meaning, you are going to age a bit differently compared to those who are not in the craft with you. Scientists used an airplane to confirm that idea.
An experiment was done using two clocks. One went up in the airplane while the other remained on the Earth’s surface. The fast-moving plane went up in the air and flew around the world in the direction that the Earth rotates. This meant it ideally would be going with the same movement of time that a clock would be going.
Once the plane landed, scientists found the clock on the airplane was a bit behind the ground clock. Yet both clocks were set to exactly the same times before the experiment began. They found that the airplane clock moved roughly 1 second per second slower than the ground clock. This proved the time on the clock was affected by the speed of the plane it was in.
While understanding spacetime and gravity might seem useful, it’s likely you want to know what they have to do with time travel. This is a good thing to question but the answer is simple. Both help us how to determine the operation of time and how we travel in it.
Basically, if you do not know how gravity changes time then it’s hard to know how time travel itself actually works. In fact, it is due to this knowledge of time and gravity that time travel is even possible at all for a human being to do in a major form. Yet lightspeed and lightyear knowledge helps when understanding that speed and time are also connected.
This was proven in the Airplane experiment and many others over the years. Due to Einstein and his Theory of Relativity, which includes quite a lot honestly, we know mankind can do a lot more than once assumed. Basically, we said all of this so you’ll understand that time travel has been technically possible for a long time.
It’s hard to know how time travel might affect humans if we indeed did manage to do it in the science fiction way. We know it would take incredibly high speeds and the problem with something like this is the force it causes. For example, on a cruise ship, you often expect to go to the front of the ship and do what you see in the Titanic film. However, what actually happens is that in spite of the ship going no faster than the average speed limit of your car.
It brings in a ton of force and you can barely walk around, much less have Leonardo DiCaprio hold you with only a small bit of hair movement. This force is minute compared to the speed of light. In fact, you can go to The Space and Rocket Center in Huntsville, Alabama to experience their G-Force machine that spins around at high speeds. It is used to simulate the force astronauts feel during liftoff.
Removing gravity in space would result in a lack of most G-Forces, which is good. However, even if we removed gravity, the speed of light will need acceleration which still causes G-Forces in space. The fact that we’ve never reached it with a manned vehicle proves we need better technology otherwise man could never survive possible major time travel. This would ideally need higher speeds to accomplish.
Time Travel Can Only Be Done Into The Future…For Now
A lot of the time when we think of time travel, we speak about how we’d go back in time. However, this is not exactly an easy thing to do. The reason for this is mostly down to the fact that we are unable to physically go back to change what already happened. However, we can shape our futures and therefore travel into the future possibly hundreds to thousands of Earth years.
An Earth Year is nowhere near the same as a year in spacetime nor can it be compared to a year on a distant planet. If one spends what they believe is an Earth Year physically traveling through space and comes back to Earth…we already know timewise things may not add up. However, depending on how far and fast they are traveling…they could very well hop into the future several Earth years ahead. Yet they won’t physically experience the change.
They’ll come back after spending just a year away to see Earth hundreds to thousands of years later. They will not have changed but generations of their family line would have already passed. Yet right now, this concept is only available when using spacetime and cannot be experienced on a planet. You could not gain the speed necessary and you’d need to deal with gravitational laws that spacetime won’t have as much of a problem with, at least outside of G-Forces.
Time Travel In Spacetime Creates A Lot Of Problems
Let’s pretend we’re able to make a manned vehicle that can travel at the speed of light. Testing this would be hard to do but just for the fun of it, let’s say we found a way to do it. Now you’re capable of traveling distances we never thought we could ever reach, all in a short time period. However, here’s the rub of that. The short trip will be your experience but not Earth’s.
Communicating with you might be impossible. At least for Earth, we can send a message in terms of light but if you’re a lightyear away it would take 1 year to get a light-made message. Yet Earth Years in total are not being considered here. Even though you’d make roughly a 2 lightyear roundtrip…you’d only age 2 years in spacetime.
Yet the Earth you return to could be thousands of years older than when you left it. What people forget is that the people on board the space shuttle would not experience Earth Year time but Earth will still age. When you discuss time travel, the only possible way to do it is truly to go into the future like this. Well, it used to be the only way.
Scientists recently discovered what appears to be a dimension that is not moving forward but rather, moving backward. We basically mean that in its aging process, it’s only getting younger and not older. This possibly means that their time only will move backward but could never move forward.
This dimension is a mirrored parallel universe scientists were shocked to discover. This is a pretty essential discovery because a mirror dimension to our own could play a role in time travel. Currently, we can only move forward in time while their universe could only move backward. However, being a mirrored universe, everything means the opposite.
Therefore, it is a universe where the left is right & up is down. On top of this, you have to look at the implications of such a place. If it is completely mirrored, that also means the people are mirror images. However, if everything is backward to us, does that mean the people and their lives are also backward? Does everyone have Benjamin Button syndrome here? Is everything in true reverse? Honestly, we don’t know….but doesn’t that make it all the more intriguing?
What does this mean to us when discussing time travel? It means that if a mirrored universe exists and we can access it, we could follow their laws when it comes to physics. If they can only move backward and we can only move forward, there is a good chance that accessing it would allow us to go backward in time.
How can this be done? That’s the complicated part. There have been some who feel wormholes could be the best possible avenue, especially if we could create our own version that could be controlled. If this ever did happen, then connecting to a mirrored universe could be possible. However, this is the stuff of science fiction and not science fact as of yet. Theoretically though, if we could access this universe then we could possibly travel back in time.
As we could enter this wormhole and then exit into space. This allows us to remove any possible gravitational issues. If we can control the wormhole, then we could open it to pop back into our own universe at the exact time we wish to go back to. Since our mirrored universe goes only backward, we’d follow their laws of physics to the letter this way. Yet if we did this, there’s a lot to consider.
Sometimes, you do not need to consider traveling through space or even focus on lightyears and speed. Perhaps, all you need to consider for time travel to be possible is Cosmic Strings. It is believed that these strings are tubes of energy that stretch across the entire length of our expanding universe.
This connects a lot of major concepts but time travel seems to be the most prominent here. Cosmic String fans believe this is possibly the best thing for time travel to be possible because these strings are leftover from the early cosmos. Since they likely contain huge amounts of mass, they could technically warp or fold spacetime around them.
It is assumed that Cosmic Strings are either infinite or they’re in never-ending loops. If two strings came close to one another, essentially parallel to the other, they’d bend spacetime so much and in such a particular way that time travel could be possible using them. Of course, this is just a theory for now as are a lot of String Theory concepts.
There are two sets of timeline theories to consider. The first is the one every science fiction movie and book seems to be based on. If you go back in time and do something, it could directly impact the time you go back to. Yet in other theories, this is not the case. Some believe that your past is constant, meaning it will never change.
Let’s pretend you went back in time and killed Baby Hitler like you might hear people mention. If you did this, some believe it will result in the future never having heard of Adolph Hitler. Yet in this “past is constant” theory, you will go back to your own time and never see a change. Hitler always existed. This is due to the fact that you have not affected your own timeline but rather, invented a new timeline that will create essentially its own new universe.
Others believe that your timeline will still always exist but you might go back to your own time to experience the change because you were absorbed into this new universe you basically created by killing Baby Hitler. Let’s explore this a bit more through effects and paradoxes.
No, we’re not going to be discussing the Ashton Kutcher movie of the same name. However, they were pretty spot on with what this theory suggests. The Butterfly Effect is part of what is known as “chaos theory.” This theory is made up of a branch of math focusing on dynamic systems where random states of disorder and/or irregularities are often governed by deterministic laws that are sensitive to initial conditions. Basically, there are underlying patterns in randomness.
The Butterfly Effect comes originally from the work of Edward Lorenz. He came up with this concept revolving around tornado and how it is influenced by minor things. In this case, the flapping of the wings of a distant butterfly and how it could have caused the tornado weeks later. Lorenz based this concept on following weather models and how weather itself can be altered over minor changes in the environment.
This is the one that has quickly become the most debated in time travel paradoxes. Called the Grandfather Paradox, one person might feel that they want to die. Perhaps they don’t though but they feel that their family was part of a lot of bad things throughout history.
They are willing to selflessly go back in time and kill their grandfather or great(x times you need) grandfather, all to ensure their family does not exist. This will sadly cause them to not exist either but by doing this, they run into a paradox. If they kill their grandfather, then technically they prevent themselves from ever existing.
Therefore, they could not have gone back in time to kill their grandfather. Basically, it means that it would be like they never went back in time at all. Now, another person could kill their grandfather as long as there was no family relation. However, they simply could not. Keep in mind that this paradox is not exclusive to grandparents but several changes one might make in the past when time traveling.
A lot like the Grandfather Paradox, the Let’s Kill Hitler Paradox works pretty much the same way. However, are some differences here too, especially when looking at the timeline theories. In this instance, a person perhaps is tired of living and wants to go back in time to kill themselves.
Apparently, they don’t have the nerve to kill themselves but could easily kill a baby that happens to be them from the past. It could be any younger version of them, however. This does not need to be a baby, technically. In any case, they go back in time but seem to fail every time they try to kill their past self. Why?
They cannot kill themselves, because they would not be alive to have done so. Yet they could cause possible damage, such as markings that they will experience. However, you too will experience them. Let’s say you shoot at your younger self but miss and shoot their arm. You could look at yourself and see a mark left by the bullet in your arm, as you were shot while you were younger by some strange man who looked a lot like you.
The Bootstrap Paradox is thought to be the most respected theory in the connected timeline. Why? It follows all the rules of the constant past concept without breaking those laws. Basically, in this paradox, you experienced something in the past that was always going to happen. It is part of a casual loop.
In this format, one event causes the second event. Yet it was the second event that was actually the cause of the first. A great example of this can be seen in DC Comics’ The Flash character. Reverse Flash goes back in time to kill young Barry Allen but fails, then the Reverse Flash decides to instead kill Barry’s mother.
Barry got himself out of the home but could not save his mother. By going back in time to save his mother, he’d never become The Flash. Therefore, he has to let his mother die to become the hero the world needs. If she never does, he does not become a forensic specialist for the CCPD the night of a Particle Accelerator Explosion, which gave him his powers. Yet if he’s never The Flash, he cannot run back in time to stop himself from being killed either. Which creates a loop of needed actions.
It’s interesting that we bring up The Flash in this scenario of time travel. He actually does go back in time to stop Reverse Flash from killing his mother in the Flashpoint Paradox story-arc. This is a key part of DC Comics that causes a few rifts in the multi-universe itself and ends up causing a Crisis Event.
In any case, when Flash does this he technically creates a new timeline and universe where his mother exists yet he is not The Flash. A lot of things are the same but many things are not. Bruce Wayne is killed instead of his parents, causing his father Thomas to become Batman while his mother actually becomes this universe’s Joker.
Superman does not land in a field but rather, in the center of the Metropolis. Wonder Woman and Aquaman have an affair leading to the death of Mera, the Queen of Atlantis. Thus causing a war that will wipe out the planet. This must be changed, so Flash finds a way to recreate the conditions that gave him powers, nearly killing himself to do so. All to go back in time. Yet this does not stop changes from happening because it still causes a rift where a third universe or timeline comes about.
If we did go back in time, it is most likely that we would end up being connected to the laws of the second timeline theory we proposed. This is the timeline where the past is constant and cannot technically be changed. When it does change, it would then create another universe branched off on its own.
Basically, if we kill Baby Hitler then we will not see the result of this in the timeline we return to. Hitler always existed in our timeline and always will. However, the interesting notion is to consider how we could end up remaining in this Hitlerless universe. One would conclude the only way to do this is to remain in the timeline we’ve gone back to.
Therefore, the changes you make would branch off a different timeline and you’d remain in it. However, you might not have to remain behind. It is interesting to note that if we did use the mirrored parallel universe to go back in time, to begin with, we’d likely be able to visit this new universe we created eventually. If we can access one universe, what stops us from accessing another? We just shouldn’t assume our time travel changes will affect our present timeline.