The Basic Flex | Time Travel |

Long enough, for me to realize it is impossible by any contemporary measures, time travel has been a big mystery waiting to be solved. To help myself solve this, I had made my own theories that I worked on, one of them unknowingly ended up being the space-time curve that Einstein himself had first decorated. Yes, you read that right, I discovered the space-time curve all by myself and now I feel weird about myself.

Moving on... We now look at some phenomena that help us understand time travel.

Time Dilation

Einstein's concept of relative time changed the perspective of the whole world. In his theory, he describes time, as the 4th dimension, to be tangled in the three-dimension space and forming an elastic-like sheet (in 2d) called the space-time curve, which looks like this

Time Travel hit his mind when he imagined riding a beam of light in space, which then made him realize would slow down the time only for him. This is time dilation. This helped develop the first theory of time traveling, and the prominent phenomena, the Twin Paradox.

Twin Paradox

Our dear Einstein imagined twin brothers A and B. Then he separated them, A was sent in a rocket traveling near to the speed of light in space, while B stayed on Earth. 

A was traveling near the speed of light, so time would be much slower for him and he wouldn't even notice it, cause everything in his surrounding within the spaceship is also being slowed down. Meanwhile for B time would be passing at normal speed. Finally, when A would arrive at Earth he would be much younger than his twin brother B. This is simply what we observe, but to actually predict it mathematically would have been much difficult because of Lorentz Transformations and many other factors in disguise. "Paradox" bumps in the suffix because sometimes it gets quite confusing to figure out who is getting older because of the relative perspective of motion with respect to each other.

Limiting our thoughts up to here is not necessary because we still have another way to dilate time and it is,

Black Holes

Blackholes are regions in space-time where gravity is so strong that nothing can escape from it. Black holes warp the space-time continuum so much that it really slows down the time around it.

Now, instead of traveling at the speed of light, we just have to orbit the black hole. But, keeping the spaceship from falling into it is challenging reminded the immense gravitational force of the black hole itself.

In both scenery, since you are moving in a slower time, the rest of the world would be older than you and once you come back to Earth, you would have time-traveled to the future. Now it is time to discover ways to travel backward in time, which just seems impossible for what we know until now.

Busted way of Travel to the Past

Previously, we used a black hole that deep warps the space-time continuum to travel to the future so you might think using something that behaves opposite to black holes would make it happen. And for that we bring a hypothetical form of matter that is as follows:

Exotic Matter

Exotic matter is something that has negative mass and negative energy. Rather than attracting, this would repel objects that come around it. And compared to any other matter, it would warp the space-time curve in a way similar to what is shown below

Before moving any forward, we need to understand some things about an exotic matter that brings about barriers to using it.

Firstly, we don't know how it is going to move through space. The exotic matter has negative mass, we know mass is actually the measure of inertia of a body, so putting this fact into the law of motion, we realize with negative mass, these exotic matters are neither going to come to a complete stop nor stay in a uniform motion.

Secondly, anticipating how time works around exotic matter is quite confusing in itself. Either it slows down the time around it since it might curve the space-time continuum as much as black holes. Or, it could make time go faster since the curving is in the opposite direction as compared to black holes.

Nevertheless, we assume it would make time go faster just to hand ourselves with a different scenario to work on. It all depends on when you arrive to the previous timeline.

So, we again bring the twin brothers for the journey. Let me call this the 'Reverse Twin Paradox'.

We send A to orbit an exotic matter and B to stay on earth as usual.

Brother A is undergoing a faster passage of time.

But brother B is under no change in the speed of time. So, once A is back, he will be older and B will be younger along with the rest of the world. It might seem like a travel to the past, but actually, it isn't.

I'll use a simple diagram to demonstrate why idealizing this is wrong, using the concept of timeline.

Let's suppose A left Earth's Timeline in 2005 and entered another timeline, say Grey Timeline. A spends the next 10 years in the Grey Timeline and then returns to earth. But, when he returns to the timeline of Earth, it has only been a year because, in the grey timeline, time moved faster. So, looking at the image we see, A left Earth's timeline in 2005 and entered in 2006, regardless of the fact that he spent 10 years in the grey timeline. So, technically, he traveled a year into the future, but in a time span of 10 years.

Similar is the case even if we find out a timeline where actually time flows backward.

Since my 11th board exam is just a few days to go, spending more time in here might cost me some grade deflation. So, this is all I've got for this post, a lot more to cover what my weirdly intellectual brain imagines. Please correct me if you find anything beyond what defines physics.

Note: I have not yet proved time travel to the past is impossible by any contemporary measures because I still have some major aspects to cover like wormholes and what supposedly is inside a black hole, which might also include me playing with the string theory. So, stay connected to enjoy more physics in simple ways.