Time and it's Weirdness

The life-span of a human being is an average of a century. That's a pretty long time for us to make the most important decisions of our lives or is it? As long as that may seem, it is apparently irrelevant compared to the universe's course of time. Let's dive in.

What is Time? 

From when each and every one of us was born to now, we've experienced the passing of time and have been under its influence but why can't we still feel it? It governs everything we do in our daily lives but it is still somewhat invisible to us. 

Taking Time as a standalone dimension

Let's start from the basics. 

• We describe a point as having zero dimensions, that is, it possesses no length or breadth. 
• We move on to a line. A straight line is the shortest distance between two points. It has one dimension as it possesses length.
• Now we take a piece of paper of a molecule thickness. It has length and breadth. It has two dimensions and therefore is two-dimensional.
• On moving forward, we can carry any object around us and we'd observe that it has length, breadth, and width. Hence, it is a three-dimensional object.

© The Verge

What does all of these have in common? +1 dimensions. You see, before you can experience 0D (zero-dimension), you need to have at least 1D. Likewise, for 1D, you need 2D, 2D needs 3D. Consequentially, 3D would require 4D. To put in simpler terms, let's take an example. We need to draw a one-dimensional line on a two-dimensional piece of paper. If we didn't describe the line in a space of higher dimension, we would never be able to conceptually imagine one dimension, only zero-dimension.

Now, all we see are 3D objects but as explained above, we need to reside in a higher dimension. By implication, our observable universe is then at least a 4D one.

How does this relate to time?

Time is a fourth-dimensional entity. We cannot see it because we can not visualize any dimension higher than 3D. Time actually governs change and enable us to perceive change as natural. This is one explanation of how time influences our universe.

Time and space

In 1915, Albert Einstein postulated the general theory of relativity. It was a magnanimous breakthrough in the field of physics and what it encompassed changed our thinking. As we've mentioned before, time is a fourth-dimensional entity but according to Einstein, time isn't a standalone entity, rather it is interwoven with space to make up a what is known as Space-time. Space-time is a fabric with governs the movement of space in accordance with time. This has incredible applications in the realm of physics. For instance, gravity is then considered as the warping of space-time in accordance with the mass of an object. Also, due to the connection of space and time, it opens the doors of transversing through time in a variety of ways. This explanation of time is more accepted.

©P. Defence

Flow of time

All of us were once young, now we're old. Buildings were new when built, now are old. We've experienced the passing of time all our lives and from that experience, we could infer that time flows forward, that the arrow of time points only in one direction, forward. This is a statement that may/may not be erroneous. You see, the way we perceive time is really dependent on a phenomenon called Entropy.

In accordance with the Second law of thermodynamics, the universe assumes a state of increasing entropy. For example, glass shattering, water splashing, thermionic emission, etc. It isn't possible to revert this increasing entropy. You may say that in a refrigerator, the cubicle is cooled thereby reducing entropy. This is partly correct but according to the First law of thermodynamics, energy is neither created nor destroyed. So, as you cool the cubicle, you heat up the surroundings. So what is the connection between entropy and time?

© Ayay.co.uk

Well, it is partly the reason why some believe time moves only forward as reversing time also means we can change the state of an entity from high entropy to low entropy without consequence. 

Another paradigm stopping the backward flow of time is what is known as the Grandfather paradox. It goes like this; 

"Suppose you have a time machine and you went back in time to kill your grandparents, your parents and therefore yourself would never have been born. Consequentially, you wouldn't have been able to build the time machine you used without being born".

This is actually one of the most popular paradoxes people use to bash the possibility of backward time travel. Even notable theoretical physicist, Stephen Hawking once said; "If traveling back in time is possible, why haven't we seen tourists from the future?".

From various sci-fi movies being made today, transversing through time in an unnatural way yield consequences and affect the fabric of space-time. While this has not been verified, there is one consequence of going back in time. Let's say you made a time machine to go back in time, you cannot go back to the time before you made the time machine. Are you wondering why? You see, transversing forward in time doesn't necessarily require a time machine (we'll get back to this) but moving back in time does. As so, two or more different time machines must be set in different points in space and time as it will then enable the traveler course through time with the machines as destination points. So if I made a time machine on April 15, 2019, I cannot go back in time earlier than April 15, 2019. This consequence, therefore, makes space for the possibility of backward time travel in the future but not necessarily now.

© Ongur

How about going forward in time?

Going forward has less undesirable effects (if any) than going back in time. There are various ways we can go forward in time:

• Using a transverse wormhole. A wormhole is a very complex mechanism that simply connects two points in space. This may even mean bending space in order to achieve the shortest possible distance between the two points. For instance, if point A and B are separated with a distance of 90million light-years (meaning it takes light 90million years to get from A to B), a transversable wormhole would fact bend space and connect the two points via an alternate route. Hence the distance will shorten immensely and enable one to get to B faster. Thinking about this, you may say we traveled faster than light without ever traveling faster than light since it took us a much less time to get to B than it did light!
• Using a spacecraft. This is, in fact, the least difficult way to transverse forward in time. We use one of the consequences of the Special theory of relativity, Time dilation. If the spacecraft accelerates to an appreciable fraction of the speed of light, weird things start to happen. For starters, time slows down for the traveler. Hence the traveler moves nor normally in space but slower through time. This causes what is known as the Twin paradox. If a twin is situated on Earth and the other travels through space at an appreciable fraction of the speed of light, on coming back, he/she would have aged less than the twin that resided here on Earth. Hence, he traveled into the future. The effects of time dilation are more apparent at higher fractions of light speed. Astronauts on the International Space Station (ISS) are 7.0milliseconds in the future.
• Using a time machine. This is the most popular and most thought of a way of moving through time. The interesting thing about this is that as we talked about the restrictions on backward time travel using a time machine, forward also has some restrictions (albeit lesser). You see, if we make a time machine now, we can travel forward in time leisurely if the time machine made still exists in the future. If not, it doesn't seem possible. Moreover, we can't travel further than machine breaks down in the future because then we wouldn't have a time machine in our possession.

©Wonderful Engineering

Time is still one of the most important yet confusing entities of our lives. As of now, we can only use instruments to measure the interval between two events. Hopefully, when mankind and its technology has evolved greatly, we would also be able to manipulate time in ways never imagined before.