Why Does Time Only Move Forward? The Mystery of the Arrow of Time

• Have you ever seen a glass cup shatter into pieces after dropping it? You do realize that the glass breaks instantly? However, those components never seem to come together on their own. This is due to the fact that time never stops. 

• Tomorrow is forgotten, but yesterday is remembered. We do not get younger; we get older. We are unable to change the order in which events occur. 

• The crucial query, though, is: Why? The majority of scientific rules are indifferent to whether time is moving forward or backward. However, time appears to have a defined course in actual life. This is known to scientists as the Arrow of Time. We'll look at what this means, why it occurs, and whether time can ever go backward in this blog.

What Is Time's Arrow? 

• All that the "Arrow of Time" represents is the unidirectional movement of time. It indicates the future by pointing to the past. We constantly experience this arrow in our daily lives: You get up, go to work or school, and then go to bed. It is not the other way around; you eat before you are satisfied. 

• Birthdays are celebrated as you get older rather than younger. But something odd emerges when we examine the laws of physics. Most of them, such as Einstein's theory of relativity or Newton's laws, function the same whether time passes forward or backward. This implies that time is not determined by the fundamental principles of nature.

Three Different Kinds of Time's Arrow

• Three distinct "arrows" of time were proposed by a physicist by the name of Arthur Eddington: 

 1. Arrow of thermodynamics The most crucial one is this one. It ultimately comes down to entropy, a metric for disorder. Over time, entropy always rises. A tidy room becomes disorganized. Hot coffee cools down. Ice melts. The thermodynamic arrow is this. 

 2. The Arrow of Cosmology This is predicated on the universe's expansion. The universe has been expanding ever since the Big Bang. Time advances with the expansion of the universe. 

 3. The Arrow of Psychology We experience time in this way. While we may recall the past, we cannot recall the future. This arrow is connected to our brains and is personal.

Entropy: The Direction of Time 

• Let's use a straightforward example to better grasp entropy. Let's say you have a fresh deck of cards. All four suits are in order, from Ace to King. It's tidy and well-organized, which is low entropy. Shuffle the cards now. Since the cards are now arranged in a random order, the entropy has grown. It's disorganized. 

• Similarly, following the Big Bang, our universe began in a highly orderly form. Things became increasingly disorganized—more entropy—over time. The passage of time is produced by this rise in entropy. Broken glass doesn't mend itself because of this. Random glass fragments are incredibly unlikely to re-form into a cup. It would indicate a decrease in entropy, which is not permitted by nature.

Physics and Time: An Odd Combination 

• The odd thing is that time is reversible if you simply consider the mathematical aspects of physics. Consider filming the collision of two pool balls. You wouldn't be able to tell which way was forward if you played the video backwards. In both directions, the physics appears the same. 

• However, entropy allows us to determine which way is forward in real life. You'll know something's amiss if one ball unexpectedly leaps back to strike the other without any reason. Therefore, whereas entropy cares about the direction of time, the rules of physics do not.

The Beginning of Time's Arrow and the Big Bang 

• Let's return to the Big Bang, the universe's inception. Everything was closely packed together immediately following the Big Bang. Surprisingly, though, its entropy was also extremely low. It's a conundrum. What caused the early cosmos to be so well-organized?

• Although the solution is yet unknown, scientists believe that time advances because of this low-entropy beginning. Entropy rose as the universe grew, and the arrow of time started to point in a single direction. Perhaps time wouldn't have any discernible direction at all if the cosmos had begun in a high-entropy condition.

Is it Possible for Time to Reverse? 

• You may be asking yourself now if time can go backward. Yes, theoretically, if entropy could drop. However, such is practically impossible in practice. If every atom in a broken glass were to move back into a flawless cup at random, the odds would be so slim that they might as well be zero. 

• Time can even move in both directions according to certain science concepts, such as quantum mechanics. However, we only see time moving in one direction when we look at the world around us. The reason for this is because the universe as a whole is becoming more chaotic. The remainder of the universe would continue to advance in time even if you created a tiny region where entropy dropped.

Could Time Be Reversed? 

• Let's pretend that time is going backwards for fun. Cigarettes would be refilled with smoke. Trees would shrink into seeds and stop growing. Individuals would become infants and then vanish. The ice would leap off the ground and revert to its cube shape. But only if entropy were reversed would this occur. And that appears to contradict all we understand about the nature of the cosmos.

So, why does time move forward?

• To sum up: Time appears to go forward because we observe changes in the world: objects grow, break, mix, and age. These shifts occur as entropy increases—things shift from order to disorder. The principles of physics do not determine the direction of time. But entropy does. Everything began in a condition of low entropy with the Big Bang. Since then, entropy has been increasing—which is what gives time its direction.