Chapter 1: The Nature of Time

Time isn’t always punctual; it can sometimes seem delayed. This notion hinges on our individual perspectives. We encounter this phenomenon in our daily routines...

Do you ever glance at your watch and feel an hour has passed, only to realize several hours have slipped by, particularly when you’re having a good time? Conversely, don’t you find yourself staring at the clock, convinced that an hour has elapsed when, in reality, only a mere five minutes have gone by, especially when you’re eagerly awaiting something? We inherently recognize that time can be deceptive and, at times, even unjust.

Before diving deeper, I wanted to share that this time I’ve chosen a different approach for my article. I thought, why not craft a story? Even better, let’s make it your story. This tale revolves around you and your new friends, Alexa and Alexie, as you all uncover the mysteries of time, movement, relativity, and invariance together. I hope you find it enjoyable.

Imagine this: on a cold, dark night, you encounter Alexa and Alexie, who appear to be lost in the woods. You feel a pang of sympathy for the frightened girls, who seem around nine years old. You decide to help them by offering them a ride to their hotel. Strangely, you know precisely where to go. After two hours of driving, you arrive at their hotel, located roughly 120 kilometers away.

The following day, you spot the girls again, this time even further from the hotel—twice the distance from where you had met them the previous night. They look even more frightened, pleading for your assistance. They claim they need to reach the hotel in two hours for a matter of life and death. You ask if they’re in trouble, and they explain that their parents are worried about them being out so late in the cold.

Initially, you think, “Pff, kids!” But realizing it’s late and their parents might genuinely be anxious, you decide to help. It's almost 10 PM. Suddenly, you remember hearing about a new moving bridge in the news three days ago, located just a few minutes away and leading directly to the hotel—a fortunate coincidence!

Now, you can drive at 60 km/h on the road, which is also moving at 60 km/h, allowing you to cover 240 km—double the distance—in the same time frame. You’re driving relative to the road, which is moving in relation to the bridge. Miraculously, you arrive on time, thanks to your understanding of relative velocity.

But wait, that moving bridge was merely a thought experiment!

How can that be? You drove on it and delivered the girls to the hotel. In fact, without that bridge, arriving by midnight would have been impossible. What’s happening? Is your experience contingent on your thoughts? Did you somehow conjure the reality of the moving bridge? No, that’s not feasible. Surely, you’re not losing your mind—just a bit fatigued. Understanding relativity isn’t straightforward.

Historically, we’ve recognized the essence of relativity since the early 17th century. Galileo observed that if a ship sails smoothly on a calm sea at a steady speed, there’s no experiment one could perform onboard to determine if it’s moving or stationary. However, external observations would yield entirely different conclusions.

We encounter this relativity in our everyday lives, just as you did days later. While walking in the woods, you come across the girls with a man—presumably their father. You don’t recall his name, but he offers to drive you home since your house lies along their route. How does he know where you live? You must have mentioned it to the girls.

As it grows late, you accept his kind offer. The car has a familiar but strange scent, and the interior is so dark, with blacked-out windows that obscure your view. The silence inside feels suffocating, and you wonder why the father has stopped the car. Everything feels unnaturally still. After a while, he reassures you that you’re almost home. Is he jesting? Or should you be concerned? How can he drive without any discernible movement?

You open the window to see that other vehicles are passing by. Minutes later, you feel the car’s brakes engage. But how? You haven’t been moving. When you step outside, you find yourself at home. After saying goodnight, you can’t shake the lingering thoughts—despite feeling stationary, you somehow arrived home.

In a moving vehicle traveling smoothly at a constant speed in a straight line, you are justified in claiming you are at rest. This illustrates the significance of relativity.

Yet, invariance may hold even greater importance than relativity itself. Einstein recognized this in 1905, initially proposing the name "Theory of Invariance" for his groundbreaking theory, later renamed "Special Relativity."

Einstein uncovered something remarkable: the speed of light is constant, unchanging across all frames of reference. Light travels through a vacuum at a speed of 300,000,000 meters per second (precisely 299,792,458 m/s). This invariance remains true, irrespective of the motion of the source or the observer.

He also discovered that time passes more slowly for clocks in motion. As one approaches the speed of light, the time experienced by the moving observer dilates compared to that of a stationary observer. In simpler terms, if you move at light speed, you’ll perceive time as moving slower.

The first video showcases a captivating story of time and relativity through music and visuals, enhancing your understanding of these concepts.

Five years pass since you last saw the girls when you receive a letter from them at your new home. How did they discover your new address? It’s so thoughtful! The letter, penned by Alexa, reveals she’s been selected for a special mission aboard the fastest rocket, venturing to a distant star. However, locating the star is tricky, meaning her mission might extend for another year or two in space.

She predicts that by the time she returns, over 100 years may have passed on Earth. Alexa kindly asks if you could check in on her sister from time to time, ensuring she finds her way home when she’s lost. You chuckle at the thought, recalling the mischievous girls and their wild imaginations.

Another five years slip by.

In the second video, you’ll explore the whimsical world of time through engaging narratives and animations that will deepen your understanding of these scientific principles.

You receive another letter, this time from Alexie. She mentions that Alexa’s space journey is progressing well. What a delightful jest! Alexie shares that she received a photo from her sister, which she’s been asked to share with you. To your astonishment, the picture shows Alexa looking exactly as she did ten years ago, holding a sign with a recent date. How is this possible? Perhaps you’re just overthinking things, or the girls are up to their old tricks.

Fatigued from pondering these mysteries, you decide to take a nap, leading to a vivid dream about a peculiar light clock. In this dream, a set of two mirrors faces each other, separated by a fixed distance, with a beam of light bouncing between them. The sound of each "tick" and "tock" resonates loudly in the room.

Suddenly, Alexa appears with another identical clock, but hers isn’t fixed in place. As it moves parallel to the stationary clock, its ticks are noticeably slower. A mysterious boy named Danny explains that when both clocks are stationary, the light beam travels vertically. However, when the clock is in motion, the beam takes a longer, diagonal path, demonstrating time dilation.

Danny’s insights reveal that time indeed slows down when in motion, an idea that applies universally, though we may not recognize it in our daily lives.

But wait—who is Danny? The bizarre aspects of your dream leave you puzzled. Oddly enough, the light clock concept was introduced by Richard Feynman in the early 1960s, highlighting the strange principles of Einstein’s theory of special relativity.

You learned about the light clock shortly after awakening from your dream. How is it possible you envisioned something before knowing of it? Perhaps you’ve encountered it before but simply don’t recall. Memory can be enigmatic.

The final letter from the girls arrives months later, titled "Simultaneity Sometimes." Their cryptic humor shines through yet again. They send along a photo taken shortly after you first met, depicting Alexa and Alexie on a train, balloons in hand.

In the letter, they describe a scenario where Danny is in the middle of the train, able to see both girls. As the train approaches Jack, who waits on the platform, the girls pop their balloons simultaneously from Danny's perspective. Yet, Jack, standing outside, witnesses one balloon popping before the other due to the speed of light reaching him sooner from the front of the train.

Another year passes, and you receive a letter marked "Return to Sender." You don’t recall sending any correspondence, but the handwriting is undeniably yours, albeit strange and incoherent.

The letter reads:

"My beloved foes from the past, my true allies from the future.

My sweet young girls, time whispers clear.

I must now save you.

Among the stars' time fabric, I’ll sail.

And I will find you.

Worry not, my entangled friends.

The cosmos paints its rhythm bright.

Believe that I will save you."

Confusion envelops you—when did you compose this? How could you have written about saving the girls? Even if you were half-asleep while writing, surely that means something significant, right?

Is the concept of sailing through the fabric of time a hint at time travel? The theory of special relativity suggests it’s possible; traveling through space near light speed could allow you to experience time differently than those on Earth.

While time travel may seem far-fetched, the underlying theories suggest it’s theoretically achievable, although physically challenging. You ponder whether such a journey might be accomplished through thought or energy rather than physical travel.

Perhaps time travel could one day become a reality. What are your thoughts?