PROLOGUE

Sephora

January 31, 2018

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Yesterday, I got back in contact with an old friend of mine via social media. We haven't seen each other for a long time, even though we're still in the same city. We used to be in the same university, with different faculties, but we are close because of the same organization.

Today, he invited me to dinner. I accepted, and I recommended one of my favorite restaurants in Argon, he didn't mind. Incidentally today I am on morning duty, so the nighttime will be quite free. So I decided after coming back from the hospital to directly meet him.

I parked the car in the parking lot of Argon's Staresto -which was filled with star decorations and happy families who also adorned the atmosphere in the restaurant. Argon's Staresto deliberately has a design as classic as possible with a fairly thick retro and vintage setting. Many dark colors dominate, chocolate for example, in harmony with the menu of the most popular dish here, the dessert Star Chocolate Panna Cota. And I like it.

"Rara.."

A voice called out to me from behind, followed by the sound of the car door closing.

I turned towards the source of the sound and waved my hand.

His name is Rio. The old friend I was referring to, who is now a physicist at the Argon City Central Laboratory. His name is famous throughout the city. Treated as a young technology expert along with several of his friends who also excelled.

He hugged me when we were face to face. "How are you? You're getting more beautiful," he whispered.

"The habit of teasing hasn't gone away long ago," I smacked his shoulder a little tighter. He complained.

"So this," He pointed to the restaurant in front of us, "Which restaurant do you recommend?"

I nodded.

"I've often heard about this from my friends at work. They say the food is delicious. But this is the first time I'm going to taste it."

"Then let's prove what your friends say."

He only replied with a smile. Then we entered the restaurant.

We talked a lot in the middle of eating the food which he finally praised for his enjoyment. He's still the same as the Rio I used to know, the Bookworm Rio with thick embellished glasses, only he's cooler and more manly now. Well, he said he was dating after being single for so long. The definition of geeky has gradually disappeared from him over time.

"Ra, you haven't answered my question at the beginning. How are you?" Rio asked as the waiter took our dirty plates from the table.

"I'm good. How are you?"

"Then, the same."

I smiled and nodded. "How are you? Are you full?"

"The food is really good. Dessert, what else," Rio replied with his chin on his head.

"Want me to introduce you to the chef?"

"Do you know him?"

I smiled again, nodding. "Her name is Starla. The pastry chef who co-founded this restaurant."

Rio weighed my words a little. As if remembering something. "Your sister?"

"That's how it is."

"Seriously? That's cool, Ra. I remember her name from your stories about your sister. Okay, she's successful now. I'm so happy."

"Thank you, Rio."

He nodded. "Sometimes, may I meet her?"

"Of course. If I'm on holiday, you should come to my home," I replied as I smoothed the ends of my hair that were starting to get messy.

"Your house remains, right?"

"We never moved, by any chance."

He accepted my invitation. And we went back to some of the things we used to talk about in college. In the past, we often discussed science, because it turns out that combining physics with medical science is a fun and exciting thing to look for in common. It reminds me, I used to often visit the physics faculty laboratory just to accompany Rio to experiment. So far, I was amazed by his discovery of the anti-gravity chamber. He only needs to combine a box measuring one meter by one, with a device that he has modified in such a way that when the two are paired the box does not accept earth's gravity at all.

When Rio did his final assignment, he asked me to help him contribute knowledge for his invention. He made a set of mind control devices by combining electromagnetic waves, energy systems, and neuron systems, which he then re-modified for robots that can help humans work in general. In keeping with my persuasion to use it on robots, which he had previously determined to apply to humans directly. It's quite crazy and beyond expectations for a child his age. However, he succeeded at that time, and the faculty credited his invention with the highest experimental score of any faculty-in history. And Rio to me is the Einstein of today. Over, maybe.

"So, what are you busy with right now?" Rio asked when it felt like we were running out of topics to talk about.

"Busy taking care of the patient. As always," I answered lightly.

Rio shrugged. "I expected the answer. What else is a doctor's busy?" He laughed because I mocked him arrogantly.

"What about you? What are you busy with at the moment?"

"Experiment."

"As always. What else does a physicist do."

He laughed again, a little louder this time. "Rara is always good at turning the conversation upside down."

I then got carried away to laugh.

"Well, what experiment are you working on? I'm guessing, crazy stuff is back."

Rio didn't answer me right away. He even smiled and laughed a little. He looked at me after that.

Feeling a little strange, I raised an eyebrow at him asking for an explanation.

"Time Machine."

I stopped whatever I was doing. My brain seemed to accept an idea that seemed beyond reason, so even thinking about it was impossible. Is it true? Rio? Invented the time machine?

"I can't believe it exists, Rio."

"But, technological advances will bring them all there, Ra."

I fell silent again. But, this time accompanied by a shake of the head in disbelief.

"How much progress have you made?"

"It's forty percent running."

I'm silent for the umpteenth. However, instead, I wanted to laugh. Rio has gone mad.

"Rio you're crazy."

"You've said it a thousand times since we were in university, Ra," Rio replied as if embarrassed by the sentence I said. "You always say I'm crazy, in every experiment you think is out of your mind." And every experiment, Rio always succeeded.

"Maybe you can explain a bit, maybe… a theory," I hesitated a little at my words, but Rio nodded.

"Look, Ra," Rio straightened his seat more upright. I'm ready to listen. "Initially I was moved by the idea of ​​'Space-Time'. Space and time cannot be defined separately, Ra. Rather, it is a unit called 'space-time'.

I'm like most people out there. Thinking that time can never be repeated. However, some of the methods I learned during my education seemed to allow and agree that time could be repeated, even changed, or perhaps abolished."

"You're not God, Rio."

"I know. Exactly!" Rio tried to hold me back from disbelief at his explanation. "I'm talking about technological developments and the combination of scientific methods, Ra. I don't want to balance God at all."

Before fully coming back to my senses, I decided to continue listening to Rio. "Okay, carry on."

"In physics, there is such a thing as relativity. This relativity has various consequences that have been proven from several experimental combinations. Among them; length contraction, time dilation, relativistic mass, maximum speed limit, mass-energy equivalence, speed causality, and relativity simultaneity. One of the effects of relativity is that it replaces the idea of ​​absolute time with the idea that time depends on a frame of reference and position."

"Then with what do you bring objects to be able to travel time?" I asked with complete confusion and an attacking question mark.

"There are several special theories that discuss media in time travel. Such as; wormholes, infinite cylinders, and their closed time-like curves, etc.," replied Rio, who was always determined to accompany the reasons for developing his experiments.

This time, I don't understand Rio's explanation. I massaged my temples, dizzy and unimaginable. However, I was holding back laughter when Rio just explained to me his simple presentation, about the time machine he created -even though it wasn't a hundred percent made yet.

"Is something funny? Is something wrong?" Rio asked in a barely audible voice.

"Seriously? You're going to create a time machine?" I asked again laughing. However, since Rio is now putting on an offended face, I immediately stopped him. "Okay, okay. Sorry for laughing at your idea.

Rio, listen to me. I know you are the most prestigious laboratory physicist in this city, in this country. I also know your achievements at university, I appreciate it, I don't doubt it either. I believe you are great. You have brains that most people don't have. But, Rio. Humans walk in a line of time from the present to the future. It will continue like that, forever."

This time it was Rio who was holding back his laughter because of the opinion I said. And that managed to make me shut up again and put on my questioning face.

"I know. But not many people think what it would be like to create a new line."

Silence again, I prefer not to argue this time. I'm lost in thinking if it's with Rio.

"What did you create a time machine for?"

He didn't answer right away. Rio looked a little thoughtful. "My experiment."

"How many physical people cloud involved in this crazy experiment?"

"Only me."

I'm confused about not playing. "Alone? Seriously."

"This isn't my official experiment at all. This is purely my desire to create a time machine," Rio replied, not wanting to be refuted.

Now, I'm massaging my temples a little harder. I looked at him in disbelief. But, unfortunately, I did not find the joking look on his face.

"I know you won't believe it, Ra. But, if it can proceed, I'll show you."

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