"Billions of years from now... the Voyager record will still be traveling."

  — Carl Sagan, Murmurs of Earth

  The route, free from the interference of tidal forces, was very peaceful. Upon returning home, she found the entire Alliance reveling, intoxicated by the victory of the war. After returning, she first went home to find documents that could prove her identity. Her father was there.

  "What is the matter?"

  Tirn spoke with a slightly sharp voice.

  "You know."

  "That is why I am asking. I was abandoned."

  Tirn stood rigidly, on guard.

  "It was during the war. And at that time, the border was completely sealed due to the Yonic incident."

  Tirn's father replied dryly.

  "Didn't you take what you wanted?"

  "I did. But only half of it was there."

  "I suppose it wasn't what you were hoping for."

  Tirn said with slight sarcasm.

  "There is no way the people called the Disc-Senders would make such a thing just to send sounds..."

  "Sounds?"

  Tirn was startled. She had only given them the parts marked as undecipherable, but it seemed they had decoded them.

  "I don't think Trusen would have built something using only such sounds. I heard that two formulas are the core..."

  Tirn's father knew.

  "I don't know about that either. I am an agent, not a scientist."

  "You went all the way into the experimental facility. And you are the only person so far who is completely fine."

  "What do you mean..."

  Tirn was flustered by the unfamiliar statement.

  "The people who worked at the facility, especially those who were there on the day of the accident, are all suffering from an unknown illness. Except you... Trusen doesn't know of your existence, so they must think it's everyone."

  Tirn thought quietly.

  "I was in the fluid computer room when the first explosion occurred that day."

  "I see... That will be a useful reference..."

  Tirn's father nodded.

  "And the rest?"

  He did not forget to press her again.

  "What about my mother?"

  "The war is over... That isn't even worth trading for."

  Tears welled up in Tirn's eyes upon hearing those words.

  "There is something you must clearly understand. No one could control this."

  Tirn's father nodded.

  "We know the outline of the incident too. The massive explosion and the undetectable toxic substance. But that is merely a lack of capability on their part..."

  For a moment, Tirn wondered if she should destroy the formulas and research materials. She had hidden them safely elsewhere to bargain with her father.

  "This is something that must be done. We have what we've deciphered as well, so if you're curious, report for duty tomorrow and come to the official residence in the afternoon. We will have a meeting there."

  He then gave her a light hug and left.

  The next day, she reported her return to the military. Her superior handed her a security oath and a transfer notice.

  "The war is over, so we no longer need field agents assigned to Trusen. This is your new post."

  The name 'Erun' was written there. It was a place dozens of cells away from the capital.

  The narrative has been taken without permission. Report any sightings.

  "May I know about the post?"

  "In my 20 years of military service, I never thought I'd be told I couldn't share information with an Intelligence Department Inspector because it's classified. The order came down for you to move immediately. Your personal belongings will be sent by mail."

  With a reluctant expression at her superior's words, she saluted and left.

  She moved to her father's official residence. There were several unfamiliar scholarly figures present.

  "Are you Tirn? The one who survived that hellscape..."

  A bespectacled scholar welcomed her.

  "Say hello. This is Dr. Eltar Barex, who researches optical physics. And over there is Dr. Senol Kurn, who deals with thermodynamics..."

  Her father introduced them one by one.

  "And the people here are the key members of the Erun Project."

  Tirn looked back at her father.

  "And based on this document, mass-energy equivalence, was it? We are going to execute it..."

  Tirn's father smiled thinly.

  "Trying to hide it won't keep it hidden, daughter... And we need your experience... One Yonic incident is enough..."

  Tirn nodded quietly.

  "First, I will tell you what the intelligence department and our research team have discovered from the Mahaten incident."

  Eltar fumbled to pull out some documents.

  "What came out of the experiment was not simply light. And it is not impossible to shield against it. The proof is Miss Tirn, right here."

  Eltar took out photos and distributed them to the others.

  "And we believe detection is also possible. Calcium tungstate was found at the site, and it emits light. However, it disappeared a few days later, that is, after the site was cleaned up. This means it reacted with something at the site, and that something is what made us tremble in fear. We will start from here."

  "That tungsten... how was it formed?"

  Tirn's father asked.

  "The impact plate in the collision experiment was probably tungsten. Because it is strong against both heat and impact. It likely oxidized as it melted at high temperatures and appears to have combined with the calcium in the firefighting water used to put out the fire. The important thing is not the path of its creation, but that the presence or absence of something can be detected."

  Eltar spoke with slight excitement.

  "I will continue next..."

  Senol said.

  "This is a very important fact regarding why we didn't know about this. Synthesizing the information that has come out over the past 6 months, it is estimated that the Disc-Senders were a civilization from 10 billion years ago."

  Everyone was dumbfounded by such an absurd number.

  "What do you mean? Are you saying it was a civilization from before the creation of the universe?"

  Tirn asked.

  "No... Ah... I apologize. Since we do not yet know the age of the universe... that is not exactly what it means. The point is, among the materials on the disc, there were details stating the uranium isotope content along with its half-life. So we conducted our own geological survey, and there was a time difference of 10 billion years."

  "Isn't that because the physical and chemical environments are different?"

  Eltar asked this time.

  "Presumably, the reason they left this data is because the rate at which it changes is constant, so they wrote it down to let us know from what era their civilization originated."

  Eltar nodded.

  "Then it makes sense. The environment was different from the very beginning."

  "Yes, that's correct. The Disc-Senders and we exist in different environments. Therefore, our approach must also be different."

  "Why didn't the Trusens know?"

  Tirn asked.

  "That is thanks to you. The Trusens were buried in the formulas and rushed into experimentation. But because you gave us the rest while leaving out the formulas, we only studied the rest."

  Tirn let out a hollow laugh.

  "Now that you've obtained that missing piece, are you going to experiment again? Repeat the tragedy of Yonic?"

  Tirn raised her voice.

  "Such a thing will not happen. Because we are going to build the facility underground... The underground will prevent explosions and the scattering of residue."

  Senol said with a confident face.

  "You said we don't know much about this..."

  "That is why we must learn... That is the challenge..."

  Tirn's father spoke as if coaxing a child.

  "And take this home and try using it. It is a gift for you. It wasn't intended, but still, we've been able to move forward knowing a little more..."

  A large box of some sort was placed next to Tirn.

  Tirn came home and tore open the box. Attached to it was a large disc and a loudspeaker. A steam-powered rotating body was also visible. She used the steam piped into her house to spin the rotator. She was startled by the unfamiliar sound coming from the loudspeaker, but it wasn't hard to realize that the rotating body was playing back recorded sounds as it spun.

  Various sounds came out one by one. There were things that sounded like animal cries and sounds with melodies. They were likely the sounds of the Disc-Senders' civilization. And finally, the voices of the Disc-Senders emerged.

  [Audio Clip: Golden Record Greetings]

  ????? ??? ?? ????? ???? ????? (Welcome from the children of planet Earth.)

  ??????? (Hello.)

  ????????? (Hello.)

  你好嗎？ (How are you?)

  Dobry den (Have a good day.)

  Goddag (It is a good day.)

  Hartelijke groeten aan iedereen (Heartfelt greetings to everyone.)

  Hello from the children of planet Earth. (Hello from the children of planet Earth.)

  Bonjour tout le monde (Hello everyone.)

  Herzliche Grü?e an alle (Warm greetings to everyone.)

  Χα?ρετε (Be glad.)

  ???? (Peace.)

  ?????? (Namaste.)

  üdv?zlet mindenkinak (Greetings to everyone.)

  Tanti saluti e auguri (Many greetings and wishes.)

  こんにちは (Hello.)

  ?????? (How are you?)

  Salvete, amici (Hello, friends.)

  各位都好吗？我们都很想念你们。 (How is everyone? We miss you all very much.)

  ?????? (Namaste.)

  God dag (It is a good day.)

  ???? ?? ??? (Peace upon you.)

  Witamy serdecznie (We welcome you warmly.)

  Olá, sauda??es (Hello, greetings.)

  ?? ???? ???? (Truth is eternal.)

  Salut?ri (Greetings.)

  Здравствуйте! Я приветствую вас! (Hello! I welcome you!)

  Srda?an pozdrav svima (Heartfelt greetings to everyone.)

  Kwaziwai (Welcome.)

  Nabad iyo caano (Peace and milk.)

  Hola y saludos (Hello and greetings.)

  H?lsningar (Greetings.)

  ??????? (Vanakkam.)

  ???????? (Namaskaram.)

  ?????? (Sawatdee.)

  Speaking once and pausing, it seemed to be repeating the same meaning in different languages. She felt that they were words of greeting.

  As that thought crossed her mind, tears blurred her vision. To the greetings sent by the Disc-Senders to a civilization 10 billion years in the future, we were answering with violence.

  Tirn looked up at the night sky. She begged for forgiveness from the Disc-Senders who must be somewhere in that sky. And she quietly murmured a greeting.

  'Nice to meet you. Me too.'