100% did not. Here are the reasons why:

1. In episode 10 Saeha said, I don’t know why but I couldn’t move past the point in time where I came from.

2. The existence of Storehouse Saeha in 2022.

If it is not possible to visit the future beyond a time traveler’s origin time, the Storehouse Saeha in 2022 should not exist if he died on 2021-10-09.

The Ghost, herself, is another clue.

• When the Ghost returned to the crime scene she intentionally stepped on a pool of blood as if it was nothing.
• While she herself admitted that she does not care what happens to them, because they are her distant past, her emotions throughout the series tells otherwise.
• They did try to find another way. If she truly does not care, she would not even bother, as she herself said, I can always turn back time.
• When the Friendly Blue Time Traveler was about to do something to the dying Saeha, the Ghost tried to stop him.

The Ghost does care, and she is as human as any of us. She stepped on the pool of blood because she knew it was fake! She visited the crime scene as a closure and as proof to herself that there is always another way—they just have to find it.

Originally, my interpretation was Saeha traveled with the Ghost before he returned the device and then died on 2021-10-09.

To borrow her own words, she tried dozens of times, to change fixed points but found no other way. She gave up. As far as she is aware, Saeha will die sometime in 2021-10 by the hands of Manok.

It did not occur to her that events that should happen will still happen as long as Saeha was recorded to have died. The Friendly Blue Time Traveler figured this out and put things into action to create a new reality.

Here is how it happened:

1. The Friendly Blue Time Traveler bumped Manok to remove the tracker. He needs him to hide.

2. He then observed if his plan to position Saeha and Manok in an area of his choosing worked. It did. Saeha was stabbed by Manok.

3. When the Ghost was standing on an open field, sad and surrendered, the Friendly Blue Time Traveler froze time and reversed it back.

4. The Ghost was caught unawares because nothing like it ever happened in her previous attempts to change the fixed point.

5. Because the Ghost was not in position to block Saebyeok’s side mirror view, she saw Manok escaping and chased him.

6. Similar to the 2021-10-09 First Version, Saeha stopped at the location where Manok was hiding, only this time with Saebyeok.

7. Manok was instead enraged against Saebyeok and decided to kill her. The Ghost intervened.

   • The Ghost struggled to stop Manok.

     • Time is juggling between two conflicting possibilities

       • the Ghost is erased
       • the Ghost still is

       This was similar to the incident in 1997-05-18 Seventh Version. Because there was another time traveler (Saeha), anything can happen.

       This time the traveler who was to be erased was the one who intervened.

     • She was can not decide how much she should intervene.

8. When the Ghost decided to stop Manok, the Foe Blue Time Traveler attacked her. He looked up. He probably saw the Grid flickers.

   • Whenever something happens that may put the existence of the Grid in jeopardy, the Grid flickers. This is why they looked up, even the Ghost did it several times.
   • This was also in episode 02. When Manok stole the salary of a worker, the Ghost reversed time. But he still stole the money repeatedly, the Ghost teleported the envelope back to the owner’s pocket instead. This was not a useless, random scene, it means something.
     • Later in the episode, Eojin said, I saw the Grid breaking again on our way back.
     • Stealing the salary of that man changed the path of Manok. The Grid did not disappear instantly because the Ghost was watching, time is juggling between two possibilities.

9. The Ghost was enraged, she chased the Foe Blue Time Traveler. The Foe Blue Time Traveler tried to lose her. When the Ghost got better with her strategy, the Foe Blue Time Traveler had no choice but to confront her.

10. The Foe Blue Time Traveler was on the defense. He even dropped his device to make her think twice.

11. The Ghost returned to the scene. Standing on her left is the Friendly Blue Time Traveler. They both watched as Saeha slowly dies. She looked up and watched the Grid gets restored.

12. The Friendly Blue Time Traveler and the Ghost teleported to Saeha.

13. The Ghost tried to stopped the Friendly Blue Time Traveler, and he said in English, It’s not me. Can’t you see it? while looking down at his device.

    • He was telling her that his device is of a different model than the one who attacked her.

14. The Friendly Blue Time Traveler created a localised timeshield around him and Saeha. At first he almost failed (clue: Saeha’s blood flowed again) because Jung Saebyeok was holding Saeha and his timeshield did not include her.

15. The Ghost noticed this so she created a timeshield with Jung Saebyeok in it. Once Saebyeok moved, the Ghost pulled her to herself—maybe to align her at the same state as her (notice that they do not touch the frozen person outside the timeshield but she did inside).

16. The Friendly Blue Time Traveler was then able to completely place the timeshield around Saeha. Based on what the Ghost did with Saebyeok, the Friendly Blue Time Traveler probably switched Saeha’s body with a faux one (or someone else did since he is maintaining his timeshield).

17. Afterwards both time travelers left. Possibly to save Saeha because he was about to breath his last.

His death, by the hands of Kim Manok, is the catalyst for these important events:

1. Former husband and wife, Jung Saebyeok and Song Eojin, comforted each other and slept together. Nine months later, sometime in July 2022, Byeori was born.

2. Director Choi Seonwool’s reputation increased and she got more authority. Her department, the Secretariat, received a major increase in funding and much needed personnel.

3. As South Korea realized there is more than one time traveler, they increased their support for the Administration Bureau and their time travel R&D. The country became even more powerful.

This question was asked by @Gizmobear on MyDramaList.

It is a case of the needs of the many outweigh the needs of the few.

Saeha saw what a world without the Grid is. Two-thirds of the world population died and many more suffer from various degenerative diseases caused by the solar wind radiation. He also found Jung Saebyeok with an irreparable damage on her face and her vocal chords. This was what broke his heart the most.

Saeha made a choice to die because they found no other way to alter events without erasing the Grid from existence. He had no idea he would be saved by another time traveler.

He is the Saeha the Friendly Blue Time Traveler saved. However, he can not reveal himself, otherwise they would risk changing recorded history.

As explained in Did Saeha die?, it is not possible for Storehouse Saeha to be Saeha before he returned the time travel device. The Storehouse Saeha is in 2022, it is not possible for 2021 Saeha to travel to 2022.

Because Kim Manok would not become a loose cannon. For Manok to become unstable, he needs to witness the brutal murder of his father.

They need a crazy Manok who will end up killing Saeha in 2021-10-09.

It is a case of the end justifies the means.

I highly doubt it.

While Kim Manok does have a 13% DNA match with the Ghost, and they both have the rarest blood type which is cis-AB, it is not enough as proof that he is the Ghost’s direct ancestor. This tells us that he is a distant relative of the Ghost.

The highest possibility of their blood relation is Manok is the Ghost’s paternal great grand uncle (baseline relatedness of 12.5%). ² There is a possibility that Kim Manok have a sibling from his original family.

This question was asked by @Bai Ying Hua on MyDramaList.

Because Kim Manok should be the one to murder Saeha.

This is the only way for events, mentioned in What is the relation of Saeha’s death to the Ghost and the Grid?, to happen.

My suspicion is Assemblyman Kim Hanseok of the Democratic Union Party that the Ghost saved from a bribery scandal.

This was in episode 02.

• The date was 2021-10-06.
• The Ghost was eating a lot of cakes.
• She checked her phone and saw a news article from 2022-06-19 11:50.
• She became worried briefly but went back to enjoying her cakes.
• She jumped forward in time to 2022-06-18 23:00 and stole the briefcase with the bribe money.
• She went back to 2021-10-07 and checked-in at an expensive hotel.
• She also bought a new phone which alarmed with a message: You have a scheduled task to do in ten hours (episode 03 train chase which will happen in the evening).

Remember Guidelines #2.b and #3? An experienced writer will not include a scene which serves no purpose in the story; and everything shown is canon. This short subplot is a good example.

Kim Hanseok and Kim Manok sharing the same family name is a coincidence. Kim is the number one most common surname in South Korea. If they are long-lost brothers, it is Kim Manok’s fate to be given the name Kim. (And may be a clue hidden by the writer.)

This was not revealed. However, if the Ghost is the same age as the actress, then she came from 2131.

There is only one Ghost, great granddaughter of Jung Saebyeok and granddaughter of Byeori.

The label Ghost was coined by the Administration Bureau, in particular by Director Choi’s Secretariat department. It only refers to the Ghost played by actress, Lee Siyoung.

If all time travelers are ghosts, then the answer is yes, but not the Ghost.

This is only possible if the show did not establish that it is based on the Static Theory of Spacetime.

Since the show established that time does not flow and later gave more clues that the show is specifically based on the Growing Block Universe theory, it is not possible for alternate timelines and parallel universes to exist. There can only be one timeline and one universe.

To borrow from Highlander: There Can Be Only One!

More likely for computing power.

Since the Grid was installed in 1997, there was still not enough computing power to handle the Grid code and its compilation. Installing the Grid later than 1997 would not give Earth a chance to deploy it properly. Installing it earlier would mean an even more primitive system.

If one laboratory already had the computing power needed to run the entire Grid software, then there is no need to install it in various laborities. In the end, in 2005, the Grid system was located in one place. This was why sometime in the latter half of 2022, only the AB and IRR buildings were attacked to bring down the entire Grid network.

This is a very good example of why a decentralised, distributed, federated, and open network is better than a centralised and closed network (or monopoly). The only way to bring down a DDFON-based system is by exploding an EMP on the entire world.

The most probable is Saeha probably gave the Ghost a medicine to her DNA problem (the knowledge came from the 1997 No Grid Reality).

This question was asked by @Zainaaa08 on MyDramaList.

Good question! Unfortunately there is no way to know who is the Blue Time Traveler. However, there are two of them!

1. Friendly Blue Time Traveler

   • He was the one who bumped into Manok to remove the tracker.
   • He was the one who saved Saeha.
   • His time device is slimmer and pointed.

   

2. Foe Blue Time Traveler

   • He was the one who attacked the Ghost.
   • His time device is wider and rounded

   

   

   

Maybe they are twins or clones or one is an earlier version of the other. Regardless, what matters at this point is the Foe Blue Time Traveler is not the same as the Friendly Blue Time Traveler.

As the Friendly Blue Time Traveler said in English, It’s not me. Can’t you see it? while he was pointing with his eyes to look at his time device (he was also aware someone who looked exactly like him fought her). Upon realising this, the Ghost let him do what he was about to.

The Administration Bureau wants to steal the time travel technology used by the Ghost since it is far advanced than the one they are developing.

They believe in helping mankind as well as to propel South Korea to be leaps ahead of everyone.

This question was asked by @LydiaDaniel on MyDramaList.

Two possible answers.

1. Future Saebyeok traveled back in time and talked to 2022 Eojin to pick up the 2022 Saebyeok.

2. Future Saebyeok talked to Future Eojin to travel back in time to pick up the 2022 Saebyeok.

In both instances, Future Saebyeok probably revealed to him that her daughter is his and her name is Byeori. This convinced him since a newly born is in danger, his daughter at that.

This question was asked by @Eliza M on MyDramaList.

The Grid that was destroyed is in 2022, not the 1997 Grid.

In episode 10, the IRR and the AB buildings were destroyed by an attack from outer space. The AB did not exist yet in 1997.

In addition, if they did destroy the 1997 Grid, the faction which destroyed it would not benefit from the 1997 No Grid Reality.

In episode 10, it was revealed that there is a group or faction watching over the events and the time travelers. The scene where a man and his assistant were talking is one such faction. (They seem to be in outer space.)

It is not possible to determine if they are for or against the Grid. Regardless, the message of that scene was to reveal there are groups who are changing events, either for the benefit of the people or for the benefit of their own pockets. In other words, whoever destroyed the Grid in 2022, they need the 1997 Grid to exist. Consider the following:

• In the 1997 No Grid Reality, the number one R&D and pharmaceutical company in the world was owned by Saeha’s parents. Which in turn means South Korea is the leading nation on Earth. Whoever destroyed the Grid in 2022, it is to their benefit that the 1997 Grid exists where Saeha’s family did not build an R&D empire.

• In the MIW Reality, South Korea forced the other labs to keep their mouths shut about South Korea’s claim that Saeha’s father was the brain behind the Grid. They showed the other nations and labs the footage of two time travelers who killed a janitor, making them believe that South Korea have time travel capabilities.

  World superpowers no doubt loathed South Korea because of it and triggered a race to develop time travel. In Star Trek terminoloy, there is a temporal [cold] war.

The man who appears to be the subordinate could be the Friendly Blue Time Traveler or the Foe Blue Time Traveler since it was played by the same actor. It is also possible it is a different character altogether, the actor probably played three characters.

He made this report to who appears to be his superior, The Grid is all gone. From all the times and layers.

His superior replied in English, You never know. Which he followed up with, in Korean, No one knows. Is there really an end?

Like his subordinate, this man is also an unknown. In the room with them is what appears to be the [dead] body of the Ghost.

Correct. However, the Grid that was destroyed was in late 2022 not the 1997 Grid.

As long as the 1997 Grid exists, and Saeha died at the hands of Manok on 2021-10, the Ghost’s mother and herself will be born. What happens after that, like the destruction of the Grid in 2022, is of no consequence to her existence.

It could very well be the reason why she decided to become a time traveler … to find a way to stop the destruction of the Grid in 2022 or to setup backups those who are against it are not aware of. However, before she can concentrate on her main objective, she had to make sure she exists because Saeha was trying to change two fixed points in time. All of them, including those who are against the existence of the Grid (from 2022 onwards), would not exist if Saeha will have his way.

This is why the Ghost told Saeha, Don’t try to change anything, and You’re the one ruining everything. Stay out of this.

This question was asked by @LydiaDaniel on MyDramaList.

The first Grid Founder, whoever that person was.

Even without the Grid there is always a possibility that time travel technology will be developed in the far future. They would no doubt be very eager to unlock the secrets of time travel especially when two-thirds of the global population were wiped out and the remaining are suffering from degenerative diseases.

Temporal Mechanics #4 stated that a time period is replaced whenever a time traveler enters that time. The earlier version no longer exist, and even if one stops the time traveler from traveling, the original version of time will never return. It will only be replaced by yet another version.

This was explained in Temporal Mechanics #4: Time period replacement.

The clue in episode 10 points to Song Eojin.

Maybe, maybe not. Since the Ghost said she was born in 2091, Byeori would be 69 years old by then.

However, the Grid was destroyed sometime the latter half of 2022. Between 2022 and 2091, Earth was hit by another solar wind (as confirmed by the 1997 Ghost). The traditional way of having babies is probably not advisable due to the radiation, and the damage in their DNAs.

Because of it In Vitro Fertilisation (IVF) is probably very common to ensure babies will develop without the risk of radiation exposure. Or, through surrogacy from healthy mothers living inside protected domes. This would make it possible for anyone to have a healthy baby regardless of age.

That considered, Byeori may be the Ghost’s mother after all. Especially after the scene wherein the Ghost carried Byeori on her arms. (Daughter taking care of her baby mother? Yeah, time travel! That is lovely and sweet too.)

A very good question! This one requires a lengthy explanation.

In the Block Universe and Growing Block Universe theories a reality or the universe is viewed as one giant block (or cube if you will).

• Think of a cube. That cube is the entirety of reality or the universe.
• Add dots from Point A to Point B horizontally until it is filled.
• Looking at it, there are now lines of dots horizontally (Y axis), vertically (Z axis), and across (X axis).
• The X axis is the length of the cube. In space dimension, it means moving forward and backward in space, like riding a car.
• The Y axis is the width. In spatial dimension, it means moving left and right, as one wold sidestep to the left or right.
• The Z axis is the height. In spatial dimension, it means moving up and down, like when flying or riding an elevator.

If this is applied in the time dimension, what does it mean?

• The X axis, or length, in time dimension means moving forward or backward in time. To put it another way: traveling to one’s relative future or past.
• The Y axis, or width, means moving left and right in time. In the many-worlds interpretation of spacetime, this is moving to alternate timelines or parallel universes. In the Static Theory of Spacetime, unfortunately I can not think of an analogy (if you can, do share in the comments below).
• The Z axis, or height, is moving up and down in time. Let’s discuss this further.

The Z axis, or height, or moving up and down, is what I call planes of existence. This is what the layers in Grid (그리드) was referring to. It can be best described as what we see glimpses of.

In the space/spatial dimension it can be explained in this way:

• You and me, we exist in our own layer or plane of existence.
• Paradise exist on a layer on top of our own.
• Damnation exist on a layer below our own.

Stories about seeing ghosts, souls, monsters, and other fantastical creatures, are glimpses of another layer or plane of existence. They are moving around us but we normally do not see them just as they should not normally see us. (Although in most fiction, they do see us.)

How this is applied in the time dimension, as the Grid (그리드) used it, and within the context of the Static Theory of Spacetime, is beyond me. Simply put, there is a layer of time on top of and below of another layer.

When the assistant said, The Grid is all gone. From all the times and layers, it means the Grid was destroyed in 2022 in all possible times, in all possible layers or planes of existence. Another way of saying it is: the Grid was destroyed in 2022 in all of spacetime.

Maybe the way Grid (그리드) used it is as a reference to the different realities. If this is the case, then this particular faction found a way to access realities which should no longer exist.

This question was asked by @Bai Ying Hua on MyDramaList.

It is microtesla (µT). A microtesla is an SI unit of magnetic flux density equal to 10^-6 teslas. ³

Okay, I do not know what it means either.

Basically, microtesla is a unit of measurement used for magnetic fields. Grid (그리드) was correct that a human being should only have a very low—0.3 or less—microtesla reading. Humans who live near high-tension power poles usually have a reading of 0.4 µT. ⁴ If one is very near, or under power lines, magnetic fields is around 20 µT. ⁵

For a human being to produce over 100 µT meant they were exposed to extremely powerful magnetic fields, which in the show’s case, time travel technology (and that level is not healthy). Here are the confirmed readings of time travelers:

• The Ghost: 408 µT
• The Friendly Blue Time Traveler: 230 µT before Saeha’s death; 237 µT after Saeha’s death
• Saeha: 106 µT

It is a Korean cultural tradition wherein adults tell the kids walk signal is blue.

The National Institute of Korea Language also explained, The reason why the green light of the traffic lights is not called the green light but the blue light seems to be because the people perceive the blue light as a relative color concept to the red light. ^{6 7}

This answer was provided by @27Aprile on MyDramaList.