Part 81: Shiina Mayuri struggles to understand Time Leaping

The memo we have lists a catalog of all the parts we should buy. Kurisu designated everything. Things necessary to upgrade the Microwave Ophone (Temp) from a device which can send mails across time to a time leap device. I'm paying the bill.

Kurisu has already started work on the Microwave Ophone (Temp)'s improvements with Daru's help.

'Data conversion of nerve impulses from the temporal lobe (hippocampus).'

It looks like that will require the software developed by Kurisu and her joint researchers. Kurisu can download that from a dedicated server, but that's not the only requirement. According to Kurisu, we need to make the headgear for searching the brain's nerve impulses ourselves, so we're going shopping for those parts.

Incidentally, while we shop, Mayuri frequently disappears, so I have to be extra attentive. As to where she disappears to, she simply squats down in front of a shop she gets interested in and endlessly stares at parts. She won't match my pace, so I don't turn around and panic when I suddenly can't find her. Each time, I'd get stuck with returning to the hall to search for her. I almost feel like the father of a lost child.

Well, Mayuri was always like this.



"Yup, okeydokey! I'll be careful. So, Okarin. How are time leaping and time traveling different?"

I wonder if she's seriously heeding my warning. Besides that, Kurisu already explained the difference between them yesterday.

"Time traveling takes your entire body across time. Time leaping takes only your memories across time. You can think of it like that."

But to the very end, only memories, without consciousness or personality, are transferred. Kurisu said that consciousness is an unknown concept.

"Hmmm, I see. Well, in that case, are the abilities of D-mails and time leaps different?"

"D-mails could only send instructions into the past. The past may change, or it may not. Its success rate is unknown, and depends on the recipient. In the case where the past does change, everyone loses their memories of what happened before the change, because the world line gets reconfigured."

Everyone except for me and my Reading Steiner, that is.

"With a time leap, on the other hand, you’re able to pour all of your memories into your own brain one week ago, for example... or at least, you should be able to."

The details depend on experimental results, though.

"Umm, for example, could I send a costume I'm making one week into the past? If Mayushii got another week before ComiMa, it would be a huge victory, or something like that."

"That might be possible with time travel, but it's not with time leaping. If you knew the answers to a test two days ago, you can go back and retake the test, but you can't go back two days with a filled out answer sheet."

"Then, will Mayushii's consciousness go inside the Mayushii one week ago?"

"Exactly."



"You can't bring objects with you, but you can bring your memories, huh... I see. But but, in that case, where does the Mayushii inside the Mayushii one week ago go?"

"Isn't she overwritten?"

We haven't tested it out, so I'm not sure, though.

"She disappears?"

"Even if she does disappear, your memories one week ago and your current memories are continuous. Even if your memories are overwritten, nothing really happens to your memories before that week. I guess you could say you're just adding your memories from one week in the future."

"Then then, if Mayushii's memories leap into the Mayushii one week ago, what happens to Mayushii's current body?"

Mayuri's thinking of some very philosophical things, huh. These are all natural questions, after all.

"Even if Mayushii's memories go pewwww one week into the past, Okarin's right here, right? From Okarin's perspective, what happens to Mayushii when her consciousness leaps?"

"You become an empty shell... no, wait, that's not it. That shouldn't be it. What Assistant's trying to do is save memories as data... so basically, it's nothing but a backup. It's not like all of your memories are being extracted from your brain as data."

So none of the memories inside the brain are lost. You won't become an empty shell.

"So, you shouldn't become an empty shell since your consciousness doesn't leap."



"Anyway, after you go back one week, you'll re-experience that week, so you'll end up here, won't you?"

Most likely nobody, including me, would recognize that fact.

"Then, will the Mayushii who experienced the week before time leaping be erased by the Mayushii who time leaped and repeated that week?"

...This is getting complicated.

"That's right. Erased. I guess you should say redone. You can completely retrace your steps, or you could take completely different actions, and you'll keep your old memories of the first erased week."

"So then, so then,"

Mayuri keeps asking me questions with all her might. She's optimistically, frantically trying to understand.

"What if, after going back a week, Mayushii doesn't go to the lab today, but instead goes out to play with her school friends in Ikebukuro? Even though Mayushii's talking with Okarin now."

"Since the past would change, the present would change too, right? The fact that you and I are talking like this should be negated."

"So Okarin wouldn't recognize it, then?"

"Yeah. That's right."



"For me?"

"No. For Mayushii."

I don't really understand.

"Maybe that's why Cris said it's not good to change the past."

She agrees with herself and starts smiling.

"Ah, hey hey hey. Can you time leap into the future?"

"Maybe you can, but there's no real point."

That's the conclusion Kurisu and I came to yesterday, since you're sending your memories from now to overwrite the memories at your destination. If you send your memories one week into the future, then that one week of future from now will all be a blank...

"The time leaping we're going to do is a demonstration of the true value of sending things to the past, and you're less likely to reach the future than you are the past. You can remember things about the past, but the future is unpredictable. For example, Mayuri, do you think you'll keep the same phone number and cellphone for all eternity?"

"...I don't know. Ehehe..."

"That's basically what it is. Also, just like how pagers became obsolete with the advent of cellphones, the cellphone may one day be replaced by some other new personal electronic device that explodes in popularity."

What's necessary for Kurisu's proposed cellphone time leap is that you must address it to yourself using your own cellphone and phone number. She considers that to be the best way to ensure any problems are localized.



Unless we figure it out, we can't fire up the discharge phenomenon whenever we feel like it, and the Microwave Ophone (Temp) can't be completed as the Time Leap Machine. But on the other hand, as long as we do find it, there's no need to regulate the amount of electron injection like SERN does.

I'm exhilarated. The Microwave Ophone (Temp) is evolving ever further. This time, we can truly outdo SERN. Time travel will become a reality. I want to experience it as soon as possible. I can't help my heart's thirst for chaos. I'm about to laugh out loud any moment now, so I consciously tighten my expression.

It's already been more than a week since we sent the first D-mail. Though I did get a threat mail, I'm not worried that fearsome black suits will come. According to Daru, SERN hasn't found out about our hacking, either.

The next problem will probably be when we time leap. We need to "borrow" the LHC to super-compress the binary data of an entire human's memory. If we do that, then there's a high probability that SERN will find out about our existence. How would we deal with that? We need to think beforehand.



Mayuri's still talking about that.

"You want to go back to your elementary school days? Hehehe, I know that feeling. If you repeat elementary school with the knowledge you have now, you'll most likely get the top grades in the school, and you'll easily handle your relationships, too."

"Yeah, and also, I thought maybe I could meet Granny again."

"...I see. That was a shame, huh."

Mayuri's grandmother passed away when Mayuri was in elementary school.

"Mm... it was a shame, but it's not like I wanted to meet her no matter what, you know? Mayushii still clearly remembers Granny's words, her smile, and her wrinkly hand that would stroke Mayushii's head... so I'm fine even if I don't go try to meet her."
"More importantly, I'd want to meet that time's Okarin again, too. Ehehe..."

"...Hmph, at that time, I was already complete as a mad scientist, a human distinctly separate from the rest of those brats. I fully understand your desire to meet the genius elementary student who exudes such an aura of fear and would one day become the mad scientist, Hououin Kyouma."

"I don't want to meet Hououin Whatshisface, I want to meet Okarin!"



No matter how many times I say it, Mayuri doesn't understand, so I disregard Mayuri's punchline.

"Let's just drop it. You haven't mentally grown up at all since that time, so nothing would change if you went back to elementary school now anyway."

"Eh? That's not true. Mayushii's a real grown up now."

"In how much you eat, maybe."

And in breast size.

"That's not true! Mayushii's properly going up the stairs to adulthood."

The stairs to adulthood, huh... I kind of want to hear the details, but I don't ask since it doesn't seem like anything big.

"More importantly, I think Okarin's the one who stopped growing after that time."

"That's why I've said so before, haven't I? At that point in time, I was already complete, fuhahahaha!"



Crap, this isn't the place to just stand and talk. Let's quickly buy those parts and head back to the lab.