"Hello, Harry. I see you're still alive and well," Myrtle said sullenly.
"Um... yes... Myrtle... I just wanted to visit you... again," Harry managed to stammer out. "You look like you could use someone... to talk to..."
"OH!" Myrtle blushed. Well, it looked like a blush, as her cheeks turned whiter and slightly more opaque than the usual translucent grey. "Are you going to join me? Soon?" She batted her eyelashes.
Harry was speechless. He paled at the thought of "joining" Myrtle. "I...au...uggh..."
"That's a good start, Harry, but if you're going to die, I'd rather you be a ghost like me than an Inferius." Myrtle frowned. "If you can't fit in the drain pipes with me, how else could we sneak into the prefects' baths together?"
Harry's jaw dropped.
"Harry! What are you doing... oh, hello." Hermione peeked around Harry's shoulder. "Myrtle! What have you done to Harry?"
"Oh, so that's the way it is, Harry? I thought you came alone to be with me and instead there's another girl here with you? You just wanted to show her off to me, didn't you? Just reminding me that I'm not good enough for you? I hate you, Harry, I hate you!" Myrtle shrieked as she plunged into a nearby toilet, sending up a spray of water.
Getting splashed with toilet water managed to snap Harry out of his reverie. Turning to Hermione with a puzzled look on his face, he said "Did Myrtle seem a little more... emotional than usual?"
Hermione became a little flustered with that. "Umm... well, I was actually trying to see if I could find the entrance and unlock it without you this morning, but Myrtle was being a bother. I dropped a calming draught into her toilet... but it seems to have had the opposite effect. It should wear off soon, though."
Harry looked at her incredulously. A calming draught did that to Myrtle? And technically, she didn't even drink it, being a ghost and all. How does that even work?
"Harry... Harry! I need you to open up the chamber."
"Oh, right." Harry turned to the sink, whispering ~Open~ in Parseltongue.
They made their way down into the chamber, and Hermione stopped dead in her tracks. "Harry... That's the basilisk you fought last year?"
"Um... yeah." Harry was feeling somewhat embarrassed, although he knew there really wasn't anything to be embarrassed about. "I did have help, though. Fawkes pecked out its eyes for me, and..."
"Harry! That thing's huge! Basilisks are a rare beast already, and the biggest ones are usually only 30 or 40 feet long! This thing's twice that! It's probably older and bigger than any other basilisk in the world! Has Dumbledore seen this?"
"No... After I got Ginny out of the chamber, it closed up and I've never bothered opening it up again. You're the first one I've brought down here since last year."
"Really? Ooh, I feel so special, Harry." Hermione grinned mischievously. "Well, anyways, about my project." Hermione opened her book bag, and began removing dozens of small stone tablets, each with rune carvings on them, placing them in a neat pile. Next, she removed a textbook, and a huge stack of parchment, covered in notes and diagrams.
Project? thought Harry. Runes? That looks so complicated. I'm glad I didn't take that course...
"This is my OWL project for Ancient Runes and Arithmancy!" exclaimed Hermione happily.
"What? Wait, OWLs? Isn't that until fifth year, Hermione? What is this all about?" Harry stared incomprehensibly at Hermione.
"Well, you see, for both Ancient Runes and Arithmancy, you need to do a project for your OWL. Well, two projects, one for each class. I just asked the professors if I could combine the two into one big project..."
Harry nodded.
"...and since I was using a time-turner, I decided to do some extra research on time travel."
Harry nodded, but with a little apprehension creeping in.
"First, I looked up what made time turners work. Obviously, there's a lot of rune work carved into this device, not to mention powerful enchantments, and all that. But the main problem is that it's limited to only a few hours of time travel. I wanted to try for something... bigger."
Harry kept nodding, but at this point his head was just moving on its own while his brain was trying to figure out what Hermione was up to.
"So, I tried to figure out what limited the time-turner's total time travel. I figured it was due to two things. First was the fact that it brought your actual body back in time. Well, it seems pretty obvious if you've learned any Muggle physics, that the more mass you move, the more energy it takes, so moving a whole person back in time would be really difficult especially if you were travelling against the normal flow of time to do it. If there was something massless to send back in time, then... "
Up and down went Harry's head. He was almost completely lost now. He never got to learn any muggle physics, other than how much faster he was than Dudley's gang, because he was smaller. Did that count as physics?
"...the next reason is a little harder to explain. Moving backwards in time is... difficult to aim. In any case, if you've read anything about thermodynamics, apparently for any given present entropic state, the past contains multiple possible states of lower entropy..."
As Harry's head continued to bob up and down, his eyes glazed over.
"The end result of all that is if you attempt to go further back in time, you could end up in a whole other universe or something or even accidentally not manage to come back forward to the present... or at least, the correct present..."
Harry finally stopped moving completely, as his mouth hung open.
"...so that's why I need to use the Chamber of Secrets."
The familiar phrase managed to snap Harry back to reality. "Chamber of Secrets? Right! Why are we down here again?"
"Weren't you listening to me? I explained it all just now, Harry."
"I tried... but then you started talking about physics and all... and I couldn't keep up, Hermione."
"Physics? What part? Most of what I was talking about involved physics."
"Um... you were saying something about your body... and mass..."
Hermione gaped at him. "Harry! That was practically at the beginning! I was talking about that stuff..." she glanced at her watch. "Twenty minutes ago! You should have said something if you didn't understand!"
Harry shrunk back nervously. "Hermione... I just didn't want to interrupt you. You looked so excited to talk about all of this, and I didn't want you to stop... could you explain it again... a bit more simply?"
Hermione sighed. "Alright, Harry. Well, basically, a time-turner is limited to a few hours of travel mainly due to 2 factors: the fact that it brings your body back with it, and the fact that it has to 'navigate' the flow of time, backwards. Does that make sense?"
Harry nodded, with comprehension this time.
"So, to make it easier to go back in time, you have to change those. Fixing the first one's pretty simple- instead of sending the whole person back, just send their memories. Memories have no mass, so it's infinitely easier to move them around."
That made sense to Harry.
"The next issue, the 'navigation', is the bigger problem. If you think about it the muggle way, it's pretty obvious you need some kind of navigating ability because time is just another dimension like the three spatial dimensions, and I guess no wizard ever bothered to keep up with advancements in muggle science, especially not in the last hundred years or so..."
"Err... Hermione? You're going into a bit too much detail again..."