Quantum Physics 123: Wednesday 16 November

[ten-and-chips.livejournal.com]

[The Doctor settles in on top of his desk, drinking coffee. He may never sit behind it again.]

Turn in your papers, please.

So today we're talking about the grandfather paradox. This theory is called such because it stems from the idea that if one travelled back in time and killed one's own grandfather before one of your parents' conception, then you yourself would not exist, therefore not having travelled in time and killed him, etc. It's a very cyclical theory. Some use it to say that backwards time travel is impossible, which I personally disagree with, but I'll leave you to make your own decision.

Two things, in my opinion, prevent the grandfather paradox from becoming a loop of insanity. The first is the fact that a paradox of this sort, in my experience, rips a gaping hole in time, which then needs to be fixed. The second is that a person may be encircled by a causal bubble of sorts, which...[a sigh] keeps his or her own self in existence despite changes to the timeline.

Any questions?


No homework, except for the fact that I want you to think about a final project proposal. You're going to examine one of the concepts we've talked about this semester, or for that matter, anything you're interested in that we haven't talked about, in depth. There'll be a paper and presentation to the class, by the end of the term. No final exam, because I can't be bothered to write one this will help you focus your thoughts in a far more productive manner.

HOWEVER...I have to approve your topic. Please come to my office hours on Friday morning and we'll discuss your ideas briefly. I'm not going to be in during the afternoon, so if you can't meet me that morning, send me an email and we'll make an appointment.

Also, since Professor Cregg will kill me if I don't mention this to you, come to the Harvest Festival on Saturday. It will be a brilliant time, I assure you.

Comments

[soniabelmont.livejournal.com]

Sonia hands her paper in to the Doctor because she *was* in class on Monday, but the player is stupid and didn't sign her in, then finds her seat and pulls out her notebook. She puts particular emphasis on the bits about this "causal bubble," and scribbles down a few ideas of her own before moving along.

[whitedeathpod.livejournal.com]

John comes into class with a bag of red lollipops from the Emporium (http://www.livejournal.com/community/fandomtownies/354877.html?thread=14391613#t14391613) under his arm.

"Lollipop, sir?" John holds the open bag out to the Doctor.

[ten-and-chips.livejournal.com]

[Ten grins and takes a cherry flavoured one. He unwraps it and pops it into his mouth (http://hclairezone.tripod.com/david/bp248.JPG).] Thanks, Mr Crichton.

[whitedeathpod.livejournal.com]

John smiles and pulls his essay out of his backpack. "Here you go, sir. One homework assignment, as promised." He hopes that it's good enough considering he fell asleep while finishing it last night.

[sogothcally.livejournal.com]

Cally attends class and turns in her assignment. She seems quiet and attentive the whole time.

[[ooc: becaue I have no time to interact today, ack. *sad procrastination-catching-up-to-me cries*]]

[carter-i-am.livejournal.com]

Sam took her seat. Since she was doing the Independent Study and just there for the discussion, she didn't turn in an essay.

[whitedeathpod.livejournal.com]

"Want a lollipop, Sam?" John takes one out of the bag and shows her. "I got enough for everyone."

[carter-i-am.livejournal.com]

"Ooh, thanks," Sam said, taking one from the bag, unwrapping it, and popping it into her mouth. "Nothing like sugar to get us through the grandfather paradox. How's your day been?"

[whitedeathpod.livejournal.com]

"Day's been okay," John says and drops his essay off on the Doctor's desk. "Woke up early, still sleepy but lollipops make the day better!"

[carter-i-am.livejournal.com]

"There are very few things that can't be made a little bit better with a lollipop," Sam agreed.

[anextimeagent.livejournal.com]

"Oooo. Can I have a lollipop? What is it with the oral fixation at this school anyway?"

[anextimeagent.livejournal.com]

[Jack hands in a paper outlining all the ways he could have screwed up the timeline by warning his future self of possible death. Despite the topic of his paper, he's in a sunny mood.]

[carter-i-am.livejournal.com]

Sam raised her hand, looking clearly skeptical. "Excuse me, sir, but could you explain a little more about how the causal bubble theory works? I'm unfamiliar with the concept."

[ten-and-chips.livejournal.com]

In a sense, Sam, what the causal bubble does is protects the time traveller from the changes to the time stream. Time is displaced everywhere but not when it involves the traveller's own existence.

[bluemanoncampus.livejournal.com]

"So it's something like a diving suit? You can interact with the immediate environment but are kept separate from it?"

[ten-and-chips.livejournal.com]

It's not an intentional effect, Mr McCoy. Merely a result of time attempting to retain integrity.

[carter-i-am.livejournal.com]

"So, if this is true, then why aren't there hundreds of people out there disrupting the time stream? What kind of physical safeguards are there to prevent this from happening?"

[ten-and-chips.livejournal.com]

The causal bubble doesn't prevent time from being distorted, merely the existence of the traveller from being erased. Hence, the ruptures in the timestream, which can, I assure you, be exceedingly destructive.

[carter-i-am.livejournal.com]

"Then it's possible that, by trying to fix the problem, you actually end up exacerbating it? Doesn't that then create a loop of travellers trying to fix those later problems?"

[ten-and-chips.livejournal.com]

I realise you have a crush on me, but really.

((As I said to Hank--I'm REALLY not in the right frame of mind to answer this right now, as I'm tired and tomorrow is my birthday, omg. So if I don't get to it, assume Ten did so.))

[carter-i-am.livejournal.com]

No, I'm actually just this big of a science geek.

((NP. Happy birthday!))

[lady-jessica-bg.livejournal.com]

Jessica hands in a paper, then begins to consider project ideas.

((ZOMG!Its-a-bubble!! *ahem*))

[bluemanoncampus.livejournal.com]

Hank hands in a well-written paper over last class's discussion, with a slight emphasis on "self-fulfilling" prophecies.

After hearing the Doctor's short lecture, Hank raises his hand.

"I see three possible ways to discount or circumvent the grandfather paradox. First, and one we have already covered, any action that the time traveler makes could create a new, 'branching' timeline, completely different from his or her own. This would obviously eliminate the prospect of self-negation, as the time traveler's origin still exists, just not in that timeline.

"Second, a theory I have heard described as the Inevitability of History states that reality is able to 'gloss over' minor paradoxes by repairing or ignoring them, more or less. So a time travelers may kill their ancestors and thereby self-negate themselves, but reality just rolls on. This would not apply to major disruptions, of course, such as setting off a massive nuclear device, but even something as 'minor' as killing John F. Kennedy's assasing prior to the assasination could be repaired by replacing the assasin with someone else.

"Finally, what if time travel is required for certain events to occur 'properly'? To use a previous example, what if a temporal local would have set off a nuclear device had a time traveler not prevented him from ever being born?"

[ten-and-chips.livejournal.com]

((The mun is REALLY not in the right frame of mind to answer this right now, as she's tired and tomorrow is her birthday, omg. So if I don't get to it, assume Ten did so.))

[bluemanoncampus.livejournal.com]

((Happy Birthday!))

[soniabelmont.livejournal.com]

Sonia hands in her paper. (http://www.rydia.net/grimmart/physics123.html) She's sure there are several unintentional paradoxes and inconsistencies in the paper, but she's confident that she understands the basic principles of the predetermination paradox.

[OOC: In fact, the player is *sure* there's tons wrong with that paper, because she is tired and her brain is busted, but omg it was kinda fun to write. She does not in any way expect Ten's player to read it, as she has read the previous comments. :D

Also, Happy Birthday!]