I might be wrong on this, but doesn't Belles Inequality (or at least the experiments testing it) show that there are no hidden variables in quantum mechanics and therefore no possibility of there being an "underlying theory" that would make quantum mechanics deterministic?
Yes, Einstein and some others. It's entitled the Einstein, Podolsky, Rosenburg Paradox (sorry if I didn't spell those right). I'm sure he meant it to show a problem with quantum mechanics, but actually the exact same principle is used in teleportation.
Sorry to digress, but I just wanted to raise a question I have about the causation of the universe that was being mentioned before.
Is it logical to say that the universe has a cause? How would such a cause be defined? Causation (as I understand it) is a temporal effect. Causes precede and determine the effect. But logically there is no "before" the universe since time is a part of the universe. Saying "before the universe" would be akin to saying "north of the north pole"....it just doesn't exist. When you're at the north pole the only direction possible is south. When you're at t0 the only temporal direction is "after".
To me this illustrates the way that what humans consider true and natural is more often than not very wrong and misleading when applied to situations beyond our normal comprehension.
This message has been edited by happy_atheist, 08-24-2004 05:34 AM
I still see no logical way to think of the universe as having a cause, since the concept "before the big bang" has no logical meaning whatsoever. There can be no "before" time, since the very degree of freedom that time is measured relative to would not be in existence. If there is no point in time when the universe didn't exist, what meaning can does the word "caused" have? The only way I can think of reconciling the universe with some cause would be if time stretched back before the big bang. I seem to remember seeing a show on the BBC (Horizon) that dealt with that possibility. I don't know how well supported the idea is though.
quote:And by the way great thought provoking post.
Thanks It's something i've always wondered about, but when I saw that Stephen Hawking shared my view that it was possibly illogical to talk of the unvierse being caused I gave it a little more credence. He mentions the idea somewhere in A Brief History of Time.
Oh I don't think causality is illogical in all situations. I think it is only applicable within time though. A cause comes before and determines the effect. If "before" doesn't exist then I simply don't know how causation would apply. I may be missing something important(which is why I brought up the question). Is causation possible without a "before"?
Well causation as we understand it requires a "before", therefore it would be silly to say the universe has a cause because it would going beyond human experience. To apply anything from human experience to the situation that is totally unlike anything we've experienced (such as saying the big bang has a cause or the universe has a creator) is wrong
It certainly is food for thought, and it would certainly be a nice solution if it were true. One thing I definately agree with from the extract is that the true nature of the universe is unlikely to be anything like we comprehend it. We only really comprehend macroscopic effects, and whenever anything strays into the quantum world a whole host of weird and wonderful things that are counter intuitive become common place.
All i'm saying is that it would be illogical to say the universe has a cause, because it would go against the definition of causation. If something DID cause the universe then our idea of causation is wrong (or at least incomplete), and it isn't going to work in the way we currently think causation does. Take the idea posted above as an example, the idea that the universe caused itself. That is not how most people think of causation.
An excellent post Tony, thats pretty much what i've been trying to say from the past few posts but I wasn't able to quite articulate it properly! I guess that'll all part of the problem of talking about something that we currently don't have a word for, leading to us trying to force square words into round concepts so to speak.
Anyway, I'd like to put forth Star Trek The Next Generation as evidence that future events can cause past effects (STTNG, that tome of scientific truth ). In the very last storyline before it ended they had Captain Picard causing life on earth to never form. He discovered a temporal anomalie, and fired something at it in an attempt to get rid of it. What he fired ending up making it worse, but because it was a temporal anomalie it got worse in the past. It ended up that it got so bad so far in the past that it destroyed the first semblences of organic molecules forming on earth as they were about to create life.
Obviously it all ended ok, because a Jean Luc from a different time sent a message to himself in the future to make stop destroying life. And there you have it, STTNG proves that causation is very much different to what we think it is lol.
quote:Are you saying that Star Trek ever has anything but good science? Why I oughta...
Actually i'm pretty certain that most of the major things in star trek have at least been hypothesized as being possible. For example teleportation, its a real phenomenon and has been performed in a lab.
i was lucky enough to give a presentation on teleportation at university when I was doing my physics degree. It took a bit of persuading my group though, they actually wanted to talk about global warming instead! lol
Yes, teleportation is based on the quantum entanglement principles Its amazing how limited our macroscopic views of the universe are. And yes I have a physics degree, but I don't profess to be any good at physics. I didn't do as well as i'd have liked. I've since moved on to do a masters in computer science which is going much better though
quote:Heh, I know that teleportation is based on quantum entanglement. I was talking specifically about your presentation.
Yes, we did our best to explain entanglement. Not the easiest of things to get your head around hehe.
quote:Out of curiosity (hope you don't mind my questions), did your physics degree require an in-depth understanding of quantum theory? Because it is definitely one of the more difficult physical concepts to wrap your mind around.
We had two courses in quantum physics, one in the second year and one in the third year. Apart from the straight quantum physics courses we also had a course in statistical mechanics in the third year. That uses quantum mechanics to derive thermodynamic principles. We also had a course in atomic physics that used a lot of quantum mechanics. Pretty much the only place it didn't pop up in was relativity.
quote:Ah yes, I understand there is something of a contention between them. They both explain things very well on their respective levels but can't be unified into a single theory of gravity, or something to that effect?
Thats right, quantum mechanics and relativity are like oil and water. They just refuse to mix. I don't know if that means either of them is wrong or that there's something more fundamental we're missing that would explain both of them.
quote:I only wish I were more familiar with the theories. Is the conflict between the physical models, themselves, or do the underlying mathematics of either model simply not balance with each other? Perhaps it's a combination of both?
Well i'm not totally sure what the conflict is myself, but i'm going to give me best educated guess. If someone out there knows a better answer feel free to tell me i'm wrong
Ok, I think the problem is that at the quantum level gravity is totally irrelevant. It is by far the weakest forece there is (my a long long way), and so juts doesn't figure at all in quantum mechanics. However, when you get into areas approaching the conditions of a singularity the gravitational field is so strong that even though gravity is extrememly weak it becomes important and needs to be figured into the quantum calculations. This is where the problem lies, no one has been able to figure out exactly what gravity does on a quantum level. The theories just seem totally incompatible. Each theory seperately was brought about to model worlds that simply don't meet under any conditions except the most extreme possible. I don't know what progress has been made though because any theory dealing with this aspect would be way beyond me