Tom Mattson

Trolling is exactly what you're doing. It's the reason you are suspended from Physics Forums' date=' and I wouldn't blame the administration here one bit if they did the same. Really? It sure looks to me like you are here to tell everyone why they are wrong, rather than increase your knowledge of physics. In fact, you've got the smug certainty of someone who thinks they don't need to increase their knowledge, when it's painfully obvious that you need it more than most.

That depends on which QED you mean. Usually, when people put it at the end of what they think is a proof, it means "quod erat demonstratum", meaning "that which is to be demonstrated".

It's pretty simple, really. "Un" is a negation. So "undeterminism" means "not determinism". By the law of double negation, "not undeterminism" is determinism.

And you didn't demonstrate it again.

A random system is one whose time evolution is not predictable. "Undeterminism" isn't a theory of mechanics. It's a feature of a particular theory of mechanics, namely the quantum theory of mechanics.

Severian, I'm with you except on a couple of points. Gotcha. Hold on: When you say "infinite lifetime"' date=' I take that as "perfectly stable against [i']decay[/i]", not "indestructible". That is, the particle that is detected would have an infinite lifetime if it were not interfered with. So say a real photon (on mass shell) is scattered off a proton, and then the outgoing (real) photon is detected. Do you say that the detected photon goes from being real to being virtual, just by being detected? Yes, I accept the evidence for the massive vector bosons. Actually, I accept the predictions of QED as evidence of virtual photons, too. I'm just saying that the squiggly internal lines (that which we normally call "virtual photons") in the Feynman diagrams are actually components of a perturbation expansion.

No, I'm referring to neutron interferometry experiments that involve 2p rotations.

I very much agree.

No' date=' you can't. There is no way to use logic to establish contingent statements about the real world. The argument you gave above is silly and irrelevant. You claim that you can derive a nontrivial fact about the world, without even once making reference to any observed facts about the world. Not surprisingly, you reached a conclusion that you can only know is true in your made-up universe, provided that no invalid inferences were made. I did not bother to check all the inferences because I already know that your argument cannot possibly accomplish your stated goal, for the reasons I already gave. There are vastly superior arguments in favor of determinism already out there. I don't agree with them, but at least they all have the required ingredient of reference to the outside world.

Yes' date=' but since it is a counterexample to your statement about statements not being true or false simultaneously, it was a good assumption on my part. I think he was killing two birds with one stone. Witty fellow, that JC.

That conclusion is perfectly compatible with undeterminism. In this interpretation, at any given moment, an electron has precisely one randomly decided location.

I think that JC is talking about self-referential statements.

It is clear that you are not up to date on what the scientific method is. I just made some long posts about this in the philosophy section' date=' which I don't care to retype: On the Problem of Demarcation: http://www.scienceforums.net/forums/showpost.php?p=10958&postcount=6 On Confirmation vs. Falsification, and Deduction vs. Induction: http://www.scienceforums.net/forums/showpost.php?p=140257&postcount=10 By any measure, QED stands up to the scientific method. No, because virtual photons have the right properties to match observational results. You can't just subsitute any old thing in for them. Of course predictions are not empirical proof. Confirmatory evidence of predictions* is empirical proof, and QED has it in spades. edit to add footnote: *That is, confirmatory evidence that is obtained in an attempt to disprove a falsifiable theory is empirical proof. Of course, it makes no sense to speak of empirical proof of something that is analytically true.

You evidently do not know how virtual photons emerge from QED.

But you haven't even laid a single glove on undeterminism with this argument. Undeterminism states that it is not possible to predict which of the Yi will emerge in a given experimental situation, and you have not provided any argument to suggest otherwise.

Yes, you take a beam of spin-1/2 particles, prepared in some quantum state |a>. I'm leaving it as an abstract vector for the time being because my whole point is that it can't be projected into physical 3-space to make a wavefunction. Now you do an experiment in which you split the beam and rotate the particles in one beam by 2p radians (say we're changing the f coordinate, for concreteness), while leaving the other beam unchanged. Upon bringing the beams together you will find that there is complete destructive interference at the point at which they meet. This indicates that the altered beam is now in the state -|a>. This is precisely the reason why there cannot be a "spin wavefunction". If we project our state vector into 3-space, we have: <r|a>=a(r,t) But to be physically meaningful, the function a should not take on 2 different values when f=0 and when f=2p. So on these grounds, we determine that spin is not a function of the coordinates. On more general grounds, if you look at the differential operator for orbital angular momentum (a physical quantity you can have a differential equation for), you will find that it gives nonsensical results when l (the orbital quantum number) is anything other than an integer.

LOL OK, how?

Binary logic is a logic in which all operators are binary. That is, the operators accept two arguments. And example is the "AND" operator. It takes two statements p,q to form the compound statement "p AND q". Compound statements in binary logic are truth-functional, which means that the truth value of the compound statement depends entirely on the truth values of the more fundamental statements (called "atoms" in some of the literature) and the meaning of the operator. It most certainly can not tell you whether the universe is deterministic, though.