Author: Sune Fischer
Date: 02:58:01 08/07/02
Go up one level in this thread
On August 07, 2002 at 04:50:39, José Carlos wrote: >On August 07, 2002 at 03:57:30, Sune Fischer wrote: > >>On August 06, 2002 at 21:09:20, José Carlos wrote: >>>>The theory has worked wonders for 70 years, passed all test, pridicted endless >>>>amounts of results (it has pridicted new particles, explained alpa and >>>>beta-radiation etc etc...), it's been one long success story from the very >>>>beginning, it's possibly the greatest achievement of the human race in the 20th >>>>century. >>> >>> General Relativity is more impressing to me. Hard to believe we live in a non >>>euclidean space... >> >>Not to me. General relativity is almost obvious once you realize the newtonian >>laws are inadequite. > > Every problem seems obvious once you have (and understand) the solution. GR >is, IMO, a great intellectual achievement. It is of course, but the clues where all there, the working theory was full of holes so it was obvious something was wrong. From there to the construction of GR is a big step, of course. Kudos Einstein, but quantum theory doesn't have the same holes AFAIK, which is why I believe it. >>It's the building block of quantum mechanichs, if you take that away there is >>nothing left. >>How will you describe the wavefunction for an electron _without_ this, and what >>do you put instead of the Scrõdinger equation? The whole thing collapses >>instantly. > > > I'm afraid I didn't express myself very well. There're mathematical models >(theories) and there's and undelying "real" structure of the universe. I doubt we will ever even understand what "energy" is, doesn't mean we can't use it as a good concept to describe things. > QM is >good (as a whole, including UP) as a mathematical model that allows good >predictions. But how can we know it describes the exact underlying structure of >the universe? If a theory describes how things behave, we are there. If you know the dimensions of the box, the color of the box, the mass of the box, the dynamics of the box - what else is there to *understand* about the box? A full descriptions is to *understand* :) > One example of what I mean: Newton laws allowed humanity to make good >predictions about gravitation. As a mathematical model, it worked well enough >for time. But the universe it described was telling to people that two bodies >atract each other according to some parameters. But why? There was no reason >beyond that. Then Einstein figured a curved four-dimension space that provided >(among other things) what Newton couldn't provide: an explanation of "what is >behind" the equations, a physical meaning. Is Einstein description "correct"? >Who knows, all we know is that it works well from a mathematical point of view. Einstein showed mass/energy equivalence, he even showed that mass and energy is a curvature of space. However, I still don't understand what mass _is_, how does energy turn into mass? Mass is some state of energy, like kinetic and potential energy I guess, but I still don't *understand* this state. I'm happy to describe it by quantum mechanics, that is all the understanding I require, and I do believe it comes out the same :) > There's no physical proof, only physical clues. > The only way to know that the apple falls always is to sit there along >eternity wathing the apple fall again and again under every possible condition. >But what if the earth chagens it path along space and start falling to the sun? >At some point, the apple wont fall to the earth, but to the sun. The history of physics have always presented theories, they work until someone designs an experiment to contradict it, then you go and make a new theory that works for the whole thing. Then when somebody shows a flaw a new theory etc... It's a slow process, but to have a theory that can _predict_ new never seen before things, is a strong indication it is correct. There is _no way_ to prove a theory, other than to prove that it works in all cases, so all physical laws are empirical, yes. > Even Descartes made a big mistake when he built his reasoning from his >starting point "cogito ergo sum". He used God to proove God existence in a non >obvious but true circular reasoning... Was it Gõdel who showed us that not all mathematical theorems can be proven? Let me know when you find a theory that explains and proves all, as a first thing you should prove our existence, I'd like to know I was here on the planet, and it wasn't all a dream ;) Seriously, you will have to accept not everything can be _proven_, can you settle for "explained"? ;) >>then a we conclude there is a force of gravity - > > > We _guess_ there's a force of gravity, until someone comes up with a better >description of the event. What about gravitons? > > >>by measurement, by emperical data. How should one *prove* this otherwise? >>Is it a matter of religion whether or not gravity exists? No, it's physics >>and it is based on observations. > > > I disagree. We observe and then try to create mathematical models about the >observations. But it's only inductive inference, we don't know what is really >behind the observations. The whole universe could very well be ruled by a single >equation, or by a million. We'll never know, I'm afraid. > >>The quantum theory is more or less complete and it doesn't fail without the >>gravity part IMO. Quantum theory doesn't describe _everything_ but in the areas >>where it does work it fits perfectly. > > > That's what I meant. It doesn't describe everything. We still lack a theory >that describes the whole universe. QM in incomplete in that sense. Well, I think I disagree, see my previous comments :) >>>b) it needs strange (anti-natural) >>>statements (measure problem, non locality); >> >>Nature is strange, sorry if that is inconvinient to you ;) >>My pet theory is that laws of nature is infinitely complex, and that >>any attempt to look for pretty solutions is bound to fail. > > > And you could be right here, of course. But can you figure out a way to be >sure about that? There isn't such a way, because we only have our (stupid?) >minds and our senses to observe the universe. How can we know we "see" >everything? Evolution, tiny incremental progress, once we were cavemen, now look at us, traveling to the Moon and soon Mars. I think we will get there, eventually :) >>Natures was not made so that humans would find it simple or easy to understand, >>its *creator* had no such concerns, so why run around and expect it to be >>simple? > > > Creator? So you need a religion element for your physical argument? ;) Every one his Creator, my Creator is the 2nd law of thermodynamics, that entropy in a closed system must increase towards a local maximum. This is enough to make the onset of evolution, so I don't need much else:) >>>c) doesn't make perfect predictions >>>(you can't predict the behaviour of a single particle); >> >>It makes predictions that falls within the uncertainty principle, did >>you expect it to contradict itself? > > > As I said before, I don't. It works well as a whole, mathematically... > > >>Youd _can_ calculate the probability for the presence of the particle, namely >>its wavefunction. >> >>>d) it's just another >>>model, we'll never know how the "real" (if such a thing exists) structure >>>of the universe is. >> >>I fear you could be right. We still need a theory to tell us the physics of a >>black hole singularity, for instance. >>Doesn't mean that the rest is wrong :) >>The problem lies in the difficulty of running experiments, we learn by >>observing, when that is impossible progress becomes hard. > > > Hawking has a theory where no singularity is needed outside a black hole, but >it doesn't seem to be generally accepted, AFAIK. In the Kerr geometry there is supposedly a ring-singularity, I haven't checked it for my self though :) >>> Non determinism is, IMO, a contradiction itself. If the same cause doesn't >>>always yield the same effect (causality principle violation) any further >>>reasoning is void. Note that every reasoning _needs_ the causality principle to >>>make sense. Reasoning is going from a premise to a conclusion using inference >>>rules. Same premises -> same conclusions, A is true _because_ B is false, etc... >> >>I don't see a problem, you _can't_ make the same premises, you can never setup >>the same experiment twice at the quantum level so where is the problem? > > > The problem is that reasoning is about making conclusions from premises. Non >determinism means same premises may lead to different conclusions if we repeat >the experiment. So reasoning process becomes absurd. No, because non-determanism means that you can _never_ run the same experiment twice. The full quantum state may be identical, but it's only probability theory so the results doesn't have to come out the same. There is no absurdity here, you can see this fenomenon in diffraction patterns, the photons have the same wavelength, same phase (if from a laser), yet they do not land on the same spot on the wall when shot through a slit. >>Do the lottery numbers come out the same every time, even when the >>experiment is the same over and over? > > > The numbers depends on the balls. The balls follow gravitation laws (and/or >whatever other laws) so, IMO, if we repeat the experiment with the same initial >conditions (balls in the same positions, same exact time moving them, same force >applied, etc) the same numbers will come out. Of course, but if you had a tiny error margin on their positional and momentum vectors (the Heisenberg inequality), then chaos would cause you to get different results. and in quantum mechanics you _do_ have to live with this uncertainty. > You said it: The clues! > Yes, clues, not proofs. > I'm not a physicist, so my opinion is not important to science world, it's >just a personal feeling, but I don't think I will convert :) > On the other hand, Einstein himself, even not accepting the background of QM, >was the expert who named Heisemberg and Schroedinger for the Nobel prize, giving >credit that way to their fantastic work, so I guess Einstein accepted the >mathematical beauty of QM, and it's usefullness as a good source of predictions. Einstein was wrong about many things, but we remember him for the things he did right :) Forget the word *proof*, it doesn't belong here if you can't accept empirical evidence as proofs. >>> This said, I have much respect for quantum theory and the brilliant scientists >>>who developed it (Heisemberg, Schroedinger, Bohr, Dirac, Pauli, De Broglie, >>>Fermi, ... even Planck and Einstein contributed!). >>> But I still believe we are nothing but deterministic machines :( >> >>Pop quiz: how do your alternative theory explain alpha-decay? > > > I don't remember what alpha-decay is :( > I'll try to read it somewhere and answer your question, I case I can :) It's not important, it's just another wonderful example of quantum mechanics explaing the statistics :) > José C.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.