Na tole dolgočasno tirado (pretežno v obliki copy-paste citatov), ki meji na citatomanijo, pa samo tole: vsakogar, ki ne sprejme tvojih 'argumentov' takoj obtožiš 'izmotavanja', ali pa še česa hujšega.problemi napisal/-a:Vojko, vsebinsko argumentiraj kje sem se motil, ker je to "izmotavanje" povsem nepotrebno. Tam sem ti podal nekaj mojih argumentov, imaš možnost podati svoje in bo to to.
Dokler tega ne storiš je nadaljnji pogovor na to temo povsem nesmiseln. Namreč kaj sploh odgovoriti na takšno misel: "Seveda je protiargument, saj kar naprej vlačiš ta Casimirjev efekt na sceno, kjer vlada STR!". Če bi vedel, o čemu sploh govori Casimirjev pojav me tega ne bi spraševal. Poglej si tisto Greenovo oddajo, mogoče boš potem vedel o čemu govorim.
No mogoče še zgolj to:
.To je eno in isto! Če nekdo reče, da neki pojav (npr. Casimirjev efekt) kot tipični kvantnomehanski pojav "ni relevanten za opis prostor-časa na veliki skali (v okviru STR)", je menda hotel s tem povedati, da spada v drugo domeno (STR), ki ni kompatibilna s KM
Tipično izmotavanje. O tem kako si teorija relativnosti ni kompatibilna s kvantno mehaniko pa beri fizika Luboša:
Torej tvoje ugotavljanje o nekompatibilnosti za ta primer ne pije ravno vode. Iz tega citata se tudi vidi, da ponavljaš nekaj za shrinkom pa ti sploh ni jasno kaj ponavljaš.Luboš Motl napisal/-a:"vacuum" and "empty space" is always the same thing, but one must always be careful what these two synonymous terms mean.
General relativity implies that the only "information" that the vacuum carries at each point is the so-called "metric tensor" - a set of numbers that allow one to calculate the distance between any two nearby points. This is enough for the vacuum to be able to bend - much like any material. One doesn't need any atomic constituents to be able to talk about geometry of the space, and to guarantee that the environment is able to get curved (and to distinguish a flat region of the vacuum from a curved one).
Quantum field theory implies that the vacuum is full of virtual particles that emerge and quickly disappear. Those virtual particles make their impact on other objects - for example, they make the electromagnetism a little bit weaker at long distances (and stronger at very short distances) than what one expects from the classical Coulomb's law etc.
However, quantum mechanics implies that the vacuum corresponds to a very particular "state" - a vector on the Hilbert space - called |0⟩. It is completely unique and as empty as you can get. In particular, it is the eigenstate of the energy operator with the minimum allowed energy - essentially zero. (More precisely, the vacuum energy density is nothing else than the magnitude of dark energy but this energy only becomes sizable for huge, cosmological volumes of space.)
The uncertainty principle of quantum mechanics implies that when one measures things such as the intensity of the electric field in the vacuum - i.e. when the physical system is found in the state |0⟩ - one may get many random values. It is not allowed for the electric and magnetic fields to be exactly zero, much like a particle can't have a well-defined position and velocity in the quantum mechanics of one particle.
So even though the vacuum has a well-defined (minimal) energy and it is as low as we can get, so the vacuum is as empty as we can get, and there are no particular "atoms" or other particles sitting in the vacuum, there's a lot of activity going on in the vacuum which can be seen by the fact that the measurements of various things, such as the density of energy at a given point, will lead to random results that are not strictly zero.
Now, the picture of the vacuum as a "literally empty space" that only has the metric tensor at each point; and the quantum picture with all the activity of virtual particles are actually fully compatible with one another. The statement of general relativity that the metric tensor has particular values at a given point should be viewed as a classical approximation, however: when we look at it precisely, the metric tensor is a set of operators, too. They will inevitably have variable and chaotic values if they're measured - that are just "approximately zero" if they're averaged over large enough volumes.
Da pa bom korekten v debati, bom citiral še to:
in pa še post, ki ga je objavil derik:Roy Simpson napisal/-a:The concept of vacuum in physics indeed comes from two different theories.
The General Relativity Vacuum is a space-time model region without matter. In General Relativity all of space-time has a "curvature" which relates to the metric which can all have measurable effects, such as the bending of light rays (in the vacuum) near a massive object. One may wish to be a little careful of how one conceptualises the vacuum of empty space however since no events occur there since there is no interacting matter there. As soon as we have interacting matter we no longer just have a vacuum. Also General Relativity has introduced a term, called the Cosmological Constant Λ, which could be said to measure the curvature of the vacuum at the Cosmological level.
In Quantum Theory there is the concept of the "Vacuum State" which is a little different: it is the lowest possible energy state of a given quantum system. This lowest possible energy state has quantum fluctuations consistent with the ΔEΔt>h Uncertainty Principle.
Thus if we straightforwardly apply the "Vacuum State" concept to the space-time vacuum we get a conceptually different model, called the "Curved Space Vacuum". Some calculations show that this combined "Curved Space Vacuum" is rather different from the vacua of the two component theories: General Relativity and Quantum Mechanics. It has some interesting properties, like Temperature, that the component theories dont have and some calculations do suggest that the "Quantum Vacuum Energy" is different from the corresponding expected Λ value by 10120. These results depend a little on what, if any, quantum fields uniformly pervade space and this aspect is not yet settled.
STR vlada, joj, joj ...derik napisal/-a: Arkani-Hamed je v že omenjenem intervjuju na podobno vprašanje približno takole odgovoril: Če zapremo v izolirano sobo skupino vrhunskih fizikov in jih prosimo, naj na podlagi istočasnega upoštevanja STR in QM povedo, kakšno je vesolje (ne da bi ga oni imeli možnost sploh videti), bi rekli, da je vesolje zelo zelo majhno. Ko bi jim potem povedali, da mi vidimo vesolje zelo zelo veliko, bi bil odgovor tak: Aha, dobro da ste nam povedali. Zadostuje namreč, da rahlo uglasimo ta dva modela, za čisto majhno majhno malenkost je treba spremeniti nekaj konstant, pa bo izračunano vesolje ravno prav veliko. Tak pristop da je sicer mogoč, a je bolje spremeniti sam koncept prostor-časa.
P.S.
Ti seveda lahko in smeš objavljati moje stare poste. Težava je zgolj v tem, da bodo argument proti "slamnatemu možu" in pritlehen poskus moje diskreditacije.
Vse, kar sem o tej temi mislil povedati, sem povedal, zato se strinjam, da zaključiva.
Kar se pa "ponavljanja za shrinkom tiče", bom rekel takole: ni me sram povzemati pravilnih argumentov za ekspertom (sam to nisem) za fiziko. Se pa malo čudno bere ta očitek od nekoga, ki v istem postu sam nameni več kot 3/4 "ponavljanju" mnenj drugih.
Za konec pa še nekaj: zelo bi bil previden pri pretencioznih 'ocenah' ne/poznavanja STR pri drugih. Spomni se, kakšne si nakladal o 'silah' v STR, o 'kuglicah' in bil seveda deležen ustreznega poduka, da STR sploh ne operira s silami...