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Old 17.06.2017., 13:42   #1
Kako je došlo do teorije relativnosti?

Zanima me kako je Einstein došao do teorije relativnosti, na čemu je temeljio svoju teoriju, eventualne prekursorske radove na koje se oslanjao, ili koje je probleme eventualno rješavao koji su ga doveli do te teorije?

Isto tako me zanima, osim jednadžbi koje postavlju u odnos brzinu, masu i vrijeme, postoji li objašnjenje "mikrostrukture" koja objašnjava te odnose?

Npr, kako se to masa povećava kad se ubrzava, što se mijenja u strukturi tih atoma da bi postali masivniji i sl.

Ili kako se vrijeme dilatira s brzinom? Postoji li neki strukturalni odgovor ili pokušaj odgovora, ili su to samo goli matematički odnosi, a u mehanizme stvarnosti iza njih se ne ulazi?
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Old 17.06.2017., 13:54   #2
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Npr, kako se to masa povećava kad se ubrzava, što se mijenja u strukturi tih atoma da bi postali masivniji i sl.
Ne, nema toga, može se i ostaviti da masa ima klasično značenje (dakle neovisno o brzini) a redefinirati količinu gibanja, i sve funkcionira. To je pedagoški (i filosofski) bolje, jer se izbjegavaju ovakva pitanja. A količina gibanja je ionako tehnički termin o kojem nemamo neke intuicije kao o masi, pa nije problem da to redefiniramo.
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Old 17.06.2017., 14:05   #3
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i sve funkcionira. To je pedagoški (i filosofski) bolje, jer se izbjegavaju ovakva pitanja.
Funkcionira matematički?

Ali zar nikoga ne zanimaju "takva pitanja" jer ne bi li bilo "zanimljivo" zašto je nešto tako na fundamentalnijoj razini, a ne samo znati za neke brojčane odnose?

Npr. iz klasične mehanike znamo jednadžbe koje povezuju tlak, temperaturu i volumen plina, ali nismo se zadovolili time nego znamo i da se iza pojma "tlaka" i "temperature" nalazi mikrostruktura čestica koje se sudaraju različitim brzinama, te sudaraju sa stijenkom.

Zar nema nikoga tko se zanima za mikrostrukturu iza jednadžbi koje samo postavljaju neke opće odnose?
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Old 17.06.2017., 14:18   #4
Da, ali zakoni koji opisuju stanje plinova su otkriveni puno prije (od skoro sto do dvjesto i nešto godina, kako koji) nego se tlak i temperaturu svelo na sudare molekula. Tako da je dovoljan (2) kad "funkcionira matematički", a ako uspijemo to povezati u suvisle predočbe, to je za više ocjene.
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Old 17.06.2017., 14:45   #5
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Da, ali zakoni koji opisuju stanje plinova su otkriveni puno prije (od skoro sto do dvjesto i nešto godina, kako koji) nego se tlak i temperaturu svelo na sudare molekula.
Zapravo zanimljiva priča, možda i ne potpuno oftopik:

This relationship between pressure and volume was first noted by Richard Towneley and Henry Power in the seventeenth century. Robert Boyle confirmed their discovery through experiments and published the results. According to Robert Gunther and other authorities, it was Boyle's assistant, Robert Hooke, who built the experimental apparatus. Boyle's law is based on experiments with air, which he considered to be a fluid of particles at rest in between small invisible springs. At that time, air was still seen as one of the four elements, but Boyle disagreed. Boyle's interest was probably to understand air as an essential element of life; for example, he published works on the growth of plants without air. Boyle used a closed J-shaped tube and after pouring mercury from one side he forced the air on the other side to contract under the pressure of mercury. After repeating the experiment several times and using different amounts of mercury he found that under controlled conditions, the pressure of a gas is inversely proportional to the volume occupied by it. The French physicist Edme Mariotte (1620–1684) discovered the same law independent of Boyle in 1679, but Boyle had already published it in 1662. Thus this law is sometimes referred to as Mariotte's law or the Boyle–Mariotte law. ...

Boyle (and Mariotte) derived the law solely on experimental grounds. The law can also be derived theoretically based on the presumed existence of atoms and molecules and assumptions about motion and perfectly elastic collisions (see kinetic theory of gases). These assumptions were met with enormous resistance in the positivist scientific community at the time however, as they were seen as purely theoretical constructs for which there was not the slightest observational evidence.

Daniel Bernoulli in 1737-1738 derived Boyle's law using Newton's laws of motion with application on a molecular level. It remained ignored until around 1845, when John Waterston published a paper building the main precepts of kinetic theory; this was rejected by the Royal Society of England. Later works of James Prescott Joule, Rudolf Clausius and in particular Ludwig Boltzmann firmly established the kinetic theory of gases and brought attention to both the theories of Bernoulli and Waterston.

The debate between proponents of Energetics and Atomism led Boltzmann to write a book in 1898, which endured criticism up to his suicide in 1906. Albert Einstein in 1905 showed how kinetic theory applies to the Brownian motion of a fluid-suspended particle, which was confirmed in 1908 by Jean Perrin.
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Old 18.06.2017., 03:47   #6
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Zanima me kako je Einstein došao do teorije relativnosti, na čemu je temeljio svoju teoriju, eventualne prekursorske radove na koje se oslanjao, ili koje je probleme eventualno rješavao koji su ga doveli do te teorije?
1.
https://en.wikipedia.org/wiki/Michel...ley_experiment

2.
https://en.wikipedia.org/wiki/Lorentz_transformation
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Old 20.06.2017., 12:53   #7
Ma u biti teorija koja to i nije, i koja funkcionira na jednom jedinom postulatu, o invarijantnosti brzine svijetla iz čega onda proizlaze sve ostale šarmantnosti, direktno matematičkim relacijima. Dakle matematički set definicija koje povezuje neke fundamentalne odnose. Pravog znanja o mehanizmima funkcioniranja toga uopće nema. I što je najgore od svega, postavkljanje takvih pitanje se čak i smatra nekakvim preispitivanjem ove "teorije relativnosti", koja je više postala nekakvom centralnom dogmom iz koje onda proizlazi čitav niz opažanja i astronomskih teorija koje onda imaju puno rupa i kontradiktornosti da ne nabrajam dalje. U suštinu mi ovo područje uopće ne razumijemo, i to najozbiljnije mislim.
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Old 20.06.2017., 13:08   #8
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Ma u biti teorija koja to i nije, i koja funkcionira na jednom jedinom postulatu, o invarijantnosti brzine svijetla ...
Šta nisu bila dva?

https://en.wikipedia.org/wiki/Postul...ial_relativity
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Old 20.06.2017., 13:13   #9
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Pa ako tako gledaš. No, nepromijenjivost zakona fizike nemaju veze sa teorijom relativnosti. Ono, što je ključno, centralno odnosno što je i dovelo do ove teorije je isključivo invarijantnost i konačnost brzine c. Sve ostalo varijable su matematički prisiljene "pokloniti" se c, koja je stavljena na pijedestal. Mehanizma i kauzalnosti u ovoj teoriji nema, nula. Ovo je samo opis opažanja spomenutog principa, i onda matematički primjenjen na sve ostalo. A zašto i kako to funkcionira. Pitaj boga dragoga
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Old 20.06.2017., 14:18   #10
Taj princip je bio motiviran ovim problemom. Najprije slika:



Einstein ovako objašnjava problem:

It is known that Maxwell’s electrodynamics—as usually understood
at the present time—when applied to moving bodies, leads to
asymmetries which do not appear to be inherent in the phenomena.
Take, for example, the reciprocal electrodynamic action of a magnet
and a conductor. The observable phenomena here depend only on
the relative motion of the conductor and the magnet, whereas the
customary view draws a sharp distinction between the two cases in
which either the one or the other of these two bodies is in motion.
For if the magnet is in motion and the conductor is at rest, there
arises in the neighbourhood of the magnet an electric fi eld with a
certain defi nite energy, producing a current at the places where parts
of the conductor are situated. But if the magnet is stationary and the
conductor in motion, no electric fi eld arises in the neighbourhood
of the magnet. In the conductor, however, we fi nd an electromotive
force, to which in itself there is no corresponding energy, but which
gives rise—assuming equality of relative motion in the two cases
discussed—to electric currents of the same path and intensity as
those produced by the electric forces in the former case.
(Einstein 1905a, 37)


James R. Brown dalje objašnjava:

Einstein then goes on to say ‘Examples of this sort . . . suggest that the
phenomena of electrodynamics . . . possess no properties corresponding
to the idea of absolute rest’ (1905a, 37). The principle of relativity is
then ‘raised to the status of a postulate’ (1905a, 38).

The crucial thing to note here is that Einstein does not rail against
either fields or currents, neither of which are observable. In fact, in the
magnetic induction example not only is the observable needle motion
the same in both cases, but the unobservable current is the same in
both cases, as well. The phenomena are identified as being the same
phenomenon in both cases; in other words, there is no distinction to
be made in the intuitive aspects of the thought experiment, so our
electrodynamic theory must adjust itself to this fact.
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Old 20.06.2017., 14:36   #11
Usput, baš sam nešto pisao o tome na Filozofiji, pa evo i ovdje: mada se redovito nastanak STR prikazuje otprilike kao Einstein riješio probleme izazvane pokusom Michelsona i Morleya, zapravo je vrlo vjerojatno da taj pokus uopće nije imao ulogu u nastanku STR.

Dear Mr. Davenport:

Before Michelson’s work it was already known that within the limits of the precision of the experiments there was no influence of the state of motion of the coordinating system on the phenomena, resp. their laws. H. A. Lorentz has shown that this can be understood on the basis of his formulation of Maxwell’s theory for all cases where the second power of the velocity of the system could be neglected (effects of the first order).

According to the status of the theory, it was, however, natural to expect that this independence would not hold for effects of second and higher orders. To have shown that such expected effect of the second order was de facto absent in one decisive case was Michelson’s greatest merit. This work of Michelson, equally great through the bold and clear formulation of the problem as through the ingenious way by which he reached the very great required precision of measurement, is his immortal contribution to scientific knowledge. This contribution was a new strong argument for the non-existence of “absolute motion,” resp. the principle of special relativity which, since Newton, was never doubted in Mechanics but seemed incompatible with electro-dynamics.

In my own development Michelson’s result has not a considerable influence. I even do not remember if I knew of it at all when I wrote my first paper on the subject (1905). The explanation is that I was, for general reasons, firmly convinced how this could be reconciled with our knowledge of electro-dynamics. One can therefore understand why in my personal struggle Michelson’s experiment played no role or at least no decisive role.

You have my permission to quote this letter. I am also willing to give you further explanations if required.

Sincerely yours,
Albert Einstein
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Old 20.06.2017., 15:00   #12
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Usput, baš sam nešto pisao o tome na Filozofiji, pa evo i ovdje: mada se redovito nastanak STR prikazuje otprilike kao Einstein riješio probleme izazvane pokusom Michelsona i Morleya, zapravo je vrlo vjerojatno da taj pokus uopće nije imao ulogu u nastanku STR.

Dear Mr. Davenport:

Before Michelson’s work it was already known that within the limits of the precision of the experiments there was no influence of the state of motion of the coordinating system on the phenomena, resp. their laws. H. A. Lorentz has shown that this can be understood on the basis of his formulation of Maxwell’s theory for all cases where the second power of the velocity of the system could be neglected (effects of the first order).

According to the status of the theory, it was, however, natural to expect that this independence would not hold for effects of second and higher orders. To have shown that such expected effect of the second order was de facto absent in one decisive case was Michelson’s greatest merit. This work of Michelson, equally great through the bold and clear formulation of the problem as through the ingenious way by which he reached the very great required precision of measurement, is his immortal contribution to scientific knowledge. This contribution was a new strong argument for the non-existence of “absolute motion,” resp. the principle of special relativity which, since Newton, was never doubted in Mechanics but seemed incompatible with electro-dynamics.

In my own development Michelson’s result has not a considerable influence. I even do not remember if I knew of it at all when I wrote my first paper on the subject (1905). The explanation is that I was, for general reasons, firmly convinced how this could be reconciled with our knowledge of electro-dynamics. One can therefore understand why in my personal struggle Michelson’s experiment played no role or at least no decisive role.

You have my permission to quote this letter. I am also willing to give you further explanations if required.

Sincerely yours,
Albert Einstein
On je samo odbacio nužnost postojanja etera koji bi bio u apsolutnom mirovanju, tj. odbacio je postojanje apsolutnog referentnog okvira, a Lorentzove transformacije koordinatnih sistema su postojale već od ranije, koje je onda upotrijebio nakon što je izbacio postojanje baznog ili apsolutnog referencijalnog okvira. Dakle svi su relativni, pa je i samo gibanje relativno. Jedino što je apsolutno je brzina svjetla.
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Old 20.06.2017., 15:44   #13
Einsteinova Opća teorija relativnosti "proizlazi" iz Specijalne;
https://en.wikipedia.org/wiki/Special_relativity
Što je povezano i s fotoelektričnim efektom (ako se ne varam, srednja je davno bila ), a preko njega i s kvantnom teorijom.
Činjenica je da mi dosta stvari o graviticiji još uvijek ne znamo, ali i tu postoje teorije, od MONDa, do loop quantum gravity, a i do pristupa gdje se gravitacija gleda kao statistička varijabla (poput temperature), a ne kao jedna od 4 osnovne sile.
Holografski pristup i teorije struna da ne spominjem.
Točno je da je potrebno razviti dublje poznavanje teorije relativnosti, jer zasada samo imamo "formule koje rade" (npr. gps ne bi radio bez OTRa), a puno shvaćanje nam izmiče.
Problem je što je tu sljedeći korak "teorija svega" ili "veliko ujedinjenje sila", s kojom se Einstein bavio cijelog života, ali do nje nije uspio doći.

Ovo što je Faro spomenuo, problemi sa tamnom energijom & materijom, pitanje crnih rupa, singularnosti i horizonta događaja u njima su granica fizike, na kojem se očekuju neki napreci.
Kao i naravno dorada standardog modela čestica, iako ništa od toga ne znači da je OTR kriv, nego da samo treba "doradu". Isto kao što je i Newtnovi zakoni trebali isto.
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Old 21.06.2017., 20:55   #14
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Što je povezano i s fotoelektričnim efektom (ako se ne varam, srednja je davno bila ), a preko njega i s kvantnom teorijom.
Nigdi veze.
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Old 22.06.2017., 20:47   #15
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Nigdi veze.
https://hr.wikipedia.org/wiki/Fotoel...ni_u%C4%8Dinak
Einstein je za njega dobio nobelovu.
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Old 23.06.2017., 20:08   #16
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https://hr.wikipedia.org/wiki/Fotoel...ni_u%C4%8Dinak
Einstein je za njega dobio nobelovu.
Da, ali fotoelektricni efekt I teorija relativnosti su dva odvojenna podrucja, bez obzira sto se oboma bavio Einstein. Fotoelktricni efekt vise ima veze s kvantnom teorijom. Po meni je opca teorija relativnosti jedna od genijalnijih ideja uopce u povijesti znanosti, a Einstein jedan od najvech umova jer ju je dovrsio gotovo potpuno Sam. Za razliku od kvantne teorije na kojoj su radili desetci fizicara I jos nije zavrsena. S razlogom se kvantna teorija zove Einstein ova nocna mora . Jer je to preveliki zalogaj i za samog Einsteina bio.
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Old 23.06.2017., 20:19   #17
A sto se tice odgovora na naslov teme, mislim daje najblizi bio upravo babunobovich sa svoja 2 linka.(ma koliko god to nevjerovatno zvucalo ) Jer upravo su netocnosti Lorentzovih transformacija pri velikim brzinama izmjerene navedenim i slicnim pokusima dovele do specijalne teorije relativnosti iz koje je opet proizasla opca.
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Old 23.06.2017., 21:22   #18
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A sto se tice odgovora na naslov teme, mislim daje najblizi bio upravo babunobovich sa svoja 2 linka.(ma koliko god to nevjerovatno zvucalo ) Jer upravo su netocnosti Lorentzovih transformacija pri velikim brzinama izmjerene navedenim i slicnim pokusima dovele do specijalne teorije relativnosti iz koje je opet proizasla opca.
Da, srednjoškolska fizika
Iz malih netočnosti do boljeg modela

Za vezu kvantne i relativnosti, da, jedna se bavi velikim stvarima, a druga malima, iako u djelovima kvantne fizike je uračunata relativnost, npr. https://en.wikipedia.org/wiki/Relati...ntum_mechanics , a cjelokupna teorija bi morala uključiti i jednu i drugu.
Načelno, fundamentalne teorije bi trebale biti jednostavne, relativnost to je, a kvantna nije.
Vidjet ćemo
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Old 23.06.2017., 21:42   #19
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Za vezu kvantne i relativnosti, da, jedna se bavi velikim stvarima, a druga malima, iako u djelovima kvantne fizike je uračunata relativnost, npr. https://en.wikipedia.org/wiki/Relati...ntum_mechanics , a cjelokupna teorija bi morala uključiti i jednu i drugu.
Načelno, fundamentalne teorije bi trebale biti jednostavne, relativnost to je, a kvantna nije.
Vidjet ćemo
Bilo je tih pokušaja, mislim da je najpoznatiji teorija struna, ali su se pokazali neuspješnima. Mislim da bi prvo trebalo dovršiti kvantnu teoriju, pa onda ići u eventualno združavanje nje i relativnosti. Ali otom potom. Vidjet ćemo
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Old 23.06.2017., 23:29   #20
Da, neko je string teorije krenuo tumačiti kao religiju
No, valjda će uskoro biti napretka na tom planu
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