Sterrekunde

Bestaan ​​daar absolute snelheid?

Bestaan ​​daar absolute snelheid?


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

Dit lyk asof almal op dieselfde bladsy is omdat daar geen 'absolute snelheid' is nie, omdat alles relatiwisties is. Dit laat my egter verward. Dit lyk asof dit ontkoppel word met die konsep dat die snelheid van die lig in werklikheid 'n onveranderlike konstante is. Maar om te sê dat alle spoed relatief tot 'n voorwerp is, is om in wese te sê: "spoed bestaan ​​nie, maar is slegs relatief tot 'n waarnemer". Maar tog is die snelheid van die lig 'n berekenbare konstante wat nooit verander nie. Hoe kan ons dan sê, bestaan ​​daar nie iets soos absolute spoed nie?

As ek 'n flitslig in die ruimte gooi wat 50 mph aangeskakel is, verhoog die spoed van die uitgestraalde lig vanaf die flitslig met 50 myl per uur in die rigting wat ek dit gegooi het? Natuurlik nie. Ons weet dit. Maar as dit werklik die geval is, hoe kan daar dan geen absolute snelheid wees wat bereken kan word deur die snelheid van die lig te bepaal wat relevant is vir die voorwerp wat ons meet nie (aangesien die ligspoed konstant is)?

Help asb, want dit pla my.


Chris, jy is eintlik op die punt om te verstaan ​​hoe spesiale relatiwiteit werk. Jy is baie naby. U hoef net een ekstra stap te neem.

om te stel dat alle spoed relatief tot 'n voorwerp is, is om in wese te sê: "spoed bestaan ​​nie, maar is slegs relatief tot 'n waarnemer"

Dit is korrek. Absolute ruimte, soos in die fisika van Newton, bestaan ​​nie. Dieselfde vir absolute tyd. Albei is net verhoudings tussen voorwerpe en tussen gebeure.

Solank as wat u aan die idees van absolute ruimte en absolute tyd hang, kan relatiwiteit nie verstaan ​​word nie. As jy dit loslaat, lyk relatiwiteit natuurlik.


Einstein het dit eenvoudig opgemerk:

A) Alle vorige eksperimente (soos Michelson-Morley) het getoon dat wanneer u die spoed van die lig meet, u altyd dieselfde resultaat kry, ongeag wat.

B) Maxwell se vergelykings vir elektromagnetiese velde (soos lig) sluit die snelheid van die lig in, en die waarde van die snelheid is raam-onafhanklik. Wat beteken dat hulle altyd die snelheid van die lig dieselfde toon, ongeag hoe die waarnemer beweeg.

Beide A en B sê dieselfde: ligspoed is altyd dieselfde. Maar hoe kan dit wees as verskillende waarnemers teen verskillende snelhede deur die absolute ruimte beweeg?

Die antwoord is: absolute ruimte is nie 'n ding nie. Ruimte is net 'n agtergrond vir 'n spesiale tipe verband tussen voorwerpe, wat 'afstand' genoem word. Tyd is net 'n agtergrond vir 'n spesiale tipe verband tussen gebeure, genaamd "duur". Maar nie ruimte of tyd is dinge nie, apart van voorwerpe en gebeure. Slegs wanneer u 'n hele klomp "afstand" tipe verhoudings saamstel, lyk dit asof daar ruimte is.

Die belangrikste ding is die snelheid van die lig. Dit is 'n fundamentele konstante van die natuur, soos die Planck-energie, ens. Hierdie heelal is so gebou dat die snelheid van die lig en ander konstante soos dit dieselfde bly, ongeag wat.

Maar ruimte en tyd is afgeleide begrippe. Dit is nie oerwerklikhede soos die snelheid van die lig nie. Hulle is dus afhanklik van die waarnemer. Vir my lyk die bundel afstandsverhoudings wat ons 'ruimte' noem, op 'n sekere manier. Vir u lyk dieselfde bundel 'n bietjie anders. Dit is goed, want ruimte is nie absoluut nie; dit is afgelei van baie ander dinge.

As jy die flitslig gooi, is die snelheid van die lig daaruit vir almal dieselfde. Maar hoe kan dit wees, aangesien verskillende waarnemers op verskillende maniere beweeg? Eenvoudig: hulle sien almal die bondels afstandsverhoudinge anders; daardie verskille is sodanig dat die snelheid van die lig altyd dieselfde bly.


En dit is 'n spesiale relatiwiteit in 'n neutedop.


Bestaan ​​daar absolute snelheid?

Ja dit doen.

Dit lyk asof almal op dieselfde bladsy is omdat daar geen 'absolute snelheid' is nie, omdat alles relatiwisties is.

Ek is 'n 'relativis', maar ek is nie op daardie bladsy nie. As gevolg van die CMBR. Google op CMBR verwysingsraamwerk en kyk na die CMBR dipool anisotropie. Dit is nie 'n absolute raamwerk in die streng sin van die woord nie. Maar u kan dit gebruik om u spoed deur die heelal te meet. En die heelal is so absoluut soos dit word.

Dit laat my egter verward. Dit lyk asof dit ontkoppel word met die konsep dat die snelheid van die lig in werklikheid 'n onveranderlike konstante is.

Ek is bevrees dat dit nie so is nie. Kyk na Is die snelheid van die lig oral dieselfde? op die webwerf PhysicsFAQ:

"Verander die snelheid van die lig in lug of water? Ja. Lig word vertraag in deursigtige media soos lug, water en glas."

"Hierdie gyroskope stuur lig rondom 'n geslote lus, en as die lus draai, sal 'n waarnemer op die lus ry, die lig meet om stadiger te beweeg as dit deur die lus in een rigting beweeg as wanneer dit in die teenoorgestelde rigting beweeg."

"In hierdie gedeelte praat Einstein nie oor 'n raam wat vrylik val nie, maar eerder oor 'n raam in rus ten opsigte van 'n swaartekrag. In so 'n raam kan die nie baie goed gedefinieerde" snelheid "van lig verskil van c, basies vanweë die effek van swaartekrag (ruimtetydkromming) op horlosies en liniale. "

Die antwoord is nee. Die spoed van die lig is nie oral dieselfde nie. Maar u meet die plaaslike snelheid van die lig dieselfde, want u definieer ons sekondes en u meters met behulp van lig. As u dit dus gebruik om die snelheid van die lig te meet, kry u altyd dieselfde antwoord. Sien opmerkings oor "Nota oor wisselende snelheid van ligteorieë" deur Joao Magueijo en John Moffat.

Maar om te sê dat alle spoed relatief tot 'n voorwerp is, is om in wese te sê: "spoed bestaan ​​nie, maar is slegs relatief tot 'n waarnemer".

Spoed bestaan. Dit kan relatief tot iets anders wees, selfs al is die iets die heelal. Maar hoewel dit net relatief is, is dit geen rede om te sê dat dit nie bestaan ​​nie. 'N Koeël is net 'n onskadelike klomp lood wat u in u hand kan weeg. Maar 'n vinnige koeël sal jou doodmaak. Dink aan hoe dit sit "spoed bestaan ​​nie, maar is slegs relatief tot 'n waarnemer".

Maar tog is die snelheid van die lig 'n berekenbare konstante wat nooit verander nie. Hoe kan ons dan sê, bestaan ​​daar nie iets soos absolute spoed nie?

Ons kan nie. Ons kan sê dat daar nie 'n absolute verwysingsraamwerk is nie, sodat u nie die eksperimentele resultate in u verseëlde boks sal beïnvloed deur die snelheid van die vak nie. Maar soos ek gesê het, die heelal is so absoluut soos dit word, en u kan u spoed relatief tot die heelal meet.

As ek 'n flitslig in die ruimte gooi wat 50 mph aangeskakel is, verhoog die spoed van die uitgestraalde lig vanaf die flitslig met 50 myl per uur in die rigting wat ek dit gegooi het? Natuurlik nie. Ons weet dit.

Reg. Omdat lig 'n E = hf golf-aard het. Die golfsnelheid hang af van die medium waardeur dit beweeg, nie van die emittorsnelheid nie.

Maar as dit werklik die geval is, hoe kan daar dan nie 'n absolute snelheid wees wat bereken kan word deur die snelheid van die lig te bepaal wat relevant is vir die voorwerp wat ons meet nie (aangesien die ligspoed konstant is)? Help asb want dit pla my.

Dit is eenvoudiger as wat jy dink. Kyk na die definisie van die tweede en die definisie van die meter:

Die SI-definisie van tweede is die duur van 9 192 631 770 periodes van die straling ...

Die meter is die lengte van die pad wat deur lug in vakuum gereis word gedurende 'n tydsinterval van 1/299792458 sekonde.

U meet die plaaslike snelheid van die lig om konstant te wees vanweë die manier waarop u u sekondes en u meters definieer, en as gevolg van die golfaard van materie. Kyk na dinge soos paarproduksie en elektrondiffraksie. Vra jouself af: as jy en jou stokke en horlosies uit klankgolwe gemaak is, sodat jy jou meters en sekonde met die beweging van klankgolwe gedefinieër het, hoe sou jy die plaaslike klanksnelheid ooit anders as 340 m meet? / s?

Wysig 14/09/2017:

Om dit wat ek hierbo gesê het te sien, sien u dit in die Einstein digitale koerante wat dateer uit 1920:

"Soos 'n eenvoudige geometriese oorweging aantoon, kom die kromming van ligstrale slegs in ruimtes voor waar die spoed van lig ruimtelik veranderlik is. Hieruit volg dat die hele konseptuele stelsel van die teorie van spesiale relatiwiteit streng geldigheid kan eis vir daardie ruimtetyddomeine waar gravitasievelde (onder toepaslik gekose koördinaatstelsels) afwesig is. "

Die spoed van lig in vacuo wissel. Kyk ook na hierdie PSE-antwoord wat professor Douglas Scott aanhaal:

"Die deurslaggewende aanname van Einstein se teorie is egter nie dat daar geen spesiale rame is nie, maar dat daar geen spesiale rame is waar die wette van die fisika verskil nie. Daar is duidelik 'n raam waar die CMB rus, en so dit is in 'n sekere sin die rusraamwerk van die Heelal. Maar om enige fisika-eksperiment te doen, is enige ander raamwerk so goed soos hierdie. Die enigste verskil is dus dat u in die CMB-rusraam geen snelheid meet ten opsigte van die CMB-fotone nie, maar dit beteken geen fundamentele verskil in die wette van die fisika nie. '

Spesiale relatiwiteit het die CMBR voorafgegaan. Sien dit ook in die Einstein digitale vraestelle, weer vanaf 1920:

"Om saam te stel, kan ons sê dat die ruimte volgens die algemene relatiwiteitsteorie met fisiese eienskappe toegerus is; in hierdie sin is daar bestaan ​​'n eter".

Kyk na Wikipedia en hierbo vir die definisie van die tweede en die definisie van die meter. Albei word met behulp van lig gedefinieer.


Lyk die snelheid van (sigbare) "lig" is dieselfde vir elke waarnemer by 'n gegewe relatiewe beweging tot ander waarnemers omdat die definisie van sigbare lig 'n spesifieke energietoestand is wat die snelheid daarvan vir elke waarnemer definieer. As dit 'n hoër of laer energietoestand was, sou dit in 'n ander deel van die elektromagnetiese spektrum gedruk word en nie meer 'sigbare' lig wees nie.

Sodanig dat twee waarnemers, die een beweeg teen 'n relatiewe beweging teen 'n ligbron, en die ander beweeg in enige tempo na die ligbron, elkeen sal die "sigbare" lig vanuit die bron op 'n konstante manier sien uitkom. Dit veronderstel 'n breë spektrum emissie. Dat alles egter verander as die bron van die lig slegs op 'n spesifieke golflengte is. In daardie geval sal faseverskuiwing plaasvind en sal die bewegende voorwerp (relatief tot die bron) nie die sigbare lig op dieselfde golflengte "sien" as die waarnemer wat geen relatiewe beweging tot die bron het nie. En as die waarnemer wat relatiewe beweging het, vinnig genoeg beweeg, kan die bronemissie moontlik heeltemal buite die sigbare ligspektrum skuif.


Stellar Aberration and Einstein's Relativity


Abstrak

Sterre afwyking word verklaar deur die relatiewe beweging tussen 'n ster en 'n waarnemer op aarde. Op grond van die beginsel van onveranderlikheid voorspel Einstein se relatiwiteit dat daar geen absolute beweging bestaan ​​nie. Gevolglik moet daar geen verskil wees tussen 'n ster met 'n snelheid ten opsigte van 'n waarnemer en 'n waarnemer wat 'n snelheid ten opsigte van 'n ster het nie. In die geval van sterre afwyking lyk hierdie voorspelling strydig met waarnemings. Daar word aangetoon dat die beskrywing van sterre-afwyking, in terme van relatiewe transversale snelheid tussen die ster en 'n waarnemer op aarde, reggestel moet word, omdat dit 'n foutiewe interpretasie van Einstein se relatiwiteit is.

1. Inleiding.
Die presiese posisie waar 'n ster in die lug verskyn, hang nie net af van die koördinate van die waargenome bron nie, maar ook van die relatiewe snelheid van die waarnemer. Die waarnemersnelheid is verantwoordelik vir 'n verskynsel genaamd 'Bradley-aberrasie' of 'Stellar aberration'. Sterre afwyking is 'n bekende verskynsel onder sterrekundiges. Dit is in 1727 deur die sterrekundige James Bradley [1] ontdek. Dit word beweer dat dit veroorsaak word deur die relatiewe dwarsbeweging tussen die aarde en die ster wat die fotone uitstoot.
Sommige outeurs [2-5] het getoon dat hierdie voorspelling nie ten volle versoenbaar is met waarnemings nie. Daar is geen beskikbare verklaring vir die feit dat, hoewel die waarnemingsdata oor sterre-afwyking versoenbaar is met 'n bewegende aarde, die simmetriese beskrywing, as die ster (en nie die waarnemer nie) die relatiewe dwarsbeweging besit, blykbaar nie lei tot waarnemings wat verenigbaar is nie met voorspellings.

2. Radiale snelhede.
Elke komponent van relatiewe beweging tussen 'n bron en 'n detector word hier afsonderlik bespreek. In die geval van radiale beweging is dit welbekend dat die relatiewe beweging tussen die bron en die detektor 'n verandering in golflengtes teweegbring, verklaar deur die "Doppler-effek". Daar is dan geen rigtingverandering van die fotone nie. Die radiale snelheid is verenigbaar met die verskil in radiale snelhede tussen die ster en die detektor. Volgens Einstein se relatiwiteit impliseer die toestand van onveranderlikheid dat daar geen absolute snelheid van die bron of van die detektor bestaan ​​nie. Waarnemings het getoon dat data in die geval van radiale beweging volledig ooreenstem met Einstein se voorspellings.

3. Dwarssnelhede.
In die geval van dwarsbeweging tussen die twee voorwerpe word 'n ander effek genaamd 'Aberrasie van die lig' voorspel en waargeneem. Na Einstein se relatiwiteit word 'n simmetriese situasie verwag, of die bron of die detektor die dwars snelheid besit. Net soos met die Doppler-effek, beteken die relatiwiteitsbeginsel van Einstein ook dat slegs die relatiewe beweging relevant is.
Daar is egter aangetoon [2-5] dat sommige waarnemings nie met hierdie voorspellings versoenbaar is nie. Die erns van die probleem is selfs oor die hoof gesien. Die afwesigheid van 'n geskikte verklaring laat die verskynsel van ligafwyking natuurlik sonder enige rasionele oplossing. Daar is beweer dat die waargenome resultate, wat afhang of die aarde of die ster beweeg, eksperimentele bewys is van die mislukking van Einstein se beginsel. Laat ons hierdie probleem ondersoek.

4. Beskrywing van die verskynsel.
'N Mens weet dat die aarde elke jaar 'n volle omtrek rondom die son voltooi. Gevolglik, aangesien die Aarde-Son-straal (Re) bekend is, is dit maklik om die aardse tangensiële snelheid te bepaal (Vt) benodig om die omtrek binne twaalf maande (T sekondes) te voltooi. Ons het:

1
Vergelyking 1 voorspel dat die gemiddelde translasiesnelheid V van die aarde rondom die son 29,79 km / s is. Die aardsnelheidsvektor verander natuurlik voortdurend in rigting en voltooi 'n volle siklus gedurende 'n periode van een jaar terwyl die aarde om die son sirkel.
Op Figuur 1 ontdek 'n waarnemer op Aarde die fotone wat uitgestraal word deur 'n stilstaande ster S, geleë in 'n loodregte rigting op die Aardsnelheid Vt. Die ster is op so 'n groot afstand van die aarde geleë dat die parallaks wat deur die baan deursnee rondom die son veroorsaak word, heeltemal weglaatbaar is. Slegs die transversale snelheid is hier van belang.
Figuur 1 Die stilstaande ster S stuur fotone in alle rigtings uit. Die aarde en die teleskoop beweeg opwaarts teen 'n snelheid V. Die teleskoop moet 'n hoek maak q met betrekking tot die werklike rigting van die komende fotone om dit op sy fokus te versamel.

Ons lees in sterrekundehandboeke dat die relatiewe snelheid tussen fotone (teen snelheid c) en die Aarde (Vt), verduidelik waarom 'n teleskoop "T" op Aarde (sien Fig. 1) op die hoek q moet wys ten opsigte van die Aardsterrigting, om die ster te kan aanwys. Figuur 1 toon dat, terwyl die fotone reguit na die aarde beweeg, hulle altyd in die as van 'n skuins teleskoop sal bly, aangesien dit sywaarts met die aarde beweeg. Die hoek q is gelyk aan:

2
Vergelyking 2 gee q gelyk aan 20,5 boog-s. Dit stem perfek ooreen met die waarde van aberrasie wat soveel keer sedert Bradley in 1727 waargeneem is. Gedurende die jaar maak die waargenome rigting van die sterre 'n oscilasie met 'n amplitude van 20,5 boë-s., Soos verwag van die Aarde-beweging rondom die Son. Die waarde van 20,5 boog-s. word die konstante van ster aberrasie genoem.

5. Oënskynlike gebrek aan simmetrie.
'N Ernstige probleem word geopenbaar as 'n mens die beskrywing van die verskynsel lees. Wetenskaplike artikels en handboeke oor relatiwiteit [6] noem of impliseer dat sterre afwyking bepaal word deur die 'relatiewe snelheid' tussen die ligbron en die detektor. Eksperimenteel is duidelik aangetoon dat dit nie so is nie. Baie oortuigende argumente is deur H. Ives [2], Eisner [3] en Phipps [4] en Hayden [5] en verskeie ander aangetoon om aan te toon dat wanneer die bron (in plaas van die detektor) beweeg, die afwyking bestaan ​​nie meer nie. Waarnemings toon duidelik dat, in teenstelling met die spesiale relatiwiteit, sterre afwyking nie afhang van die relatiewe beweging tussen die bron en die detektor nie, maar slegs bestaan ​​wanneer die detektor beweeg. Handboeke verduidelik die resultate slegs wanneer die waarnemer beweeg. Daar is geen bekende verklaring vir die saak wanneer die bron beweeg nie.
Die gebrek aan simmetrie, tussen die gevalle of die bron of die detektor beweeg, word duidelik getoon [5] aan die hand van die skeiding van binêre sterre. 'N Mens kan die beweging van individuele sterre van 'n binêre stelsel vanuit hul spektrum betroubaar bepaal vanaf die periodieke Doppler-verskuiwing van die spektrale lyne van die sterkomponente. Daarom verkry sterre van 'n binêre stelsel voldoende relatiewe transversale snelheid om 'n belangrike afwyking te lewer. So 'n afwyking word nie waargeneem nie. Sommige vraestelle rapporteer nie-realistiese hipoteses om die afwyking as die ster beweeg te verklaar. Die verklaring is afkomstig van die bewering dat ons nie die werklikheid of die "Umbrella Analogy" waarneem wat deur Eddington en sommige genoem is nie.

6. Afwykingsmeganisme.
Kom ons kyk na figuur 2, 'n sterbron S en 'n detektor wat op die aarde geleë is. Bron S stuur fotone in alle rigtings uit met snelheid c. In die fisika word fotone beskou as deeltjies en word hulle voorgestel as koeëls wat vanaf die oppervlak van die emitter S met 'n snelheid c uitgegooi word. Na 'n kort tydsperiode na emissie vorm die fotone wat op een oomblik uitgestraal word, 'n sfeer rondom die ster soos getoon (gestippelde sirkel) op figuur 2. Laat ons nou dink dat die ster S (in plaas van die Aarde) 'n dwars opwaartse snelheid het soos getoon in figuur 2.


Figuur 2 In hierdie geval beweeg die ster opwaarts ten opsigte van die Aarde. Fotone wat uit die nuwe rigting gestuur word b bereik nou die aarde.

Ons weet dat die resulterende snelheid U van die uitgestraalde koeëls (fotone) die relativistiese som van die stersnelheid V en die snelheid van die lig c is. Uit figuur 2 sien ons dat V loodreg is op die rigting van die lig wat aarde toe gaan. Die algemene snelheidssamestellingsformule wat die som van V en c gee, soos gegee deur M ller [6], is:

3
Aangesien die rigting van V loodreg op c is, het ons (c V) = 0. Dit lewer:
4
waar kry ons:
5
Vergelyking 4 gee aan dat die eindsnelheid van die lig steeds streng is c maar die rigting het verander deur die hoek d, waar:
6
Gevolglik sal die fotone dan nie meer die aarde bereik nie.
Kom ons kyk nou na (fig. 2) die fotone (of koeëls) wat uit S in rigting a uitgestraal word, wanneer die ster oorspronklik rus (V = 0). Die koeëls wat in daardie rigting uitgestraal word, is aangedui as a, sodat 'n mens hul rigting kan herken. Ander koeëls wat in ander rigtings uitgestraal word, word b, g, d, e, h, i, k en l gemerk met betrekking tot die ster S.
Wanneer die ster opwaarts beweeg met 'n snelheid V, sal deeltjies gemerk a nie meer die detektor op aarde bereik soos hierbo bereken nie. Hulle het 'n nuwe rigting onder die hoek d, gemerk m, en sal die aarde mis. Die ander deeltjiebundel wat oorspronklik in die rigting b wys, word egter nou afgewyk deur 'n hoek d in die rigting van a, omdat die afwaartse komponent van b gelyk is aan die opwaartse komponent van V. Daarom vergoed die hoek d gegee aan straal b vir die opwaartse snelheid V. Daarom neem die fotone rigting van a.
Gevolglik het daardie fotone geen dwars snelheidskomponent nie, aangesien die snelheid V van die ster presies die snelheidskomponent van die lig in die rigting b in die teenoorgestelde rigting kanselleer. Daarom sal hierdie fotone die aarde bereik sonder om enige sterre afwyking te lewer. Dit is bekend in wiskunde dat 'n vektor, gemaak van die som van twee oorspronklike vektore, alle inligting verloor oor die individuele komponente wat die finale vektor gevorm het. Daar is absoluut geen moontlikheid vir die bron op daardie plek om deeltjies op so 'n manier te stuur dat dit met 'n transversale snelheid op die aarde sal kom nie, aangesien dit onmoontlik is dat enige deeltjie (foton) met 'n transversale snelheid die aarde kan bereik. . Gevolglik is enige transversale snelheid V van die bron S heeltemal onopspoorbaar.

7. Verenigbaarheid met Einstein se teorie?
Hierdie resultaat moet in terme van relatiewe beweging ondersoek word. In relatiwiteit word gesê dat daar geen absolute snelheid bestaan ​​nie. Slegs die relatiewe snelheid tussen twee voorwerpe het 'n fisiese betekenis. Hoe kan dit verenigbaar wees met die bostaande beskrywing van ster aberrasie? Hierdie skynbare paradoks word opgelos as 'n mens noukeuriger in ag neem wat die twee voorwerpe is. In die geval hierbo beskryf, behels die afwyking van die lig duidelik die relatiewe beweging tussen die koeëls (fotone) en die detektor. Dit behels nie die relatiewe beweging van die stelsel wat die koeëls afgevuur het nie (genoem bron). In werklikheid is die ster, waaruit die deeltjies vrygestel word, nie meer as die steun waaruit die deeltjie (koeëls) ontstaan ​​het nie. Foutief is die relatiewe snelheid tussen die ster en die aarde in ag geneem, terwyl die relatiewe snelheid tussen die inkomende deeltjies (koeëls of fotone) en die aarde in ag geneem moet word. Aan die hand van die laaste oorweging kom ons uiteindelik voor dat die beginsel van relatiewe beweging wat Einstein beskryf, in hierdie geval toegepas kan word.
Die interpretasiefout wat hier bespreek word, stem presies ooreen met die situasie wat voorkom as 'n jagter op sy prooi skiet. Niemand beweer dat hy die transversale snelheid van 'n lopende jagter kon bereken uit die kennis van die rigting van die koeël wat na die prooi beweeg nie. Die invoerhoek van die koeël in die prooi hang af van die relatiewe snelheid tussen die prooi en die koeël en nie die snelheid relatief tot die jagter nie. As die jagter vorentoe hardloop, moet hy sy geweer in 'n hoek rig met 'n agterwaartse komponent om sy teiken te bereik.
'N Mens moet aflei dat dit 'n fout was om te beweer dat die afwyking van die lig veroorsaak word deur die relatiewe transversale snelheid tussen die ster en die aarde. 'N Mens moet sê dat dit die gevolg is van die relatiewe transversale snelheid tussen die aarde en die komende fotone. Gevolglik kan Einstein se relatiwiteitsbeginsel in hierdie spesifieke geval toegepas word.

8. Hoes vir ander modelle vir lig.
Daar kan baie maklik gesien word dat die uiteensetting hierbo oor die afwyking van die lig net so goed op die golfmodel van lig toegepas kan word as op die model van fotone. Die gevolge is heeltemal identies. Geen ligafwyking word verwag as die emitter (in plaas van die golf) 'n transversale snelheid het nie. 'N Mens kan ook die vraag vra: "Kan ons 'n soortgelyke interpretasie vir die afwyking vind as lig volgens die moderne fisika beskryf word?' N Mens moet onthou dat die moderne fisika sy interpretasie vind met die gebruik van die Kopenhagen-interpretasie. Die Kopenhagen-interpretasie impliseer dat fotone nie onafhanklik van die waarnemer bestaan ​​en op die oomblik van opsporing geskep word. Die verklarings wat hier gegee word, kan gevolglik nie direk toegepas word nie. Die vraag is eintlik nie sinvol nie, aangesien daar in die moderne fisika beweer word dat verklarings nie noodwendig versoenbaar hoef te wees nie. Dit word duidelik gestel deur Heisenberg self as hy skryf: "Die wet van kousaliteit word nie meer in die kwantumteorie toegepas nie." As ons die beginsel van kousaliteit nie aanvaar nie, is dit nie sinvol om na die oorsaak van sterre afwyking te soek nie. .
Sonder om die wiskunde van moderne fisika te verander, (maar sonder om die Kopenhagense interpretasie van moderne fisika te gebruik), is dit egter moontlik om aan te toon dat fisiese verskynsels op 'n oorsaaklike manier beskryf kan word. Dit is onlangs in meer besonderhede getoon. Daar kan aangetoon word dat, met behulp van 'n oorsaaklike beskrywing van die moderne fisika, die verskynsel van sterre ligafwyking klassiek verklaar word.

Erkenning.
Die skrywer wil die finansiële hulp van die Nasionale Wetenskaplike en Ingenieurswetenskaplike Navorsingsraad van Kanada erken en die uitruil van korrespondensie met Dr. T. E. Phipps.

---------------------------------------------
Belangrike opmerking oor relatiwiteit Sterre afwyking is 'n korreksie wat absoluut nodig is om 'n logiese stelsel van koördinate vir sterre en sterrestelsels te kry, wat geldig is te alle tye die hele jaar en selfs in enige tydvak. Sonder sterre afwyking is dit onmoontlik om 'n samehangende stelsel van koördinate in die heelal daar te stel. Sterre afwyking hou rekening met die snelheid van die waarnemer as gevolg van die rotasie van die aarde en ook die vertaling daarvan rondom die son.
Daar is nou uiters akkurate tabelle van koördinate van astronomiese voorwerpe wat die akkurate waarnemings van baie groot teleskope op die aarde en selfs in die ruimte rapporteer. 'N Hoër akkuraatheid word selfs verkry deur interferometriese metodes te gebruik. Dit lyk asof daar amper geen beperking is op die akkuraatheid wat bereik kan word nie.
Al hierdie 'baie akkurate' koördinate is egter bereken sonder om enige regstellingsfaktor te betrek as gevolg van die regte beweging van die waargenome voorwerp (ster of sterrestelsel). Hierdie prosedure is duidelik foutief met Einstein se relatiwiteitsbeginsel, wat beweer dat dit slegs te wyte is aan die relatiewe snelheid. Hierdie tabelle word bereken sonder om die relatiewe snelheid tussen die aarde en die galaktiese voorwerp in ag te neem. Slegs die rotasiesnelheid en translasie van die aarde rondom die son word in ag geneem. In die geval van teleskope wat wentel, word die ster aberrasie as gevolg van die snelheid van die satelliet ook in ag geneem.
Gelukkig is dit duidelik dat alle wetenskaplikes vergeet om Einstein se relatiwiteitsbeginsel hier toe te pas. Die algemeen aanvaarde prosedure is nie versoenbaar met die Einstein se relatiwiteitsbeginsel nie. Gevolglik moet ons aflei dat Einsteins relatiwiteitsbeginsel verkeerd is. Daardie aanvaarde stelsel van koördinate (wat eintlik ten opsigte van die son is) word eintlik beskou as 'n ABSOLUTE stelsel van koördinaat.
Daar is ook 'n ander belangrike vraag wat geopper moet word. Gee hierdie stelsel van koördinate die 'werklike' posisie van sterre? Aangesien die werklike relatiewe snelheid tussen die waarnemer en die ster al nie in ag geneem word nie (in stryd met Einstein se beginsel), is dit logies om hierdie Son se koördinate te gebruik? Ons weet dat die berekening van die ster aberrasie hierbo beskryf, ooreenstem met die gebruik van Son se koördinate. Lei daardie stelsel (van koördinate) tot samehangende resultate? Die antwoord is NEE, nie heeltemal nie. Laat ek 'n voorbeeld gee.
Laat ons aanneem dat ons gedurende enkele millennia astronomiese waarnemings doen. Gedurende hierdie millennia beweeg die sonnestelsel met snelheid V om die middel van ons sterrestelsel. Na baie millennia sal ons sien dat baie afgeleë sterrestelsels in die heelal sal verskyn om ossillasies te maak vir elke rotasie van ons son om ons sterrestelsel. Daarom moet ons stelsel van koördinate, gebaseer op die sonraam, reggestel word as gevolg van hierdie nuwe (galaktiese) ster-afwyking, as gevolg van die snelheid van die son rondom ons sterrestelsel. As gevolg van die uiterste akkuraatheid in die meting van koördinate, sal ons vroeër of later rekening moet hou met die ander regstelling as gevolg van die rotasie van ons sterrestelsel. Daar sal geen ander keuse wees as ons samehangend wil bly nie. Daar is ook nog 'n klein regstelling wat ontstaan ​​as gevolg van die versteuring van ons son in ons plaaslike sterrestelsel, as gevolg van die interaksie met naburige sterre.
Die uiteindelike regstelling van ster-afwyking behels die absolute snelheid van ons son in die heelal. Daardie absolute snelheid is reeds bepaal. Ons het in die artikel gesien: 'Big Bang Cosmology Meets an Astronomical Death' dat die dipool van die 3K kosmiese straling te wyte is aan die regte beweging van ons son in die heelal. Natuurlik is die kosmiese straling te danke aan die emissie van die Planck-straling van interstellêre gasse in die heelal, wat op 3K is, soos uiteengesit in die vraestel: "Die oorsprong van die 3 K-straling" en ook in die papier: "Die 3 K Mikrogolfagtergrond en die Olbers-paradoks
Die asimmetrie (dipool) van daardie Planck-straling is te wyte aan die absolute regte beweging van ons son in die heelal. Dit wys dat dit nou moontlik is om die absolute verwysingsraamwerk in ons heelal te bepaal. Daar bestaan ​​geen ander stelsel van koördinate wat samehangende gegewens kan gee nie.

[1] J. Bradley "Rekening van 'n nuwe ontdekte beweging van die vaste sterre"Phil. Trans. 35 bl. 637 (1728).
[2] H. E. Yves "Ekstrapolasie van die Michelson-Morley-eksperiment"J. Opt. Soc. Am. 40, pp. 185-190 (1950)
Ook - P. Marmet, 'The Overlooked Phenomena in the Michelson-Morley Experiment'
[3] E. Eisner, "Afwyking van lig van binêre sterre - 'n paradoks?"Am. J. Phys. 35, pp.817-819 (1967)
[4] T. E. Phipps "Relatiwiteit en afwyking, "Am. J. Phys., 57, pp., 549-550 (1989) ook Phipps T. E., Jr.,"Sterre afwyking vanuit die oogpunt van die hipotese van stralingskonveksie."Fis. Opstelle 4, 368, (1991)
[5] H. C. Hayden, Sterre afwyking,"Galilean Electrodynamics, 4. pp. 89-92 (1993)
[6] C. Moller, Die Relatiwiteitsteorie, (Oxford 1972)
[7] W. Heisenberg, "Fisika en filosofie, die rewolusie in die moderne wetenskap"New York, Harper and Row, (1966) p. 88
[8] P. Marmet, "Absurditeite in die moderne fisika: 'n oplossing"Les ditions du Nordir, Simard Hall, 165 Waller, Ottawa, K1N 6N5, Kanada (1993).

------------------------------
R sum Le ph nom ne d'aberration stellaire est expliqu par la vitesse relative transversale entre l' toile et l'observateur sur terre. Ceci est en conformit avec le principe d'invariance d'Einstein. Ainsi, il ne doit y avoir aucune diff rence entre une toile ayant une vitesse par rapport un observateur et un observateur se d pla ant par rapport a une toile. Il est observ que dans le cas de l'aberration stellaire, certains r sultats semblent incompatibles avec ce principe d'Einstein. On d montre ici que la description de l'aberration stellaire en terme de vitesse relative transversale entre les toiles et la terre devrait tre corrig e cause qu'elle est une interpr tation erron e de la relativit d 'Einstein.


Hoe om absolute snelheid te meet

jy is in 'n vliegtuig wat ooswaarts vlieg met 'n kopwind van 10 km / u. Die snelheid van die vliegtuig word gemeet deur die windspoed buite die vlak te meet en dan aan te pas vir enige kopwind. Laat ons sê dat u 'n resultaat van 200 km / u (nadat u die kopwind toegelaat het) kry.

Sonder dat u weet, is die melkweg, wat die melkweg genoem word, op 400 km / h weswaarts, dus is u snelheid 200 km / u agteruit!

maar DIE heelal is op pad na 400 000 km / u, so u spoed is nou. ummm. baie EN jou oë begin brand :)

Aangesien 'n foton in alle verwysingsraamwerke 'n konstante snelheid het en die veronderstelling dat die tegnologie tot die punt beweeg dat die snelheid van 'n foton akkuraat gemeet kan word. By measuring the speed of the plane relative to the speed of photons (measured simutaneously in all three dimensions) you should be able to derive the true speed of the plane regardless of the frame of ref? true or false :)

You will need to measure the speed of the photons simutaneously in 3 dimesnsions (east, west,south,north,up,down) as it may turn out the plane could be moving in any direction.

this would be similar to measuring the planes velocity realtive to the michelson morely experiment.


12 Answers 12

Within the context of Newtonian mechanics, there's a simple answer: velocities are not absolute, but differences in velocities are. So you can state that acceleration occurs unambiguously.

In special relativity, this is a bit more complicated because of relativistic velocity addition, but all observers can unambiguously compute a "proper" acceleration for every object, which is the acceleration in that object's momentary rest frame.

In fact, the same logic still works in general relativity acceleration is unambiguous even in a universe without matter. However, in certain philosophical stances inspired by general relativity, the question is trickier because one might take a hardline Machian position, where motion should only be defined in relation to other matter. But in this case you can still answer the question because there is motion relative to the exhaust.

A rocket's thrusters function by ejecting reaction mass (exhaust). You can measure the movement of the rocket by its distance from its reaction mass. The rocket moves relative to its reactant.

You can say the rocket didn't move, but not because it can't be measured. The center of mass of a rocket-reactant system* never goes anywhere—not even in our universe**—because the force of the rocket on its reactant is equal and opposite to the force of the reactant on the rocket. In this sense, the rocket-reactant system's center of mass is unaffected by the thrusters because the thrusters are internal to the system in question.

** Unless acted upon by an outside force.

how can we say a rocket accelerates in empty space ?

According to third Newton law, body in a rocket will experience pseudo-force with direction opposite to that of rocket acceleration. That is - rocket acceleration will induce body weight which can be observed / measured :

It's much like water "feels" centrifugal force. What you actually will not be able to distinguish is that if rocket flies with acceleration OR if it has already landed at some planet given that astronauts were sleeping in a journey and no windows to see planet surface and rocket's dashboard is broken showing false acceleration. It is a direct conclusion of Equivalence principle.

Acceleration en relative velocities

An absolute velocity can not be measured, that's correct. But an absolute acceleration can. E.g. with a simple scale.

Measuring the acceleration, you can know your velocity. This is a system that is e.g. already since long time used in airplanes known as inertial navigation system.

There is the other part, the relative velocity, as already mentioned in other answers: while the absolute velocity is not measurable, differences are. And in this case the difference to the exhaust of the rocket can be measured.

Relative velocities are the enigste ones that actually matter.

If we set up the universe using Newton's mechanics, we can get a (mostly useless) definition of absolute velocity from the big bang itself. If momentum is conserved while energy is not (which it cannot be), absolute velocity is defined from the big bang's initial reference frame.

We can do the same in general relativity for some sets of initial conditions but not others, but there is no simple proof for this because conservation of momentum and conservation of energy are linked in general relativity. In all of the ones for which this works, the absolute velocity is equivalent to the velocity of the cosmic background radiation.

Rockets accelerate by pushing mass out the back. The weak forces resulting from CMB interaction are negligible for any reasonable rocket, therefore if fired in deep space, the reasonable reference frame is the initial frame of the rocket, and there is no change to position of the center of mass of rocket + exhaust. As we should expect from this, engine efficiency is exponential with engine exhaust velocity.

So, the effective answer to your question is "we don't care". The laws of physics from the time of Newton never really cared what the effective frame is. If you take the laws of physics and take the limit* as $c$ goes to infinity, Newton's mechanics drop out again.

*Yes I know taking the limit of a constant makes no mathematical sense. What we're looking for is reintroducing Newton's assumption that the speed of light is too large to matter for anything else.

if it is a universe with the same dimensions and physical laws as our own, then the rocket would move per action and reaction, whether or not there was any other mass or energy in the universe. Then the rocket would be moving away from the gasses it expelled.

from whatever i have read this is a fundamental open q. properties of space and time are not known in an "empty" universe and hence concept of motion is not clearly understood. you might want to read about spinning water bucket thought experiment

I will firstly answer in the context of relativity. Die proper acceleration, meaning the acceleration as measured in the reference frame of the rocket, which is related to the "force" felt by the rocket, is independent of its velocity (relative to any other observer). However the rocket's acceleration as measured in other reference frames does depend on the relative velocity: $vec a' = vec a/gamma^3$ , where $gamma := (1-(v/c)^2)^<-1/2>$ is the Lorentz factor. Hence other frames measure a lower acceleration for the rocket. The " $vec a$ " terms are accelerations in space (3-accelerations) to be precise also this simple formula applies only when the relative velocity lines up with the acceleration direction (again, I mean in space only). Tsamplaris 2010 is a nice reference, see $S7.2$ .

To take a very different perspective, from philosophy of physics and Newtonian gravity, you can actually define or interpret "acceleration" as relative if you really want to. (I mention this as a curiosity only, and if the reader is pragmatic or prefers a simple answer then ignore this and just say "acceleration is absolute".) John Norton, in a 1995 article subtitled "Acceleration is relative", writes

Relativity of Acceleration

The decomposition of gravitational free fall into an inertial trajectory and a gravitational deflection is conventional we are free to divide free fall motion into any combination of inertial motion and gravitational deflection we please, as long as the latter corresponds to a gravitational potential satisfying Poisson's equation.

Presumably this could be extended to the rocket example here.

First of all, Leroy's question has nothing whatsoever to do with rockets. His question is about motion in space. Scientists have been pondering the issue of motion in space for at least five centuries. At the beginning of the twentieth century a consensus began to form in the scientific community that a law of nature exists mandating that inertial motion relative to space cannot be measured, and that absolute space does not exist. That consensus about absolute motion and absolute space is stronger today than ever before. Although it is generally accepted by the scientific community that if a rocket experiences a period of acceleration in space, the rocket's velocity in space will change accordingly, but the century old consensus requires that the rocket cannot have a velocity relative to space because there is no such entity like absolute space for the rocket's motion to be relative to. It takes considerable arm waving to wrap your mind around what seems like contradicting assertions.

Obviously there are inconsistencies in prevailing scientific thought about space and motion in space, and these inconsistencies are most likely what prompted Leroy to post his questions. The root cause of the inconsistencies is the century old consensus that absolute space does not exist. Ironically, the supporters of this consensus readily accept that the Lorentz Transformation correctly depicts space and time for inertial observers in empty space. What they don't realize is that the transformation contains a hidden trail-head of a logic path leading to mathematical proof that absolute space actually does exist.

If you accept that the Lorentz Transformation correctly depicts space and time for inertial observers in empty space, then you must also accept that absolute space and time does exist. This is simply a mathematical fact. It is mathematically impossible to express that space and time perceived by inertial observers is a function of their relative velocity, without also establishing a prime reference of space relative to which all velocity is measured.

For those of you interested in the mathematical proof of the above declarations check out my paper The Prime Reference which you can download from my website. Just click on the link in the lower right portion of my picture. When you get to my site click on The Nerds Room, and when you get there click on The Prime Reference. For those of you interested in the ramifications of this revelation check out my Dick & Jane book about relativity that is available on Amazon.


Can Absolute Velocity be Measured?

Just a silly idea i have, please debunk it since i cannot figure it out:

Provided to us is a spacecraft equipped with a particle acceleration and detection systems.

The craft is set on a course where it would not be interrupted by any interstellar objects and cuts its propulsion systems for the entire duration of the experiment.

A stream of electrons are accelerated to a certain speed (let’s say 0.8c) in the particle accelerator. The mass of an electron in the stream is then measured when the electron stream passes, say, in the direction the spacecraft is traveling.

This measurement of electron mass when the electron stream passes in the direction the spacecraft is traveling is repeated for various speeds (0.82c, 0.84c, 0.86c, 0.88c and 0.9c). We then plot these values on a graph (e.g Figure 1). This graph represents the increase in mass of the electron at various velocities relative to the spacecraft.

The graph we obtained is then compared to the graph of:

*9.10938215x10-31 kg is the rest mass of an electron

to see where it fits in. This can be achieved by comparing the change in gradients of both graphs. We then superimpose the graph we got (Figure 1) onto the graph of the equation of Figure 2a

We are now able to determine our velocity through spacetime in the direction the electron was traveling when it was measured by taking a point on the graph we obtained and subtracting the relative speed of the electron from its actual speed as reflected from the superimposed graph.

Example: In Figure 1, we measure the relative speed of the electron, W, to be say 0.8c. When we superimpose the graph, the point which contains W now reads off the new graph as X (lets say 0.83c), so we deduce that we are moving through spacetime at a velocity of 0.03c in the direction the electrons were traveling when their mass was measured.

This experiment is repeated where the mass of the electron is measured as it is traveling in various other directions to determine our absolute velocity through spacetime. The direction which yields the largest velocity will give us the absolute velocity of the spacecraft through spacetime.

The absolute velocity of the spacecraft through spacetime can be compared with the velocity of the spacecraft relative to the cosmic microwave background radiation (CMBR) reference frame.

If both velocities are the same, we can assume that the CMBR reference frame (and the black hole/object that gave birth to big bang) is/was moving at an absolute velocity of 0 m/s through space.

However, if both velocities were different, we can deduce that the CMBR reference frame (and the black hole/object that gave birth to big bang) is/was moving through space at a certain velocity.

This comparison would shed some light on the physical nature of the big bang itself, allowing us to eliminate a few of the seemingly infinite number of theories that surrounds the beginning of the universe we know today.


Does Absolute Velocity Exist? - Sterrekunde

Nobody knows if any particles exist, including photons. This is an ambiguity in quantum theory.

Quantum theory is incomplete in that there is know way of knowing if only waves exist, or only particles exist or both exist all the time. It is a matter of interpretation, or belief or faith.

(Help me out on the particle does not exist part
Does this mean that the entity does not have particle properties or is this a reference to having a surface boundary.)

Feymann did QED theory using particles only. But he also had to use positrons coming back from the future. Can you beoieve that. Yet he got a theory that is said to be the most accurate theory ever based on measurements.

(Would it follow that if you exceed the speed of light you can go backward in time. That is the way it is presented in the science fiction movies. I have never considered it to be actually possible but if I am to consider the speed of light not to be absolute. This may take some thought on my part to form an opinion.)

But at face value, quantum mechanics is only about waves or eigenfunctions, which have no physical existence. It is presumed that the waves collapse into point particles when we try to measure the waves. But there is no theory of the collapse. The moment of collapse is the only moment that a particle even exists for it immediately becomes some other sort of wave, like the eigenfunctions of an electron, if the response to detecting the light is a current. In this interpretation only waves existmost of the time.

(When you say no physical existence would you define a magnetic field as existing or not?)

The state to which the waves collapse to is random for a single collapse. Only the sum of a great number of collapses is predited by the eigenfunctions. An alternative interpretation is that each individual collapse creates a seprpate universe and that every possibility is realized all the time. Can you believe that?

(I am doing my best but this is stretching me a little.
If you read my post containing the coin toss on the end of the other thread. It proves that a specific result can occur on each individual happening and at the same time the sum total of the happenings can still conform to a random law.
Just because the mathematics allow something does not mean it is actually true. Many times there is a negative solution to an equation set when there is no real life condition which matches it. This does not prevent the equation from being correct if the positive solution is used. On the other hand the negative solution can give us a clue there may be an alternate solution.)

Bohm theory is the only theory where both waves and particles exist at the same time, and both are real. The waves then guide the particles as to where they go. I actually like this one the best, but it is perhaps the least popular among physicists. But some believe it in like it was a religion.

(I would say Bohm is correct. Louis de Broglie proved that all matter has a velocity below which it will act as a wave, and above which it will act a particle. Bohm may not have the ability to put an equation to his thoughts but that is no little task. History if full of ideas which took many generations and new forms of mathematics to explain logically.)

The point is that physicists tend to believe in one interpretation or another, as a matter of faith. There is no rational basis to choose one over the other. The mathematics is essentially the same and the predictions always the same no matter which interpretation you believe in.

Now you seem to believe that only particles exist and you seem to assign classical properties to these particles, like saying that a photon has a particular spin now and forever.

(I use the particle approach because it is easier for me to visualize.
I believe that all that can be experientially detected by physical means exists as waves which may exhibit wave or particle properties.
If waves interact that have very different wavelengths then the interaction has predominantly particle properties.
If the waves interact that have similar sized wavelengths then the interaction has predominantly wave properties.
However neither property is ever totally nonexistent.)

Well, photons are described by Maxwell's equations, a wave theory. In that theory you can propagate linearly polarized waves, which have at the same time two opposite spins, or in reality no spin at all. Or you can propagate circularly polarized waves, which have either right handed spin or left handed spin. However, if you measure a linearly polarized wave with circularly polarized you detect circular polarization.

That is all classical thinking. It seems to be the same as your explanation. But it does not include the randomness inherent in quantum mechanics. In quantum mechanics any individual photon is in all possible states at the same time until a measurement makes it collapse to a particular state, or choose a particular universe, or. You see, it is incoeerect to use classical thinking to describe quantum effects.

Worm Holes: They are never connections to every other piece of matter in the universe.

Although in string theory such connections could be the result of compactification of 16 of the 26 dimensions of boson string theory. But that is not the worm holes of GR theory. GR Worm holes exist in 4-d.

The 6-d thread that connects specific entangled particles are not worm holes and the entanglement can be broken resulting in the precipatation of the thread into 4-d space as axions.

So worm holes cannot extent thru black hole event horizons. mIf particle pairs happen to straddle the event horizon, their entanglement is broken as in Hawking's black hole radiation theory.

( Ok, if it helps, the worm hole connect to a common membrane with zero space density. Does that help? It is not my intention to change your ideas but I must poke it some to understand them. I envisioned the worm holes as a door or connection point.)

And photons never have mass. They only have momentum, if, of course, they even exist.

(If the photon entity existed only as a wave would you consider that existing?)

(You asked!
I am trying to understand how gravity works according to your thinking.
Information travels from one mass .. Uh .. Entity to another.
Each entity has a center.
The information conveyed must contain a vector direction to the second mass, a quantity of matter and a distance to the other mass for gravity to respond correctly. The information is conveyed in zero time.
Am I correct so far?.
Does the entanglement convey the actual force or just information?)


5. Absolute Space in the Twentieth Century

5.1 The Spacetime Approach

After the development of relativity (which we will take up below), and its interpretation as a spacetime theory, it was realized that the notion of spacetime had applicability to a range of theories of mechanics, classical as well as relativistic. In particular, there is a spacetime geometry &mdash &lsquoGalilean&rsquo or &lsquoneo-Newtonian&rsquo spacetime &mdash for Newtonian mechanics that solves the problem of absolute velocity an idea exploited by a number of philosophers from the late 1960s (e.g., Earman 1970, Friedman 1983, Sklar 1974 and Stein 1968). For details the reader is referred to the entry on spacetime: inertial frames, but the general idea is that although a spatial distance is well-defined between any two simultaneous points of this spacetime, only the temporal interval is well-defined between non-simultaneous points. Thus things are rather unlike Newton's absolute space, whose points persist through time and maintain their distances: in absolute space the distance between bl-now and q-then (where bl en q are points) is just the distance between bl-now and q-now. However, Galilean spacetime has an &lsquoaffine connection&rsquo which effectively specifies for every point of every continuous curve, the rate at which the curve is changing from straightness at that point for instance, the straight lines are picked out as those curves whose rate of change from straightness is zero at every point. (Another way of thinking about this space is as possessing &mdash in addition to a distance between any two simultaneous points and a temporal interval between any points &mdash a three-place relation of colinearity, satisfied by three points just in case they lie on a straight line.)

Since the trajectories of bodies are curves in spacetime, the affine connection determines the rate of change from straightness at every point of every possible trajectory. The straight trajectories thus defined can be interpreted as the trajectories of bodies moving inertially (i.e., without forces), and the rate of change from straightness of any trajectory can be interpreted as the acceleration of a body following that trajectory. That is, Newton's First Law can be given a geometric formulation as &lsquobodies on which no net forces act follow straight lines in spacetime&rsquo similarly, the Second Law can be formulated as &lsquothe rate of change from straightness of a body's trajectory is equal to the forces acting on the body divided by its mass&rsquo. The significance of this geometry is that while acceleration is well-defined, velocity is not &mdash in accord with the empirical determinability of acceleration but not of velocity, according to Newtonian mechanics. (A simple analogy helps see how such a thing is possible: betweenness on a curve, but not &lsquoup&rsquo is a well-defined concept in Euclidean space.) Thus Galilean spacetime gives a very nice interpretation of the choice that nature makes when it decides that the laws of mechanics should be formulated in terms of accelerations not velocities.

5.2 Substantivalism

Put another way, we can define the complete predicate x accelerates as trajectory(x) has-non-zero-rate-of-change-from-straightness, waar trajectory maps bodies onto their trajectories in Galilean spacetime. And this predicate, defined this way, applies to the water in the bucket if and only if it is rotating, according to Newtonian mechanics formulated in terms of the geometry of Galilean spacetime it is the mechanically relevant sense of the word in this theory. But this theoretical formulation and definition have been given in terms of the geometry of spacetime, not in terms of the relations between bodies acceleration is &lsquoabsolute&rsquo in the sense that there is a preferred (true) sense of acceleration in mechanics and which is not defined in terms of the motions of bodies relative to one another. (Note that this sense of &lsquoabsolute&rsquo is broader than that of motion relative to absolute space, which we defined earlier. In the remainder of this article we will use it in the broader sense. The reader should be aware that the term is used in many ways in the literature, and such equivocation often leads to significant misunderstandings.) Thus if any of this analysis of motion is taken literally then one arrives at a position regarding the ontology of spacetime rather like that of Newton's regarding space: it is some kind of &lsquosubstantial&rsquo (or maybe pseudo-substantial) thing with the geometry of Galilean spacetime, just as absolute space possessed Euclidean geometry. This view regarding the ontology of spacetime is usually called &lsquosubstantivalism&rsquo (Sklar, 1974). The Galilean substantivalist usually sees himself as adopting a more sophisticated geometry than Newton but sharing his substantivalism (though there is room for debate on Newton's exact ontological views see DiSalle, 2002). The advantage of the more sophisticated geometry is that although it allows the absolute sense of acceleration apparently required by Newtonian mechanics to be defined, it does not allow one to define a similar absolute speed or velocity &mdash x accelerates can be defined as a complete predicate in terms of the geometry of Galilean spacetime but not x moves in general &mdash and so the first of Leibniz's problems is resolved. Of course we see that the solution depends on a crucial shift from speed and velocity to acceleration as the relevant senses of &lsquomotion&rsquo: from the rate of change of position to the rate of rate of change.

While this proposal solves the first kind of problem posed by Leibniz, it seems just as vulnerable to the second. While it is true that it involves the rejection of absolute space as Newton conceived it, and with it the need to explicate the nature of an enduring space, the postulation of Galilean spacetime poses the parallel question of the nature of spacetime. Again, it is a physical but non-material something, the points of which may be coincident with material bodies. What kind of thing is it? Could we do without it? As we shall see below, some contemporary philosophers believe so.


Velocity of light and absolute rest

Unfortunately neither absolute motion nor absolute rest are standard terms as far as I know. So that doesn't help.

Light is always moving in all frames of reference, it is true.

With respect to what? Light has a constant relative speed of 299792458 m/s with respect to whoever is measuring it.
So, the speed of light as measured by any observer does not depend on the relative velocity of the source to the observer.
In addition, changing it own velocity doe not change the speed of that same light as measured relative to the source as measured by the source.

So for example, let's assume that we have two objects, A and B approaching each other, and at the moment they pass each other a flash of light is emitted. It doesn't matter whether A of B emits the flash. For an observer watching these two meeting, the light expands outward at c, while Both A and B move on from the point of emission. Like this.

However, If you are at rest with respect to A, this is what happens according to you

The light expands outward from A after B passes by and B chases after the left edge of the expanding light

If you were at rest with respect to B, then this is what happens

Now B remains at the center of the flash, while A chases after the right edge of the flash.

Thus is is more appropriate to say that the speed of light is invariant rather than absolute (Absolute implies that there is one single frame of reference which everyone agrees is the one that the speed of light is constant with respect to.)


SPECIAL RELATIVITY

The theory of Spesiale Relatiwiteit, published by Einstein in 1905 (when he was 26 years old), describes how objects behave when they have a constant velocity. Ten years later, in 1915, Einstein published his theory of Algemene Relatiwiteit, which describes how objects move when they are accelerated by gravity. (General Relativity is the subject of tomorrow's lecture today we'll stick to the simpler case of Special Relativity.) Special Relativity can be summed up in one brief sentence:

All speeds are relative, except for the speed of light, which is absolute.

A concise sentence -- but what does it mean? Let's start by examining what is mean by ``relative speed''. A professor paces across a lecture platform.
Her speed relative to platform=
1 meter/second
Her speed relative to center of Earth=
360 meters/second
Her speed relative to center of Sun=
30,000 meters/second
Her speed relative to center of Galaxy=
220,000 meters/second

Which of the above speeds is the ``correct'' speed? They are all correct. When you state the speed of a material object, like a professor or a star, you are stating the speed relative to some other object. For massive objects, all speeds are relative. As another example of the relative nature of speeds, consider a criminal barreling down High Street, driving his getaway car. As seen by an innocent bystander, the car has a velocity v = 30 meters/second (about 67 mph). The criminal draws his gun, and shoots a bullet in the direction he is traveling. Relative to the car, the bullet has a velocity u = 250 meters/second (the muzzle speed of a bullet from a .45 automatic).

To summarize the situation:
Speed of car relative to bystander = v = 30 meters/second

Speed of bullet relative to car = u = 250 meters/second

To find the speed of the bullet relative to the bystander, just add the speeds together:
Speed of bullet relative to bystander = v + u = 280 meters/second.

The question ``What is the speed of the bullet?'' doesn't have a single answer. The speed of the bullet relative to the car is 250 meters/second. The speed of the bullet relative to the bystander is 280 meters/second. For that matter, the speed of the bullet relative to the center of the galaxy is 220,000 meters/second. There is a critical caveat attached to the theory of Special Relativity: all speeds are relative, except for the speed of light , which is absolute.

As an example of the absolute nature of the speed of light, consider the same criminal roaring down High Street in his getaway car. Relative to a bystander, the car has the same speed v = 30 meters/second. Now, however, the criminal draws a laser gun. A laser produces electromagnetic radiation, so relative to the car, the laser beam will travel at the speed of light: c = 300,000,000 meters/second.

To summarize the new situation:
Speed of car relative to bystander = v = 30 meters/second

Speed of light beam relative to car = c = 300,000,000 meters/second

What is the speed of the light beam relative to the bystander? A classical physicist, like Galileo or Newton, would say the speed is v+c = 300,000,030 meters/second. This, however, is WRONG. The correct answer, given by Einstein, is that the speed of the light beam relative to the bystander is c = 300,000,000.

The speed of light is absolute that means it is the same seen by any observer, no matter how fast the observer is moving relative to the light source. THE OBSERVED SPEED OF LIGHT IN A VACUUM IS ALWAYS 299,792.459 KILOMETERS PER SECOND. (Parenthetical comments: it is necessary to add the qualification ``in a vacuum'' since interactions with matter can slow down a light beam. The exact value of the speed of light is usually rounded off to 300,000 km/sec for practical purposes. The speed of light is the speed of all electromagnetic radiation, from radio to gamma-rays.)

The fact that the speed of light is constant has been experimentally verified, first by a pair of physicists in Cleveland in 1887. The fact that the speed of light is absolute, while all other speeds are relative, has some bizarre consequences. Suppose I hand you a light bulb, and send you away from Earth with a speed equal to 99% the speed of light. You say:
``The light bulb is stationary. The light from the bulb is moving at a speed c.''
On the other hand, I say:
``The light bulb is moving at a speed 0.99c. The light from the bulb is moving at a speed c.''

Two observers are moving at a speed 0.99c relative to each other. Each observer, using his own yardstick and clock, measures the speed of a particular beam of light to be the same. The only way the two observers to observe the same speed for the beam of light, Einstein concluded, is for odd things to be happening to the yardsticks and clocks with which they measure the speed of light.

Relativistic Time Dilation

Whose clock is correct? Both are correct. THERE IS NO SUCH THING AS ABSOLUTE TIME. The rate at which time flows is different for different observers.

Relativistic Length Contraction

Whose yardstick is correct? Both are correct. THERE IS NO SUCH THING AS ABSOLUTE SPACE. The distance between two points is different for different observers. Please note that the relativistic effects mentioned above (time dilation and length contraction) are all very small unless the relative speed is close to the speed of light.


The Oceans and Marine Geochemistry

P.D. Nightingale , P.S. Liss , in Treatise on Geochemistry , 2003

6.03.3.4 The Oceans as a Sink for Atmospheric Gases

6.03.3.4.1 Ozone

The oceans acts as a one-way sink for atmospheric ozone due to the high reactivity of the gas with components in the surface water. The dominant reaction at the surface appears to be with iodide ions and unidentified organic surfactants ( Garland et al., 1980 ). Given that this reactivity makes the sea a perfect sink, calculation of the downward flux involves only knowledge of the atmospheric concentration and the appropriate deposition velocity . Early estimates of the deposition flux give values of ∼5×10 14 g yr −1 . More recent estimates are in agreement with this. It has proved possible to check these values using the micrometeorological technique of eddy correlation (see Section 6.03.2.3.2(iv) ) applied from an aircraft, which appears to work well in this case ( Lenschow et al., 1982 ).

6.03.3.4.2 Sulfur dioxide

Like ozone, sulfur dioxide is subject to deposition into the oceans, with no re-emission. This arises from the high reactivity of the gas in seawater, which ensures its rapid destruction in the water and effective zero surface-water concentration driving the one-way flux ( Liss, 1971 ). The high solubility and aqueous reactivity of SO2 makes its exchange subject to gas phase control (see Section 6.03.2.1.1 ).

6.03.3.4.3 Hydrogen cyanide and methyl cyanide

Hydrogen cyanide (HCN) and methyl cyanide (CH3CN) are trace gases in the atmosphere occurring at the 100–200 pptv level. Their main source is biomass burning, with smaller contributions from automobiles and industry. Concentration measurements over the oceans show lower amounts in the marine boundary layer, and this has been attributed to uptake by the oceans ( Singh et al., in press ). These authors have used a simple box model to try to quantify the uptake and deduced that ocean surface waters have to be ∼20% undersaturated to achieve balance. Since there are no measurements of HCN or CH3CN in seawater, it is currently not possible to verify these undersaturations, nor is anything known about the destruction processes for the gases in seawater. The box model suggests a deposition to the global ocean of 1.3 Tg N yr −1 HCN and CH3CN, which is ∼4% of the total yearly amount of nitrogen entering the oceans via atmospheric deposition (mainly in the form of nitrate and ammonium in rain and particles).

6.03.3.4.4 Synthetic organic compounds

Synthetic organic compounds are a vast group of man-made chemicals here we consider only a small subset including the polychlorinated biphenyls (PCBs) and various chlorinated organic pesticides (e.g., DDT, chlordane, and dieldrin), for which there are particular environmental concerns. They are emitted to the atmosphere during use or disposal and are found dispersed throughout the environment. Deposition to the oceans occurs by both wet and dry processes, in varying proportions for the different compounds, although gaseous deposition is always a significant route (25–85% of total) ( Duce et al., 1991 ). Re-emission is also possible where the concentration gradient changes sign, either because of reduced air concentrations or elevated water concentrations, or both. From the point of view of gas exchange, many of these compounds are interesting since both gas and liquid phase resistances are significant for their air–sea exchange, which is not the situation for most gases where one or other resistance is dominant (see Section 6.03.2.1.1 ).

6.03.3.4.5 Chlorofluorocarbons

Measurements of methyl chloroform or 1,1,1-trichloroethane (CH3CCl3) showed that this compound was significantly unsaturated in the equatorial Pacific Ocean ( Butler et al., 1991 ). Loss rates were supported roughly by known hydrolysis rates and the authors calculated that ∼6% of atmospheric CH3CCl3 is removed by consumption in the oceans. With this exception, most of the chlorofluorocarbons were originally thought to be stable in the water column.

The first evidence that this assumption was incorrect was provided by observations of carbon tetrachloride (CCl4) removal in the Baltic Sea under anoxic conditions ( Krysell et al., 1994 ). A later investigation in the Black Sea found that reductions in CCl4, CHCl3, CH3CCl3, dibromomethane and dibromochloromethane, and bromodichloromethane were related to oxygen/hydrogen sulfide concentrations ( Tanhua et al., 1996 ). Most of the CCl4 was transformed to CHCl3 as an intermediate product. Subsequent work in a fjord in Norway showed that CFC-11 was also removed in anoxic waters ( Shapiro et al., 1997 ). Loss rates of both CCl4 and F11 in anoxic waters are probably due to biological rather than chemical removal ( Lee et al., 1999). It also seems likely that some of the chlorofluorocarbons are removed in fully oxygenated surface waters. Observations show that there is a deficit of CCl4 in the Antarctic surface and bottom waters ( Meredith et al., 1996 ). Finally, fluorinated compounds such as CFC-113 are degraded in warm surface waters of the temperate North Atlantic, the tropical western Pacific, the Eastern Mediterranean, and even the Weddell Sea ( Roether et al., 2001 ). CFC-113 depletions were ∼3% yr −1 , with possibly accelerated rates in the mixed layer or near the surface.

Selected dechlorination of chlorinated compounds by soil bacteria has long been recognized ( Vogel et al., 1987 ). It seems likely to us that there is a biological transformation of these compounds by marine bacteria, particular as marine bacteria can transform CH3Br (see Section 6.03.3.3.2 ). Not only are these compounds likely to be removed from oceanic and coastal waters under anoxic and suboxic conditions, but given that compounds such as CH4 and N2O are thought to be produced in suboxic micro-environments within the water column (see Section 6.03.3.2.9 ), it seems reasonable to assume that the same sites might be areas of chlorofluorocarbon removal.