# Kategorie Argief: Fisika

Fisika was my eerste liefde. Hierdie kategorie bevat die poste wat die naaste aan my hart. Twintig jaar van nou af, As hierdie blog oorleef, hierdie kategorie sal waarskynlik my mees blywende insigte hou. En twee honderd jaar van nou af, as ek onthou ten alle, dit sal wees vir hierdie insigte; nie vir die soort van persoon wat ek is, die geld wat ek maak, of enigiets anders. Slegs vir my eerste en laaste liefde…

# Persepsie, Fisika en die rol van die lig in die filosofie

Werklikheid, as ons voel dit, is nie heeltemal ware. Die sterre sien ons in die nag lug, byvoorbeeld, is nie regtig daar. Hulle kan verskuif het of selfs dood teen die tyd wat ons kry om dit te sien. Dit onwerklikheid is te danke aan die tyd wat dit neem vir die lig uit die verre sterre en sterrestelsels om ons te bereik. Ons weet van die vertraging.

Selfs die son wat ons so goed ken, is reeds agt minute oud teen die tyd dat ons dit sien. Hierdie feit blyk nie veral graf epistemologiese probleme te bied – As ons wil weet wat aangaan op die son nou, Al wat ons moet doen, is om te wag vir agt minute. Ons het net na 'korrekte’ vir die ondergang van ons persepsie as gevolg van die beperkte spoed van lig voordat ons kan vertrou wat ons sien. Dieselfde verskynsel in die sien van 'n minder bekende verskynsel in die manier waarop ons waarneem bewegende voorwerpe. Sommige hemelse liggame lyk asof hulle beweeg 'n paar keer die spoed van lig, terwyl hulle 'n ware’ spoed moet 'n baie minder as dit wees.

Wat is verbasend (en selde uitgelig) is dat wanneer dit kom mosie sensing, ons kan nie terug-bereken in dieselfde soort manier as wat ons kan te stel vir die vertraging in die waarneming van die son. As ons 'n hemelse liggaam beweeg teen 'n hoë spoed onwaarskynlike, Ons kan nie bereken hoe vinnig of selfs in watter rigting dit is 'regtig’ beweeg sonder om eers sekere verdere aannames te maak.

Einstein het verkies om die probleem op te los deur die behandeling van persepsie as verwring en die uitvind van nuwe fundamentele eienskappe in die arena van fisika – in die beskrywing van ruimte en tyd. Een kern idee van die spesiale relatiwiteitsteorie is dat die menslike idee van 'n ordelike verloop van gebeure in tyd moet laat vaar word. In werklikheid, want dit neem tyd vir die lig van 'n gebeurtenis op 'n afgeleë plek om ons te bereik, en vir ons om bewus te wees van dit geword, die konsep van 'nou’ nie meer sin maak, byvoorbeeld, wanneer ons praat van 'n sonvlek wat op die oppervlak van die son net op die oomblik dat die sterrekundige is probeer om dit af te neem. Gelyktydigheid is relatief.

Einstein plaas geherdefinieer gelyktydigheid deur die gebruik van die oomblikke in die tyd wat ons ontdek die geval. Opsporing, as hy dit gedefinieer, behels 'n ronde-reis reis van die lig soortgelyk aan radar opsporing. Ons stuur 'n sein uit wat teen die spoed van lig, en wag vir die besinning. As die weerspieël pols van twee gebeurtenisse bereik ons ​​op dieselfde oomblik, dan is hulle gelyktydige. Maar 'n ander manier van kyk na dit is eenvoudig te noem twee gebeurtenisse 'gelyktydige’ As die lig van hulle bereik ons ​​op dieselfde oomblik. Met ander woorde, ons kan die lig wat deur die voorwerpe onder waarneming gebruik eerder as om seine na hulle en kyk na die besinning.

Hierdie verskil kan klink soos 'n muggezifterĳ tegniese, maar dit maak 'n groot verskil aan die voorspellings wat ons kan maak. Einstein se keuse lei tot 'n wiskundige prentjie wat baie wenslik eienskappe, insluitend dié van die maak van verdere teoretiese ontwikkeling meer elegante. Maar dan, Einstein het geglo, as 'n saak van geloof wil dit voorkom asof, dat die reëls van die heelal moet wees 'n elegante.’ Egter, die ander benadering het 'n voordeel wanneer dit kom by die beskrywing van voorwerpe in beweging. Omdat, natuurlik, ons radar gebruik nie die sterre in beweging te sien; ons bloot die lig voel (of ander bestraling) kom van hulle. Tog gebruik van hierdie soort sensoriese paradigma, eerder as 'n radar-agtige opsporing,’ die heelal resultate in 'n leliker wiskundige prentjie te beskryf. Einstein sou goedkeur nie!

Die wiskundige verskil toegevoeg verskillende filosofiese standpunte, wat op sy beurt deur sien tot die begrip van ons fisiese beeld van die werklikheid. As 'n illustrasie, veronderstel ons waarneem, deur 'n radio-teleskoop, twee voorwerpe in die lug, met min of meer dieselfde vorm, grootte en eienskappe. Die enigste ding wat ons weet vir seker is, is dat die radio golwe uit hierdie twee verskillende punte in die lug bereik ons ​​op dieselfde tydstip. Ons kan net raai wanneer die golwe het begin om hul reis.

As ons aanvaar (as ons gereeld doen) dat die golwe begin die reis ongeveer op dieselfde tydstip, ons uiteindelik met 'n foto van twee 'n ware’ simmetriese lobbe meer of minder die pad sien hulle. Maar daar is nog 'n, verskillende moontlikheid en dit is dat die golwe ontstaan ​​uit dieselfde voorwerp (wat in beweging) op twee verskillende oomblikke in tyd, die bereik van die teleskoop op dieselfde oomblik. Hierdie moontlikheid sal ook nog 'n paar spektrale en temporale eienskappe van sodanige simmetriese radio te verduidelik. So wat van hierdie twee foto's moet ons as werklike? Twee simmetriese voorwerpe as ons sien hulle of een voorwerp beweeg in so 'n manier om ons te gee wat die indruk? Is dit regtig saak watter een is die 'regte'? Is 'n ware’ iets beteken in hierdie konteks?

Spesiale Relatiwiteit gee 'n ondubbelsinnige antwoord op hierdie vraag. Die wiskunde reëls uit die moontlikheid van 'n enkele voorwerp wat in so 'n manier as twee voorwerpe na te boots. Wese, wat ons sien is wat daar buite. Tog, As ons gebeure definieer deur wat ons sien, die enigste filosofiese standpunt wat sin maak, is die een wat koppel die Deteksie werklikheid van die oorsake lê agter dit wat waargeneem.

Dit verbreek is nie ongewoon in filosofiese denkrigtings. Phenomenalism, byvoorbeeld, is van mening dat ruimte en tyd is nie objektiewe werklikhede. Hulle is bloot die medium van ons persepsie. Al die verskynsels wat in die ruimte en tyd gebeur is bloot bundels van ons persepsie. Met ander woorde, ruimte en tyd is kognitiewe konstrukte wat voortspruit uit persepsie. So, al die fisiese eienskappe wat ons toeskryf aan die ruimte en tyd kan net van toepassing op die fenomenale werklikheid (die werklikheid van 'dinge-in-die-wêreld’ as ons voel dit. Die onderliggende werklikheid (wat die besit van die fisiese oorsake van ons persepsie), teenstelling, bly buite ons kognitiewe bereik.

Tog is daar 'n kloof tussen die standpunte van die filosofie en die moderne fisika. Nie vir niks het die Nobelprys wen fisikus, Steven Weinberg, wonder, in sy boek Dreams van 'n teorie, waarom die bydrae van filosofie fisika was so verrassend klein. Miskien is dit omdat die fisika het nog om vrede te maak met die feit dat wanneer dit kom by die sien van die heelal, Daar is nie so iets soos 'n optiese illusie – wat is waarskynlik wat Goethe bedoel het toe hy gesê, Optiese illusie is optiese waarheid.’

Die onderskeid (of die gebrek daaraan) tussen optiese illusie en waarheid is een van die oudste debatte in die filosofie. Na alles, dit is oor die onderskeid tussen kennis en die werklikheid. Kennis word beskou as ons siening oor iets wat, in werklikheid, is 'werklik die geval is.’ Met ander woorde, kennis is 'n weerspieëling, of 'n geestelike beeld van iets eksterne, soos getoon in die figuur hieronder.

In hierdie foto, die swart pyl stel die proses van die skep van kennis, Dit sluit persepsie, kognitiewe aktiwiteite, en die uitoefening van suiwer rede. Dit is die prentjie wat die fisika het gekom om te aanvaar. Hy erken dat ons persepsie onvolmaakte mag wees, fisika aanvaar dat ons kan kry deur middel van toenemend fyner eksperimentering nader en nader aan die eksterne werklikheid, en, meer belangrik, deur beter teoretisering. Die Spesiale en Algemene Teorieë van Relatiwiteit is voorbeelde van briljante aansoeke van hierdie siening van die werklikheid waar eenvoudige fisiese beginsels meedoënloos agtervolg gebruik formidabele masjien van suiwer rede om hul logies onvermydelik gevolgtrekkings.

Maar daar is nog 'n, alternatiewe siening van kennis en werklikheid wat reeds vir 'n lang tyd. Dit is die mening dat met betrekking tot vermeende werklikheid as 'n interne kognitiewe verteenwoordiging van ons sensoriese insette, soos hieronder geïllustreer.

In hierdie siening, kennis en beskou die werklikheid is beide interne kognitiewe konstrukte, Hoewel ons het gekom om te dink van hulle as afsonderlike. Wat is eksterne is nie die werklikheid soos ons dit sien, maar 'n onkenbare entiteit wat aanleiding gee tot die fisiese oorsake agter sensoriese insette. In die illustrasie, die eerste pyl stel die proses van waarneming, en die tweede pyl verteenwoordig die kognitiewe en logiese redenasie stappe. Ten einde hierdie siening van die werklikheid en kennis toe te pas, ons het die aard van die absolute werklikheid te dink, onkenbare soos dit is. Een moontlike kandidaat vir die absolute realiteit is Newton-meganika, Dit gee 'n redelike voorspelling vir ons beskou die werklikheid.

Om op te som, wanneer ons probeer om die ondergang te danke aan persepsie te hanteer, het ons twee opsies, of twee moontlike filosofiese standpunte. Een daarvan is die ondergang as deel van ons tyd en ruimte te aanvaar, as Spesiale Relatiwiteit doen. Die ander opsie is om te aanvaar dat daar 'n "hoër’ werklikheid te onderskei van ons Deteksie werklikheid, wie se eiendom kan ons net vermoede. Met ander woorde, een opsie is met die ondergang te leef, terwyl die ander is opgevoede raaiskote te stel vir die hoër werklikheid. Nie een van hierdie keuses is besonder aantreklik. Maar die raai pad is soortgelyk aan die oog in phenomenalism aanvaar. Dit lei ook natuurlik hoe die werklikheid beskou word in kognitiewe neurowetenskap, wat die studie van die biologiese meganismes agter kognisie.

Die kinkel in hierdie storie van die lig en die werklikheid is dat dit lyk asof ons al hierdie het bekend vir 'n lang tyd. Die rol van die lig in die skep van ons werklikheid of heelal is in die hart van die Wes-godsdienstige denke. 'N heelal sonder lig is nie net 'n wêreld waar jy hom het die ligte af. Dit is inderdaad 'n heelal sonder self, 'n heelal wat nie bestaan ​​nie. Dit is in hierdie konteks dat ons die wysheid agter die stelling dat 'die aarde was woes te verstaan, en nietig’ totdat God veroorsaak lig te wees, deur te sê: "Laat daar lig wees.’

Die Koran sê ook, "Allah is die lig van die hemel en die aarde,’ wat weerspieël word in een van die ou Hindoe geskrifte: 'Lei my van die duisternis tot die lig, lei my uit die onwerklik om die werklike.’ Die rol van die lig in die neem van ons van die onwerklik leemte (die niks) 'n werklikheid is inderdaad vir 'n lang verstaan, lang tyd. Is dit moontlik dat die antieke heiliges en profete geweet dinge wat ons nou eers begin te ontbloot met al ons veronderstel vooruitgang in kennis?

Daar is ooreenkomste tussen die noumenal-fenomenale onderskeid van Kant en die phenomenalists later, en die Brahmaan-Maya onderskeid in Advaita. Wysheid van die aard van die werklikheid van die repertoire van spiritualiteit is herontdek in die moderne neuro, wat behandel werklikheid as 'n kognitiewe verteenwoordiging wat deur die brein. Die brein gebruik die sensoriese insette, geheue, bewussyn, en selfs taal as bestanddele in concocting ons sin van die werklikheid. Hierdie siening van die werklikheid, egter, is iets fisika is nog nie in staat om te kom met. Maar tot die mate wat die arena (ruimte en tyd) is 'n deel van die werklikheid, fisika is nie immuun teen die filosofie.

In werklikheid, as ons druk op die grense van ons kennis verder, ons ontdek tot dusver ongekende en dikwels verrassende verbindings tussen die verskillende takke van die menslike pogings. Tog, hoe kan die diverse domeine van ons kennis onafhanklik te wees van mekaar as alle kennis is subjektiewe? As kennis bloot die kognitiewe verteenwoordiging van ons ervarings? Maar dan, dit is die moderne wanbegrip om te dink dat die kennis is ons interne voorstelling van 'n eksterne werklikheid, en dus apart van dit. In plaas daarvan, erkenning en die gebruik van die interkonneksies tussen die verskillende gebiede van die menslike strewe om mag die noodsaaklike voorvereiste vir die volgende fase in die ontwikkeling van ons kollektiewe wysheid.

 Box: Einstein se TreinEen van Einstein se beroemde gedagte-eksperimente illustreer die behoefte om te dink oor wat ons bedoel met gelyktydige gebeure. Dit beskryf 'n hoë-spoed trein gedruis in 'n reguit baan verby 'n klein stasie as 'n man staan ​​op die stasie platform kyk dit spoed deur. Tot sy verbasing, as die trein verby hom, twee bliksemschichten slaan die spoor langs weerskante van die trein! (Gerieflik, vir later navorsers, hulle punte brande op die trein en op die grond verlaat.) Aan die man, blyk dit dat die twee bliksemschichten slaan op presies dieselfde oomblik. Later, die merke op die grond deur die treinspoor onthul dat die plekke waar die weerlig getref was presies ewe ver van hom. Sedertdien het die bliksemschichten gereis dieselfde afstand na hom, en aangesien hulle aan die mens verskyn om te gebeur op presies dieselfde oomblik, Hy het geen rede om nie tot die gevolgtrekking dat die bliksemschichten getref op presies dieselfde oomblik. Hulle was gelyktydige. Egter, veronderstel 'n bietjie later, die man aan 'n dame passasier wat gebeur te wees in die buffet motor gesit, presies in die middel van die trein, en kyk by die venster uit by die tyd van die bliksemschichten getref. Dit passasier hom vertel dat sy gesien het die eerste weerlig bout die grond getref het naby die enjin aan die voorkant van die trein effens voor wanneer die tweede een op die grond getref langs die bagasie motor aan die agterkant van die trein. Die effek het niks te doen met die afstand wat die lig moes reis, as beide die vrou en die man was ewe ver tussen die twee punte wat die weerlig getref. Maar hulle het waargeneem die volgorde van gebeure heeltemal anders. Hierdie meningsverskil van die tydsberekening van die gebeure is onvermydelik, Einstein sê, as die vrou is in effek op pad na die punt waar die flits van die weerlig getref naby die enjin -en weg van die punt waar die flits van die weerlig getref langs die bagasie motor. In die klein hoeveelheid van die tyd neem om dit vir die ligstrale die dame te bereik, omdat die trein beweeg, die afstand wat die eerste flits moet reis om haar krimp, en die afstand wat die tweede flits moet reis groei. Hierdie feit kan nie opgemerk word in die geval van die treine en vliegtuie, maar wanneer dit kom by die kosmologiese afstande, gelyktydigheid regtig nie sin maak nie. Byvoorbeeld, die ontploffing van twee verre supernovas, gesien as gelyktydige uit ons uitkykpunt op die aarde, sal verskyn om plaas te vind in verskillende tyd kombinasies van ander perspektiewe. In Relatiwiteit: Die Spesiale en Algemene teorie (1920), Einstein het dit op hierdie manier: "Elke verwysing liggaam (koördineer stelsel) het sy eie spesifieke tyd; tensy ons word vertel dat die verwysing-liggaam wat die verklaring van die tyd verwys, Daar is geen sin in 'n verklaring van die tyd van 'n gebeurtenis.’

# Tsunami

The Asian Tsunami two and a half years ago unleashed tremendous amount energy on the coastal regions around the Indian ocean. What do you think would’ve have happened to this energy if there had been no water to carry it away from the earthquake? I mean, if the earthquake (of the same kind and magnitude) had taken place on land instead of the sea-bed as it did, presumably this energy would’ve been present. How would it have manifested? As a more violent earthquake? Or a longer one?

I picture the earthquake (in cross-section) as a cantilever spring being held down and then released. The spring then transfers the energy to the tsunami in the form of potential energy, as an increase in the water level. As the tsunami radiates out, it is only the potential energy that is transferred; the water doesn’t move laterally, only vertically. As it hits the coast, the potential energy is transferred into the kinetic energy of the waves hitting the coast (water moving laterally then).

Given the magnitude of the energy transferred from the epicenter, I am speculating what would’ve happened if there was no mechanism for the transfer. Any thoughts?

# Universe – Size and Age

I posted this question that was bothering me when I read that they found a galaxy at about 13 billion light years away. My understanding of that statement is: At distance of 13 billion light years, there was a galaxy 13 billion years ago, so that we can see the light from it now. Wouldn’t that mean that the universe is at least 26 billion years old? It must have taken the galaxy about 13 billion years to reach where it appears to be, and the light from it must take another 13 billion years to reach us.

In answering my question, Martin and Swansont (who I assume are academic phycisists) point out my misconceptions and essentially ask me to learn more. All shall be answered when I’m assimilated, it would appear! 🙂

This debate is published as a prelude to my post on the Big Bang theory, coming up in a day or two.

 Mowgli 03-26-2007 10:14 PM

Universe – Size and Age
I was reading a post in http://www.space.com/ stating that they found a galaxy at about 13 billion light years away. I am trying to figure out what that statement means. To me, it means that 13 billion years ago, this galaxy was where we see it now. Isn’t that what 13b LY away means? If so, wouldn’t that mean that the universe has to be at least 26 billion years old? I mean, the whole universe started from one singular point; how could this galaxy be where it was 13 billion years ago unless it had at least 13 billion years to get there? (Ignoring the inflationary phase for the moment…) I have heard people explain that the space itself is expanding. What the heck does that mean? Isn’t it just a fancier way of saying that the speed of light was smaller some time ago?
 swansont 03-27-2007 09:10 AM

Quote:
 Originally Posted by Mowgli (Post 329204) I mean, the whole universe started from one singular point; how could this galaxy be where it was 13 billion years ago unless it had at least 13 billion years to get there? (Ignoring the inflationary phase for the moment…)

Ignoring all the rest, how would this mean the universe is 26 billion years old?

Quote:
 Originally Posted by Mowgli (Post 329204) I have heard people explain that the space itself is expanding. What the heck does that mean? Isn’t it just a fancier way of saying that the speed of light was smaller some time ago?

The speed of light is an inherent part of atomic structure, in the fine structure constant (alpha). If c was changing, then the patterns of atomic spectra would have to change. There hasn’t been any confirmed data that shows that alpha has changed (there has been the occasional paper claiming it, but you need someone to repeat the measurements), and the rest is all consistent with no change.

 Martin 03-27-2007 11:25 AM

To confirm or reinforce what swansont said, there are speculation and some fringe or nonstandard cosmologies that involve c changing over time (or alpha changing over time), but the changing constants thing just gets more and more ruled out.I’ve been watching for over 5 years and the more people look and study evidence the LESS likely it seems that there is any change. They rule it out more and more accurately with their data.So it is probably best to ignore the “varying speed of light” cosmologies until one is thoroughly familiar with standard mainstream cosmology.You have misconceptions Mowgli

• General Relativity (the 1915 theory) trumps Special Rel (1905)
• They don’t actually contradict if you understand them correctly, because SR has only a very limited local applicability, like to the spaceship passing by:-)
• Wherever GR and SR SEEM to contradict, believe GR. It is the more comprehensive theory.
• GR does not have a speed limit on the rate that very great distances can increase. the only speed limit is on LOCAL stuff (you can’t catch up with and pass a photon)
• So we can and DO observe stuff that is receding from us faster than c. (It’s far away, SR does not apply.)
• This was explained in a Sci Am article I think last year
• Google the author’s name Charles Lineweaver and Tamara Davis.
• We know about plenty of stuff that is presently more than 14 billion LY away.
• You need to learn some cosmology so you wont be confused by these things.
• Also a “singularity” does not mean a single point. that is a popular mistake because the words SOUND the same.
• A singularity can occur over an entire region, even an infinite region.

Also the “big bang” model doesn’t look like an explosion of matter whizzing away from some point. It shouldn’t be imagined like that. The best article explaining common mistakes people have is this Lineweaver and Davis thing in Sci Am. I think it was Jan or Feb 2005 but I could be a year off. Google it. Get it from your local library or find it online. Best advice I can give.

 Mowgli 03-28-2007 01:30 AM

To swansont on why I thought 13 b LY implied an age of 26 b years:When you say that there is a galaxy at 13 b LY away, I understand it to mean that 13 billion years ago my time, the galaxy was at the point where I see it now (which is 13 b LY away from me). Knowing that everything started from the same point, it must have taken the galaxy at least 13 b years to get where it was 13 b years ago. So 13+13. I’m sure I must be wrong.To Martin: You are right, I need to learn quite a bit more about cosmology. But a couple of things you mentioned surprise me — how do we observe stuff that is receding from as FTL? I mean, wouldn’t the relativistic Doppler shift formula give imaginary 1+z? And the stuff beyond 14 b LY away – are they “outside” the universe?I will certainly look up and read the authors you mentioned. Thanks.
 swansont 03-28-2007 03:13 AM

Quote:
 Originally Posted by Mowgli (Post 329393) To swansont on why I thought 13 b LY implied an age of 26 b years:When you say that there is a galaxy at 13 b LY away, I understand it to mean that 13 billion years ago my time, the galaxy was at the point where I see it now (which is 13 b LY away from me). Knowing that everything started from the same point, it must have taken the galaxy at least 13 b years to get where it was 13 b years ago. So 13+13. I’m sure I must be wrong.

That would depend on how you do your calibration. Looking only at a Doppler shift and ignoring all the other factors, if you know that speed correlates with distance, you get a certain redshift and you would probably calibrate that to mean 13b LY if that was the actual distance. That light would be 13b years old.

But as Martin has pointed out, space is expanding; the cosmological redshift is different from the Doppler shift. Because the intervening space has expanded, AFAIK the light that gets to us from a galaxy 13b LY away is not as old, because it was closer when the light was emitted. I would think that all of this is taken into account in the measurements, so that when a distance is given to the galaxy, it’s the actual distance.

 Martin 03-28-2007 08:54 AM

Quote:
 Originally Posted by Mowgli (Post 329393) I will certainly look up and read the authors you mentioned.

This post has 5 or 6 links to that Sci Am article by Lineweaver and Davis

http://scienceforums.net/forum/showt…965#post142965

It turns out the article was in the March 2005 issue.

I think it’s comparatively easy to read—well written. So it should help.

# Twin Paradox – Take 2

The Twin Paradox is usually explained away by arguing that the traveling twin feels the motion because of his acceleration/deceleration, and therefore ages slower.

But what will happen if the twins both accelerate symmetrically? That is, they start from rest from one space point with synchronized clocks, and get back to the same space point at rest by accelerating away from each other for some time and decelerating on the way back. By the symmetry of the problem, it seems that when the two clocks are together at the end of the journey, at the same point, and at rest with respect to each other, they have to agree.

Then again, during the whole journey, each clock is in motion (accelerated or not) with respect to the other one. In SR, every clock that is in motion with respect to an observer’s clock is supposed run slower. Or, the observer’s clock is always the fastest. So, for each twin, the other clock must be running slower. However, when they come back together at the end of the journey, they have to agree. This can happen only if each twin sees the other’s clock running faster at some point during the journey. What does SR say will happen in this imaginary journey?

(Note that the acceleration of each twin can be made constant. Have the twins cross each other at a high speed at a constant linear deceleration. They will cross again each other at the same speed after sometime. During the crossings, their clocks can be compared.)

# Unreal Time

Farsight wrote:Time is a velocity-dependent subjective measure of event succession rather than something fundamental – the events mark the time, the time doesn’t mark the events. This means the stuff out there is space rather than space-time, and is an “aether” veiled by subjective time.

I like your definition of time. It is close to my own view that time is “unreal.” It is possible to treat space as real and space-time as something different, as you do. This calls for some careful thought. I will outline my thinking in this post and illustrate it with an example, if my friends don’t pull me out for lunch before I can finish.

The first question we need to ask ourselves is why space and time seem coupled? The answer is actually too simple to spot, and it is in your definition of time. Space and time mix through our concept of velocity and our brain’s ability to sense motion. There is an even deeper connection, which is that space is a cognitive representation of the photons inputs to our eyes, but we will get to it later.

Let’s assume for a second that we had a sixth sense that operated at an infinite speed. That is, if star explodes at a million light years from us, we can sense it immediately. We will see it only after a million years, but we sense it instantly. I know, it is a violation of SR, cannot happen and all that, but stay with me for a second. Now, a little bit of thinking will convince you that the space that we sense using this hypothetical sixth sense is Newtonian. Here, space and time can be completely decoupled, absolute time can be defined etc. Starting from this space, we can actually work out how we will see it using light and our eyes, knowing that the speed of light is what it is. It will turn out, clearly, that we seen events with a delay. That is a first order (or static) effect. The second order effect is the way we perceive objects in motion. It turns out that we will see a time dilation and a length contraction (for objects receding from us.)

Let me illustrate it a little further using echolocation. Assume that you are a blind bat. You sense your space using sonar pings. Can you sense a supersonic object? If it is coming towards you, by the time the reflected ping reaches you, it has gone past you. If it is going away from you, your pings can never catch up. In other words, faster than sound travel is “forbidden.” If you make one more assumption – the speed of the pings is the same for all bats regardless of their state of motion – you derive a special relativity for bats where the speed of sound is the fundamental property of space and time!

We have to dig a little deeper and appreciate that space is no more real than time. Space is a cognitive construct created out of our sensory inputs. If the sense modality (light for us, sound for bats) has a finite speed, that speed will become a fundamental property of the resultant space. And space and time will be coupled through the speed of the sense modality.

This, of course, is only my own humble interpretation of SR. I wanted to post this on a new thread, but I get the feeling that people are a little too attached to their own views in this forum to be able to listen.

Leo wrote:Minkowski spacetime is one interpretation of the Lorentz transforms, but other interpretations, the original Lorentz-PoincarÃ© Relativity or modernized versions of it with a wave model of matter (LaFreniere or Close or many others), work in a perfectly euclidean 3D space.

So we end up with process slowdown and matter contraction, but NO time dilation or space contraction. The transforms are the same though. So why does one interpretation lead to tensor metric while the others don’t? Or do they all? I lack the theoretical background to answer the question.

Hi Leo,

If you define LT as a velocity dependent deformation of an object in motion, then you can make the transformation a function of time. There won’t be any warping and complications of metric tensors and stuff. Actually what I did in my book is something along those lines (though not quite), as you know.

The trouble arises when the transformation matrix is a function of the vector is transforming. So, if you define LT as a matrix operation in a 4-D space-time, you can no longer make it a function of time through acceleration any more than you can make it a function of position (as in a velocity field, for instance.) The space-time warping is a mathematical necessity. Because of it, you lose coordinates, and the tools that we learn in our undergraduate years are no longer powerful enough to handle the problem.

# Of Rotation, LT and Acceleration

In the “Philosophical Implications” forum, there was an attempt to incorporate acceleration into Lorentz transformation using some clever calculus or numerical techniques. Such an attempt will not work because of a rather interesting geometric reason. I thought I would post the geometric interpretation of Lorentz transformation (or how to go from SR to GR) here.

Let me start with a couple of disclaimers. First of, what follows is my understanding of LT/SR/GR. I post it here with the honest belief that it is right. Although I have enough academic credentials to convince myself of my infallibility, who knows? People much smarter than me get proven wrong every day. And, if we had our way, we would prove even Einstein himself wrong right here in this forum, wouldn’t we? Secondly, what I write may be too elementary for some of the readers, perhaps even insultingly so. I request them to bear with it, considering that some other readers may find it illuminating. Thirdly, this post is not a commentary on the rightness or wrongness of the theories; it is merely a description of what the theories say. Or rather, my version of what they say. With those disclaimers out of the way, let’s get started…

LT is a rotation in the 4-D space-time. Since it not easy to visualize 4-D space-time rotation, let’s start with a 2-D, pure space rotation. One fundamental property of a geometry (such as 2-D Euclidean space) is its metric tensor. The metric tensor defines the inner product between two vectors in the space. In normal (Euclidean or flat) spaces, it also defines the distance between two points (or the length of a vector).

Though the metric tensor has the dreaded “tensor” word in its name, once you define a coordinate system, it is only a matrix. For Euclidean 2-D space with x and y coordinates, it is the identity matrix (two 1’s along the diagonal). Let’s call it G. The inner product between vectors A and B is A.B = Trans(A) G B, which works out to be $a_1b_1+a_2b_2$. Distance (or length of A) can be defined as $\sqrt{A.A}$.

So far in the post, the metric tensor looks fairly useless, only because it is the identity matrix for Euclidean space. SR (or LT), on the other hand, uses Minkowski space, which has a metric that can be written with [-1, 1, 1, 1] along the diagonal with all other elements zero – assuming time t is the first component of the coordinate system. Let’s consider a 2-D Minkowski space for simplicity, with time (t) and distance (x) axes. (This is a bit of over-simplification because this space cannot handle circular motion, which is popular in some threads.) In units that make c = 1, you can easily see that the invariant distance using this metric tensor is $\sqrt{x^2 - t^2}$.

Continued…

# The Unreal Universe — Discussion with Gibran

Hi again,You raise a lot of interesting questions. Let me try to answer them one by one.

You’re saying that our observations of an object moving away from us would look identical in either an SR or Galilean context, and therefore this is not a good test for SR.

What I’m saying is slightly different. The coordinate transformation in SR is derived considering only receding objects and sensing it using radar-like round trip light travel time. It is then assumed that the transformation laws thus derived apply to all objects. Because the round trip light travel is used, the transformation works for approaching objects as well, but not for things moving in other directions. But SR assumes that the transformation is a property of space and time and asserts that it applies to all moving (inertial) frames of reference regardless of direction.

We have to go a little deeper and ask ourselves what that statement means, what it means to talk about the properties of space. We cannot think of a space independent of our perception. Physicists are typically not happy with this starting point of mine. They think of space as something that exists independent of our sensing it. And they insist that SR applies to this independently existing space. I beg to differ. I consider space as a cognitive construct based on our perceptual inputs. There is an underlying reality that is the cause of our perception of space. It may be nothing like space, but let’s assume, for the sake of argument, that the underlying reality is like Galilean space-time. How would be perceive it, given that we perceive it using light (one-way travel of light, not two-way as SR assumes)? It turns out that our perceptual space would have time dilation and length contraction and all other effect predicted by SR. So my thesis is that the underlying reality obeys Galilean space-time and our perceptual space obeys something like SR. (It is possible that if I assume that our perception uses two-way light travel, I may get SR-like transformation. I haven’t done it because it seems obvious to me that we perceive a star, for instance, by sensing the light from it rather than flashing a light at it.)

This thesis doesn’t sit well with physicists, and indeed with most people. They mistake “perceptual effects” to be something like optical illusions. My point is more like space itself is an illusion. If you look at the night sky, you know that the stars you see are not “real” in the sense that they are not there when you are looking at them. This is simply because the information carrier, namely light, has a finite speed. If the star under observation is in motion, our perception of its motion is distorted for the same reason. SR is an attempt to formalize our perception of motion. Since motion and speed are concepts that mix space and time, SR has to operate on “space-time continuum.” Since SR is based on perceptual effects, it requires an observer and describes motion as he perceives it.

But are you actually saying that not a single experiment has been done with objects moving in any other direction than farther away? And what about experiments on time dilation where astronauts go into space and return with clocks showing less elapsed time than ones that stayed on the ground? Doesn’t this support the ideas inherent in SR?

Experiments are always interpreted in the light of a theory. It is always a model based interpretation. I know that this is not a convincing argument for you, so let me give you an example. Scientists have observed superluminal motion in certain celestial objects. They measure the angular speed of the celestial object, and they have some estimate of its distance from us, so they can estimate the speed. If we didn’t have SR, there would be nothing remarkable about this observation of superluminality. Since we do have SR, one has to find an “explanation” for this. The explanation is this: when an object approaches us at a shallow angle, it can appear to come in quite a bit faster than its real speed. Thus the “real” speed is subluminal while the “apparent” speed may be superluminal. This interpretation of the observation, in my view, breaks the philosophical grounding of SR that it is a description of the motion as it appears to the observer.

Now, there are other observations of where almost symmetric ejecta are seen on opposing jets in symmetric celestial objects. The angular speeds may indicate superluminality in both the jets if the distance of the object is sufficiently large. Since the jets are assumed to be back-to-back, if one jet is approaching us (thereby giving us the illusion of superluminality), the other jet has bet receding and can never appear superluminal, unless, of course, the underlying motion is superluminal. The interpretation of this observation is that the distance of the object is limited by the “fact” that real motion cannot be superluminal. This is what I mean by experiments being open to theory or model based interpretations.

In the case of moving clocks being slower, it is never a pure SR experiment because you cannot find space without gravity. Besides, one clock has to be accelerated or decelerated and GR applies. Otherwise, the age-old twin paradox would apply.

I know there have been some experiments done to support Einstein’s theories, like the bending of light due to gravity, but are you saying that all of them can be consistently re-interpreted according to your theory? If this is so, it’s dam surprising! I mean, no offense to you – you’re obviously a very bright individual, and you know much more about this stuff than I do, but I’d have to question how something like this slipped right through physicists’ fingers for 100 years.

These are gravity related questions and fall under GR. My “theory” doesn’t try to reinterpret GR or gravity at all. I put theory in inverted quotes because, to me, it is a rather obvious observation that there is a distinction between what we see and the underlying causes of our perception. The algebra involved is fairly simple by physics standards.

Supposing you’re right in that space and time are actually Galilean, and that the effects of SR are artifacts of our perception. How then are the results of the Michelson-Morley experiments explained? I’m sorry if you did explain it in your book, but it must have flown right over my head. Or are we leaving this as a mystery, an anomaly for future theorists to figure out?

I haven’t completely explained MMX, more or less leaving it as a mystery. I think the explanation hinges on how light is reflected off a moving mirror, which I pointed out in the book. Suppose the mirror is moving away from the light source at a speed of v in our frame of reference. Light strikes it at a speed of c-v. What is the speed of the reflected light? If the laws of reflection should hold (it’s not immediately obvious that they should), then the reflected light has to have a speed of c-v as well. This may explain why MMX gives null result. I haven’t worked out the whole thing though. I will, once I quit my day job and dedicate my life to full-time thinking.

My idea is not a replacement theory for all of Einstein’s theories. It’s merely a reinterpretation of one part of SR. Since the rest of Einstein’s edifice is built on this coordinate transformation part, I’m sure there will be some reinterpretation of the rest of SR and GR also based on my idea. Again, this is a project for later. My reinterpretation is not an attempt to prove Einstein’s theories wrong; I merely want to point out that they apply to reality as we perceive it.

Overall, it was worth the \$5 I payed. Thanks for the good read. Don’t take my questions as an assault on your proposal – I’m honestly in the dark about these things and I absolutely crave light (he he). If you could kindly answer them in your spare time, I’d love to share more ideas with you. It’s good to find a fellow thinker to bounce cool ideas like this off of. I’ll PM you again once I’m fully done the book. Again, it was a very satisfying read.

Thanks! I’m glad that you like my ideas and my writing. I don’t mind criticism at all. Hope I have answered most of your questions. If not, or if you want to disagree with my answers, feel free to write back. Always a pleasure to chat about these things even if we don’t agree with each other.

– Best regards,
– Manoj

# Anti-relativity and Superluminality

Leo wrote:I have some problems with the introductory part though, when you confront light travel effects and relativistic transforms. You correctly state that all perceptual illusions have been cleared away in the conception of Special Relativity, but you also say that these perceptual illusions remained as a subconscious basis for the cognitive model of Special Relativity. Do I understand what you mean or do I get it wrong?

The perceptual effects are known in physics; they are called Light Travel Time effects (LTT, to cook up an acronym). These effects are considered an optical illusion on the motion of the object under observation. Once you take out the LTT effects, you get the “real” motion of the object . This real motion is supposed to obey SR. This is the current interpretation of SR.

My argument is that the LTT effects are so similar to SR that we should think of SR as just a formalization of LTT. (In fact, a slightly erroneous formalization.) Many reasons for this argument:
1. We cannot disentagle the “optical illusion” because many underlying configurations give rise to the same perception. In other words, going from what we see to what is causing our perception is a one to many problem.
2. SR coordinate transformation is partially based on LTT effects.
3. LTT effects are stronger than relativistic effects.

Probably for these reasons, what SR does is to say that what we see is what it is really like. It then tries to mathematically describe what we see. (This is what I meant by a formaliztion. ) Later on, when we figured out that LTT effects didn’t quite match with SR (as in the observation of “apparent” superluminal motion), we thought we had to “take out” the LTT effects and then say that the underlying motion (or space and time) obeyed SR. What I’m suggesting in my book and articles is that we should just guess what the underlying space and time are like and work out what our perception of it will be (because going the other way is an ill-posed one-to-many problem). My first guess, naturally, was Galilean space-time. This guess results in a rather neat and simple explantions of GRBs and DRAGNs as luminal booms and their aftermath.

# Discussion on the Daily Mail (UK)

On the Daily Mail forum, one participant (called “whats-in-a-name”) started talking about The Unreal Universe on July 15, 2006. It was attacked fairly viciously on the forum. I happened to see it during a Web search and decided to step in and defend it.

#### 15 July, 2006

##### Posted by: whats-in-a-name on 15/07/06 at 09:28 AM

Ah, Kek, you’ve given me a further reason to be distracted from what I should be doing- and I can tell you that this is more interesting at the moment.I’ve been trying to formulate some ideas and there’s one coming- but I’ll have to give it to you in bits.I don’t want to delve into pseudoscience or take the woo-ish road that says that you can explain everything with quantum theory, but try starting here: http://theunrealuniverse.com/phys.shtml

The “Journal Article” link at the bottom touches on some of the points that we discussed elsewhere. It goes slightly off-topic, but you might also find the “Philosophy” link at the top left interesting.

##### Posted by: patopreto on 15/07/06 at 06:17 PM

Regarding that web site wian.One does not need to ead past this sentence –

The theories of physics are a description of reality. Reality is created out of the readings from our senses. Knowing that our senses all work using light as an intermediary, is it a surprise that the speed of light is of fundamental importance in our reality?

to realise that tis web site is complete ignorant hokum. I stopped at that point.

#### 16 July, 2006

##### Posted by: whats-in-a-name on 16/07/06 at 09:04 AM

I’ve just been back to read that bit more carefully. I don’t know why the writer phrased it like that but surely what he meant was:(i) “Our perception of what is real is created out of the readings from our senses.” I think that most physicists wouldn’t argue with that would they? At the quantum level reality as we understand it doesn’t exist; you can only say that particles have more of a tendency to exist in one place or state than another.(ii) The information that we pick up from optical or radio telescopes, gamma-ray detectors and the like, shows the state of distant objects as they were in the past, owing to the transit time of the radiation. Delving deeper into space therefore enables us to look further back into the history of the universe.It’s an unusual way to express the point, I agree, but it doesn’t devalue the other information on there. In particular there are links to other papers that go into rather more detail, but I wanted to start with something that offered a more general view.

I get the impression that your study of physics is rather more advanced than mine- as I’ve said previously I’m only an amateur, though I’ve probably taken my interest a bit further than most. I’m happy to be corrected if any of my reasoning is flawed, though what I’ve said so far s quite basic stuff.

The ideas that I’m trying to express in response to Keka’s challenge are my own and again, I’m quite prepared to have you or anyone else knock them down. I’m still formulating my thoughts and I wanted to start by considering the model that physicists use of the nature of matter, going down to the grainy structure of spacetime at the Plank distance and quantum uncertainty.

I’ll have to come back to this in a day or two, but meanwhile if you or anyone else wants to offer an opposing view, please do.

##### Posted by: patopreto on 16/07/06 at 10:52 AM

I don’t know why the writer phrased it like that but surely what he meant was:

I think the write is quit clear! WIAN – you have re-written what he says to mean something different.

The writer is quite clear – “Once we accept that space and time are a part of the cognitive model created by the brain, and that special relativity applies to the cognitive model, we can ponder over the physical causes behind the model, the absolute reality itself.”

Blah Blah Blah!

The writer, Manoj Thulasidas, is an employee of OCBC bank in Singapore and self-described “amateur philosopher”. What is he writes appears to be nothing more than a religiously influenced solipsistic philosophy. Solipsism is interesting as a philosophical standpoint but quickly falls apart. If Manoj can start his arguments from such shaky grounds without explanation, then I really have no other course to take than to accept his descriptions of himself as “amateur”.

Maybe back to MEQUACK!

# Superluminal Laser Dots

A discussion in the Science Forums on the appearance of a laser dot on a ceiling. It is thought that if you pointed a laser dot on a ceiling and turned the laser gun fast enough, you could create superluminal laser dots. Could you, really?