Special Relativity- "Twin Paradox" Rujuk pg.2 #28

dauswq

neutrino tu menatang apa plk?

ce citer....
otai_g Post at 27-9-2011 01:42

ade student fizik Msia explen sedikit mengenai neutrino...hope boleh membantu

http://eforum4.cari.com.my/viewthread.php?tid=602173

winamp05

terlalu banyak info dan pelajaran yg boleh didapati dalam thread ni. mudah pulak tu nak memahaminya. so aku cadang thread ni di highlight dan di digest. walau mod sendiri yg bukan, apa salahnya kalau dgest thread sendiri kalau ianya mmg betul betul bermanfaat ye dak momod ? thehehehe...... hanya cadang.

winamp05

terlalu banyak info dan pelajaran yg boleh didapati dalam thread ni. mudah pulak tu nak memahaminya. so aku cadang thread ni di highlight dan di digest. walau mod sendiri yg bukan, apa salahnya kalau dgest thread sendiri kalau ianya mmg betul betul bermanfaat ye dak momod ? thehehehe...... hanya cadang.

dauswq

Reply 42# winamp05

tak berapa cukup info lagik sbrnye, TT pun agak malas nak update{:4_241:}

winamp05

Reply  winamp05

tak berapa cukup info lagik sbrnye, TT pun agak malas nak update
:funk ...
dauswq Post at 22-10-2011 01:32 PM

untuk yg "ahli" dalam bidang berkenaan rasa tak cukup. tapi untuk yg bukan "ahli" dalam bidang disebut terasa dah banyak. lagi pon kalau admin buat cleaning xde la board ni terkena tempias. thehehe.

dauswq

Reply 45# winamp05

oh i see..thx for the advice

dauswq

Reply 45# winamp05

aku ade simpulkan kt post twin paradox kot2 ade yg masih tak fhm..hehe

dauswq

Particles Faster Than the Speed of Light? Not So Fast, Some Say

Elwood H. Smith

      By DENNIS OVERBYEPublished: October 24, 2011   

So asks the Irish band the Corrigan Brothers in a new song, “Einstein and the Neutrinos,” that is the latest rollicking riff on news that shocked the scientific world last month.


A group of physicists from Italy claimed they had observed the subatomic particles called neutrinos traveling faster than the speed of light. That, of course, is the cosmic speed limit declared in Albert Einstein’s theory of special relativity in 1905.


If they are right — and the jury is still out — Einstein might have some explaining to do. Among other things, a neutrino or anything else that went faster than the speed of light could go backward in time.


Physicists, who are quite sure that in fact E does still equal MC squared — whatever may come of this experiment — have expressed skepticism. But that has not stopped the ghostly neutrinos, which can sail through miles of solid lead with impunity, from achieving a sort of pop culture fame not seen since 1960, when John Updike published a poem about them in The New Yorker:        
The Earth is just a silly ball        
To them through which they pass        
Like dustmaids down a drafty hall        
Or photons through a sheet of glass.        
Neutrino time-travel jokes have proliferated on the Internet. Example: “We don’t serve faster-than-light neutrinos here,” said the bartender. A neutrino walks into a bar.        
Under a YouTube video of the Corrigan Brothers (who played at President Obama’s inauguration), one commenter observed: “Irish Folk & particle physics — what a combo.”


The neutrino news came from a group of physicists based at the Gran Sasso underground laboratory in Italy and doing business under the apt acronym Opera. The neutrinos, they reported on Sept. 23 in a paper and at a special symposium at CERN, the European Center for Nuclear Research, had beaten a metaphorical light beam from CERN to Gran Sasso, a distance of 457 miles, by 60 nanoseconds.


The initial response of physicists assembled at CERN and around the world was that there was probably a mistake somewhere in the experiment. Einstein’s theory is the basis of all modern physics, and has been tested a zillion times.


Technically, relativity does allow some particles, known as tachyons, to go faster than light — in fact it forbids them to slow down to light speed. The hitch is that they would have imaginary masses, whatever that means. And there is also the possibility, in some versions of string theory, of particles’ taking a shortcut through another dimension. But allowing anything to travel faster than light would open up the possibility of all kinds of problems with cause and effect and even time travel.


“It looks too big to be true,” Alvaro de Rujala, a CERN theorist, said at the time.        
Or as the Corrigan Brothers put it:        
Was old Albert wrong?        
Oh can it be,        
that fabulous theory —        
relativity —        
is being debunked        
for the first time?        
But he still might be right,        
old Albert Einstein.


Physicists, in the meantime, have been flooding arXiv.org, the physics Internet archive, with papers debunking the Opera experiment and defending Einstein. In one paper, two professors from Boston University, Andrew G. Cohen and the Nobelist Sheldon L. Glashow, showed that if the neutrinos had been going faster than light en route to Gran Sasso, they would have lost energy at a fearsome rate by emitting other particles, causing distortions in the beam that were not seen by Opera.        
Another paper — by Gian Giudice of CERN, Sergei Sibiryakov of the Institute for Nuclear Research in Moscow and Alessandro Strumia of the University of Pisa in Italy and the National Institute of Chemical Physics and Biophysics in Tallinn, Estonia — argued that according to the Standard Model, the reigning theory in particle physics, if neutrinos could violate relativity, electrons should violate it also, something that has also not been observed.


Last week, in what sounded like the coup de grâce in some circles, Ronald A. J. van Elburg, an artificial intelligence researcher at the University of Groningen in the Netherlands, suggested that the Opera group had failed to make a relativistic correction for the motions of the GPS satellites used in timing the neutrino beams. The resulting error, he said, amounted to 64 nanoseconds, almost exactly the universe-shaking discrepancy the Opera researchers were hoping to explain.


That paper got wide attention. It was mentioned on a physics blog of the magazine Technology Review, and was published by the Massachusetts Institute of Technology and other news sites around the Internet as a possible explanation of the neutrino mystery. “If it stands up, this episode will be laden with irony,” Technology Review wrote. Far from breaking Einstein’s relativity, it went on, “the faster-than-light measurement will turn out to be another confirmation of it.”        
The Opera collaborators and other outside physicists now say Dr. van Elburg’s analysis is wrong and reflects confusion about how GPS systems work.


In an e-mail, Antonio Ereditato, a spokesman for Opera, said the paper did have some errors, but he declined to go into details.

“You understand well that we cannot reply to anybody claiming to have an explanation of our result in terms of trivial mistakes,” he said.


Reached in Groningen, Dr. van Elburg said that an improved version of his manuscript was now under peer review.        
John Learned, a neutrino physicist at the University of Hawaii, wrote in an e-mail that while the Opera results might not be right, “they are still not easily dismissed.”


“It is very unlikely to me that any distant observer will point out the error of their ways,” he continued. “If a screw-up, it is probably in the details not accessible to outsiders.”


Meanwhile, Halloween is almost here. Don’t be surprised if you have already seen Einstein in a neutrino costume.

dauswq

mbhcsf posted on 11-10-2010 11:04 AM
tapi tulah kan

persoalan utama saya

saya tambah sedikit ape yg saya dalami nak bg fahami lagi konsep relativiti ni...
for quick thinking question...@mnm77 dipersilakan utk berfikir sekali...
tidak melibatkan pengiraan tp ade kena mengena ngan formula lorrent transformation...


ada satu kes yg mana ketiga-tiga orang budak lelaki mempunyai perspektif berbeza mengenai jarum jam di dinding dalam lif dengan jarum jam di dalam kedua-dua bilik lobby & apartment 101 (tingkat ke-100) yg dihubung ngan lif dan juga tangga.



budak A  & C pada mulanya berada di tingkat bawah iaitu bilik A. Budak B pula berada di apartment 101.
A masuk ke dalam lif, B dan C stay di dalam bilik masing2. A , B & C masing-masing mencatat masa awal di dalam lif, di dalam bilik apartment 101 dan di luar bilik lobby sebaik sahaja lif bergerak.
Lif digerakkan dengan halaju menghampiri halaju cahaya (~0.999 c atau 2.99 x 10^8 m/s).
Sebaik sahaja lif tiba di bilik apartment 101, A , B & C masing-masing mencatat masa akhir di dalam lif, di dalam bilik apartment 101 dan di luar bilik lobby. Mereka masing-masing bawa keluar jam dinding.
Setelah dibanding antara satu sama lain, didapati B & C mencatatkan perbezaan masa yang sama, manakala A mencatatkan perbezaan masa yang "lain" (maknanya salah satu jam dinding mereka terlambat dari yang jam dinding lain).

Andai kata halaju lif hampir seragam dr awal bergerak smpilah akhir mendarat in such a way that pecutan awal (slps lif mula bergerak) dan pecutan akhir (sblm lif mendarat) yg menyebabkan masa yg diambil terlalu kecil (~nanoseconds) tidak diambil kira,  dan andai juga ruang antara lif adalah vakum,
apakah justifikasi anda terhadap perbezaan masa antara A, B & C? jam siapa yang lebih lambat? jam siapa yang lebih cepat?

mnm77

dauswq posted on 30-3-2013 02:24 AM
saya tambah sedikit ape yg saya dalami nak bg fahami lagi konsep relativiti ni...
for quick thinking question...@mnm77 dipersilakan utk berfikir sekali...
tidak melibatkan pengiraan tp ade kena mengena ngan formula lorrent transformation..

Saya masih belum hadam baca thread ni...hehehe.. mungkin juga di luar bidang saya dan di luar kefahaman saya...

ada satu kes yg mana ketiga-tiga orang budak lelaki mempunyai perspektif berbeza mengenai jarum jam di dinding dalam lif dengan jarum jam di dalam kedua-dua bilik lobby & apartment 101 (tingkat ke-100) yg dihubung ngan lif dan juga tangga.

Ok. Satu kes.

budak A  & C pada mulanya berada di tingkat bawah iaitu bilik A. Budak B pula berada di apartment 101.
A masuk ke dalam lif, B dan C stay di dalam bilik masing2. A , B & C masing-masing mencatat masa awal di dalam lif, di dalam bilik apartment 101 dan di luar bilik lobby sebaik sahaja lif bergerak.
Lif digerakkan dengan halaju menghampiri halaju cahaya (~0.999 c atau 2.99 x 10^8 m/s).
Sebaik sahaja lif tiba di bilik apartment 101, A , B & C masing-masing mencatat masa akhir di dalam lif, di dalam bilik apartment 101 dan di luar bilik lobby. Mereka masing-masing bawa keluar jam dinding.
Setelah dibanding antara satu sama lain, didapati B & C mencatatkan perbezaan masa yang sama, manakala A mencatatkan perbezaan masa yang "lain" (maknanya salah satu jam dinding mereka terlambat dari yang jam dinding lain).

Kes betul ke ni sampai lif boleh laju macam tu? Kes virtual kan?

Andai kata halaju lif hampir seragam dr awal bergerak smpilah akhir mendarat in such a way that pecutan awal (slps lif mula bergerak) dan pecutan akhir (sblm lif mendarat) yg menyebabkan masa yg diambil terlalu kecil (~nanoseconds) tidak diambil kira,  dan andai juga ruang antara lif adalah vakum,
apakah justifikasi anda terhadap perbezaan masa antara A, B & C? jam siapa yang lebih lambat? jam siapa yang lebih cepat?

Justifikasi?

Hmmm.... saya belum terima 100% lagi tentang teori berlaku perubahan masa (atau teori relativiti berkaitan masa) apabila halaju menyamai kelajuan cahaya (atau lebih)... macamana ye saya nak beri justifikasi?

Takde jam yang lambat atau cepat, cuma relatif masa yang dilalui oleh A tu jadi singkat. Relatif masa yang dilalui oleh B dan C tu sama. Ini secara teori...Saya belum terima 100% pasal teori ni....hehe...tu pun kalau saya tak tersilap pasal teori ni... sekarang kepala dok sakit dari semalam....

midory

twin paradox.. snng2 nnti nak try la bace bende nih...

dauswq

mnm77 posted on 1-4-2013 10:44 AM
Saya masih belum hadam baca thread ni...hehehe.. mungkin juga di luar bidang saya dan di luar kefa ...

saya nak explen clearly, tp kena ade gambar plak...
sbb learning relativity must by gambar supaya penerangan lebih jelas...

berkenaan jwpn u tu, you are halfly correct...
jam ketiga-tiga sepatutnya bergerak pada waktu yg sama..tetapi disebabkan mereka berada dalam frame yg berbeza, jadi jawapan mereka berikan sangat berbeza antara satu sama lain...

B & C menunjukkan jarum jam yang sama...
tetapi jarum jam A "terlambat" sikit kerana disebabkan "time dilation factor"...
time dilation factor ni saya ada jelaskan di post #28
Ini adalah dari pandangan kita di luar lif...
bagaimana pula pandangan A di dalam lif?
A tetap merasakan jam dindingnya adalah sama dengan jam dinding B & C.
kenapa? sebab A berada dalam lif dan dia tidak merasakan perubahan "relativiti" yang berlaku dari pandangan lain...maksudnya dia hanya fikirkan calculation berdasarkan pandangan nya sahaja...
walaupun begitu, mereka tidak salah dalam memberikan judgement...

kes ni boleh dibandingkan ngan kes "twin paradox" yg mana kembar A yg menaiki kapal angkasa ke planet dlm galaksi lain kemudian kembali ke bumi di mana dia sendiri merasakan dia sama umur dengan kembar B di bumi. Tetapi, kembar B membuktikan A lebih muda darinya sbb jamnya bergerak lambat dari jam B  di bumi...
kenapa A pulak rasa dia sepatutnya sama umur ngan B? jwpnnya sama spt di atas...

cuma biler kita faham konsep ini, maka kita boleh faham kenapa muon, neutrino (hasil bombardment partikel2 kecil atau sinaran komik yg dibebaskan matahari ngan molekul2 di angkasa ) boleh dikesan di bumi walaupun half life mereka sangat-sangat rendah yang mana mereka will completely decayed before arriving at earth by just using normal Newton motion formula...

sbnrnya teori relativiti dibukti benar by experiment...dan dr teori ni gak, einstien dapt idea tuk formulate e=mc2 tu...
kemudian, quantum mechanic berkembang selari ngan relativity lalu terhasilnya cabang fizik yg lebih luas spt cosmology, high energy physics...

mnm77

dauswq posted on 2-4-2013 12:09 PM
saya nak explen clearly, tp kena ade gambar plak...
sbb learning relativity must by gambar supaya ...

Thanks for explanation...

Err... firstly I do not reject the theory completely, rather I could not satisfy with the given explanation (yet), maybe I don't fully understand the theory, or possibly, because it is not proven (to me), it is just a theory which might be right or might be wrong as well.

berkenaan jwpn u tu, you are halfly correct...
jam ketiga-tiga sepatutnya bergerak pada waktu yg sama..tetapi disebabkan mereka berada dalam frame yg berbeza, jadi jawapan mereka berikan sangat berbeza antara satu sama lain...

Ehh ada halfly correct... interesting... jawapan saya tu saya 'infer' the effect of time dilation, sebab tu saya kata:

Takde jam yang lambat atau cepat, cuma relatif masa yang dilalui oleh A tu jadi singkat

merujuk kepada time frame yang berbeza, tapi masalahnya dari jawapan saya tu pasal time dilation, saya sendiri belum convince dengan teori tu!

cuma biler kita faham konsep ini, maka kita boleh faham kenapa muon, neutrino (hasil bombardment partikel2 kecil atau sinaran komik yg dibebaskan matahari ngan molekul2 di angkasa ) boleh dikesan di bumi walaupun half life mereka sangat-sangat rendah yang mana mereka will completely decayed before arriving at earth by just using normal Newton motion formula...

Hmmm... tengah cuba memahami....

sbnrnya teori relativiti dibukti benar by experiment...dan dr teori ni gak, einstien dapt idea tuk formulate e=mc2 tu...
kemudian, quantum mechanic berkembang selari ngan relativity lalu terhasilnya cabang fizik yg lebih luas spt cosmology, high energy physics..

Mungkin saya ni terkebelakang pasal teori ni, nak tahu jugak experiment tu... camne ye?

mnm77

Satu lagi persoalan saya.... kenapa kena laju cahaya baru berlaku perubahan relatif masa?

Kalau halaju 0.8c, berlaku atau tak berlaku perubahan relatif masa? Justification?

dauswq

mnm77 posted on 2-4-2013 12:45 PM
Thanks for explanation...

Err... firstly I do not reject the theory completely, rather I cou ...

ooo cth soalan yg saya guna tu mmg dummy jek...
just for understanding theory ni dr kaca mata besar...
ngan badan kita ditambah ngan berat kapal angkasa lagi, to attain extremely super speed (closed to a speed a light )mmg terlalu sukar kot tuk develop teknologinya   in future...

ok..ni saya terjumpa gambarajah yg menarik psl time dilation ni...

(Top) You see a beam of light go up, bounce off the mirror, and come straight down. (PANDANGAN DIRI SENDIRI DALAM LIF/KAPAL ANGKASA)
(Bottom) Amber sees the beam travel along a diagonal path.
(PANDANGAN ORANG LUAR  TERHADAP KAPAL ANGKASA)

dummies saya guna tadi - twin paradox & clock boleh dibayangkan spt di atas...

relativiti ni kita boleh tgk aplikasinya lebih kpd mikroskopic partikel yg travel with speed of light...
kesemua equation melibatkan motion partikel kecil ni mengunakan konsep relativiti (time dilation etc) measured in our frame..dlm frame partikel ni, kita tak perlu risau sgt sbb we can just use simple newton equation....
machine yg digunakan utk detect motion partikel ini tidak boleh measure in particle's frame sbb machine ni mengira dlm its own frame (maksudnya pandangan kita ke arah partikel itu)...

sbrnye einstein just develop its special relativity theory supaya dia boleh kaitkan hubungan mass-energy biler melibatkan partikel yg travel with speed of light..menggunakan newton law of motion, he seemed failed to conclude his findings...
yg mana die beranggapan bila objek yg berat travel ngan sangat laju, its energy will be infinite based on newton law of motion...???
as we know from newton law of motion , momentum , p = m v dan dari momentum terhasilnya energy...
tetapi experiment yang dibuat pada 1880-an telah tunjukkan bahawa cahaya tidak mempunyai mass , macammana plak cahaya ini boleh ada energy?? it must be from momentum dan cara define momentum ni bukan lagi dari p = mv tetapi einstein develop sendirik based on his special relativity theory...
(pada mase ni jgk rmi scientist tak leh terima elektron/proton sbg partikel sbb they will rather believe them as charges disebabkan  teori quantum mechanics pun belum develop lagi )

einstein gunakan pembayang di mana ada satu box ini berada dalam vaccuum...
satu partikel cahaya dilepaskan dari penghujung kiri box...
berdasarkan pemahaman kita, box akan melantun ke belakang apabila cahaya itu dilepaskan ke depan (sama spt pistol bila kita tembak, pistol melantun ke belakang)...skrg ni box bergerak ke kiri...
kemudian cahaya itu bertemu penghujung kanan box, transfer kesemua momentumnya menyebabkan box yg bergerak terhenti...
wlpn begitu, tiada daya luar dikenakan ke atas box mahupun partikel cahaya, maka centre of mass fixed (F= m a) berdasarkan newton law of motion ...bagaimana box boleh bergerak pada masa yg sama center of massnya fixed?

maka dengan itu, einstein perkenalkan idea di mana kita tak boleh view "energy" dan " mass" sbg kuantiti berbeza : energy is equivalent to mass but not the same...
oleh demikian, momentum tidak boleh lagi viewed as p = m v tetapi dalam bentuk energy , p = E/ c.

Dari erti kata lain, box bergerak ngan momentum, p = m v manakala cahaya bergerak dengan momentum p = E/c.

maka dari sini gak dia develop E =mc2...boleh baca kt internet camne einstein derive this formula...

e=mc2 experiments ni boleh dilihat dlm pelbagai experiment melibatkan nuclear fission dll

dauswq

mnm77 posted on 2-4-2013 12:54 PM
Satu lagi persoalan saya.... kenapa kena laju cahaya baru berlaku perubahan relatif masa?

Kalau  ...

ini kerana "cahaya" yg kita nampak dr deria penglihatan ini jelar entiti yg kita guna tuk measure perbandingan antara motion objek ngan motion cahaya...
dan kita tahu cahaya  sangat pantas, tiada mass & takkan memecut otherwise dunia ini akan jadi gila...
so menggunakan "cahaya" sbg perbandingan is a good solution rather thn elctron/proton dll...

dan didapati, bila halaju objek menghampiri halaju cahaya, its time become slightly dilated...


let say if the speed is 0.1c, maka pecahan di bawah denominator itu sangat kecil compared with 1. oleh itu, time tu tak byk berbeza dari time sebelumnya...kita boleh terus gunakan newton law of motion

mnm77

Ok thanks @dauswq for the explanation. Memang equation E=mc2 tu ada aplikasinya, tapi estimation je..... tentu ada ralat, dan setakat ni equation tu masih berguna untuk certain process.

Berbalik kepada theory of relativity

Einstein's theory menyatakan c (speed of light) always constant, relative to EVERYTHING, untuk kita terima pakai theory of relativity, kan?

Nak pakai teori tu, kena terima c sebagai malar. Kan?

Sebabnya, dari 'postulated' c yang constant tu maka boleh timbul penjelasan tentang 'time dilation'.

Betulkah c tu constant (malar) relative to everything?

Soalan saya seterusnya akan menyusul..... jeng jeng jeng....

mnm77

Artikel ni agak menarik....

Inconstant Speed Of Light May
Debunk Einstein
By Michael Christie
8-7-2

SYDNEY (Reuters) - A team of Australian scientists has proposed that the speed of light may not be a constant, a revolutionary idea that could unseat one of the most cherished laws of modern physics -- Einstein's theory of relativity.

The team, led by theoretical physicist Paul Davies of Sydney's Macquarie University, say it is possible that the speed of light has slowed over billions of years.

If so, physicists will have to rethink many of their basic ideas about the laws of the universe.

"That means giving up the theory of relativity and E=mc squared and all that sort of stuff," Davies told Reuters.

"But of course it doesn't mean we just throw the books in the bin, because it's in the nature of scientific revolution that the old theories become incorporated in the new ones."

Davies, and astrophysicists Tamara Davis and Charles Lineweaver from the University of New South Wales published the proposal in the August 8 edition of scientific journal Nature.

The suggestion that the speed of light can change is based on data collected by UNSW astronomer John Webb, who posed a conundrum when he found that light from a distant quasar, a star-like object, had absorbed the wrong type of photons from interstellar clouds on its 12 billion year journey to earth.

Davies said fundamentally Webb's observations meant that the structure of atoms emitting quasar light was slightly but ever so significantly different to the structure of atoms in humans.

The discrepancy could only be explained if either the electron charge, or the speed of light, had changed.

IN TROUBLE EITHER WAY

"But two of the cherished laws of the universe are the law that electron charge shall not change and that the speed of light shall not change, so whichever way you look at it we're in trouble," Davies said.

To establish which of the two constants might not be that constant after all, Davies' team resorted to the study of black holes, mysterious astronomical bodies that suck in stars and other galactic features.

They also applied another dogma of physics, the second law of thermodynamics, which Davies summarizes as "you can't get something for nothing."

After considering that a change in the electron charge over time would violate the sacrosanct second law of thermodynamics, they concluded that the only option was to challenge the constancy of the speed of light.

More study of quasar light is needed in order to validate Webb's observations, and to back up the proposal that light speed may vary, a theory Davies stresses represents only the first chink in the armor of the theory of relativity.

In the meantime, the implications are as unclear as the unexplored depths of the universe themselves.

"When one of the cornerstones of physics collapses, it's not obvious what you hang onto and what you discard," Davies said.

"If what we're seeing is the beginnings of a paradigm shift in physics like what happened 100 years ago with the theory of relativity and quantum theory, it is very hard to know what sort of reasoning to bring to bear."

It could be that the possible change in light speed will only matter in the study of the large scale structure of the universe, its origins and evolution.

For example, varying light speed could explain why two distant and causally unconnected parts of the universe can be so similar even if, according to conventional thought, there has not been enough time for light or other forces to pass between them.

It may only matter when scientists are studying effects over billions of years or billions of light years.

Or there may be startling implications that could change not only the way cosmologists view the universe but also its potential for human exploitation.

"For example there's a cherished law that says nothing can go faster than light and that follows from the theory of relativity," Davies said. The accepted speed of light is 300,000 km (186,300 miles) per second.

"Maybe it's possible to get around that restriction, in which case it would enthrall Star Trek fans because at the moment even at the speed of light it would take 100,000 years to cross the galaxy. It's a bit of a bore really and if the speed of light limit could go, then who knows? All bets are off," Davies said.

source
http://rense.com/general28/erin.htm

dauswq

mnm77 posted on 2-4-2013 03:46 PM
Ok thanks @dauswq for the explanation. Memang equation E=mc2 tu ada aplikasinya, tapi estimation je. ...

yup, you are right psl estimation if and only if we firmly believe that c= 3.0 x 10^8 m/s..

setakat ini penemuan hanya berkisar pd pemalar c= 3.0 x 10^8 m/s ini shj, kita tak pernah lagi jumpa c berubah ikut keadaan..
jika nilai c lain dari yang asal, maka there is something wrong...special relativity bukan lagi jadi fundamental theory tp menjadi pendukung kpd theory baru...

dauswq

dan lagi kita tak pasti wht will happen apabila cahaya ini memecut.... when the velocity is no longer constant..
sbb apa lagi kita bandingkan klu tidak cahaya?
jadi everything will be messed, ngan quantum mechanic theory semua menjadi berterabur...