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Offline SteveW

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The Speed Of Light
« on: 10/01/2007 23:00:27 »
My question is this. As I understand things, when the big bang happened, time started, and everything started to move away from that central point. Why is it then that we can look back in time to a period close to the big bang. Surely we would have to be moving away from the big bang at faster than the speed of light to do this? I thought that this was impossible! I can understand that when looking at distant objects we see them at a time in the past, but, surely as they came from the same origin as us then there must even be a limit to this.
I am not a scientist, so please try not to confuse me.


 

Offline ukmicky

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The Speed Of Light
« Reply #1 on: 11/01/2007 01:40:54 »
Hi steve welcome to the forum. Some people believe that space expanded from one pont others believe that the big bang happened everywhere in an already infinate universe.

But to answer you question yes space has and still is expanded faster than the speed of light and in fact the rate of expansion is believed to be speeding up.
 

Offline Pentcho Valev

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The Speed Of Light
« Reply #2 on: 11/02/2007 09:41:10 »
EINSTEIN'S SECOND LAW

http://www.physicstoday.org/vol-60/iss-1/12_2.html :
"Why no Einstein's laws? Since my undergraduate days, I have been puzzled by the fact that we have Newton's laws of motion but only Einstein's theory of special relativity. We have finished celebrating the 100th anniversary of the publication of the theory of special relativity, and it seems to me that after a century of validation, it's time to rename it as more than just a theory. I propose that we, as physicists, define a set of Einstein's laws, just as we have Newton's laws, Coulomb's law, or Faraday's law. I begin the discussion by offering the following three laws: The laws of physics are identical in all non-accelerating (that is, inertial) frames. The vacuum speed of light, c, is the same for all inertial frames. The total energy E of a body of mass m and momentum p is given by E = [√m2c4 + p2c2]. In particular, the energy of a body measured in its own rest frame is given by E = mc2, and the energy of a massless body is E = pc."

Consider again Einstein's Second Law:

Einstein's Second Law (original version): "The vacuum speed of light, c, is the same for all inertial frames." (In fact, the original 1905 version of Einstein's Second Law was a bit different but this is irrelevant here.)

This extremely important Law was improved by Einstein himself in the following way:

Einstein's Second Law (improved): The observer's frame may be inertial but if the observer and the light source are at different gravitational potentials, the speed of light is variable and obeys the equation c'=c(1+V/c^2), where V is the gravitational potential relative to the light source.

This improved version of Einstein's Second Law was gloriously confirmed in 1960 when Pound and Rebka measured a gravitational redshift factor equal to 1+V/c^2. Then clever Einsteinians deduced the ultimate version of Einstein's Second Law:

Einstein's Second Law (ultimate version): If the relative speed of the observer and the emitting body is zero, light is always propagated in empty space with a variable speed c'=c(1+V/c^2) where c is the initial speed of photons relative to the emitting body and V is the gravitational potential relative to the place of emission. Equivalently, if the observer and the place of emission are at the same gravitational potential, light is always propagated in empty space with a variable speed c'=c+v where v is the relative speed of the observer and the emitting body.

Clever Einsteinians were going to inform the world about the ultimate version of Einstein's Second Law but suddenly they realised the ultimate version was incompatible with the original version. The money-spinner called the theory of relativity was in danger so clever Einsteinians postponed the publication of the ultimate version until some new money-spinner was devised.

Pentcho Valev
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Offline Pentcho Valev

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The Speed Of Light
« Reply #3 on: 24/02/2007 07:59:22 »
SHOCK AND HORROR AND VARIABLE SPEED OF LIGHT

A few years ago Einstein's hypnotists found it suitable to make some more money by challenging Einstein's principle of constancy of the speed of light:

http://www.prospect-magazine.co.uk/article_details.php?id=5538
Paul Davies: "Einstein's famous equation E=mc2 is the only scientific formula known to just about everyone. The "c" here stands for the speed of light. It is one of the most fundamental of the basic constants of physics. Or is it? In recent years a few maverick scientists have claimed that the speed of light might not be constant at all. Shock, horror! Does this mean the next Great Revolution in Science is just around the corner?"

The "maverick scientists" created various "Variable Speed of Light" theories, became famous, got enough money and of course there was no Great Revolution in Science around the corner. So now there are no shock and horror in Einstein's cult and the selfsame Paul Davies can happily return to the original idiocy based on Einstein's false principle of constancy of the speed of light:

http://www.asuwebdevil.com/issues/2007/02/23/news/699963
"For this prof, it's only a matter of time.....Davies said an object traveling at a given speed experiences time slower relative to a stationary object. The faster the object moves, the slower it experiences time, he said. If a man traveled at 99 percent the speed of light for a certain amount of time to a point in space, then turned around and came back, he would find people on Earth aged years more than he did."

There is another reason why relativity hypnotists experience so much happiness now. The "maverick scientists" managed to discredit the true principle of variability of the speed of light (c'=c(1+V/c^2) or c'=c+v) that Einstein himself introduced when he did not know how else to explain the gravitational redshift. So when one tries to explain that the speed of light is variable the standard reaction is something like this: "What? Variable speed of light? Magueijo's theory? That is not serious!"

Pentcho Valev
pvalev@yahoo.com
 

Offline lightarrow

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The Speed Of Light
« Reply #4 on: 24/02/2007 17:09:20 »
SHOCK AND HORROR AND VARIABLE SPEED OF LIGHT
A few years ago Einstein's hypnotists found it suitable to make some more money by challenging Einstein's principle of constancy of the speed of light:
http://www.prospect-magazine.co.uk/article_details.php?id=5538
Paul Davies: "Einstein's famous equation E=mc2 is the only scientific formula known to just about everyone. The "c" here stands for the speed of light. It is one of the most fundamental of the basic constants of physics. Or is it? In recent years a few maverick scientists have claimed that the speed of light might not be constant at all. Shock, horror! Does this mean the next Great Revolution in Science is just around the corner?"
The "maverick scientists" created various "Variable Speed of Light" theories, became famous, got enough money and of course there was no Great Revolution in Science around the corner. So now there are no shock and horror in Einstein's cult and the selfsame Paul Davies can happily return to the original idiocy based on Einstein's false principle of constancy of the speed of light:
http://www.asuwebdevil.com/issues/2007/02/23/news/699963
"For this prof, it's only a matter of time.....Davies said an object traveling at a given speed experiences time slower relative to a stationary object. The faster the object moves, the slower it experiences time, he said. If a man traveled at 99 percent the speed of light for a certain amount of time to a point in space, then turned around and came back, he would find people on Earth aged years more than he did."
There is another reason why relativity hypnotists experience so much happiness now. The "maverick scientists" managed to discredit the true principle of variability of the speed of light (c'=c(1+V/c^2) or c'=c+v) that Einstein himself introduced when he did not know how else to explain the gravitational redshift. So when one tries to explain that the speed of light is variable the standard reaction is something like this: "What? Variable speed of light? Magueijo's theory? That is not serious!"
Pentcho Valev
pvalev@yahoo.com


In which way a spinning disk generate anti-gravity?
 

Offline Pentcho Valev

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The Speed Of Light
« Reply #5 on: 03/03/2007 12:51:54 »
EINSTEIN AND THE EMISSION THEORY OF LIGHT

http://philsci-archive.pitt.edu/archive/00001743/02/Norton.pdf John Norton, "Einstein’s Investigations of Galilean Covariant Electrodynamics prior to 1905":

Einstein: "I certainly knew that the principle of the constancy of the velocity of light is something quite independent of the relativity postulate [see chapter 7 in his "Relativity" where he derives the former from the latter]; and I considered what would be more probable, the principle of the constancy of c, as was demanded by Maxwell’s equations, or the constancy of c, exclusively for an observer sitting at the light source. I decided in favor of the first, since I was convinced that each light [ray] should be defined by frequency and intensity alone, quite independently of whether it comes from a moving or a resting light source."

Needless to say, this argument of Einstein's against the emission theory of light is absurd but John Norton gives a more serious reason why Einstein abandoned this theory:

"The principle of relativity, if implemented in Galilean kinematics, dictated that the modified theory must embody an emission theory of light. We know that Einstein entertained such a theory.....Einstein leveled objections against all theories of this type. Some were technical complications. The most fundamental, however, was that these EMISSION THEORIES ADMITTED NO FIELD THEORY.

However at the end of his life Einstein said:

"I consider it quite possible that PHYSICS CANNOT BE BASED ON THE FIELD CONCEPT, i.e., on continuous structures. In that case, nothing remains of my entire castle in the air, gravitation theory included, [and of] the rest of modern physics."

So one can "consider it quite possible" that modern physics died long time ago.

Pentcho Valev
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Offline Pentcho Valev

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The Speed Of Light
« Reply #6 on: 10/03/2007 08:54:00 »
HOW EINSTEINIANS CONTRADICT EINSTEIN

Very carefully indeed. At the conference

http://quantum.leeds.ac.uk/~sonwm/fop07/

philosopher Jeremy Butterfield of Cambridge will inform the relativity cult that the problem with signals travelling faster than light is difficult. He has just discovered that "the idea that influences propagate at most as fast as light" can be violated:

http://quantum.leeds.ac.uk/~viv/FoP07abstracts/Butterfield.pdf

Philosophers' main task will be to find the best language to present the violation. Philosopher Jeremy Butterfield of Cambridge has already discovered this form of presentation:

http://talks.cam.ac.uk/talk/index/5570 : Jeremy Butterfield "Reconsidering Relativistic Causality": "I discuss the idea of relativistic causality, i.e. the requirement that causal processes (signals) can propagate only within the light-cone. After briefly locating this requirement in the philosophy of causation, my main aim is to draw philosophers' attention to the fact that it is subtle, and even problematic, in contemporary physics. For there are scenarios in which it fails."

Other presentations may be offered and a poll in the relativity cult will finally determine the best one. In any event, the world should continue to sing "Divine Einstein" enthusiastically:

http://www.haverford.edu/physics-astro/songs/divine.htm
http://www.bnl.gov/community/Tours/EinsteinPics/Einsteine.jpg

Pentcho Valev
pvalev@yahoo.com
 

Offline Soul Surfer

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The Speed Of Light
« Reply #7 on: 10/03/2007 09:43:39 »
Pentcho Valev  I would give your presentations on the limits of relativity theory much more credence if you did not adopt the extreme language of the third rate  tabloid hack in the way you presented it.  I am also sure that the respected scientists who's work you quote would feel the same way about this.  Uncertainty theory describes precisely how all physical laws break down in extremis and to present these limits as some sort of malevolent plot is totally unnecessary and makes you look like some sort of stupid crank.

To go back to Steve's original question.  The expansion of the universe is precisely what it says the expansion of space itself and not just things coming out of a big explosion at high speeds limited by the velocity of light.  As such it is possible for parts of the universe to be travelling away from other parts at speeds greater than that of light.  This just means that these parts cannot communicate with each other at this time.  If the expansion is slowing down  it may be possible to communicate in the future but if (as current observations seem to suggest ) the expansion is speeding up some parts of the universe may have communicated with us in the past but cannot communicate now.
« Last Edit: 10/03/2007 09:55:36 by Soul Surfer »
 

Offline Pentcho Valev

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« Reply #8 on: 15/03/2007 08:09:33 »
WILL EINSTEINIANS ABANDON THE FALSE SECOND POSTULATE?

The eternal trouble in Einstein's cult: The theory of relativity is an excellent money-spinner but one based on Einstein's false second postulate - the principle of constancy of the speed of light. So Einsteinians have never stopped trying to get rid of this postulate:

http://www.worldscibooks.com/physics/4114.html :"They lead to an unexpected affirmative answer to the long-standing question of whether it is possible to construct a relativity theory without postulating the constancy of the speed of light and retaining only the first postulate of special relativity. This question was discussed in the early years following the discovery of special relativity by many physicists, including Ritz, Tolman, Kunz, Comstock and Pauli, all of whom obtained negative answers."

http://o.castera.free.fr/pdf/chronogeometrie.pdf : Jean-Marc Lévy-Leblond “De la relativité à la chronogéométrie ou: Pour en finir avec le “second postulat” et autres fossiles”: “D’autre part, nous savons aujourd’hui que l’invariance de la vitesse de la lumière est une conséquence de la nullité de la masse du photon. Mais, empiriquement, cette masse, aussi faible soit son actuelle borne supérieure expérimentale, ne peut et ne pourra jamais être considérée avec certitude comme rigoureusement nulle. Il se pourrait même que de futures mesures mettent enévidence une masse infime, mais non-nulle, du photon ; la lumière alors n’irait plus à la “vitesse de la lumière”, ou, plus précisément, la vitesse de la lumière, désormais variable, ne s’identifierait plus à la vitesse limite invariante.”

The problem is that even the most convoluted attempt to build a relativity without Einstein's false second postulate unavoidably leads to reestablishing the old Newtonian-Galilean mechanics:

http://www.chapitre.com/CHAPITRE/fr/NEUF/product/eisenstaedt-jean/avant-einstein-relativite-lumiere-gravitation,9782020672924.aspx?donnee_appel=CHAPITRE : Jean Eisenstaedt, "AVANT EINSTEIN: RELATIVITE, LUMIERE, GRAVITATION": À l'université, on ânonne sans trop comprendre : « la vitesse de la lumière est indépendante de celle de sa source ». Le principe de relativité jeté aux orties, l'éther entre en scène, un mot savant dont on n'a jamais vraiment su ce qu'il recouvre : un désastre !.... Newtoniens impénitents, ces « philosophes de la nature » ont tout simplement traité la lumière comme faite de vulgaires particules matérielles : des « corpuscules lumineux ». Mais ce sont gens sérieux et ils se sont basés sur leurs Classiques, Galilée, Newton et ses Principia où déjà l'on trouve des idées intéressantes. À la fin du XVIIIe siècle, au siècle des Lumières (si bien nommé en l'occurrence !), en Angleterre, en Écosse, en Prusse et même à Paris, une véritable balistique de la lumière sous-tend silencieusement la théorie de l'émission, avatar de la théorie corpusculaire de la lumière de Newton. Lus à la lumière ( !) des théories aujourd'hui acceptées, les résultats ne sont pas minces : toute une préhistoire émerge ainsi ! Une physique des rapports entre la lumière, la relativité, la gravitation... De très nombreux tests, expériences et effets aujourd'hui bien connus, peuvent s'y lire. Il s'agit de rien moins que d'une cinématique classique (galiléo-newtonienne) de la lumière, cohérente avec le principe de relativité et donc comparable par anticipation avec la cinématique einsteinienne. Il y manque bien sûr - et ce n'est pas rien ! - l'étrange loi de composition des vitesses (qui ne s'ajoutent plus si simplement) de Lorentz et l'interprétation plus tardive de Minkowski, qu'Einstein lui-même eut bien du mal à accepter...... Les « relativités » d'Einstein, cinématique einsteinienne et théorie de la gravitation, ont la triste réputation d'être difficiles... Ne remettent-elles pas en cause des notions familières ? Leur « refonte » est d'autant plus nécessaire."

http://www.courses.fas.harvard.edu/~phys16/Textbook/ch10.pdf : p. 35:"Relativity without c....it is easy to imagine a universe where the speed of light depends on the frame of reference. Light could behave like a baseball, for example. So let's drop the speed of light postulate and see what we can say about the coordinate transformations between frames, using only the relativity postulate." p.38:"There is only one decision to be made when constructing the spacetime structure of an (empty) universe. You just have to say whether V is finite or infinite, that is, whether the universe is Lorentzian or Galilean."

Pentcho Valev
pvalev@yahoo.com
 

Offline Atomic-S

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« Reply #9 on: 08/04/2007 06:26:57 »
I understand that existing, generally accepted accepted relativity theory does indeed allow for light propagating, in vacuo, at various different speeds if gravitation is present; but that at any one point of observation light passing that point would always appear, to an observer located there, to have the universally recognized constant speed of light (2.9.....x10^8  m/sec).  It is very important, when discussing how light or anything else behaves, to carefully state the situation of the observer, and also the situation of the object being observed, and to state whose measuring instruments are being used to describe the relationship between the observer and the thing observed. When light is said to move at a certain speed, we need to ask, as seen by whom, and as measured by what instruments? If these things are not clear, all kinds of nonsense will result.
 

Offline lightarrow

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« Reply #10 on: 08/04/2007 20:03:50 »
I understand that existing, generally accepted accepted relativity theory does indeed allow for light propagating, in vacuo, at various different speeds if gravitation is present; but that at any one point of observation light passing that point would always appear, to an observer located there, to have the universally recognized constant speed of light (2.9.....x10^8  m/sec).  It is very important, when discussing how light or anything else behaves, to carefully state the situation of the observer, and also the situation of the object being observed, and to state whose measuring instruments are being used to describe the relationship between the observer and the thing observed. When light is said to move at a certain speed, we need to ask, as seen by whom, and as measured by what instruments? If these things are not clear, all kinds of nonsense will result.

Infact, when you say: "generally accepted relativity theory does indeed allow for light propagating, in vacuo, at various different speeds if gravitation is present" you are actually talking about <<how light would propagate if we considered the space as flat>>. But it's not! Actually, light doesn't change direction (or speed) passing near a massive object, if we admit that space is warped there!
Light cannot do anything else than follow the geodesic. Actually, it would be bent if it moved straight!
« Last Edit: 08/04/2007 20:05:30 by lightarrow »
 

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