Albert Einstein, the Rational World and the Zombie World

[Pentcho]

Albert Einstein, "Relativity", Chapter 7: "There is hardly a simpler law in physics than that according to which light is propagated in empty space. Every child at school knows, or believes he knows, that this propagation takes place in straight lines with a velocity c=300000 km/s."

 

Chapter 22: "...the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light VARIES WITH POSITION."

 

The rational world would ask: How does the velocity of propagation of light VARY WITH POSITION? Increases and becomes greater than c=300000 km/s? Decreases? Increase and decrease depend on what?

 

The zombie world asks nothing. It learns by rote, celebrates, worships, sings dithyrambs, eats and teaches how to learn by rote, celebrate, worship, sing dithyrambs and eat.

 

Pentcho Valev

[danny8522003]

Is this talking about light curving due to geodesics? If not or if so, what is the purpose of this post?

[swansont]

The context of the discussion is very important here. If I'm not mistaken, the quote about velocity of propagation varying with position came during Einstein's development of GR, and not as a conclusion of the theory. AFAIK it is one of the things that led him to conclude that space is curved - that the velocity is changing but the speed isn't, if viewed from a "flat" perspective.

[insane_alien]

c is a scalar quantity and velocity is a vector. the direction of the vector can change and the magnitude remain the same. that is what is happening here. you ar epointing out non existent holes. go learn something about vectors before you post.

[Pentcho]

The context of the discussion is very important here. If I'm not mistaken, the quote about velocity of propagation varying with position came during Einstein's development of GR, and not as a conclusion of the theory. AFAIK it is one of the things that led him to conclude that space is curved - that the velocity is changing but the speed isn't, if viewed from a "flat" perspective.

 

You are mistaken. See again the quotations from Einstein's "Relativity", think on them and finally take notice of what one of your gurus says on sci.physics.relativity:

 

> AFAIK Einstein basically thought in German, which does not have

> different words for "speed" and "velocity" ("die Geschwindigkeit" is

> used for both). Certainly his "velocity of propagation" could be phrased

> as "speed of propagation" without changing the underlying physics.

 

> Tom Roberts tjroberts@lucent.com

 

Pentcho Valev

[LazerFazer]

> AFAIK Einstein basically thought in German' date=' which does not have

> different words for "speed" and "velocity" ("die Geschwindigkeit" is

> used for both). Certainly his "velocity of propagation" could be phrased

> as "speed of propagation" without changing the underlying physics.

[/quote']

 

for the general information of the public, there are two distint terms for speed and velocity. speed is indeed translated with "Geschwindigkeit". however, the small distinction if direction matters is put by "lineare Geschwindigkeit".

finally, how do you know that he (Einstein) did not use "lineare Geschwindigkeit" in his papers? did you actually read the original thesis? f yes please inform me as i would like to know more about the original.

 

PS: please capitalize nouns when you use german.

 

Cheers,

LF

[timo]

@Pentcho: Not that I understood what you´re talking about at all. But the fact that there is a common word for velocity and speed doesn´t mean that both interpretations are correct. You have to determine from the context which one is meant.

 

@LazerFazer: Honestly, I´ve never heard of the term "lineare Geschwindikeit" before. This doesn´t nessecarily mean that this term doesn´t exist but it´s most certainly not widely used, nowadays. Well, perhaps it was during Einstein´s times.

[Pentcho]

@Pentcho: Not that I understood what you´re talking about at all. But the fact that there is a common word for velocity and speed doesn´t mean that both interpretations are correct. You have to determine from the context which one is meant.

 

Velocity and speed do indeed have different meanings in today's physics and this has been used by relativists for confusing the problem. Yet the problem is easy to solve. According to Einstein's second postulate, some X is independent of the speed of the light source or observer. Also, this X has a constant value of c=300000 km/s in vacuum. Finally, Einstein says in Chapter 22 that the second postulate is invalid in a gravitational field and the same X VARIES WITH POSITION. Clearly, X is the SCALAR, the speed. "Velocity" is a bad term in this case: Einstein's second postulate is about the SCALAR, not about the vector.

 

Pentcho

[LazerFazer]

@Pentcho

Velocity and speed do indeed have different meanings in today's physics and this has been used by relativists for confusing the problem. Yet the problem is easy to solve. According to Einstein's second postulate' date=' some X is independent of the speed of the light source or observer. Also, this X has a constant value of c=300000 km/s in vacuum. Finally, Einstein says in Chapter 22 that the second postulate is invalid in a gravitational field and the same X VARIES WITH POSITION. Clearly, X is the SCALAR, the speed. "Velocity" is a bad term in this case: Einstein's second postulate is about the SCALAR, not about the vector.

[/quote']

 

velocity of propagation of light VARIES WITH POSITION.

 

Here is a contradiction in your argument. In your first post' date=' it states VELOCITY, and yet here you claim that its SPEED thats being discussed here. You are aware that when anything is accelerating, it's velocity is changing. Also, when said object is 'in orbit' or going in a circlular path, its velocity is definately changing, while the speed could be staying the same?

 

@Atheist

LazerFazer: Honestly, I´ve never heard of the term "lineare Geschwindikeit" before. This doesn´t nessecarily mean that this term doesn´t exist but it´s most certainly not widely used, nowadays. Well, perhaps it was during Einstein´s times.

 

I also have not completed physics education in Germany, however, a friend of mine has heard this term during the mechanics section. Also, this term kan be found in the "Duden", so if you hesitate to believe, please take a look. Other than that I do agree with you so far, that it is mostly apparent from the context what is meant when a German says "Geschwindigkeit". Or, direction and speed are just referred to as seperate entities, if velocity is not to be used at all.

 

Cheers,

LazerFazer