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For the fine structure constant i have posted something for the others constants really i don't know what would happen may be remain the same .... Merged post follows: Consecutive posts merged Yes thank you about your answer.... Merged post follows: Consecutive posts mergedDear DH I read more carefully the article and i have one notice it says: "Is the speed of light constant? What would it mean to say that c varied with time? Would it actually mean anything? In conventional units, the metre is defined as the distance that light travels in about 3 nanoseconds. (This is not quite the same thing as saying that the metre is the distance travelled in 1/c seconds.) Suppose that we calibrate marks on a ruler using this definition one year, then next year find that light takes longer than 3 ns to travel the length of the ruler. According to the definition, we wouldn't say that the speed of light had fallen, but that the ruler had lengthened. How could that be? What would that mean? Now the size of the ruler depends upon the size of atoms, which in turn is related (in our units) to quantum mechanical and electrical quantites. Could the atoms in the ruler have grown because electricity had faded, or because Planck's constant had increased? How would we know which?" Obviously the guy is doing wrong here: if the speed of light slow down the clock that we are using to measure the time that the light travels the ruler tick slower so the marks on the ruler will be the same and the ruler will have the very same length as it has in the first measurement. I m suspecting that the very same thing is happening with the constants that the swansont has referred before. (Is something like the scale factor in FWR metric.). Is not the same but is about the same confusion.... PS: And one last thing if a constant varies does not meaning that the laws of physics are changing form

Yes DH i m sorry for the misunderstanding you have right. But i don't know how to express it different. My question is about a hypothetical speed of light change... Lets restate it and i hope to be clear in this time: You have a device which measuring the speed of light. The SOL is changing ; your device will show something different?

thank you mooeypoo

"you mean the 4-vector for velocity? its always constant in magnitude, it can only change direction. handled nicely by general relativity. input the data into its equations and you'll get your answer." Nope i mean 4D accelaration an hypothetical SOL change ok? read the previous posts you are completely out of scope.

4D (SOL if you prefer) speed acceleration.... help me to understand what is your question here. Merged post follows: Consecutive posts mergedfor all i mean for all the matter which included in time space

Ok forget the phrase how i can measure it. Focus in the previous experiment which i restate it in that: You have a device which measuring the speed of light. Suddenly the 4D speed is changing for all with the same rate; your device will show something different? You say "If, hypothetically, all of the constants were scaling at the same rate, such that these measurements of any invariant didn't change, we wouldn't notice." And of course you will notice that because of your inertia (your mass).The SOL would be "unchangeable" and you would feel a mysterious acceleration. (Hypothetically speaking IF the SOL changing). Merged post follows: Consecutive posts mergedOne last thing for the fine structure constant from Wikipedia we have: Arnold Sommerfeld introduced the fine-structure constant in 1916, as part of his theory of the relativistic deviations of atomic spectral lines from the predictions of the Bohr model. The first physical interpretation of the fine-structure constant α was as the ratio of the velocity of the electron in the first circular orbit of the relativistic Bohr atom to the speed of light in the vacuum.[4] Equivalently, it was the quotient between the maximum angular momentum allowed by relativity for a closed orbit, and the minimum angular momentum allowed for it by quantum mechanics. It appears naturally in Sommerfeld's analysis, and determines the size of the splitting or fine-structure of the hydrogenic spectral lines. So this ratio (the ratio of the velocity of the electron in the first circular orbit of the relativistic Bohr atom to the speed of light in the vacuum) would be unchangeable to the SOL variations. I m not expert in that so this could be incorrect.

No i m asking that: from the fact that the speed of all in 4D time space is the same C how i can measure it?. An example is the following: you have a device which measuring the speed of light. Suddenly the 4D speed is changing with the same rate; your device will show something different? Regarding with fine structure constant really i don't know what would happened int this case.... the value would be the same but i can't say anything else... i have a wiki in fine structure http://en.wikipedia.org/wiki/Fine-structure_constant and it has a topic about the constancy of fine structure.

Dear D H Thank you for your answer it was my mistake to involve cosmic accelerations but i hadn't any better example in order to answer to the previous post. This which is not clear in my mind is : how we can measure something which is absolute (or invariant if you prefer). If you kind enough and read my first posts (until the post #13 i think) you will see what it is my confusion.

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Yes from this point and then i lost it!!!

Answered ?? where? tell me the post number... I don't think that from post 12 and above i got something..

The are not relatives with the thread and my questions

Or even worse if everything in the world changes their 4D speed at the same rate then an observer could "feel" this change but would still measure the same value for SOL.....

As the SR says (and is proved with many experiments) that is the speed of everything in this world is same and it has the same value with the SOL. So far that we know... Merged post follows: Consecutive posts mergedLet put this a little bit different: Now we have a SOL as we know it and then a cosmic acceleration is happening; the world would be the same before and after that acceleration? in this case something has changed an acceleration happened (even is theoretical and forbidden by the SR). Merged post follows: Consecutive posts mergedPs: with cosmic acceleration i mean SOL acceleration sorry any misleading s Merged post follows: Consecutive posts mergedI think that my questions are boring.... (and my English bad)

Then somehow that's interesting the SOL could increase or decrease without any consequences

In other word if everything are running in 4th dimensional time space with the same speed how can find a methodology to measure it? For example a increase in SOL will cause a clock to tick faster and all reactions will be faster including the observator 4th dimensional speed.Let imagine that we have 2 mirrors in distance 30 *10^8 meters then an observator measure the time that takes a ray of light to go from one mirror to another; it finds that it take one second. Now if the SOL decrease and the he want to repeat the measurement what would be the result? That i m asking. George

I want to know if something is absolute (like the speed of light) then is measurable too.

I have stacked with the following question : Let assume that the light speed was 5 Km/h and we attempting to measure it. What would be the result of that measurement? Thanx in advance George