Who came up with the idea of relative time?

[geordief]

Is there a record of who it was who introduced the idea of using separate measurements of time as applied in different frames of reference?

 

I mean ,was this idea  worked with before the idea that space and time could be  connected mathematically into one  concept?

 

(I was trying to work this out from scratch and I was trying to  imagine using a non moving clock such as a caesium clock as a time keeper that would apply to both reference frames until I realized that  this clock would also be viewed according to reference frames.)

 

Who might have been the first person to have realized that you might have to consider "time" separately for each frame of reference?

 

I am hoping it wasn't just Einstein and that others before him had worked with the idea.(which has obviously been shown experimentally to be correct)

 

[Bufofrog]

I believe it is just good old Einstein.  Why do you hope it wasn't Einstein?

[geordief]

Well it would mean there might have been  a history of false assumptions ,followed by tentative mathematical attempts  ending finally with a mathematical model  that  worked.

More interesting in that sense than a eureka moment .Even a record of Einstein's thought processes leading up to that  point might be fascinating.
 

It is not Lorentz who was the man ,was it who unified Space and Time in the sense I am asking about.?

 

Did he give the two relatively moving observers their own clocks effectively?

How did Einstein's formulation surpass his? 

 

 

[Strange]

I haven't read about this for a long time, but the two main people before Einstein (as far as I remember) were Lorentz and Poincare. Lorentz came up with the idea of length contraction and time dilation, purely based on empirical results (he always assumed there was some sort of "mechanical" explanation - such as speed shortening the bonds between atoms). Poincare did some more mathematical work on it (showing that it was a hyperbolic rotation, and various other clever mathy things).

It was Einstein who put it all on a more formal basis by showing that relativity could be derived from first principles.

The concept of a "frame of reference" is much older (not sure when it was first used). But the idea that observers would make different measurements depending on their frame of reference is due to the above.

[geordief]

28 minutes ago, Strange said:

Lorentz came up with the idea of length contraction and time dilation

Thanks. Yes that seems very much to to be what I was looking for.

"He discovered that the transition from one to another reference frame could be simplified by using a new time variable that he called local time and which depended on universal time and the location under consideration He discovered that the transition from one to another reference frame could be simplified by using a new time variable that he called local time and which depended on universal time and the location under consideration" 

and

" In 1900 and 1904, Henri Poincaré called local time Lorentz's "most ingenious idea" 

https://en.wikipedia.org/wiki/Hendrik_Lorentz

Seems like Poincare  gave Lorentz all the historical  credit.

 

 

 

 

30 minutes ago, Strange said:

The concept of a "frame of reference" is much older (not sure when it was first used). But the idea that observers would make different measurements depending on their frame of reference is due to the above.

I am guessing it may have been Gallileo

Edited July 24, 2019 by geordief

[StringJunky]

25 minutes ago, geordief said:

I am guessing it may have been Gallileo

It appears so, from a Wiki I read, as part of Galilean relativity of velocity ideas but it was  not called that formally at the time.

Edited July 24, 2019 by StringJunky

[dimreepr]

6 hours ago, geordief said:

I am hoping it wasn't just Einstein

Why?

[Bufofrog]

2 hours ago, geordief said:

Well it would mean there might have been  a history of false assumptions ,followed by tentative mathematical attempts  ending finally with a mathematical model  that  worked.

There was a long history of false assumptions.  In this case it was the false assumption that time was absolute.  Time dilation a result of the mathematics of relativity.  Experimentation done afterwards supported that time dilation occurs which supports the theory of relativity.

[Strange]

1 hour ago, geordief said:

I am guessing it may have been Gallileo

The concept seems to have originated with Galilean relativity (but beware of Stigler's law of eponymy: https://en.wikipedia.org/wiki/Stigler's_law_of_eponymy).

But there was still the assumption of absolute time and space, as Bufofrog says.

[geordief]

15 minutes ago, dimreepr said:

Why?

I answered that in reply to Bufofrog  in post #3

https://www.scienceforums.net/topic/119646-who-came-up-with-the-idea-of-relative-time/?do=findComment&comment=1111125

Another reason,I suppose  could be that I hadn't been paying attention if I thought it was just him

1 minute ago, Strange said:

 

But there was still the assumption of absolute time and space, as Bufofrog says.

Around that earlier Galilean time you mean?  Or or you agreeing  with Bufofrog that for Lorentz time was still absolute even though he introduced the idea of "local time"?(I know he was still assuming the existence of an aether)

[swansont]

Galilean relativity had the concept that the laws of physics were the same in all frames, but AFAIK time and space were absolute, which worked if c was infinite.

[geordief]

https://www.johnrot.net/works/local-time/

 

Someone has written a musical piece based on "Local Time" as  developed by Lorentz and then Poincare

 

”We have not a direct intuition of simultaneity, nor of the equality of two durations. If we think we have this intuition, this is an illusion.” – Henri Poincaré, The Measure of Time, 1898

[Schmelzer]

On 7/24/2019 at 6:00 PM, Bufofrog said:

I believe it is just good old Einstein.  Why do you hope it wasn't Einstein?

Wikipedia  attributes this to Joseph Larmor (1897) at least for electrons and  Emil Cohn (1904) for clocks in general. One would have to research when Lorentz and Poincare became aware of this, but I'm not too much interested in such questions of priority. 

[studiot]

Actually the first recorded words were due to 

Spoiler

Shakespeare

Rosalind 1599

Time travels in divers paces with divers persons

As you like it Act 3 scene 2.

 

[Eise]

On 7/24/2019 at 1:30 PM, Bufofrog said:

I believe it is just good old Einstein. 

Definitely not. Voigt, FitzGerald, Larmor,  and as already mentioned by Strange, Poincaré, and Lorentz were some of the theoreticians that derived (parts of) the Lorentz transformations (why do you think they are called like that by Poincaré and, even by Einstein?).  Einstein himself clearly stated that special relativity was so to speak 'in the air', waiting to be discovered.

The problem is that some of them just derived correction factors to explain the null-result of the Michelson-Morleyor similar experiments, others could not get rid of the idea of a preferred frame of reference (the aether), especially Poincaré and Lorentz. Abraham Pais, in his biography of Einstein, Subtle is the Lord, even goes so far to say that Poincaré never really understood special relativity. But notwithstanding, Poincaré made important contributions, also about the mathematical properties of the Lorentz transformations.

Many physicists were aware that there was a tension between classical mechanics and the electromagnetic theory of Maxwell, and tried to solve it. Einstein did it on basis of less premises than anybody else (the two postulates of SR), and so also got rid of the idea of a preferred frame of reference, i.e. the aether.

For a (far from complete) overview, see History of special relativity.

1 hour ago, Schmelzer said:

One would have to research when Lorentz and Poincare became aware of this, but I'm not too much interested in such questions of priority. 

It is not just priority; it is definitely part of history of science, and as such, well, just interesting. How is it possible that people came to such counter-intuitive ideas?

And that research is already done: read Pais.