I How does Einstein define simultaneity in his 1905 paper?

[GrayGhost]

Aufbauwerk 2045,

Also, in OEMB Section 1 when Einstein talks about an observer "in the neighborhood" of the clock, or the clock "in the neighborhood" of the event, he's only minimizing the light travel time (delay) from event to clock, and/or clock to observer('s eyes). An observer (A) at a train station with clock in hand, knows the train arrived at 7pm ... little hand at 7 and train at station. If an observer (B) 20 light seconds away (say also at rest with the train station) awaits light signals from that distant event, the received light image shows the clock arrived at the station at 7, by the clock on the wrist of he at the station. However, this distant observer's own clock then reads 7:00:20, not 7 ... because light takes 20 sec to traverse a 20 light-sec separation. If that observer (B) used his own clock to define the event, he'd say the train arrived at 20 sec after 7. So this is what Einstein is pointing out in Section 1, when he talks about "in the neighborhood of". As stated in the thread already, he's defining the situation whereby the light's flight time from event to clock, or clock to eyes, is "negligible enough for all intents and purposes". As such, your own clock's time readout that you see "is essentially" the time the event occurred (train at station). The observer, his clock, and the event, are essentially in-the-same-place-at-the-same-time.

Best Regards,
GrayGhost

 

[GrayGhost]

Sorry, I have a type-O correction in my prior ...

I wrote ... ", the received light image shows the clock arrived at the station at 7, by the clock on the wrist of he at the station."

I should have written ... ", the received light image shows the train arrived at the station at 7, by the clock on the wrist of he at the station."

The paper reference being ... http://www.fourmilab.ch/etexts/einstein/specrel/www/

Best Regards,
GrayGhost

 

[mabool]

EDoMb Section 1 is called Definition of Simultaneity.

It does not define simultaneity of separated clocks. It defines synchrony of separated clocks.

EDoMB Section 2, in connection with "discovered length" makes reference to "definite time." Definite time is simultaneity at separate locations, the endpoints of a rigid body.

Section 2 ultimately uses synchrony and not simultaneity for discovered length, synchrony having been plausibly defined in Section 1.

Einstein's article in The 14th Encyclopedia Britannica ( title: Space-Time ) roughly 1930, says "there is no such thing as absolute simultaneity."

Algebraically, simultaneity at separate locations A and B is: tA = tB. No such equation appears in EDoMB and is very hard to find anywhere on the web. It is not in the EB article.