User talk:TimothyRias/temp3

3rd para- Lorentz invariance

I would suggest briefly mentioning that Lorentz invariance depends on c. For example,

...theories satisfy a special symmetry called Lorentz invariance, which depends on c.

--Bob K31416 (talk) 12:42, 27 November 2009 (UTC)

Sure. Also feel free to make such tweaks yourself. TimothyRias (talk) 12:45, 27 November 2009 (UTC)

2nd para - almost simultaneous events

Re "The last item states that the order in which distant and almost simultaneous events occur, depends on the motion of the observer with the consequence that such events cannot have a causal relation."

It wasn't clear to me what you meant here. Were the events distant from each other or from an observer? Could the "almost simultaneous events" be the emission of light and the detection of that light elsewhere, in which case they would be causally related and contradict the excerpt? --Bob K31416 (talk) 13:34, 27 November 2009 (UTC)

I wasn't quite happy with that formulation yet. The technical point that needs to get across is that the order of spacelike separated events (i.e. events for which the spatial distance is larger then the temporal difference) depends on the motion of the observer. In fact, any two spacelike events have a frame for which they are simultaneous. So, to answer your question "the emission of light and the detection of that light elsewhere" would not be an example of "distant almost simultaneous events".

This needs to formulated in a clearer more accessible way. The problem with the previous text was that it actually described relativity of simultaneity as if it were time dilation. I'm open for suggestion for a better formulation. TimothyRias (talk) 14:11, 27 November 2009 (UTC)

While I was looking into a better formulation, I realized that simultaneity was singled out. Perhaps it should begin with "For example," if that's what you meant? --Bob K31416 (talk) 16:58, 27 November 2009 (UTC)

Here's a possible formulation.

For example, two events that occur at different places may be simultaneous to an observer who is moving at one velocity, but may not be simultaneous to an observer who is moving at a different velocity.

--Bob K31416 (talk) 23:32, 27 November 2009 (UTC)