Understanding Spacetime Diagrams: Event E & Coordinates in K & K

[jainabhs]

Hi
I have some very basic doubts on spacetime diagrams.
Please refer the figure attached.
Here in this spacetime figure an event E is shown as observed from K and K'.
K' moves with v with respect to K.
The axis CT is tilted angle alpha following vt, so that any event that occurs at x' = 0 in K' would occur at x = vt in K.
For frame K, to find space coordinate of the event, draw a perpendicular to x-axis.

But to find time coordinate draw a perpendicular to CT. why??
I don't get this and moreover the length of perpendicular gives x'??
Please explain

Abhishek Jain

 

[robphy]

On a Minkowski-spacetime diagram, you should be drawing Minkowski-perpendiculars... not Euclidean-perpendiculars. Minkowski-perpendiculars to radii are tangents to hyperbolae, just as Euclidean-perpendiculars to radii are tangents to circles.

 

[morrobay]

Hello
I had some problems with that exact diagram, its from:
www.colvir.net/prof/richard.beauchamp/rel-an/rela.htm
I recall pervect stating there is a lot of misinformation on relativity on the internet.

 

[bernhard.rothenstein]

space-time diagrams

Hello
I had some problems with that exact diagram, its from:
www.colvir.net/prof/richard.beauchamp/rel-an/rela.htm
I recall pervect stating there is a lot of misinformation on relativity on the internet.

I only mention that different space-time diagrams we find in the literature define i the same way the space-time diagrams of the involved events. As I learned from a teacher of mine: There is no advantage without disadvantage. See please for instance a book by Shadowitz devoted to the subject.

 

[country boy]

...I have some very basic doubts on spacetime diagrams.
Please refer the figure attached. ...

I agree that the problem seems to be with this particular diagram. Can you construct a Minkowski diagram in the usual way, with a 45-degree diagonal representing a light path? Then a moving reference frame is drawn with x' and ct' axes at equal angles from the diagonal and on opposite sides of it. Just as lines of constant t are parallel to x, lines of constant t' are parallel to x' (and not perpendicular to each other). Likewise, constant x' lines are parallel to t'.

I know this is elementary, but it's worth going through the exercise to see if it clears up your doubts.