yeh well, I once understood this, but now looking at it today I can't get it to make sense intuitively.(adsbygoogle = window.adsbygoogle || []).push({});

The quantity:

dx^{2}+dy^{2}+dy^{2}-c^{2}dt^{2}

is the same for every intertial frame in SR - just like length is the same in all inertial frames in classical mechanics. Now I am not sure that I understand intuitively why the above quantity is invariant. Can someone explain to me?

For me it should rather be something that expresses that light travels the same distance in every same dt, so maybe rather cdt = cdt' but then again dt and dt' are in general different right? So long since I did SR

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# The minkowski metric

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