Recent content by Friggle

Does that mean you are talking about an absolute spacetime geometry, independent of an observer? That sounds great to me, actually, I just thought that such an absolute spacetime was explicitly negated by the relativity theories. There is no one-and-only reference frame, right? Wouldn't an...

The reason why I prefer to think about the path through spacetime in the frame of reference of the observer is that this allows me to think of time and ageing being an effect caused by an object moving through some background space. Even if it is not a space in an absolute sense but rather some...

This is surprisingly insightful to me: Much about the apparent contradictions and misinterpretations about SR out there to me seem to stem from exactly this often incorrectly or imprecisely perceived picture: I was always thinking of relative speed in terms of a varying distance between objects...

Got it. Thanks.

You mean, a straight line vs. a helix in direction of the time coordinate. Correct?

Great! Think I was confusing speed with velocity!? Is relative speed the first derivative of distance between objects, while velocity is the first derivative of position? Then SR and time dilation are all about velocity and not about speed. True?

First, thanks to all of you, that has already helped a lot, overall. I again stumbled on the above from PeroK: I now fully agree that it's proper acceleration, since somebody in the rocket clearly could measure it using just a local accelerometer. So, that's just fine. What I'm struggling with...

I feel that this one really helps. Need to let this sink in for a while, thanks :-) Seems that if I know my own acceleration (the acceleration of my reference frame which I can measure locally with an accelerometer) and then observe the velocities of other objects within my reference frame I...

I agree, and I didn't intend to express any doubts to this. What I meant is the whole acceleration profile instead. This certainly also includes all times where acceleration is zero but time is spent in the accelerated state. And clearly, the bulk of time dilation comes from these...

Admittedly, this is a nice analogy but I feel it doesn't quite fit the purpose: I'm not asking for the relative speed of the objects in the experiment (which would be responsible for the speed ticket). I'm interested in their accumulated ageing, and it seems that the acceleration profile is...

I get your point here. But the allelerated mass in terms of energy or momentum is still clearly the rocket. And this acceleration to its tangential speed has been brought in in its past. Isn't the centripedal acceleration youbtalk about only coordinate acceleration as opposed to proper acceleration?

Certainly agree, that one was nonsense ;-)

OK, so I summarize my current understanding: 1.) When two objects move relative to each other and "look" at each other, then the way or magnitute they recognize or measure things like distance, speed or time with respect to the other object solely depends on their relative speed. The history...

And back to the not-occuring time dilation between cl1 and cl2 in Exp 1 above: Is there some well comprehensible statement (ideally in natural language without maths) why the velocity between cl1 and cl2 does not matter? Time dilation between them is always zero, right? No matter how fast they...

Thanks to both of you! Doesn't GR say that in proximity to mass (i.e. in a gravity field, i.e. curved spacetime), time goes slower? And since gravity is the same as acceleration I thought that there should be some share of the observed time dilation between cl1 and cl3 or cl2 and cl3 caused by...