# What does it mean to move through time?

Tags: time
P: 3,187
 Quote by goodabouthood [..] Also, is there no such thing as a true stationary object in our Universe? For example everything seems to be moving around something else. Now if all the motions of the Universe were frozen, would time be frozen? What I am seeing for time in my mind is movement. I still am confused.
Yes, "time" depends on movements: from the start, the concept of time has been based on natural clocks such as the solar day. If everything is frozen then all clocks are frozen as well.
P: 244
 Quote by bobc2 It is quite common in discussions and writings on special relativity to see the concept of observers moving along their world lines (their own rest system time axis) at the speed of light. Here is a space-time diagram showing a black rest system with a blue inertial frame in motion with respect to the black coordinates. In this sketch we use proper time to show the points corresponding to arrival of black and blue guys after 30 years of travel at the speed of light (events A and B). Event C is the point of arrival for the black guy after about 26 years of travel. If the black guy is at event A after 30 years along with the blue guy, how is it that the blue guy can "see" him back at the black 26 year event C? I know you will say it's just time dilation, but physically how does it happen?
It's a very nice question Bob, and one that have me question both 'distances', as well as 'time'. Defined from my view, which then will be a idea of 'locality' the local 'time/clock' always will be an invariant, a 'constant' coupled to 'c'. But if I then look at some other frame of reference like something moving relative me they will seem out of 'sync' with my definition of my clocks durations. And as the Lorenz contraction must be a 'symmetry' in my book, to make sense of what 'A' sees, relative what I see, then the question to me becomes one of what a 'distance' really is, as well as that time dilation.

If I define it from locality then what you see will be your reality, as what I see will be mine. The reason we find them different is conceptual, meaning that to do this we have to compare our frames of reference relative each other. What that states to me is that you at no 'time' or 'place' ever will find a contradiction, other than conceptually, when comparing.

But it doesn't answer the question of why it can happen, it just give me a reason, which then, to me, must be 'c'.

If distances and time is 'plastic' relative motion, mass (& energy, whatever that is), then SpaceTime is plastic. And the 'plasticity' is defined locally. But we also have this 'radiation propagating' (and gravity). Radiation is what you observe, all measurements are done through, and in, it. Radiation is the constant 'c' joining my definition of a 'distance' and a 'time' to yours through Lorentz transformations.

Gravity is something else, it's coupled to mass and to me representing a 'constant inertia' relative accelerated (uniform, but to me as I define it as inertia, all) motion. We define it in 'displacements' relative some positional 'point' (inside times arrow 'locally' defined). To see what I'm aiming on here we need to consider the equivalence principle, making all 'mass' constantly uniformly accelerating..

In fact, looking at this way there is no motion without a 'inertia' involved, at some stage, even though 'uniformly moving' at some later stage. That we can't define where that uniform motion came from doesn't state that there wasn't a 'inertia/acceleration/gravity' involved at a initial SpaceTime point. Although the idea of a 'inflation' makes it somewhat tricky.

And then we have mass.
And 'energy' as some weird idea of a 'ground state', as I see it.

But compare that to indeterminacy.

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