Dumb question: In special relativity, if you have a traveler

>>7673523
Yes, but keep in mind that since they are both in inertial frames, they will BOTH measure proper time in BOTH cases. They will both see time passing slower for the other person compared to their own time- the proper time for themselves is evaluated with v = 0, so the integral is just coordinate time, whereas the other person will have a nonzero v and thus a lesser proper time.

>>7673523

OPs pic gives missing info. The earth moves around the sun, as the sun moves around the milkyway as it rotates around the center of the universe.

So even a tiny millisecond jump in a time machine would displace you the fuck away from earth

>>7673523
There is no "proper time" all observers will measure their time to be proper from their point of view.

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>>7673561
"Proper" time as used in physics means the observer's own time.

>>7673523
Yes.

>>7673523
I think relativity seems to rely so heavily on logical loopholes because it's really a severely misframed version of a picture we've just begun to scratch the surface of.

>>7673548
Which reference frame is this in?

>>7674357
It doesn't matter, it's all clearly happening.

>>7673548

Gravity keeps me in the planet as i travel 1 second per second into the future.

>>7674358
Just as the sun is clearly revolving around the Earth? Relativity denies the existence of absolute frames of reference, so how can you say "when traveling through time, a person stays in the same absolute spot"? You'll have to play with inertial frames of reference to get any kind of answer.

>>7674374
Without an absolute frame of reference, yes, the sun is orbiting the Earth... if you're the sun.

This is a disjointed mess. Perspective matters as far as how things will appear to you, how distance works, and how time works, but all this says absolutely nothing about an absolute frame of reference. It just indicates nothing can have it, not that there isn't one to be had (or more likely, accessed).

>>7673548

Right, except the entire comic strip depends on some sort of notion of absolute rest. Which doesn't exist. We're in a thread about relativity for christ's sake, you would think someone would have picked up on that.

>>7674380

Of course there's no absolute reference frame. Or do you think that any time machine will magically know exactly where the center of mass of the universe is? HAHA

>>7673523
>In special relativity, if you have a traveler moving at a velocity v and an observer at rest, can you treat it as the traveler at rest and the observer at moving at velocity -v? In the first case, the traveler would measure proper time, but in the second case the observer would measure proper time?

Yes because time dilation is an optical illusion in SR

>>7674445
And yet things exist. Things have a position in space. Things move directions, things have all that stuff. I haven't the slightest how you can make it work without an absolute reference frame.

Even the idea of velocity suggests it. The notion of directionality practically requires it.

>>7673548
Maybe it would help to know that theoretical time machines imagined by physicists have been more like space-and-time tunnels with an existence at both ends. If there is a point in one of those where a traveler would be caught by a hidden frame of absolute rest then it is not obvious where it would be.

>>7674451
I'm tempted to say "shit just exists, and moves and has velocity and direction in relation to everything else." Is this a completely absurd idea for me to even consider?

>>7674588
I would say so. If everything just moves relative to everything else, it's just an indirect way of describing absolute positions.

I can look up at the light emitted by the north star. It traveled here at a speed, and it took time to do so. With enough time, I could do the same. I could stop being here and become there. Why? How? Reference frame doesn't matter. It doesn't matter what I'm looking at. It doesn't matter what's looking at me. If it's physically possible to arbitrarily move from point A to point B, and one does it, that implies the existence of absolute positions.

I'm not a physicist. I just want to know what really makes it all tick.

I've seen this "earth moving during time-travel" question so many time, i'm finally gonna answer it.

It just doesn't make any sense to move in time, and stay at the same place! And you don't need Einstein relativity, Galilee's is enough! There is no absolute speed (regadless of the description you use), so staying still just doesn't make sense.


For OP's question, it's a good apparent paradox of special relativity : depending on the point of view i get contradictory results.
Well, not exactly, cause you can't compare duration from differents point in space : if the 2 persons are billions of kilometers appart, it's quite difficult to determine wich is the oldest!
And if they come back toward each other at some point, one of them has to accelerate (at least), and therefore the situation ain't symetric any more!

In special relativity, you've got to be extra-careful about what you observe, and from where! only things at the same place same time can be compared, just doesn't make sense to ask yourself : "is my d*ck bigger than a imperial destroyer coming toward us at 0.99 c, at the other side of the galaxy"

>>7674595
>If everything just moves relative to everything else, it's just an indirect way of describing absolute positions.
That's very true. People can take "relativity" a bit too literally, the simple fact that "everything can be measured relative to everything else" exist within all topologies (such as traditional Euclidean space).

In a sense, there are absolute positions in relativity. There kind of have to be or you're describing something rather absurd (or at least incomplete). But the thing about General Relativity is that those positions do not exist within a static three-dimensional space in which things move around to with respect to time, but rather those positions exist within a four-dimensional space-time in which every point in space-time has an orientation of "time" that is relative to its position in space-time (but isn't so different from others that they ever contradict). The exact description of the topology of this space time is something extremely mathematical and not something I'm going to pretend to understand fully well (having only a passing interest/knowledge in it), but I don't think it's that hard if you really want to learn it.

So, to bring it back to the original context, "going back in time" in the old Euclidean (3D space with things moving around in it) is a simple matter of taking a position in that 3D space and putting it at that same point at a different time. But in Relativity, since time is not an independent axis, "traveling back in time" requires some inventive interpretations to even guess how it would behave.

>>7674339
More like a subject you've just begun to scratch the surface of.

>>7675836
Yes.

>>7674612
>That's very true. People can take "relativity" a bit too literally, the simple fact that "everything can be measured relative to everything else" exist within all topologies
Nobody is taking it too literally. There is no absolute reference frame in any topology, because the coordinate system is always arbitrary and can be transformed to any other coordinate system. They are all equally valid.

>In a sense, there are absolute positions in relativity. There kind of have to be or you're describing something rather absurd
I'm sorry that the universe is a little too absurd for your brain to handle

>The exact description of the topology of this space time is something extremely mathematical and not something I'm going to pretend to understand fully well (having only a passing interest/knowledge in it), but I don't think it's that hard if you really want to learn it.
It apparently is hard to learn because you don't get it.

>>7673548
>>7674358
>>7674380
>>7674451
>>7674595
Not you again. We already gave you everything you need to teach yourself about relativity. Stop fighting it and just accept there isn't an absolute reference frame. Claiming things exist is proof that relativity is incorrect is the same as claiming God's made us because we exist.

>>7675875
Directionality. Location. Speed.

If the motion of all bodies can only be considered relative, it necessitates the existence of an absolute. I'm sorry that you're an undergrad trapped in an awkward intermediary stage of being unable to see a picture, nor convince others of the coherence and elegance behind your supposed understandings. You sponged up what you think is relativity, congrats. Why are you having so much trouble making me see things your way? Hint, you can tell yourself it's my own deficit all you want, part of you doesn't actually believe it.

>>7675906
>I'm sorry that you're an undergrad trapped in an awkward intermediary stage of being unable to see a picture
I'm sorry you're a NEET that can't understand that more than one picture can describe what's going on.

>If the motion of all bodies can only be considered relative, it necessitates the existence of an absolute.
How? Please be rigorous and detailed and show me step by step how "motion of all bodies being considered relative" leads logically to "the existence of an absolute is necessary." This is a new thread, so there's no way to vaguely refer back to old posts that do nothing to help your case.

I have already talked to you in the past about this. The fact that the speed of light is constant to everyone implies there is no absolute reference frame. Two people moving relative to each other at constant velocity will feel stationary from their own pov. Even when one accelerates relative to the other, they will feel stationary but experience a force. I can't make it any more clear, the rest is up to you to figure out.

>>7675906
It doesn't necessitate it. The only absolute you need for the universe to make sense is C.