/sci/ - Science & Math

Why? it's just a theory a guass

What a troll question. Radio waves are always at c.

both, that's the point of relativity. if you are asking how that is possible, it is because time changes in exactly the correct way to make it possible.

>>3593170

But how? How can they be C relative to both the spacecraft and the green planet?

>absolute reference point

What is that?

>>3593182
That's the entire point - the speed of light is the same in all inertial reference frames. You're just saying it doesn't make sense to you, which is perfectly understandable.

>>3593182
Because they are waves in space, dude

>>3593182

from wiki:

1. First postulate (principle of relativity)

The laws by which the states of physical systems undergo change are not affected, whether these changes of state be referred to the one or the other of two systems of coordinates in uniform translatory motion.

2. Second postulate (invariance of c)

As measured in any inertial frame of reference, light is always propagated in empty space with a definite velocity c that is independent of the state of motion of the emitting body.

see, postulate number 2.

>>3593188
I think they're just defining all of the velocities relative to it

>>3593182
>How can they be C relative to both the spacecraft and the green planet?

Because the frame of reference in which the planets are motionless and the frame of reference in which the spacecraft are motionless are different, and thus will experience different distances and durations.

>>3593189
>That's the entire point - the speed of light is the same in all inertial reference frames. You're just saying it doesn't make sense to you, which is perfectly understandable.

:(
I created this thread because I wanted someone to help me understand it.

>>3593188
>What is that?

I am aware that there is no such thing as a real absolute reference point. That's why I specified that it's a "theoretical" absolute reference point; IE, a point that has been arbitrarily designated to be "absolute".

Here's a better and simpler diagram of my question.

>>3593203
>I think they're just defining all of the velocities relative to it

Ok, but there is no such point such that all of those velocities can be correct.

If the planet is moving 0.1C relative to the reference point, and the ship is moving 0.1C relative to the planet, then the ship CANNOT be moving 0.2C relative to the reference point. Velocities do not add like that.

>>3593182
Galilean velocity transformation is wrong. It's only even approximately right for low relative velocities.

V_relative =/= V1 + V2.

>>3593207
Even before Einstein, scientists had discovered that light always moves at the same velocity despite your reference frame. The problem was reconciling this with our physics, which said that if you throw a ball at 1 m/s while you're moving at 1 m/s, then the ball appears 2 m/s to someone stationary. Einstein worked out that space and time both distort when you get to high velocities. You measure velocity in distance/time, so if you change the values of distance and time, you can always get the same speed. And that's what happens: as you move faster, your time gets slower, and your lengths get smaller, so that every reference point always observes the speed of light as c.

>>3593214

time slows down/space gets stretched in weird ways so that the speed of light is the same in all reference frames.

If your time moves slower, you perceive light as moving faster. Hence it all works out in the end, light always travels at exactly c.

>>3593204
>Because the frame of reference in which the planets are motionless and the frame of reference in which the spacecraft are motionless are different, and thus will experience different distances and durations.

Explain, then, the exact relationship between the two reference frames in the diagram in >>3593214, where the relative speed of the spacecraft from the planet is 0.1c. What about that relationship causes the light to appear to be moving at exactly C in both reference frames?

Quite simple. Light doesn't have mass, so the speed of the object which emits it doesn't influence the speed at which it travels relative to any chosen frame of reference.

>>3593242
>If your time moves slower, you perceive light as moving faster.

So... shouldn't the light relative to the spacecraft be perceived as moving 1.1c, or something?

>>3593262
No, because time looks different to the spacecraft.

Light is ALWAYS at c. It's time and space that are fuzzy.

the spaceship is aging a little slower than the planet, so when he looks back at the planet, he sees the waves arriving slower than c, but for the planet, it would be c. same way in reverse. the planet would see the spaceship traveling lower in time. or is that backwards?

>>3593269
>he sees the waves arriving slower than c

NOPE.

>>3593267
>Light is ALWAYS at c. It's time and space that are fuzzy.

The problem is that you're being vague. You're giving generals, when I'm looking for the specifics of a given scenario.

Take the scenario in the diagram in >>3593214. If the spacecraft is moving away from the planet at 0.1c, what exactly is the relationship between the passage of time in the two reference frames, that causes the light to be perceived in both as moving at exactly C?

>>3593244
http://en.wikipedia.org/wiki/Velocity-addition_formula#Special_theory_of_relativity

http://www.youtube.com/watch?v=6rl3Z9yCTn8

watch all 4 then come back with any additional questions

>>3593276
i meant from his perspective and using normal speed addition, should be faster (it was backwards), as he sees the wave traveling at c and the planet at 0.1c he will think it is arriving at 1.1c if the pilot didnt know relativity.

>>3593262

If you look in your original pic, you claim that the planets are each moving at .1c relative to the black dot, the spaceship is moving at .1c relative to the planets, so the spaceship is moving at .2c relative to the black dot. This is actually incorrect, once you get up into the range of velocities approaching c, velocities no longer add.

If you truly want to understand relativity you have to go through the math. It's technically described here but it's never easy to learn math for the first time with wikipedia:
http://en.wikipedia.org/wiki/Lorentz_transformation

If you've taken linear algebra you might be able to follow this:
http://www.physics.umd.edu/~yakovenk/teaching/Lorentz.pdf

This site seems all right:
http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/ltrans.html

One thing to remember when reading these transformations is that they relate two entire coordinate systems, not just positions in space or time. When they say " x' = x/(...) ", they mean for any x in the primed reference frame and any x in the non-primed frame.

>>3593269

No. Both see the light traveling at C. Each is aging slower in the other's reference frame. All effects are symmetrical.

you are over complicating the thing. take the planet as the reference and let them be stationary, let the plane fly at 0.1c

>>3593296
This looks very good so far (not OP)

OP, it sounds like what you want is a basic introduction to special relativity. /sci/ should not be that introduction. I'll try and find something that is clear and simple but sufficient to explain length and time contraction, but I don't have anything offhand.

>>3593311

yeah but there's no math...it's not exactly true, if you really want to understand this stuff you've gotta go through the math.

>>3593320
I haven't hit their SR part yet, so I can't comment. Their explanation of classical relativity was very good, and now they're leading in to a discussion of the speed of light and special relativity.

I agree that if you REALLY want to understand, you need the math. But this documentary is a hell of a lot better than just being confused.

>>3593305
yes, thats why the speed of light isnt really different for them. it only appears to be because of that effect.

>>3593154
but there is no absolute reference point.

>>3593344
>really different
Really according to whom?

In any case, light always moves at c.

OP here, I just paused at 6:17 in the second video.

Why does the person with the "moving" clock perceive the "still" clock as moving slower? Shouldn't he perceive the "still" clock as moving faster?

>>3593378

In other words, when the "mover" arrives at another planet, and contacts the "stander" on the original planet, more time would have elapsed for the "stander"; so the "stander's" clock would have HAD to have been moving faster.

>>3593370
according to SR

>>3593384

Or does the difference only arise during acceleration and deceleration?

>>3593378
No, because according to the bottom ("moving") guy, he is actually sitting still, while the top ("still") guy is the one moving. In other words, the animation is from the perspective of the top; if it were from the perspective of the bottom it would look exactly the same.

>>3593384
>>3593390
We're dealing with inertial reference frames (no acceleration).

And everyone sees relatively moving clocks as running slow. The video just bases everything on the ASSUMPTION that everyone records the same speed for light, but the need for that result is very fundamental. They mentioned it briefly when talking about electromagnetism. Either the Maxwell equations were wrong, or Galilean velocity addition is wrong (or the third option is that the universe does not have consistent physics, but no, that's not what we see). Turns out Maxwell was right, the speed of light is a constant for all observers, and moving clocks seem to run slow.

We don't agree on WHEN things happen, because simultaneity is relative, but we agree on WHAT happens.

>>3593395
Right. Top clock says the bottom clock is "moving", and vice versa. Just like when you're in a car, and things are speeding past you. Velocity is relative, and there is no absolute reference point.

>>3593400

The question I'm asking, however, is why, when the person on the starship returns to the earth, all his grandhchildren are older than him. If he always perceived earth's clocks as moving slower than his, then there's no room for them to have suddenly sped up and resulted in the passage of many years during his absence.

>>3593400

>And everyone sees relatively moving clocks as running slow.

What? No. If you're moving away from them, yes, towards them = speed up. If we're talking about near-light speeds.

>>3593416

>>3593412
Ah, that's the twin paradox.

The trick is that he SWITCHES reference frames when he turns around, while the people on the planet do not switch frames.
http://en.wikipedia.org/wiki/Twin_paradox#Resolution_of_the_paradox_in_special_relativity

>>3593416
You're confusing relativistic doppler shift with time dilation.

>>3593429
(cont)
Basically, while making the acceleration to turn around, the traveling twin sees the clocks on Earth go really fucking fast. What he sees while he is accelerating is a non-inertial frame, and special relativity isn't enough to detail this. SR can tell you what happens before and after the acceleration though, and GR can tell you what he observes while accelerating.
http://en.wikipedia.org/wiki/Twin_paradox#Viewpoint_of_the_traveling_twin

Alright. I'm going to summarize the impression I'm getting from these videos. The videos are not stating this explicitly, which makes me worried that I might be fucking this up.

Lightspeed is the impossible speed. All speeds are equally infinitely less than lightspeed. If, for example, you were to choose the planet earth as your arbitrary absolute reference point, and start flying away from it, constantly accelerating, you would perceive that light almost seems to be accelerating "with" you, in that you're not getting any closer to its speed. However, due to length contraction (?), the earth appears to be accelerating away from you at an increasing velocity which slowly approaches the speed of light.

Am I completely off, here?

>>3593456
Hmmmm.... I don't really understand what you're thinking, so we haven't really connected yet.

Everyone sees light moving at the same speed in vacuum. The distances and times we measure depend on the relative motion of the people doing the measuring.

Nothing with mass can reach a relative velocity of c to anything else with mass. In this sense, the speed of light is the ultimate speed limit. You could reconfigure your definition of velocity to put c at infinity, but that would mean redefining your units of distance and time in equally unusual ways, and there's no need to do it that I'm aware of.

>>3593472
(cont)
However, what you said about what you observe about light and the planet are both correct. Light beams always move away from you at c, while the planet gets closer and closer to c as you continue to accelerate. But no matter how much or how long you dump energy into accelerating, you will never see Earth receding at c.

>>3593472
>Hmmmm.... I don't really understand what you're thinking, so we haven't really connected yet.

Okay. Let me describe a hypothetical experiment.

You have a spaceship. This spaceship has as much power as you want it to have. Not infinite, but as much as you could possibly care to equip it with. You're going to use this ship to try and accelerate as close to the speed of light as you can.

Onboard the spaceship, there is a device that shoots a ray of light, forward (in the direction of travel, away from the earth). In front of this device is another device, that detects the light hitting it, and tells you how long the light took to cross the distance between the two devices; in other words, the device measures the speed of light, relative to you, while you're travelling.

Now, you set off from earth, accelerating. Behind you, earth zips away, growing more and more distant, at a speed approaching the speed of light.

But, no matter how fast you go, your twin devices keep giving you the same reading for the speed of light. It's still faster than you by the same degree. You're not getting any closer to it. Therefore, it seems to be accelerating "with" you, counterintuitively.

>>3593497
Yes, you've got the observation right.

A deep understanding of WHY all this is makes any sense requires a lot of math and thinking, not to mention the observations that tell us this is what the universe is really like, and not just a neat idea. It comes down to the physics of the universe obeying a Lorentz transformation rather than a Galilean one.

>>3593520
>A deep understanding of WHY all this is makes any sense requires a lot of math and thinking, not to mention the observations that tell us this is what the universe is really like, and not just a neat idea. It comes down to the physics of the universe obeying a Lorentz transformation rather than a Galilean one.

That's not really the "why", though; that's the "how". Measuring just how much the clocks seem to dilate when perceived from different reference points, and all that. That's all quantification, but it's not qualification.

The qualification – the why – is a simple property statement: lightspeed is, relative to itself, infinite. It is impossible to get any closer to lightspeed than you're already going, even if you are constantly accelerating relative to some other point.

A question, though: if, for the spaceship, a 10-lightyear journey only lasts a week, and fuel is burned at the same rate throughout, do the people on earth, for whom the journey seems to last several years, perceive the spaceship's fuel consumption as dropping to a very low level once the spaceship is near lightspeed?

>>3593537
>A question, though: if, for the spaceship, a 10-lightyear journey only lasts a week, and fuel is burned at the same rate throughout, do the people on earth, for whom the journey seems to last several years, perceive the spaceship's fuel consumption as dropping to a very low level once the spaceship is near lightspeed?

Yes, because in the Earth's reference frame, time on the ship is moving very slowly.

>>3593552

Alright. Next question.

As the astronaut's ship accelerates, signals from earth start reaching it at a slower rate, from the perspective of earth. But wouldn't, due to time dilation, the signals appear to start reaching the astronaut faster? The people on earth start receiving his replies at a slower rate; but shouldn't he be receiving theirs at a faster rate, relative to his own perception of time? The video said he would perceive the people on earth as slowing down.

>>3593537
>simple property statement: lightspeed is, relative to itself, infinite.
this statement is simply false. there is no such thing as a reference frame of light.

as for the whole post, you lost me there a bit. light travels at the speed of light in a vacuum from any inertial frame of reference, and that is all. all effects that it brings with it are understood through mathematics, and without it, you cannot fully comprehend what is going on. you have all the basic ideas behind special relativity, all that is left to do is to explore maths of it if you want to have deeper understanding of why

>>3593563

Er, wait. His perception of time would be slowing down at the same rate his receipt of signals would; so while he's accelerating, he would NOT perceive time on earth slowing down. Would he?

And then when he stops accelerating, and is going at a constant speed, he should start receiving messages very slowly. Then when he starts decelerating, the messages start reaching him more quickly, though still not at normal speed. It's only once he's back at the same speed as earth that he starts receiving messages in realtime, but they're delayed.

Then when he turns around and starts heading back, the signals start reaching him really fast, and it's like time on earth is rapidly accelerating. When he arrives home, his grandchildren are older than him.

It makes sense. It's the Doppler effect, applied on relativistic scales and terms.

>>3593565
>this statement is simply false. there is no such thing as a reference frame of light.

But it's only false because it's impossible to have a reference frame of light, because time wouldn't pass in it; all speed would be infinite. Hence, the statement is, at least for practical purposes, if not in technical truth, accurate.

>>3593537
Well, the speed of light being constant in ALL reference frames is a POSTULATE of special relativity. All attempts to derive the lorentz-transformation (the set of equations that quantifies the change in time and length) without this postulate have failed thus far, as far as I'm aware at least.

>A question, though: if, for the spaceship, a 10-lightyear journey only lasts a week, and fuel is burned at the same rate throughout, do the people on earth, for whom the journey seems to last several years, perceive the spaceship's fuel consumption as dropping to a very low level once the spaceship is near lightspeed?
Well, the amount of fuel used is the same for both reference frames - that is non-negotiable.

Now for you, the journey took so and so long. And assuming your fuel-consumption is constant, you could divide the mass you burned divided by time.

From the earth, you took a lot longer, so doing the same calculation, wouldn't somebody on earth conclude you had a different, i.e. lower rate of fuel consumption, then?


Besides, there's the problem that the momentum as seen from earth isn't p=mv anymore, and the fact that you are accelerating, where we'd have to apply general relativity.

Dunno if any of my rambling is consistent, I'm tired.

Ooh! Another question.

A spaceship is flying in a circle around the sun at near lightspeed. Does the astronaut in the spaceship still experience time dilation relative to the earth, or can he only experience time dilation if he is travelling towards or away from the earth?

>>3593630
http://www.popsci.com/science/article/2010-09/superaccurate-clocks-prove-your-head-older-your-feet

>>3593630
Uhh... If it moved around the sun, it would also occasionally move towards as well as away from the earth.

If you mean it flies around the earth: the answer is yes, there is time dilation.

>>3593648
Here's a thing: time dilation isn't dependent on moving relative to another object. It's dependent on /moving/. A rotating object experiences time dilation relative to another, with the further out parts experiencing more than the inner parts.

>>3593648
>Uhh... If it moved around the sun, it would also occasionally move towards as well as away from the earth.

I mean, it's so far away from the sun that, moving at near-lightspeed, it completes a circuit of the sun in one year, and thus is always the same distance from the earth. I didn't think to specify something like that, sorry.

>If you mean it flies around the earth: the answer is yes, there is time dilation.

:/
But it has zero velocity relative to the earth. It changes *direction* from the earth, relative to other objects, but not distance.

>>3593655
>Here's a thing: time dilation isn't dependent on moving relative to another object. It's dependent on /moving/.

:S
But you CAN'T be moving, EXCEPT relative to something else. ALL motion is relative. No motion is absolute.

>>3593672
If you accelerate, you FEEL it, like being "pushed" into the seat of your car. More acceleration means that you're being "pushed" harder

And for circular motions, being farther away from the center of rotation = higher force/acceleration.

>>3593672
In rotational motion, the edges are moving relative to the center. I think that's all he meant.

>>3593681
>And for circular motions, being farther away from the center of rotation = higher force/acceleration.
You've got that backwards, I think.

>>3593687
From an outsider's view, you'd say a person in a circular orbit would need a higher centripetal force applied to him to be kept in orbit the higher the radius is.

From the point of view of a spaceship that is rotating around, say the sun, with the windows closed, you'd feel a force. By Einsteins equivalence principle, it's no different from a gravitational force, you couldn't tell.
Without knowing what the fuck is going on, you don't know there is actually a centripetal force anywhere.
I was referring to the latter in >>3593681

>>3593682
>In rotational motion, the edges are moving relative to the center. I think that's all he meant.

But how do you know you are? For all you know, the center of mass of the nearest fifty galactic superclusters could, by chance, happen to be residing currently in the middle of our sun, with everything in the nearest 500 megaparsecs revolving around that point, in which case the spaceship might actually be moving much slower than you could measure just from reference points alone.

There are no absolute reference points: only relative motion can be measured, or is relevant in physics. So, while the spacecraft might have a high relative velocity compared to Neptune or a distant star, it still would only have very low relative motion compared to the earth; and therefore there should not be significant time dilation.

>>3593672
Except all relativity has at one of it's cores: locality.

For someone traveling near c, it doesn't matter whether they're traveling towards or away, the time dilation is the same.

>>3593702
>From an outsider's view, you'd say a person in a circular orbit would need a higher centripetal force applied to him to be kept in orbit the higher the radius is.
No, I still don't think that's right. a = v^2/r for circular motion.

>>3593714
...which is equivalent to ω²*r.
Sine the spaceship was supposed to be aligned with the earth, they better have the same ω.

>>3593703

Nobody's responding, so I'll say what I think might be the rebuttal to this.

While movement and position are not absolute, direction is. (Or at least, mostly is. It might experience some bendiness in the presence of gravitational fields.) Therefore, rotational movement around the sun, keeping the same distance to the earth, would still be relative motion to the earth.

>>3593703
>>3593748
Do you know how a circular orbit comes about?
There needs to be a force directed to the center of the orbit.
As soon as forces are at play, there's acceleration.
Accelerations are not relative. You better believe you will feel them somehow in your spaceship.
But the earth would feel a different acceleration than you would, if both were to orbit with the same angular frequency ω.

You don't even need relative motion for time-dilation to occur. Even different positions in a gravitational field can cause clocks to move differently.

>>3593771

Alright. How about two satellites, both in low-earth orbit, making many circuits of the earth per day, and keeping the same relative orbital positions to each other. They're both the same distance from the center of gravity; they're both moving at the same speed around that center of gravity; but they *are* revolving around each other, from the perspective of the other, with respect to the fixed stars. Do they experience time dilation, relative to each other? Or do they keep the same time?

>>3593785
>same relative orbital positions
>moving around eachother
wat

>>3593785
>they *are* revolving around each other
How would they?
>with respect to the fixed stars
The stars aren't gonna look fixed at all when you are revolving around the earth.

I don't seem to understand you scenario. Can you clarify?

>>3593800
>>3593803
>How would they?

Guys. Think about it. The satellites are in 1:1 resonance with each other. The entire three-body system (the earth and the two satellites) is rotating with respect to the fixed stars. From the perspective of each body, it looks like the other two are revolving around it at the same rate.

>>3593785
>from the perspective of the other, with respect to the fixed stars.
This is a contradiction.

>>3593785
There would be no SR time dilation, and since they experience the same acceleration, there would be no GR time dilation either (between the two satellites).

>>3593828
>fixed stars
by the way, are we re-inventing an absolute reference frame now, which we have previously established to be bullshit?
Anyway, I'm goin got bed now.

>>3593849
>This is a contradiction.

No it is not. See the post above yours, for an explanation.

>>3593861
>by the way, are we re-inventing an absolute reference frame now, which we have previously established to be bullshit?

The "fixed" stars serve only as absolute rotational reference points; they do not serve as absolute positional reference points.

At least, that's my understanding.

>>3593896
> absolute rotational reference points
what

>>3594072
>what

Dude. If you have no absolute rotational reference points, or anything approximating them, then there's absolutely no way to tell if a system is rotating. In which case, my last spaceship scenario is valid, and no time dilation would occur.

>Thread about relativity
>Josef: Ctrl+F, "increas"
>One result, "increasing", that doesn't refer to mass increasing with velocity
/sci/, I am proud

>>3593182

Different wavelenghts from different perspectives. In relativity, instead of light changing speed when seen from different platforms, it changes frequency to make up the difference.

Just as change in speed -> change in energy, so does change in frequency.

>theoretical absolute reference point

what

>from which of these points will the speed of light be c?

All of them, everywhere, always.

>>3594267

He means just an ordinary reference point. The fact htat he's taking speeds in reference to that point is confusing him, he's wondering how the fuck like can come back at c from all those differently moving objects.

>>3594164
>If you have no absolute rotational reference points, or anything approximating them, then there's absolutely no way to tell if a system is rotating.
Sure there is. Look for a fictitious centrifugal force.

>>3594293
>He means just an ordinary reference point

An ordinary reference point would be relative like the others.

The problem is that the universe does not allow for an absolute reference point, and trying to shoehorn one in is just going to break the physics you're trying to employ as a tool to get answers. End result: completely nonsensical answers.

tl;dr: we don't have the luxury of ignoring known physics

ive always wondered how the hell time dilation works, since there is no absolute reference point.
if im in a spaceship going .9c away from earth, then turn around and go back to earth the same way, how would the pilots grandchildren be older than him? its simply two objects pushed away from each other, then pushed together. why does one age faster than the other?
they move away from each other, and therefore are each others reference points equally.

>>3594431

The space ship is the one gaining kinetic energy, and therefore relativistic mass.

>>3594431
Dilation happens when they accelerate. Earth does not accelerate.

>>3594468

Earth is always accelerating.

>>3594431

Because of the turnaround. You're right, the phase of smooth motion is completely symmetrical. However, only the spaceship undergoes acceleration, when it turns around. This shifting across a whole range of reference frames "locks in" the time dilation, and introduces the asymmetry that means that the spaceship crew experience much less time than the guy on earth.

>>3594477

That's not the point, we're idealizing things. And in any case the acceleration is much less and more gradual than that undergone by the rocket.

>>3594477
Yeah, sure. As fast as that starship.

>>3594431
>>3594431
this is just the twins paradox, it's like the oldest one in relativity...

and it's because one of the objects in question was rapidly accelerating and decelerating, i.e. it did not remain in the same inertial reference frame

>>3594449
so the speed is irrelevant? only acceleration, or gaining of momentum influences time dilation? also fun to think about, to the veiwpoint of the spaceship, the universe is gaining momentum in the opposite direction.

>>3594513
Acceleration isn't relative.

>>3594529 herp derp. i know it isn't relative.
i said its fun to think about.
so to be clear if i go .999c relative to earth my time is no different? that makes a bit more sense to me.
one more stumbling block down.

>>3594556

Except for the whole issue of getting to .999c in the first place.

>>3594569
thank god i have that one figured out now. ive raged against the idea of faster objects experiencing time slower.
100 Internets to you sir.

>>3594513

The speed creates time dilation, but it's only while they're moving. If the two objects are ever to come back into contact and be at rest relative to each other, it's the acceleration that determines the amount of "final" time dilation that they experience.

Imagine their world lines tracing out through space time, and curving back together. The length of the world line indicates how much time dilation has been experienced by the end of the journey, but because this is non-euclidean space-time it's ass-backwards, and a longer world line means less time experienced.

Thus the longest world line measured from separation of objects to their reunion will experience the least time. The longest line will be the one that is bendiest, with the most curves. and curves in a world line are equivalent to acceleration.

Thus it's acceleration that determines which twin has aged the most by the time they get back together.

This point is often missed by the usual explanations of the twin "paradox". They focus too much on the world likes being at angles to each other - relative motion- rather than on the overall length of each world line, which is the critical factor.

>>3594468
>>3594513
>>3594529
>>3594569
>>3594620
>>3594621


Blind leading the blind. Relativity has ABSOLUTELY NOTHING TO DO WITH ACCELERATION.

Jesus fucking Christ. Light doesn't accelerate, morons. It's just travelling at c; and yet for a beam of light there is no passage of time. i.e. nothing to do with acceleration.

>>3594620

You, in particular, are a fucking tool who have allowed yourself to form a totally incorrect notion of what time dilation is.

>>3595564

Shut up you fucking lemon. The twin paradox is entirely dependent on acceleration making a difference between the world lines of the two twins. Until that acceleration phase, both twins can accurately say that the other twin has aged less than they themselves have.

The fact that you don't understand this indicates that you have only a layman's knowledge of relativity. Even an introductory mathematical treatment covers this topic in detail.

>>3595564

Alright then why does one twin show more aging more than the other one, when they are both back on earth?

If it's just the inertial motion that matters, both can equally well say that the other is the one who has moved, so why is there a difference in their aging when they are both back in the same frame and their aging can be compared?