If time is the same for the universe, then how does any of the guys here explains "the effect of the twins " according to Einstein's theory?? — vesko

Check: Twin paradox

Time dilation has been verified, and is in use.

thanks jorndoe.
It is difficult for me to understand this paradox but as you say it is verified with tests.

This and this are almost entirely maths free descriptions of special relativity's use of the speed of light as 'cosmic speed limit' and how it has a consequence of time dilation. This is a series of videos that culminate in a calculation of 'what speed do the photons in a torchlight on a moving cart travel at?' intended for entirely lay audiences.

thanks.

this is not a paradox but a simple error of judgment on behalf of the twin who perceives the ships' clock to be ticking slower. Special relativity is itself relative to its own "special" circumstance and will not resolve with general relativity without the same special conditions. By definition we cannot resolve the two directly but by identifying false paradoxes such as this one which is no more than a perception or belief issue if special relativity can't prove that which we know by practice then obviously something is there that shouldn't be or something is missing.

that's is a perceptual problem and not a paradox

Could time dialation not be studied with particle beams fired into a rotating electromagnetic field? Is this not already a thing?

can you explain to me what is perceptual problem,if possible with examples. Thanks.

Like I did I the first response. There is no paradox since we know thanks to general relativity the actual truth value of the time that passes for each twin. A man can be wrong without creating a paradox.

A man can be wrong without creating a paradox. — Myttenar

Who is wrong? The guy who labelled as a paradox the twin-experiment? It is indeed not a paradox. But you're also labelling it a perceptual problem, so again, who's perceptual problem?

↪vesko this is not a paradox but a simple error of judgment on behalf of the twin who perceives the ships' clock to be ticking slower. — Myttenar

OK, you think one of the twins has a perceptual problem. Not so. He sees his clock ticking at normal pace, and he's right. If you assert that he is wrong about this, then please don't explain this stuff to vesko.

can you explain to me what is perceptual problem,if possible with examples. Thanks. — vesko

There isn't one. Everybody is correct about their ages and the durations of their experience. The only problem is the presumption of absolute time, which is something no instrument can measure, and hence has no evidence of existence.

As for A and B series being the same, yes, but both work for a place, even one that moves around. For any place (say where this ping-pong ball is), events are ordered the same way for both series. There is no difference. For two locations (say here and planet Zog), events are ambiguously ordered, both in A and B series. Either way, there is no difference between the series. Neither is an assertion of a metaphysical stance and hence neither is right or wrong. It's just two different ways of referencing the same things.

Does it means that absolute time is some dimension not known or measured by us on this planet??

Does it means that absolute time is some dimension not known or measured by us on this planet?? — vesko

Absolute time is fiction. I can't prove there are no invisible pink unicorns, but I can't detect them either.
To say there is no absolute time is to say there is no detectable actual time of the universe. It is meaningless to say exactly when some supernova occurred in Andromeda galaxy for instance. An arbitrary frame of reference must be presumed to do that. Pretty much any statement without a specified reference frame presumes absolute time and/or space. Absolute time would imply that all events anywhere are objectively ordered and that there is a correct frame, but again, no way to determine that frame if light speed is the same in all frames.
Light speed being the same in all frames is the only empirical evidence that led to relativity. Myttenar's picture of things (somebody is wrong) can be falsified by lightspeed measurements.

Read a good tutorial on relativity, especially some of the initial thought experiments that led to the SR parts, and not just the articles that teach the conclusions. The thinking behind it helps so much, and helps one to drop the ingrained presumption of absolute time.

With the twins, the travelling twin's time is dilated in the Earth frame, but in the space ship frames, it is the Earth twin whose time is dilated and exhibits less duration.

The video series I linked titled 'Gamma' from Sixty Symbols on Youtube has a worked example on how to deal with the relativity of simultaneity

yeah well... The reconciliation of special and general relativity lies in relative perspective.

Does the red-shift seen in the color of light from distant stars represent the distance between us and that star, as in has distance been tightly correlated to that effect through another reliable measure of distance?

Because there's other interpretations, such as a doppler frequency shift due to velocity between us, which looks a bit odd in the face of light-speed is always the same in every frame of reference. Particularly when those measurements suggest a speed of closure or departure between them and us greater than c.

And it also looks peculiar when placed in the immediate vicinity of the Expanding Universe theory, where distance is said to change. Sorta makes one wonder what exactly is meant by velocity = distance/time

Does the red-shift seen in the color of light from distant stars represent the distance between us and that star, as in has distance been tightly correlated to that effect through another reliable measure of distance?

Because there's other interpretations, such as a doppler frequency shift due to velocity between us, which looks a bit odd in the face of light-speed is always the same in every frame of reference. — AngleWyrm

Doppler shift, yes. Light is the same speed in any frame. It is not the same frequency or wavelength. Those are frame dependent measurements.
A photon has no objective wavelength or frequency, but a full spectrum beam of light bears the fingerprint of the frame of the source of the light. Hence the speed of some distant star can be assessed by the measurable shift of the light frequency.

Because there's other interpretations, such as a doppler frequency shift due to velocity between us, which looks a bit odd in the face of light-speed is always the same in every frame of reference. Particularly when those measurements suggest a speed of closure or departure between them and us greater than c.

And it also looks peculiar when placed in the immediate vicinity of the Expanding Universe theory, where distance is said to change. Sorta makes one wonder what exactly is meant by velocity = time/distance — AngleWyrm

If I understand correctly, the activity which results from the expanding universe does not qualify as "motion". So the "distance" between objects may be increasing, but this is not properly called a motion.

Does anyone here disagree that speed is a measurement defined as velocity = distance/time?

If distance loses it's meaning of 1 lightyear = 1 lightyear the fraction distance/time becomes meaningless as well.

Does that look like science or fiction?

Does anyone here disagree that speed is a measurement defined as velocity = distance/time? — AngleWyrm

Speed is distance/time. Velocity is a vector, so it has a directional component. One can accelerate (also a vector quantity) and change velocity without changing speed.
Speed and velocity are not absolute properties of objects. They are relations between things.

If distance loses it's meaning of 1 lightyear = 1 lightyear then I suggest that isn't science it's some sort of perspective modification that is creating meaninglessness.

It is still distance, but Meta's post above is correct. Distance is a local measurement that begins to alter meaning for significantly separated things.

Seems to me that change takes time, so as to be classified as change in the first place.
Which, together with the mentioned empirical perspective (no change implies no time), intrinsically relates time and change.
Was it Aristotle that noted they're not the same thing, though?
Change and motion and such could be many things, whereas time is more specific (e.g. concurrent duration).

Seems to me that change takes time, so as to be classified as change in the first place.
Which, together with the mentioned empirical perspective (no change implies no time), intrinsically relates time and change. — jorndoe

Change takes time, that is self-evident, but why does no change imply no time? Don't you think that it is possible that time could be passing while things are staying the same?

In other words if there is no change/movement in universe ,than there will be no time category.

Human beings make categories. Without a human being there is no time category. I'm asking if you think that there could be time without change. Or is the time category just an empty category?

certainly ,no change means no time ,. And also no humans means that nobody can realise the time ,including we in this forum ☺

Why do you say "certainly, no change means no time". Humans realize time through change. The principle used is simple, If change occurs, then there is time. How can you invert this to say "if there is time, then there is change", to make your statement with certainty?

In other words, we know that time is necessary for change, because we abstract time from change. Therefore we know all instances of change involve time or else this abstraction would be invalid. But we do not ever proceed from the observance of time, to conclude that change has occurred. We cannot make this abstraction. Therefore we cannot know with any certainty that all instances of time involve change.

You have committed a fallacy of false equivalence, thinking that because all change involves time therefore all time involves change, as if time and change are equivalent.

You have committed a fallacy of false equivalence, thinking that because all change involves time therefore all time involves change, as if time and change are equivalent.
Yes I do. and time itself is a change