What is time??

hansda said:
Does relativity happen at the source ?
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Relativity applies everywhere. However, something you seem to be missing is that "relativity" is a comparison of the how an event or events, unfold when observed from two or more different interial frames of reference.

The Lorentz transformations, which lie at the heart of special relativity, provide a mechanism through which observes in different inertial frames of reference can convert what they observe to what an observer in the other frame of reference would observe.

There is a second role that the transformations play. In the second situation the Lorentz transformations can be used to calculate or determine how time is dilated relative to an object's velocity. This affect, time dilation, is unobservable under most common every day velocities and only comes into play when velocities of objects with mass, become relativistic.., reach a significant fraction of the speed of light.

An object, which has mass when accelerated to a significant fraction of the speed of light experiences time dilation. The progress of time for such an object slows down as its velocity increases toward "c".
 
OnlyMe said:
Relativity applies everywhere. However, something you seem to be missing is that "relativity" is a comparison of the how an event or events, unfold when observed from two or more different interial frames of reference.

The Lorentz transformations, which lie at the heart of special relativity, provide a mechanism through which observes in different inertial frames of reference can convert what they observe to what an observer in the other frame of reference would observe.

There is a second role that the transformations play. In the second situation the Lorentz transformations can be used to calculate or determine how time is dilated relative to an object's velocity. This affect, time dilation, is unobservable under most common every day velocities and only comes into play when velocities of objects with mass, become relativistic.., reach a significant fraction of the speed of light.

An object, which has mass when accelerated to a significant fraction of the speed of light experiences time dilation. The progress of time for such an object slows down as its velocity increases toward "c".
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Please review your example of "Lightning and Thunder " ; which you posted earlier .
 
hansda said:
Please review your example of "Lightning and Thunder " ; which you posted earlier .
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What has that analogy to do with the current context?

Lightening and thunder were used as an analogy intended to demonstrate how two observes could perceive events, with differing time delays, that both observes know occurred at the same time. It is straight out of SR 101.

And it does not even begin to deal with the length contraction and time dilation aspects of the Lorentz transformations, except as they may be applied to reconcile the lightening and thunder as perceived from two differing frames of reference.

I really fail to understand what you think that analogy was meant to demonstrate or how it applies or is in conflict with the current discussion!
 
Can they change the oscillation of cesium(Cs) atom or revolution of our earth
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Sure.

An observer in relative motion to the cesium atoms will measure a different rate of oscillation than will an observer stationary relative to the atoms.

Same is true of the rate of revolution of the earth.

Now when you say that time is defined by the ocsillation of the cesuim atom, you measure the time by counting the oscillations, and upon reaching 9,192,631,770, you say ET VIOLA... one second. So if it takes two observers a different interval to reach 9,192,631,770 in their counting of the same cesium atom, then the second has a different length to each observer.
 
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AlexG said:
Sure.

An observer in relative motion to the cesium atoms will measure a different rate of oscillation than will an observer stationary relative to the atoms.

Same is true of the rate of revolution of the earth.

Now when you say that time is defined by the ocsillation of the cesuim atom, you measure the time by counting the oscillations, and upon reaching 9,192,631,770, you say ET VIOLA... one second. So if it takes two observers a different interval to reach 9,192,631,770 in their counting of the same cesium atom, then the second has a different length to each observer.
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Isn't it Doppler's effect ; which you have explained as above ?
 
There are two main ways to get time dilation. One way is SR or velocity and the other is GR or gravity. The orbiting space station gains time dilation due to velocity or SR, but since there is less gravity the GR contribution is the opposite. Is the observed time dilation a net amount; >SR minus <GR?
 
hansda said:
You mean to say , the oscillation of cesium atom at the source will change ( slower , due to relative motion between the source and the observer) .
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Lets just use a clock. If you could somehow see a clock in the space ship zooming by you at relativistic speeds then you sould see that he clocks hands are moving slower than yours. But it is not just the clock, time is actually passing slower for the space ship. So for someone in the space ship, the clock would seem to be running completely normally, because the persons would be also experiencing the slower time.
 
What is interesting about SR and time slowing, is everything in the slowed reference will be impacted, including forces, so everything coordinates together. The slowing of the cesium atom oscillation means the EM force got weaker, so the atom can't vibrate as fast.

If force equals mass times acceleration (F=MA) and, acceleration = d/t/t, since t is changing due to relativity, the force is changing because the new equation is A* =d/t*/t* and F*=MA*. The weaker force in time can't make the cesium vibrate as fast.

This has some interesting implications. Say a star was in a reference with time dilation, forces, such as the EM force of the sodium atoms would change. A weaker EM force, means a red shift directly in normal atomic output even before it leaves the atom.

The way to prove this, if we measured cesium emissions, since the frequency slows when this atom is on orbit, that means a red shift will occur in its output, since a red shift also implies frequency will lower. We look at cesium for time, but frequency drops means red shift.

What is important about this is universal space-time does not have to expand for energy to red shift. An SR movement of objects in fixed universal space-time, if it causes SR time dilation, will red shift directly inside the atom by tweaking the EM force; like cesium red shift which later we can compare and see there was a frequency loss.
 
origin said:
Lets just use a clock. If you could somehow see a clock in the space ship zooming by you at relativistic speeds then you sould see that he clocks hands are moving slower than yours. But it is not just the clock, time is actually passing slower for the space ship. So for someone in the space ship, the clock would seem to be running completely normally, because the persons would be also experiencing the slower time.
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In your example above , the space-ship is having a relativistic speed . So, time is slowing down the clock carried on-board the space-ship.


The atom in its oscillation will be having an instantaneous speed , which is also quite high . So , time should also slow down this oscillation of an atom . But, does it happen so ?
 
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