# Need Clarification for time dilation effects

• NATURE.M
In summary, Essentially, the principle of relativity states that the laws of physics are the same for all observers in uniform motion, with the only difference being that their clocks will be running slow.
NATURE.M
So basically, my physics class has begun focusing on SR. And i just wanted to clarify something. I have been referencing:

http://physics.mq.edu.au/~jcresser/Phys378/LectureNotes/SpecialRelativityNotes.pdf

On page 23, it states "A clock will be observed to run at its fastest when it is stationary in a frame of reference."
I always thought that the clock that is stationary in a reference frame will run slower. Like if the clock C' is stationary relative to reference frame S'. Now S' moves at speed v relative to another reference frame S. Apparently, the clocks in S are running slow from the viewpoint of an observer in S. However, they measure the clocks in S' to be running more slowly. Is this a true statement?
If so, since he clocks in S' are stationary, shouldn't they be running faster according to the above statement? This appears contradictory to me with what was just mentioned (considering its true).

NATURE.M said:
So basically, my physics class has begun focusing on SR. And i just wanted to clarify something. I have been referencing:

http://physics.mq.edu.au/~jcresser/Phys378/LectureNotes/SpecialRelativityNotes.pdf

On page 23, it states "A clock will be observed to run at its fastest when it is stationary in a frame of reference."
I always thought that the clock that is stationary in a reference frame will run slower. Like if the clock C' is stationary relative to reference frame S'. Now S' moves at speed v relative to another reference frame S. Apparently, the clocks in S are running slow from the viewpoint of an observer in S. However, they measure the clocks in S' to be running more slowly. Is this a true statement?
If so, since he clocks in S' are stationary, shouldn't they be running faster according to the above statement? This appears contradictory to me with what was just mentioned (considering its true).

Clocks that are stationary in a reference frame tick at the same rate as the Coordinate Time of the reference frame. Clocks that are moving according to a reference frame tick slower and so take longer to tick the same amount of time than the Coordinate Time of that reference frame. Time Dilation is the ratio of the elapsed Coordinate Time of a reference frame to the elapsed time on a clock. The faster it moves, the greater this ratio.

If a clock is inertial (moving at a constant velocity) and moving in a particular Inertial Reference Frame (IRF), you can transform to the IRF in which the clock is stationary and the Time Dilation will be 1.

So if you have two clocks in relative inertial motion, each one will have a Time Dilation factor of 1 in its own rest frame and the other clock will have a Time Dilation factor that is greater than 1.

It's a symmetrical relationship.

Does that help?

I'm still a bit confused though. The following reference (pg. 7-8)
http://cosmo.nyu.edu/hogg/sr/sr.pdf initially made a lot of sense to me.
Namely, I find the following statement to make a lot of sense for the most part:

"Consider two observers, Deepto (D) and Erika (E), moving relative to one another in spaceships...D measures E’s speed to be u with respect to D’s rest frame. By the principle of relativity, E and D must observe the same speed of light, so we are forced to conclude that E will measure longer time intervals ∆t′ between the flashes in D’s clock than D will...The time intervals between flashes of D’s clock are longer as measured by E than as measured by D. This effect is called time dilation. Moving clocks go slow."
(rest of description on pg. 7 of link)

So I guess what I'm trying to ask is when they say "moving clocks go slow" are they referring to the motion of D's clock relative to E, in this particular case.
I understand the symmetry of the situation enables you to say that D measure's E's clock to go slow as well.

NATURE.M said:
So I guess what I'm trying to ask is when they say "moving clocks go slow" are they referring to the motion of D's clock relative to E, in this particular case.
No, they are referring to the tick rate of the clock. That is what I said in my first response to you. The faster a clock moves in a particular reference frame, the slower it ticks which is the same as saying it takes more Coordinate Time for it to tick a given amount of its own Proper Time.

Oh that's makes a lot of sense. In the case of E measuring D's clock, basically the time interval between 2 tics is larger than the time interval that D observes between the two tics. I guess the way I was interpreting "moving clocks go slow" was pushing me into a hole.
Thanks alot!

NATURE.M said:
Oh that's makes a lot of sense. In the case of E measuring D's clock, basically the time interval between 2 tics is larger than the time interval that D observes between the two tics. I guess the way I was interpreting "moving clocks go slow" was pushing me into a hole.
Thanks alot!
You're welcome.

## 1. What is time dilation and how does it occur?

Time dilation is a phenomenon in which time passes at different rates for different observers. It occurs due to the effects of gravity and relative motion on the fabric of space-time.

## 2. What are some real-life examples of time dilation?

One of the most well-known examples of time dilation is the time difference experienced by astronauts in space compared to people on Earth. Another example is the difference in time experienced by objects in orbit around the Earth compared to those on the surface.

## 3. How is time dilation related to Einstein's theory of relativity?

Einstein's theory of relativity explains time dilation as a consequence of the curvature of space-time caused by massive objects. This theory also predicts that time dilation will occur in situations where there is relative motion between objects.

## 4. Does time dilation only occur in extreme situations like space travel?

No, time dilation occurs in all situations where there is gravity or relative motion. However, the effects are only noticeable at high speeds or in the presence of strong gravitational fields.

## 5. Can time dilation be observed and measured in daily life?

Yes, time dilation can be observed and measured in daily life through experiments and observations. For example, the Global Positioning System (GPS) takes into account time dilation effects to accurately determine locations on Earth.

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