Exploring Time Dilation: Understanding the Concept of Relativity in SR

In summary, according to the documentary, time slows down to prevent the maximum speed, c, to be broken. This is done by the way time works in our universe, which is that the speed of light is constant. This means that clocks on a rocket moving near the speed of light will run slow.
  • #1
Duder999
7
0
I watched a documentary that introduced SR.

Ok, I don't know the theory very mathematically. But what I know of and the documentary says is that time itself slows down to prevent the maximum speed, c, to be broken. It said that if time doesn't slows down, when we ride a rocket moving close to c,lets say 99%, and if we'd move at a some other speed on the rocket , let's say 2% of c, the total speed of us is 101% which means time has to slow down so that c may never be reach. (Enlighten me on this if it is wrong.)

Anyways, my question is if light travels at the speed of light, how would time (in the perspective of light) behave?
 
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  • #2
When we say that time slows down in a rocket traveling at 99% of c, we mean that the clocks traveling in that rocket are running at a low rate. It takes a clock to measure time. Clocks are made out of matter which means they can never travel at c. Since light travels at c, it cannot have a clock traveling along with it in order to measure time, correct? That means it cannot have a perspective on time. Does that make sense to you?
 
  • #3
So light doesn't have a perspective on time?
 
  • #4
Light doesn't have a "perspective" on anything. It has no rest frame.
 
  • #5
Duder999 said:
So light doesn't have a perspective on time?

elfmotat said:
Light doesn't have a "perspective" on anything. It has no rest frame.
Yes, elfmotat, is correct.
 
  • #6
Duder999 said:
Anyways, my question is if light travels at the speed of light, how would time (in the perspective of light) behave?
Another version of an answer:
For a photon, which travels on a lightlike geodesic, the space-time interval and thus the proper time interval of two events is zero. This kind of geodesic is called null geodesic therefore.
So, one could argue from the "perspective" of a photon that the time stands still. On the other side, one should be careful with the wording "perspective" in this very case, because as was already said one can't define a restframe for a photon.
 
  • #7
Ok then. Then why does two photons moving in different direction have a center of mass frame but a single photon doesn't
 
  • #8
Because the single photon moves with c, the center of mass for photons moving in different directions however doesn't.
 
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  • #9
good posts above...takes time and some reflection to understand what they mean...

Time slowing for a fast moving observer can be thought of in many different ways...there
are a lot of fascinating and not obvious effects. That's why it took an 'Einstein' [a smart fellow] to discover them...and he developed his insights before most of the math, somehow understanding things were different than almost all other scientists believed at the time.

When George posts

...we mean that the clocks traveling in that rocket are running at a low rate...

he's referring to the ticking of the clock [passing of time] in the rocket as seen by an outside observer; inside the rocket an observer sees her local time in the rocket tick by at the normal rate, but observes the outside observer's clock ticking slow! In this example from special relativity, different speed observers usually don't agree on the passage of time.

the documentary says is that time itself slows down to prevent the maximum speed, c, to be broken.

I guess that's ok as a start, but misses a lot of what's really happening. Keep in mind we think we understand WHAT is happening[confirmed by many experimental observations] and that's what we model mathematically. We don't fully understand WHY it happens.

For unknown reasons, so far, everyone observes light when measured in flat spacetime as 'c'. [It gets a bit more complicated if gravity is present.] Einstein realized this means that instead of space and time being fixed and immutatable, they are not: it is the speed of light that is constant [fixed and immutable].

In other words, when you travel faster and faster your measures of distant space and time change, those measures locally [right where you are, in your own frame], are not affected: it's called space contraction and time dilation in relativity. Two things affect the passage of time, that is the tick rate of a clock when viewed from a distance: relative speed and gravitational potential.

...how would time (in the perspective of light) behave?

Our mathematics doesn't, strickly speaking, cover that as posted by others. That particular question, as noted above, has no 'real' meaning in relativity. It's kind of like asking "Is red a happy color?" But a rough, crude, answer is that "a photon doesn't age". This
means that when viewed from an outside inertial frame, IF a clock could be carried along at lightspeed, it is believed it would be observed to stop ticking. We know this slowing occurs as velocity inscreases because some fast moving decay particles have been observed to last longer than expected..if they were stationary...their 'half lives' [life times] are extended beyond what is expected as we observe them whizzing by.
 
  • #10
timmdeeg said:
Because the single photon moves with c, the center of mass for photons moving in different directions however not.

To elaborate: such a frame is a theoretical construct, however it represents imagined rulers, generally with clocks added to them. No clocks and rulers can move at c but if they could, they would measure zero volume and zero time. That's not useful. :tongue2:
 

1. What is time dilation?

Time dilation is a phenomenon in which time appears to pass slower for an object in motion compared to an object at rest. This effect is predicted by Einstein's theory of relativity and has been proven through various experiments and observations.

2. How does time dilation occur?

Time dilation occurs because of the relationship between time and space. According to Einstein's theory of relativity, time and space are not absolute, but rather are relative to the observer's frame of reference. As an object moves through space, it also experiences a change in its perception of time, resulting in time dilation.

3. How is time dilation measured?

Time dilation can be measured through various experiments, such as the famous Hafele-Keating experiment, which used atomic clocks to measure the difference in time between a clock on a fast-moving airplane and a clock on the ground. The difference in time between the two clocks is a result of time dilation.

4. What factors can affect time dilation?

The two main factors that can affect time dilation are the speed of an object and the strength of its gravitational field. The faster an object moves, the greater the effect of time dilation. Similarly, the stronger the gravitational field an object is in, the greater the effect of time dilation.

5. Can time dilation be observed in everyday life?

Yes, time dilation can be observed in everyday life, although the effects are extremely small. For example, satellites orbiting Earth experience time dilation due to their high speeds, which must be accounted for in order for GPS systems to function accurately. Additionally, astronauts on the International Space Station also experience slightly slower time compared to those on Earth due to their high speeds and location in Earth's gravitational field.

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