Time Dilation in SR: Exploring the Speed of Light and Spaceship Movement

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In summary, the concept of time dilation in special relativity means that time appears to move slower in a frame of reference that is moving at high speeds relative to another frame. This is why a ray of light launched from a moving spaceship will still appear to travel at the speed of light, regardless of the direction it is launched. This phenomenon is relative and does not affect the crew on the spaceship, who experience time as normal.
  • #1
Giulio B.
A spaceship is moving, then it launches a ray of light behind itself.
if time in the spaceship is slower than in other frames that are moving less fast, shouldn't the ray appear much faster than c?

this thing works with a ray launched in front of the ship, but behind, shouldn't the time go faster to let us see the ray at c speed?
thanks.
 
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  • #2
Giulio B. said:
A spaceship is moving, then it launches a ray of light behind itself.
if time in the spaceship is slower than in other frames that are moving less fast, shouldn't the ray appear much faster than c?

this thing works with a ray launched in front of the ship, but behind, shouldn't the time go faster to let us see the ray at c speed?
thanks.


No. First of all "The time on the ship" relative to the ship isn't slowed at all. As far as the crew of the ship are concerned, they might as well be at rest. That's why their state is caled the "Rest Frame" of the ship. Ship time is only slowed as experienced by an observer for whom the ship is moving fast.

So the ship, at rest with respect to itself, emits a light beam in any direction, and the crew measures the beam's light speed, and whaddayaknow, they get c.
 
  • #3
Someone traveling behind the ship, catching up to it with greater speed, would meet the beam of light head on and also measure the light's speed at c.

A third person watching the two ships both whiz by from a nearby planet would also measure the light's speed at c.
 
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  • #4
if time in the spaceship is slower than in other frames that are moving less fast

This isn't quite right. In SR, everything's relative. One frame can not be said to be moving faster or slower than another. From the spaceship's frame, time is moving slower both ahead and behind it. From a planet's frame (as the spaceship goes whizzing by) time is moving slower on the spaceship. Both frames see a time contraction and a length contraction that force c to be the same speed in any reference frame.
 

Related to Time Dilation in SR: Exploring the Speed of Light and Spaceship Movement

1. What is time dilation in special relativity?

Time dilation in special relativity is the phenomenon where time appears to pass slower for objects that are moving at high speeds relative to an observer. This effect is caused by the constant speed of light and the fact that the laws of physics are the same for all observers in uniform motion.

2. How does time dilation occur?

Time dilation occurs because the speed of light is constant for all observers, regardless of their relative motion. This means that as an object's velocity approaches the speed of light, time appears to slow down for that object from the perspective of an outside observer.

3. What is the relationship between time dilation and the speed of light?

The speed of light is a fundamental constant in the universe, and it plays a crucial role in time dilation. According to special relativity, the speed of light is the same for all observers, regardless of their relative motion. This means that as an object approaches the speed of light, time appears to slow down for that object from the perspective of an outside observer.

4. Can time dilation be observed in everyday life?

Yes, time dilation can be observed in everyday life, although the effects are usually very small. For example, GPS satellites have to take into account the effects of time dilation due to their high speeds in orbit, otherwise, the GPS system would not work accurately.

5. How does time dilation affect space travel?

Time dilation plays a significant role in space travel, especially for objects moving at high speeds such as spacecraft. As an object moves closer to the speed of light, time appears to slow down for that object relative to an observer on Earth. This means that astronauts on a spaceship traveling at high speeds will experience time passing slower compared to people on Earth. This effect becomes more pronounced the longer the journey and the faster the speed of the spaceship.

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