Time dilation

Definition

Time dilation is a phenomenon in which the elapsed time between two events is longer for an observer in relative motion compared to an observer at rest. It results from the principles of special relativity, specifically the invariance of the speed of light.

5 Must Know Facts For Your Next Test

1. Time dilation occurs because the speed of light remains constant for all observers, regardless of their relative motion.
2. The time dilation formula is given by $t' = t / \sqrt{1 - v^2/c^2}$ where $t'$ is the dilated time, $t$ is the proper time, $v$ is the velocity of the moving observer, and $c$ is the speed of light.
3. At speeds much less than the speed of light, time dilation effects are negligible; they become significant as velocities approach that of light.
4. Time dilation has been experimentally confirmed through observations such as muons decaying more slowly when moving at high speeds compared to when at rest.
5. GPS satellites must take into account both general and special relativistic effects, including time dilation, to provide accurate positioning data.

Review Questions

• What causes time dilation according to special relativity?
• How does velocity affect the degree of time dilation experienced by an observer?
• Provide an example where time dilation has been experimentally observed.

Related terms

Special Relativity: A theory formulated by Albert Einstein that describes how measurements of space and time differ for observers in different states of motion.

Proper Time:

The elapsed time between two events as measured by an observer who sees both events occur at the same location.

Lorentz Factor:

$\gamma = \frac{1}{\sqrt{1 - v^2/c^2}}$, which modifies measurements in spacetime due to relative motion.