# Speed of Light & Time: Einstein's Theorem Explained

• krishnasrikar
In summary, time slows down at the speed of light, so if a person travelling at the speed of light were to reach their destination in a shorter amount of time than if they travelled at a slower speed. Additionally, time stops for photons travelling at the speed of light, meaning that they would age less than a person travelling at a slower speed.
krishnasrikar
1. As Einstein's theorem says "time slows down at the speed of light", does it mean that if humans travel at speed of light in future, time will slow down for the travelers as well.

2. If the above one is true, then would it mean that they would reach their destination quicker than assumed. For eg: suppose it would take around 4 light years to reach a 'X' star, would the traveler gets aged by 4 yrs or lower than that i.e. does time slow down.

3. Is time slowing down around the light particles (photons).

sorry for the grammar, i am not good in english.

krishnasrikar said:
1. As Einstein's theorem says "time slows down at the speed of light", does it mean that if humans travel at speed of light in future, time will slow down for the travelers as well.
Time stops at the speed of light, it slows down as you get faster.
it even works today at any speed. It's just that the effect becomes greater the faster you go.
If you cross the atlantic on concorde you age a few microseconds less.

2. If the above one is true, then would it mean that they would reach their destination quicker than assumed. For eg: suppose it would take around 4 light years to reach a 'X' star, would the traveler gets aged by 4 yrs or lower than that i.e. does time slow down.
Time passes slower for the traveller, if it takes 4years for an outside observer the traveller's watch would measure less time.

3. Is time slowing down around the light particles (photons).
At the speed of light no time passes for a photon

mgb_phys said:
Time stops at the speed of light, it slows down as you get faster.
it even works today at any speed. It's just that the effect becomes greater the faster you go.
If you cross the atlantic on concorde you age a few microseconds less.

Time passes slower for the traveller, if it takes 4years for an outside observer the traveller's watch would measure less time.

At the speed of light no time passes for a photon

What happens when time stops.

## 1. What is the speed of light?

The speed of light is a fundamental constant in physics and is approximately 299,792,458 meters per second in a vacuum. This means that light travels at this speed in empty space and is the fastest known speed in the universe.

## 2. How did Einstein's theorem explain the relationship between speed of light and time?

Einstein's theorem, also known as the theory of relativity, explains that the speed of light is constant for all observers, regardless of their relative motion. This means that as an object's speed increases, time slows down in order to maintain the speed of light as a constant.

## 3. Why is the speed of light considered the universal speed limit?

The speed of light is considered the universal speed limit because it is the maximum speed at which all matter and information can travel. According to Einstein's theory of relativity, as an object approaches the speed of light, its mass increases and it requires infinite energy to reach the speed of light.

## 4. Does the speed of light ever change?

No, the speed of light is a constant and does not change. However, it can appear to change when traveling through different mediums, such as air or water, as it is affected by the density and composition of the medium.

## 5. How is the speed of light measured?

The speed of light is measured using a variety of methods, including using lasers and mirrors to measure the time it takes for light to travel a known distance. It can also be calculated using the relationship between the speed of light, frequency, and wavelength of electromagnetic radiation.

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