Real time effects of light, light speed, and the sun?

In summary, the conversation discusses the concept of light speed and how it relates to the distance between the Sun and Earth. It is mentioned that it takes approximately four years for light to travel from the Sun to Earth. The question is then posed whether, in theory, if the Sun were to be destroyed, would we still receive light and heat for four years. It is also questioned whether the Sun we see in the sky is the actual physical Sun or just an image, and if the Sun were to explode, how long it would take for us to see the effects. The conversation also touches on the topic of gravity and its speed of propagation.
  • #1
rolandov00
3
0
If I am to understand correctly, light speed is the speed at which light travels through space. As I also am led to believe, our sun is some four lightyears away. I recall hearing that since it takes roughly four years for light to travel from the sun to us, the light we see during the day actually originated from the sun from four lightyears ago. That being said, in theory if the sun were destroyed (and we could ignore the gravitational effects that would create) would we continue to have light and heat for four years?

Also, if any of what I heard/described above is accurate, is the sun we see from sunrise to sunset the actual, physical sun, or is it just an image? i.e. if the sun theoretically exploded and we were still intact, would we see the results immediately, or would it take some four years till we see a change?
 
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  • #2
rolandov00 said:
If I am to understand correctly, light speed is the speed at which light travels through space. As I also am led to believe, our sun is some four lightyears away. I recall hearing that since it takes roughly four years for light to travel from the sun to us, the light we see during the day actually originated from the sun from four lightyears ago. That being said, in theory if the sun were destroyed (and we could ignore the gravitational effects that would create) would we continue to have light and heat for four years?
Also, if any of what I heard/described above is accurate, is the sun we see from sunrise to sunset the actual, physical sun, or is it just an image? i.e. if the sun theoretically exploded and we were still intact, would we see the results immediately, or would it take some four years till we see a change?

Hi rolandov00!
The Sun is about 8 lightminutes from the earth.
(But our next nearest star is about 4 lightyears away.)
So if the sun suddenly disappeared it would take 8 minutes before we noticed it (including gravitational effects).
 
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  • #3
Thanks for the answer.
 
  • #4
Actually, although it is known what gravity does, how it does it is not known. No "gravitons" have been found so if the sun were to suddenly vanish, it is not known whether gravity would instantly disappear, or like light, continue for some minutes.
 
  • #5
Peter Watkins said:
Actually, although it is known what gravity does, how it does it is not known. No "gravitons" have been found so if the sun were to suddenly vanish, it is not known whether gravity would instantly disappear, or like light, continue for some minutes.

No, we are fairly confident that gravity propagates at or close to the speed of light. Certainly not instantaneously.

See: http://en.wikipedia.org/wiki/Speed_of_gravity
 

1. How does light travel through space and how fast does it move?

Light is a form of electromagnetic radiation that travels through space at a speed of approximately 299,792,458 meters per second. This speed is known as the speed of light, and it is the fastest speed at which energy can move through space.

2. What are the real time effects of light on our daily lives?

The real time effects of light on our daily lives are numerous. Light allows us to see and perceive the world around us, regulates our sleep patterns, supports plant growth, and provides energy for photosynthesis. Light also plays a crucial role in communication, technology, and many other aspects of our modern society.

3. How does the sun's light impact our planet?

The sun's light is essential for supporting life on Earth. Without the sun's light, Earth would be a cold and dark planet. The sun's light provides energy for photosynthesis, which is the process by which plants produce oxygen and food for other organisms. The sun's light also helps regulate Earth's climate and weather patterns.

4. What is the relationship between light and time?

The relationship between light and time is complex. The speed of light is a constant, and it plays a crucial role in our understanding of time. The theory of relativity states that as an object moves faster, time will appear to slow down for that object. This phenomenon is known as time dilation and has been proven through experiments involving the speed of light.

5. How does light affect the color and appearance of objects?

Light affects the color and appearance of objects through a process called absorption and reflection. When light strikes an object, it can be absorbed, reflected, or transmitted. The color of an object is determined by the wavelengths of light that it reflects. For example, objects that appear red absorb all wavelengths of light except for red, which is reflected back to our eyes.

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