Hypothetical situation, what is seen before light arrives?

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SUMMARY

The discussion centers on a hypothetical scenario where an opaque barrier is placed between the Earth and the Sun, blocking sunlight for one hour. When the barrier is removed, observers on Earth will see the Sun's light for an additional 4 minutes and 9.5 seconds due to the time it takes for photons to travel from the Sun to Earth, which is approximately 8 minutes and 19 seconds. The light particles, or photons, that were already en route will continue to reach Earth until they are exhausted, resulting in a sudden transition from light to darkness. This scenario illustrates the concept of light travel time and the behavior of photons in space.

PREREQUISITES
  • Understanding of basic physics concepts, specifically light and photons.
  • Familiarity with the Speed of Light and its implications in space.
  • Knowledge of time delay in light travel, particularly the 8 minutes and 19 seconds from the Sun to Earth.
  • Conceptual grasp of barriers affecting light propagation.
NEXT STEPS
  • Research the properties of photons and their behavior in different mediums.
  • Study the implications of light travel time in astrophysics.
  • Explore the concept of light barriers and their effects on visibility.
  • Investigate real-world applications of light speed in telecommunications and astronomy.
USEFUL FOR

Anyone interested in physics, particularly those exploring concepts of light, astrophysics, and the behavior of photons. This discussion is beneficial for students, educators, and science enthusiasts seeking to understand light propagation and its effects on observation.

zanthal
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Before I get pounced on by academics from near and far, I just want to mention that I'm no longer a college student and never took a course in physics. All of my knowledge on the subject is practical and thus the answer to this eludes me. So in advance please forgive me if the answer to this seems elementary and/or a waste of time.

Hypothetical situation:

One day, an gigantic opaque barrier of some kind is placed between the Earth and the sun, completely blocking the view and the light of the sun visible from Earth for an entire hour.

In a period of a few seconds, that barrier is removed.

What would this situation look like from the perspective of an observer on earth? What does the sun look like before it's light has arrived on earth, can it be seen at all?

Would the observer still see the sun's light for minutes after the barrier had been put in place, as the remaining light particles finished their journey to the eye of the observer on earth?
 
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The light from the Sun takes about 8 minutes 19 seconds to travel to Earth.

You can think of light as particles - much like marbles - but much smaller. Particles of light are called photons and they travel in straight lines at the Speed Of Light, which is the speed limit for everything in the universe.

Photons travel out in all directions from the sun, but the light we see from the sun is only the photons that travel straight towards Earth.

Let's say you stick a giant barrier directly between the Sun and the Earth at time t=0.

Then at time t=0 the photons between the barrier and the Sun will hit the barrier and either get absorbed, reflected or whatever else, but for the sake of argument, let's assume they don't get passed the barrier, and so they don't reach Earth. These photons are normal photons traveling at light speed.

The photons in between the barrier and the Earth will continue towards Earth at Light Speed. However, there are only 4 minutes 9.5 seconds before the photons that were passed the barrier at t=0 run out, and so you will get 4 minutes 9.5 seconds of light, and then sudden darkness.

If you are still confused, think about a tap with water running out of it, and then suddenly you place a card in between the tap and the bottom of the sink.
 
No that makes sense to me actually, it's just such an unthinkable situation that it's hard to imagine what would really happen in real time.

Thanks for the reply :biggrin:
 

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