B How can I conceptualise light and the known universe

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Light takes time to travel, meaning we see objects as they were in the past, depending on their distance from us. The speed of light is constant, and it moves through spacetime at this speed, which affects our perception of distant objects. For example, if an object is five light-years away, the light we see from it reflects its appearance from five years ago. This concept illustrates how observing the universe allows us to look back in time. Understanding these principles can help conceptualize the vastness of the known universe and our place within it.
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I am having a large amount of trouble conceptualising the idea of light taking time to reach places, how we are seeing into the past when we look further out and the idea of the known universe.

If someone could please elaborate on those points it would be much appreciated.
 
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It takes time for light to travel from its point of origin to its destination. What you are seeing is the light given off from an object at the time that it left that object.
 
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Lewis123 said:
I am having a large amount of trouble conceptualising the idea of light taking time to reach places, how we are seeing into the past when we look further out and the idea of the known universe.

If someone could please elaborate on those points it would be much appreciated.
What Borg said is pretty much all there is to it. Light travels at the speed c, so it can only move through the universe at that speed. Keep in mind that what we see is simply light reflected off objects and traveling through spacetime at speed c to us.
 
Another way to think about this...
Imagine that someone 5 light years away takes a selfie and then could send that picture to you at the speed of light. It would take 5 years to reach you so you would be seeing what they looked like 5 years ago. Does that make more sense?
 

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