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    Question ID:   16022         Current Version: 1
Question: What is cosmological horizon?
Category: Science > Astronomy & Space
Keywords: cosmic particle, cosmological horizon
Type: what
Rating:(0 ratings)    Views: 222    Discussions: 0   In Watch Lists: 1  

 
    Answer:

The cosmological horizon, also known as the particle horizon, is the maximum distance from which particles could have traveled to the observer in the age of the universe. It represents the boundary between the observable and the unobservable regions of the universe.

The concept of the cosmological horizon refers to the boundary or outer limits of the Universe that we can establish contact with, i.e., the farthest extent of the observable Universe that can be seen through the best telescopes. This is approximated by the currently observed farthest galaxies that formed in the first billion years of time in our Universe's history. This Horizon is also conceptualized as the surface dividing spacetime (which includes all locatable 4-dimensional points) into what we can see and measure from what is hidden and unobservable. The observable therefore must lie within our Light Cone, an imaginary surface that encloses all possible paths of light reaching us since the beginning of time. 

Source: NASA

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