If we can see galaxies 12 billion light years away,that means that the universe must be at least 12 billion years old because that is how long it took the light from these galaxies to reach us.

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This is known as the cosmological principle and is widely accepted in the scientific community. It is based on the fact that the speed of light is constant, and the distance light can travel in one year is one light year. Therefore, if we observe a galaxy that is 12 billion light years away, it means that the light we are seeing from it started traveling towards us 12 billion years ago when the universe began.

If We Can See Galaxies 12 Billion Light Years Away,that