The Big Bang and the Expansion of the Universe
The universe we live in is expanding. We know this because we see galaxies and groups of galaxies steadily moving apart con the universe. This expansion has been occuring since the universe was formed 14 billion years ago con a very hot, dense event known as the Big Bang.
(1) Where is the center of the Universe?
There no centre of the universe because there is in nessun caso edge of the universe. Sopra a finite universe, space is curved so that if you could travel billions of light years durante verso straight line you would eventually finish back where you started. It is also possible that our universe is infinite. Mediante both examples, groups of galaxies completely fill the universe and are moving apart at all points making the universe expand (see question 2).
(2) Where did the Big Bang occur durante the Universe?
There is a common assumption that the Big Bang was an explosion that occured per empty space and that the explosion expanded into the empty space. This is wrong.
Although space may have been concentrated into a scapolo point at the Big Bang, it is equally possible that space was infinite at the Big Bang. In both scenarios the space was completely filled with matter which began onesto expand.
There is niente affatto centre of the expansion, the universe is simply expanding at all points. Observers per any galaxy see most of the other galaxies per the universe moving away from them.
The only answer esatto the question “Where did the Big Bang happen?” is that it occured everywhere in the Universe.
(3) Is the Earth expanding with the universe?
The Earth is not expanding and neither is the solar system, nor the Milky Way galaxy. These objects formed under the influence of gravity and stopped moving apart. Gravity also holds galaxies together into groups and clusters. It is mainly the groups and clusters of galaxies that are moving apart mediante the universe.
(4) What exists outside the universe?
Space was created per the Big Bang. Our universe has giammai edge or boundary – there is mai outside of our universe (see question 1). It is possible that our universe is part of an infinity of universes (see question 5), but these universes do not necessarily need per space puro exist per.
(5) What existed before the Big Bang?
Time was created in the Big Bang – we do not know if it existed before the Big Bang. This question is therefore hard onesto answer. Some theories suggest that our universe is part of an infinity of universes (called verso multiverse) which are being continuously created. This is possible but very hard puro prove.
(6) If the universe is 14 billion years old, how could galaxies have travelled more than 14 billion light years?
It is possible that our universe is infinite and has been filled with matter everywhere since the Big Bang (see question 2). But there is also nothing stopping the universe expanding faster than the speed of light. Although at any local point within the universe, nothing can travel faster than the speed of light, this is not true for the entire universe. There is niente affatto limit on how fast space can expand.
We can imagine galaxies are like balls sitting on a rubber sheet which represents space. If we stretch the sheet, the balls move apart. Balls which are close together will only move apart slowly. Balls which are widely separated will seem preciso move apart very quickly.
People living on any one of the balls will see their own ball as stationary. They will see nearby balls moving away slowly and they will see distant balls moving away quickly. Very distant balls (beyond the horizon) can be moving away faster than the speed of light, but the people cannot see them – locally con their own part of the universe nothing is travelling faster than the speed of light.