Questions about "Big Crunch" http://map.gsfc.nasa.gov/universe/uni_shape.html From the picture above, it looks like the universe has three kinds of shapes. ( Density>1, density<1, density=1) So how the density of the universe will be(if it'll ever) be smaller than 1? How does it change? What 'affects' it? Also, what will happen happen at the Big Crunch? What will happen when Big Crunch starts to happen? Will the stars burn out? Since the universe will be getting smaller, will the earth and other planets etc be flat? If not, how will they be affected by it? Will we(or the ones who'll be able to live) witness to it? Or will it be instant? I guess I asked a lot of questions but I felt like I have to know them all. Thanks in advance.