Density--as a factor in closing cosmos

[unlearningthemistakes]

Consider throwing a ball off the earth’s surface. If the balls velocity is less than the escape velocity, it will slow down and fall back, regardless of how small or large its mass is. A ball thrown with a velocity greater than the escape velocity will slow down a bit while it is still influenced strongly by the earth’s gravity and then coast outward as the earth’s gravity affects it less and less. If it doesn’t run into anything, the ball will travel out to infinity and never return to earth.<br /><br />Now consider the universe and the galaxies within it…<br />Any one galaxy in the universe is analogous to the ball…<br />The galaxies were once all “thrown away” from one another, for we now see an expansion. <br /><br />Consider a galaxy at some distance from us…<br /><br />Newton showed that the net effect of all matter spread within some space acted as if this total mass were concentrated at the center ( as long as the matter is distributed uniformly…) If there is enough mass within that space, the escape velocity will be larger than the expansion velocity. Note that “enough mass within that space” means a high enough density. ( the meaning of density here is related to how closely galaxies are packed together; the closer they are, the higher the density..) <br /><br />If the density is large enough, the galaxies will not have escape velocity; the expansion velocities will decrease with time and eventually reverse as gravity herds all the galaxies together….<br />If the average density is too low, the galaxies will have more than escape velocity; gravity will never bring then galaxies all together, and expansion will continue indefinitely…<br />Whether the universe is open or closed depends on the density of energy and matter within it. A large enough density curves spacetime so that it warps around itself to close the cosmos…<br /><br />As I could remember, We don’t have enough mass to close this universe..<br /><br /> <div class="Discussion_UserSignature"> <p>pain is inevitable</p><p>suffering is optional </p> </div>

 

[jatslo]

You are demonstratively intelligent; however, comparative research analysis on behalf of mass and weight is justified, because there is more than one solution to artificial gravity: The pressure created by the weight of matter is not required. Yes, I can back this up, but now is not the time, because I do not want to tip my hand to the competition.