Space Exploration/Question on Space
I recently read that there are more than 100 billion galaxies in the universe.
1. How and what method(s) do scientist use to calculate this figure?
2. How can a scientist state with confidence that there this amount when we cannot access other galaxies? Also how do scientist know where the universe ends and what if where we think it ends, it really does not end or what if the vast magnitude that we perceive is nothing but an illusion and it is not as large as we think it is
3. What really exists on these galaxies and how can we know?
Miramar / Pembroke Pines,Florida
About 170 billion galaxies are detected but most galaxies are hidden behind dark matter and other galaxies. My estimate is 500 galaxies in the universe.
1) we count galaxies like we count other small things in mass; like biologists count sperm or trees in the jungle or schools of fish ... We count individual galaxies in various square sectors of say 1x1 arc seconds, then calculate averages for various density. galaxies can be told apart from stars because they are fuzzy and usually elongated or disc like. Stars are pin-pricks of light regardless how much is zoomed in by the telescope. The images of various frequencies; light, infrared, radio, etc, are laid on one another to get a better overall picture.
2) We can only guess the amount because some are small and others are hidden behind other objects. you are right, our telescopes cannot see all galaxies. We have now detected galaxies about 14 billion light years away. This at the speed of light is the furthest material on the edge of the giant explosion "Big Bang" that took place 14 billion years ago. Beyond that is nothing. The universe is expanding like an explosion and more galaxies are formed as stars mass together. Some galaxies collide and unite, others disappear in their own black hole at the center. The disappearing mass is turned into "tachyon-radiation" (my own created double-word) which radiates out over the speed of light causing gravitation when colliding with material and helping to form new solar systems and new galaxies. A cycle of galaxy renewal.
3) Most galaxies are just like ours but come in various shapes. The nature of galaxies are identical. There are three galaxies near our milky way, so we can study them in detail. Andromeda is a most typical galaxy, very similar to ours, yet we collided with the Magellanic clouds making a bit of a mess.
Rudolf "Rangutan" Graspointner
Best Galaxy-Group image ever? >>> http://news.nationalpost.com/2012/09/26/nasas-amazing-hubble-extreme-deep-field-
If you have FaceBook, there is a group called "Universe" dealing with this subject.
Sorry about the delay, I got caught up in a project to try get a ticket to space >