And now for a brief response to Fabian's question:
So, recently the question was posed: what would happen if the nearby Andromeda Galaxy were to crash into our own milk way?
Well, first things first. The Andromeda galaxy (catalogue M-31) is indeed our closest galaxy, but it is about 25 million light years away from us. That is to say, it takes light itself (the fastest thing in the universe) 25 million years to travel from us to M-31. In fact, we cannot logically be certain that it is still there! Since we are seeing what it looked like 25 million years ago when the light left Andromeda, we cannot be absolutely certain what it looks like right now.
But, that aside, it is possible for Andromeda to “hit” us here in the Milky Way. Remember, Gravity is always attractive. Yes, it gets weaker with distance, but it is still tugging us together, even over a distance of 25 million light years. As of right now, the movement of our two galaxies as affected by their shared gravitational attraction is bringing them together at a rate of about 100 kilometers per second. While this may sound fast, it is much, much slower than the speed of light. We can guess that the two galaxies will “collide” in over 4 billion years. So, personally, I’m unworried.
So, what would actually happen? Well, first off, it is important to realize that although galaxies are huge and contain trillions of stars, they are still mainly empty space. So, as they fall towards each other, speeding up, they would eventually “hit,” which means mainly that they would fall through each other…kind of like firing two shotguns so that the pellets intersect…most would miss actually hitting something.
So, two things would happen as they pass through each other. First, they would speed up as they fall closer and closer to each other, because gravity gets stronger as things get closer together. Then, they would mainly pass through and by each other, and start slowing down. As their momentum would carry them on through each other, the gravity would now be tugging at them, slowing them down until they reverse direction and head back towards each other again. This would happen over and over, each galaxy slowing down bit by bit until they have merged into a giant new galaxy.
“But what about us? What about Earth?” Well, that brings us to the second likely effect. While it is tremendously unlikely that any part of Andromeda will directly “hit” Earth, all the gravitational force from the masses in the other galaxy would have a huge effect, tugging on not only Earth, but on everything else in the galaxy and solar system. A lot of things that currently have a stable orbit would get tugged out of that orbit, either spiraling into whatever is nearby or gradually escaping into deep space. The basic structure of each galaxy would be torn apart. This video below is a computer simulation of two galaxies falling towards each other. It shows some of what I am trying to describe.
The best bet for Earth is that at the minimum, a lot of the comets and meteors that are currently orbiting the solar system out at its very edges would get knocked loose, and start to fall through the system. This would lead to an increased number of impacts with Earth, and probably cause mass devastation for any living things at that time.
the_road_to_revolution.docx |
cells_of_currents_and_catastrophes.docx |