If there was a Big Bang and everything is moving away from a central point?

Question

Then how can the Milky Way and the Andromida galaxies collide??

Answer 1

First of all, it is important to get a feel for the scale of the expansion. The distance between the Milky Way and the Andromeda spiral is about 2-3 million light years. This is close as galaxies go. The Virgo cluster of galaxies is about 60-80 million light years away and this is *still* considered a close cluster.

So while there is an overall expansion, there are also eddies and currents in that expansion. In the case of the Milky Way and the Andromeda spiral, the gravity between the two is pulling us together faster than the expansion is pushing us apart. This is fairly common for galaxies that are close together. The 'peculiar motion' of galaxies in clusters tends to be around 200kilometers per second.

The rate of expansion is about 70 kilometers per second per megaparsec. In other words, two galaxies that are 3 million light years away from each other would be separating at 70 kilometers per second due to the expansion. If they were 30 million light years away, they would be separating at 700 kilometers per second. If you compare these numbers to the peculiar motion, you can see that for galaxies that are close, the peculiar motion can overwhelm the expansion. It is only for more distant galaxies that the expansion gives a clear signal.

It should be emphasized that the Big Bang was not an explosion in any usual sense. It was NOT an expansion from a central point! Instead of things moving through space, it is space itself that is expanding. I know, a strange concept, but that is how the math goes.

Answer 2

On the immense scale of the entire universe, space is expanding. However, there are huge regions within the universe where the gravitational attraction between massive structures can overcome that general expansion. The Milky Way and the Andromeda galaxies moving towards each other is just one example.

By the way...there is no 'central point' to the universe. At the instant of the Big Bang space itself was first created, so it can be said that the universe 'happened' every where at once. The big word for this is 'isotropic,' meaning that no matter where you are in the universe that place will appear like the center, such as our viewpoint from here on Earth.

Answer 3

If Galaxies are moving radially relative to a moving Universal barry center Then then is no way collison could occur,Since radial motion involves increasing spread with distance.
However since Creation may not have be the same physical phenomenon as described by the Big Bang. Galaxies may be moving into a continually changing orbit would give the same optical illusion that we are presently observing.
I assume that in this modern time to much faith is given to the Big Bang theory. There is a need for more scientific open mindness.

Answer 4

Things arent moving away from a central point.

Rather, things are, on a large scale, moving away from each other - and the farthest objects are receding the fastest. This does not mean that there are not objects that move at speeds above or below the 'average' curve of recession vs. distance.

You can certainly find some neighboring galaxies moving toward each other...but, the farther away you search from any particular galaxy, the faster you will find that others recede from it on average.

Answer 5

The big bang is not expanding from a single point, points all over the universe are just spreading out thinner and thinner.

But there are small local motions that can make nearby things approach each other even as, in general, distant objects in the universe are getting more distant from each other, and the more distant they are the faster they are getting farther from each other.

Yes, the Andromeda galaxy is very close on a cosmological scale. In fact, it may surprise you to learn that is actually looks bigger in our sky than the Moon does. We can't see it very well only because it is dim. It does not take magnification, like with a telescope, to see it, it takes light intensification, like with night vision goggles, to see it.

Answer 6

different rates of motion. if 1 is traveling at a set speed of 5 and the other at a set speed of 10, the 10 will overtake the 5 given enough time.

different vectors of motion. just because things may have started moving away from a central point in no way means that they continues upon a straight path. any number of interactions along the way would have altered their courses.

gravity or other forces of attraction/repulsion that we do not yet comprehend.

also the possibility (although a low probability) that space is essentially a curved sphere (or torrid, or tesseract) and that our 3 dimensions exist only upon it's surface, thus at some point there is the possibility of colliding with any other object in the universe (not to even go into the flow of time & other dimensional possibilities)

Answer 7

The big bang was a total explosion and when something explodes, all of the particles do not simply move away from each other. There is a great deal of chaos and things may collide. Also, with galaxies, they orbit and move in circles. Sometimes two orbits may get in each other's paths, which can cause a collision.

Answer 8

The flowing away bit is the general condition, little variations occur, and some area have a collective mass that is enough to locally reverse the general trend.
If it was not for it, how could stars stay in one galaxy instead of being scattered?
The universe is make of clusters of galaxies that can get more compact, but the clusters in general fly away from one another.

Answer 9

because they are not moving at an equal speed through space... It's like 2 cars going the same way on a one way street... at some point if the car behind is going at a faster speed, then he will at some point collide with the first car that is going slower. It's just too bad that galaxies don't have brakes like cars do...

Answer 10

In general (and over long distances) things tend to move away from each other. Over very large distances, the expansion of space increases the distance between objects.

However, if the distances are small enough for gravity to prevail, then objects can still "fall" towards each other. For example, if you toss a rock up in the air, the expanding space will not be sufficient to prevent the rock from falling back to Earth.

Inside the "Local Group", the distances are still "small enough" for gravity to win over expansion. Therefore, the galaxies are still in orbit around each other (or, more precisely, around the group's centre of mass).