Honest question, people, I really don't know that much about it. but from what I understand, the Big Bang says that there was a big explosion and everything in space is moving away from this point. And if something in space is moving, it will keep moving until something acts on it.. so how could we be on a collision course with another galaxy? http://news.yahoo.com/milky-way-galaxy-doomed-head-crash-andromeda-194656925.html
not my expertise at all but Ill give it a shot...like any explosion where the bits go is determined by their size and shape, galaxy's are no different, paths cross, gravity pull changes trajectories, collisions occur...
Moving away from what point? Everywhere in the universe is that point. Clap your hands together. OMG! They moved together!
Very good question. I don't know the answer but I'm going to take a guess. It almost certainly results from gravity. Our galaxy is a part of a group of galaxies that astonomers call the "local group." I forget how many galaxies are involved but ours and Andromeda are the two big ones. They interact with each other gravitationally, even as the distance between our group and other groups of galaxies increases. While the universe in general is expanding, elements of the universe such as our local group interact with each other gravitationally. Hopefully you will get a better answer than I offered.
The centers of most galaxies are black holes , massive ones . A black hole to put it simply it is gravity that went mad , because those holes are massive they don't suck as much matter as smaller ones so all this matter rotates them creating galaxies . Galaxies are usually coming in clusters , this is because of black hole's gravitational fields are interacting , with time they merge creating even bigger holes and much larger galaxies (although there is a process that limits galaxy's size but i don't remember how this works, i am not a specialist i have just read a little ). During the process of merging some stars are accelerated to such degree (because of gravity pull) that they are kicked in outer space , very big stars do have the potential to become black holes and start gather matter around them.
thanks to the people that offered honest answers back. I thought about gravity but wondered if the gravity would be enough to overcome the momentum from the Big Bang...but I guess maybe the momentum would fade over time and thus gravity would start having a stronger effect? Would momentum fade in space though? maybe it would because of the action of gravity? it's an interesting thing to think about and a welcome break from worrying about day to day stuff...LOL..nothing happens too fast in astronomy.
and then the stars 'kicked out' would gradually stop moving away and start getting pulled back or to another body? I guess I was thinking about space being empty and there not being anything to slow something down once it starts moving..
There was no "big explosion" in space. The BBT did not cause everything in space to move away from a point. The BBT addresses what happened after 10[SUP]-43[/SUP] seconds after space-time was created. The "explosion" is the creation of space-time itself. BBT states that the expansion of space-time is increasing the distance between objects on a galactic scale. However gravity overcomes the expansion of space-time if the galaxies are gravitationally bound. Our imminent collision with Andromeda is the the result of the gravitational attraction between the Milky Way and Andromeda galaxies. Hubble image of colliding galaxies:
there was at one time the thought that the big bangs repeated in a continual expansion and contractions as gravity overcame the expansions...I think the belief is now the universe will continually expand until what? I don't know...an interesting concept that may explain this is the "multiverse", an unlimited of number of universes popping into existence, a mind boggling concept of time and space that we can't measure or ever see...
What Wyly says is the current thinking as far as I know. The current belief is that the universe will continue expanding forever. Although forever is a dicey word as well since space and time are interrelated in ways we do not fully understand. While gravity has a tendency to want to pull things together, most objects in the universe are far enough away from other objects that gravity alone can't get the job done. The notion that ours is only one of many universes is fairly popular now. That notion helps explain how gravity can help the expansion rather than slow it. Advocates of that theory think other universes are pulling on ours as ours pulls on them. These folks think there might have been billions of big bangs. The distances involved in these issues are truly mind boggling. As an example, the star (actually a 3 star system) nearest our own is called Alpha Centauri and is located about 4 1/2 light years away. That means that light which travels at 286,000 miles per second would take 4 1/2 years to get there. A current space ship with current technology would take more than 30,000 years to get there. There are billions of stars in our 30,000 light year wide galaxy and there are billions of galaxies. Imagine the distances between galaxies. Or at least try to. Cosmology is a science that deals with a very strange and poorly understood subject.
It's not due to the black holes. If the black hole at the centre of our galaxy was pulling Andromeda to us it'd have swallowed the entire Milky Way long ago.
that was my understanding...I watched a program where a number of the experts were debating the possibilities...the multiverse concept wasn't new but when evidence seemed to point to an infinitely expanding universe the multiverse concept was reexamined to explain a universe dispersing into the dark void dying a cold death...so as one universe winks out there are others forming constantly, and on a scale so large we'll never know of their existence except through math...
Due to "dark energy". However... gravity will still have a pull no matter how far an object is away from another object. Dark energy has a stronger pull than gravity. What has spured my curiosity is why particles that collide in an accelerator spin off in spirals. I am just a working slug...I know very little.
Dark energy is not as popular as the multi universe theory. Many physicists turn their noses up at something that is invented and isn't detectable. The purpose of dark energy is to complete some mathematical equations that help explain things we don't understand about the universe. My own view is that we need to understand those things without inventing undetectable masses. Many would agree with me.
That, at least, is known. They spin off in a curved manner because of their electrical charge. The direction of the curved motion depends on the polarity of the charge.
A SCIENTIFIC THEORY is based upon facts, laws and hypothesises, is testable and falsifiable, has no evidence that can't be worked into the theory (has never been demonstrated to be false) and due to the overwhelming amount of evidence in support is considered the best hypothesis (all theories are hypothesis but not all hypothesises are theories) available. It is however not considered proven as proof is considered impossible in science. Science is based upon probability not absolute certainty.
The big bang refers to a singularity of all mass in the entire universe merged into a point so small it literally takes up NO space. This is postulated in Einstein's theory of general relativity. It exploded in something like a millionth of a millionth of a millionth of a second and expanded very fast. This is called "inflation". SO, the big bang does not relate to a collision of 2 galaxies. BUT, we are indeed on a collision course with our nearest (and larger) neighbor, Andromeda. It's expected to occur in about 4 billion years. The Milky Way and Andromeda are the two largest galaxies in our local group and it's believed both have absorbed other galaxies in the past. In fact, we are absorbing two small galaxies now, called the Larger and Smaller Magellanic Clouds.
That's wrong. Super-massive black holes are at the center of most if not all galaxies. Beyond a certain point (even horizon) the gravitational pull from the SMBH is not enough to pull in the other elements in the galaxy. But the gravitational attractions do keep the galaxy together. A Black hole will pull in anything that's within it's even horizon. Additionally, as a SMBH gets denser, it's pull is stronger, enlarging the event horizon.
