How does expansion fit in with colliding galaxies?

by EndofMysteries 24 Replies latest members adult

• 

  EndofMysteries

  then link me what you consider a very good answer and I'll agree or tell you why it's not a really good answer. 
• 

  OUTLAW

  "How does expansion fit in with colliding galaxies?"

                                   

                                       Shit that Travels..

                                Can Bump into Other Shit..
  

              
• 

  OneEyedJoe

  If gravity can overcome the expansion, could there be a scenario where instead of infinite expansion and one day no galaxies seeing anything outside of their galaxy instead be that galaxies collide, creating larger ones with more mass and stronger gravity,  and eventually they all eat up one another?  (like when droplets of water touch they become one larger one)
  

  
  

  Yes.  Conventional wisdom held for a long time that the universe would end in a "big crunch" like what you talk about - in this scenario the total of all the gravity of the universe is sufficient to overpower the expansion and eventually pull all matter into a single point again.  Relatively recently (something like the past 20 years or so) it was determined that the rate of the universe's expansion is actually increasing.  This means that the more likely outcome is a "big freeze" in which all the stars eventually die and matter is so spread out that new stars cannot form.  

  Back to your original question, if you're having trouble visualizing it, think of our galaxy and andromeda as drops of water on the balloon, to use your analogy.  If those drops of water are close enough together on one side, even while you inflate it, they could still roll together.  There would still be other drops of water that would be too far away to ever collide with these two, but those two are still able to come together locally even while moving away from all other droplets.
• 

  Marvin Shilmer

  "If gravity can overcome the expansion,..."

  Who said gravity can overcome the expansion? 

  In this case the gravitational effect is like two automobiles traveling on a more-or-less parallel path and the two drifting into one another. Think of two cars traveling down two lanes of a US Interstate Highway. Then imagine these two cars meeting one another on the dashed white center-line. Now imagine the same concept only with two herds of animals merging but going in more-or-less the same direction. The two herds have collided/merged but more-or-less continue on the same general path. 

  
  
• 

  prologos

  Think of the membrane of your expanding balloon as being of different thickness, even different tensile resistance in different places. The thicker parts pull tighter, even to the point where they do not expand at all in some point, like in a black hole, where the outward movement through time stops, and the rest is like a hernia.  The universe, the membrane is clumpy, and like money, it tends to accumulate where there is already lots. and, as to the expansion, one idea is that the void has energy, and the expansion brings additional dark energy into the universe, fuelling the acceleration.  
• 

  EndofMysteries

  oneeyesjoe - Thanks for that reply.  The big freeze, about everything dying and being too far apart, that's the first time I've heard of that, it's interesting though.

  On everything combining into a big crunch, if that could/would happen, then that made me wonder if the big bang was the result of something similar having already happened and it would be an endless cycle. 

  Marvin & Pro - nice answers too.  the reason for the question was it was presented to me in a way that made it seem there was no room for bumping or not.  And with gravitational pulls from many sources in many directions hard to make sense they wouldn't have any impact and interfere with expansion.  Based on Newton's law that objects in space will move at a constant speed unless they encounter interference so then could gravitational pulls in different directions throw off from expansion like a yoyo or is it like Marvin said they are moving real fast on a highway and can only zigzag a bit. 

  
  
• 

  Viviane

  I'm jot doing the work for you. Read any one of a number of books or watch any; f the science shows on the universe.
• 

  EndofMysteries

  I'm jot doing the work for you. Read any one of a number of books or watch any; f the science shows on the universe.

  
  

  Let me rephrase what you've really been saying the whole thread.  "I have no damn idea about this topic, but I want everybody to think I'm really smart because I have a low self esteem, so I'm going to make some smart ass comments telling people to read a book or google so they think I already know the answer and find it simple and then they'll think I'm really smart without me having to do any work!" 

  
  

  
  
• 

  Viviane

  No need to get upset because you don't know how to use Google and educate yourself.
• 

  Marvin Shilmer

  "Based on Newton's law that objects in space will move at a constant speed unless they encounter interference so then could gravitational pulls in different directions throw off from expansion like a yoyo or is it like Marvin said they are moving real fast on a highway and can only zigzag a bit."

  Gravity does not interfere with expansion.

  Gravity is part of why we see things maneuver as they do within the expansion.