Steam Users' Forums Physics brahs: I have a question about the universe expanding.
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 08-05-2012, 02:22 PM #1 josephdinatale   Join Date: Aug 2008 Reputation: 545 Posts: 102 Physics brahs: I have a question about the universe expanding. If the universe is expanding, then what is it expanding into? Here's a picture I made to illustrate my point: http://i3.photobucket.com/albums/y89...Untitled-3.png A finite universe expanding doesn't make sense. To me, it would only make sense if the universe was infinite. Let's say the universe was the set of numbers {1, 2, 3, ...}. This is an infinite set of numbers. Well let's "expand" the universe by adding the number 2.5. Well the set is still infinite. Therefore it can expand but still be infinite. Therefore the is no "outside" the universe.
 08-05-2012, 02:24 PM #2 arisaka      Join Date: May 2009 Reputation: 398 Posts: 1,434 I always thought that everything inside the universe is expanding.
08-05-2012, 02:25 PM   #3
Porcupeth

Join Date: Dec 2011
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Posts: 1,868
Quote:
 Originally Posted by josephdinatale If the universe is expanding, then what is it expanding into?
the next big bang

 08-05-2012, 02:26 PM #4 sdaniels7114   Join Date: Oct 2007 Reputation: 2516 Posts: 74 I think its because its not expanding the way an empty balloon expands; but then again I just barely got past F=MA. So don't take my word for it.
 08-05-2012, 02:32 PM #5 Mr.Ceefus      Join Date: Feb 2010 Reputation: 1735 Posts: 826 Some believe it will expand to a certain point and then collapse back in on itself becoming a singularity again. I have no friggin idea either way.
 08-05-2012, 02:34 PM #6 Modiga-Disabled     Volunteer Moderator Join Date: Nov 2004 Reputation: 10352 Posts: 10,008 Imagine a balloon. Now imagine the Universe as we know it is the surface of that balloon. Imagine the balloon is then inflated. The surface of the balloon is thus expanding. What is it expanding into? The air around. Imagine trying to travel in the direction of expansion while being constricted to the balloon's surface. And there you have it, a simple model that is almost entirely but not quite unlike how the Universe works. __________________ Need something? PM me or contact support
 08-05-2012, 02:35 PM #7 Master Splinter   Join Date: Jul 2012 Reputation: 1584 Posts: 92 That's one of the most intriguing question in the current physics paradigm: What's beyond our Universe? And no matter how much anyone on these forums think they know about physics, no one will be able to truthfully answer that question. There are many theories: Some say that our Universe is just an "hologram" formed from the information of other parallel dimensions called "branes", and that, whatever it is, is what lies beyond our Universe. Others suggest our Universe is just one of many, and that the Big Bang was a result of a collision with another Universe. The analogy is that our Universe(s) are akin to the bubbles formed when you boil water, and that Universe(s) come and go; what lies beyond that? just the "water"...
08-05-2012, 02:37 PM   #8
IcarusNine

Join Date: Jun 2005
Reputation: 5771
Posts: 2,568
Quote:
 Originally Posted by josephdinatale Let's say the universe was the set of numbers {1, 2, 3, ...}.
A. Your analogy is terrible.
B. There isn't really a difference between the expansion of a finite universe and the expansion of an infinite universe for how easy it is to comprehend.
C. Your analogy really is terrible.

 08-05-2012, 02:43 PM #9 Smertnik      Join Date: Oct 2007 Reputation: 1709 Posts: 4,011 I think there comes a point in physics when you can't use familiar analogies anymore, both in micro- and macrocosmos.
 08-05-2012, 02:50 PM #10 trojanrabbit.gg      Join Date: Mar 2010 Reputation: 6544 Posts: 1,646
08-05-2012, 02:53 PM   #11
marie pavie

Join Date: Jan 2005
Reputation: 28435
Posts: 10,307
Quote:
 Originally Posted by josephdinatale If the universe is expanding, then what is it expanding into?
Ein Sof.

or
This romance novella will help to explain it

Last edited by marie pavie: 08-05-2012 at 02:58 PM.

 08-05-2012, 02:57 PM #12 Chris C177      Join Date: Apr 2009 Reputation: 173 Posts: 850 It's expanding into nothing, as far as I understand it. Literally nothing.
 08-05-2012, 03:06 PM #13 CouncillorDayv      Join Date: Jul 2012 Reputation: 8 Posts: 13 There's a perfect way to explain expansion - the best way is visually, but I forgot the vid I first saw this on, so this is a little exercise. Open an image editing program and im the middle of the page, draw a few black splodges. These are your stars. Make that a selection and expand it by 10% - everything gets bigger. Now if you take the expanded section and move it around a bit, try to line up the new, big stars with the old small ones. Line up their centers and you'll see that, the universe is expanding AWAY from that star. Move to a different star, and the universe appears to be expanding away from THAT star now. The universe doesn't really expand from a point, more it's just getting bigger, pulling itself out. Galaxies don't fly away from the center of the universe. It just GROWS. All physical matter is contained within Universe. The Universe is everything. There is a finite amount of matter (matter = energy = can not be created from scratch) and, at the Big Bang, this was all compressed into a veeeeeery very very very small space. Now it's the same matter, but in a more open space, and it forms stars and planets and even life. Dunno if that was good enough, but hot damn I love astrophysics.
 08-05-2012, 04:46 PM #14 ZoSo15   Join Date: Nov 2007 Reputation: 568 Posts: 1,673 Modiga's example is perfect. The things is, in order for us to comprehend the expansion of the universe we have to "cheat" and imagine the 3-dimensional universe as a 2-dimensional surface. As 3-dimensional beings we are incapable of comprehending what the universe is expanding into because it's outside our realm. Pretty interesting stuff. If you still have trouble understanding then smoke a bowl and try again. lol
 08-05-2012, 05:11 PM #15 Larry1212      Join Date: Apr 2009 Reputation: 2659 Posts: 3,669 http://discovermagazine.com/2009/oct...ighboring-one/ *Pretends to have read article*

 Steam Users' Forums Physics brahs: I have a question about the universe expanding.

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