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Curious6
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Just wondering what the general scientific community thinks about this topic.
I would think that an "open" universe would imply a boundary. Otherwise, you would be talking about the instantaneous existence of infinite space. That would deny any attempt to find the cause and thus the logical consistency of existence.Curious6 said:Apparently though, in a closed Universe, the mass and the gravitational attraction in the Universe cancel out to give zero total energy. Does that mean that this does not hold anymore in our Universe if it is flat?
And what exactly does "flat" mean? Every particle that has mass begins to curve space close to its center. Does flat only a reference to the space between particles? Is it a comment about how much empty space there is between particles that appears flat? If so, then wouldn't things appear flat even with small distances and continue to be flat at large distances?meteor said:Flat is the common consensus, though I was reading Roger Penroses's "The large, the small and the human mind" and he believes that the universe is open (hence hyperbolic geometry), but this book was written before the results of WMAP
whydoyouwanttoknow said:All the evidence seems to point at the universe been flat but I believe most scientists believe that it really is closed and they're searching for evidence.
whydoyouwanttoknow said:All the evidence seems to point at the universe been flat but I believe most scientists believe that it really is closed and they're searching for evidence.
Euclidean geometry on large scales.Mike2 said:And what exactly does "flat" mean?
Curious6 said:Is the Universe Closed, Flat, or Open?
Just wondering what the general scientific community thinks about this topic.
this answers the original question, but then Curious asks further:Chronos said:It is either flat, or so close to flat we cannot yet tell the difference. WMAP is the most recent confirmation.
http://map.gsfc.nasa.gov/m_mm/mr_content.html
----------Curious6 said:Apparently though, in a closed Universe, the mass and the gravitational attraction in the Universe cancel out to give zero total energy. Does that mean that this does not hold anymore in our Universe if it is flat?
In this thread:marcus said:But how can one imagine the universe bootstrapping itself into existence always keeping the total or net energy nearly zero? Can someone offer a physical way of imagining this? Or point us to a better than usual explanation on line?
I will try to respond to curious second question: Curious I think this can work whether it is spatially finite or infinite. If you can imagine positive and negative nearly canceling in a finite U then probably you can imagine the same thing happening in a sufficiently large finite piece of an infinite U.
Then, altho there is no total mass-energy for an infinite U, you can say that the mass-energy per cubic lightyear is balanced by the negative gravitational potential energy per cubic lightyear. the cancelation could happen in large finite volumes---which seems to be the same thing.
the difficulty (for me) is to imagine how it happens in the first place, even for the finite universe.
Chronos said:I would like to explore the 'something from nothing' question a bit further. It probably isn't appropriate, however, in this thread. I have some tenuous thoughts that could use a good spanking. I suspect jcsd, and perhaps a few others, would appreciate that opportunity.
turbo-1 said:On the quantum level, it is apparently possible to "borrow" enough energy to create a sea of virtual particle-antiparticle pairs, as long as they annihilate within some pretty tight guidelines. For the universe to arise from nothing and to exist for so long, one might expect that the "borrowing" involved to avoid the dreaded "something from nothing" deficit would have to be perfectly balanced throughout the life of the universe and self-correcting to the nth degree. That's a pretty tall order. I'm all ears (no appropriate Smilie for that one).![]()
The concept of the universe being closed, flat, or open refers to its overall shape or curvature. A closed universe would have a positive curvature, meaning it would eventually loop back on itself. A flat universe would have a neutral curvature, like a sheet of paper, where parallel lines never meet. An open universe would have a negative curvature, meaning it would continue to expand infinitely.
Scientists use various methods to determine the shape of the universe, including observations of the cosmic microwave background radiation, measurements of the cosmic expansion rate, and studies of the distribution of matter in the universe. These methods allow us to measure the overall curvature of the universe and determine its shape.
The evidence supporting each type of universe is still being studied and debated. Some studies of the cosmic microwave background radiation suggest a flat universe, while other measurements of the cosmic expansion rate suggest either a closed or open universe. The distribution of matter in the universe also provides evidence for each type of universe, with some studies showing a uniform distribution for a flat universe and others showing large voids for an open universe.
The shape of the universe has major implications for the fate of the universe. A closed universe would eventually reach a maximum size and then collapse in a "Big Crunch" event. A flat universe would continue to expand forever, but at a slower rate. An open universe would also expand forever, but at an increasing rate due to the presence of dark energy. The shape of the universe also affects the geometry of space and the laws of physics within it.
The shape of the universe is thought to be constant over time, as it is determined by the overall amount of matter and energy in the universe. However, the expansion rate of the universe and the amount of dark energy could potentially change over time, affecting the curvature and ultimately the shape of the universe. Additional research and observations are needed to fully understand the dynamics of the universe's shape and how it may change over time.