What is the shape of the Universe?

[ashish27]

Spherical, Conical, Cubical, or saddle shaped? What is the current shape of this expanding balloon? Has there been any findings in this regard?

 

[alokmohan]

Considerations of the shape of the universe can be split into two parts; the local geometry relates especially to the curvature of the observable universe, while the global geometry relates especially to the topology of the universe as a whole—which may or may not be within our ability to measure.<br /><br />The extrapolation of the local geometry of space to the geometry of the whole universe is not without a specific ontological stance regarding how space and time coexist. Current thinking demands that space and time be considered as two aspects of a single 'spacetime'.<br /><br />Nevertheless it still makes sense to speak about three-dimensional concepts referring to the universe, like the Hubble volume.<br /><br /><br />[edit] Local geometry (spatial curvature)<br />The local geometry is the curvature describing any arbitrary point in the observable universe (averaged on a sufficiently large scale). Many astronomical observations, such as those from supernovae and the Cosmic Microwave Background (CMB) radiation, show the observable universe to be very close to homogeneous and isotropic and infer it to be accelerating. In General Relativity, this is modelled by the Friedmann-Lemaître-Robertson-Walker (FLRW) model. This model, which can be represented by the Friedmann equations, provides a curvature (often referred to as geometry) of the universe based on the mathematics of fluid dynamics, i.e. it models the matter within the universe as a perfect fluid. Although stars and structures of mass can be introduced into an "almost FLRW" model, a strictly FLRW model is used to approximate the local geometry of the observable universe.<br /><br />Another way of saying this is that if all forms of dark energy are ignored, then the curvature of the universe can be determined by measuring the average density of matter within it, assuming that all matter is evenly distributed (rather than the distortions caused by 'dense' objects such as galaxies). This assumption is justified by th

 

[h2ouniverse]

Indeed, curvature close to zero, for the four commonly admitted dimensions.<br /><br />For potential other dimensions, as the ones considered in string theory, you can have very complicated shapes. (Calabi-Yau spaces)

 

[yevaud]

True, that. In some forms of Heterotic String Theory, the "shape" of the universe is an Orbifold, encompassing "compactified" additional dimensions. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[ashish27]

hmmn, lokks like the Universe gets different shapes in different theories. <img src="/images/icons/rolleyes.gif" /><br /><br />

 

[alokmohan]

Steady state universe is better that way.No beginning ,no end. I t can have no shape,it is infinite.

 

[h2ouniverse]

But notions of "beginning" and "end" are time-dependent and human brain-dependent. That human minds are more comfortable or not with "absence of beginning" is of secundary importance in the reality of universe.<br />

 

[h2ouniverse]

in reply to<br />-------------<br />Steady state universe is better that way.No beginning ,no end. I t can have no shape,it is infinite. <br /><br />------------<br /><br />Alokmohan,<br /><br />I am afraid you are expressing a religious prejudice there<br /><br />Best regards.

 

[alokmohan]

Steady state theory is the first theory of cosmology,precedindg big bang.It is not a religious view.Modern version of this theory is quasi steady state theory.Of course I am proud that the leading proponent is Indian J.V.Narlikar. Why you call it a religious prejudice?Will you clarify?

 

[pyoko]

"There is no spoon." <div class="Discussion_UserSignature"> <p> </p><p> </p><p><span style="color:#ff9900" class="Apple-style-span">-pyoko</span> <span style="color:#333333" class="Apple-style-span">the</span> <span style="color:#339966" class="Apple-style-span">duck </span></p><p><span style="color:#339966" class="Apple-style-span"><span style="color:#808080;font-style:italic" class="Apple-style-span">It is by will alone I set my mind in motion.</span></span></p> </div>

 

[ashish27]

Narlikar may be the proponent of QSST but his theory has no observational evidence so far.

 

[h2ouniverse]

Hi alokmohan,<br /><br />Sorry if I overreact but being uneasy with the notion of beginning or end of time (for what it means) is often related either with belief in the cyclic nature of the universe, or with atheism.<br />I was just surprised that you seemed to express scientific preference based on a feeling of annoyance with a finite time dimension.<br />Again, apologies if I have made overdue deductions or have been disrespectful. That was not the intention.<br /><br />Best regards.<br />

 

[Kalstang]

<font color="yellow">What is the shape of the Universe?</font><br /><br />Here is the most honest and non speculative answer here. <br /><br />The shape of the universe is....Unknown. In order for this question to actually be able to be answered we would have to either A: find a definate, non penatrable edge and then fully explore it or B: look at the universe from <i>outside</i> the universe. <div class="Discussion_UserSignature"> <font color="#ffff00"><p><font color="#3366ff">I have an answer for everything...you may not like the answer or it may not satisfy your curiosity..but it will still be an answer.</font> <br /><font color="#ff0000">"Imagination is more important then Knowledge" ~Albert Einstien~</font> <br /><font color="#cc99ff">Guns dont kill people. People kill people</font>.</p></font><p><font color="#ff6600">Solar System</font></p> </div>

 

[yevaud]

Actually, Alok isn't posting religion. He's saying that a steady-state universe is infinite, which is in fact implied.<br /><br />Though the other point is wrong, at least mathematically. It's shape will be asymptotically flat. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[origin]

A steady-state universe would need some new physics to work. An infinitely old universe would be a cold dead place due to entropy. Every process increases the entropy of the universe by the 3rd law of thermodynamics. That explicitly implies that an infinitely old universe would have no usable energy left. <br /><br /> <div class="Discussion_UserSignature"> </div>

 

[yevaud]

Oh, denying none of that, surely. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[alokmohan]

H20,dont bother ,you are a good poster.You honestly said what you think.

 

[alokmohan]

Thanks.It is oldest theory,not much known.Hoyle propounded this theory.He sarcastically named what is at present known to be big bang theory.Name persists ,Hoyle forgotten.

 

[georgewaters]

The shape of the earth depends on one's view point (focal point). A closer look gives it a rough edge sherical look. A distance view gives it a clearn spherical look. Anyway, whether close or further, the earth true shape remains spherical. <div class="Discussion_UserSignature"> <p>GEORGEWATERS OJEIGBE</p><p>JOHN HOLT PLC.</p><p>LAGOS, NIGERIA</p><p> </p> </div>

 

[georgewaters]

The answer has not been answered. <div class="Discussion_UserSignature"> <p>GEORGEWATERS OJEIGBE</p><p>JOHN HOLT PLC.</p><p>LAGOS, NIGERIA</p><p> </p> </div>

 

[georgewaters]

You have not answered the question. <div class="Discussion_UserSignature"> <p>GEORGEWATERS OJEIGBE</p><p>JOHN HOLT PLC.</p><p>LAGOS, NIGERIA</p><p> </p> </div>

 

[alokmohan]

About spoon.What do you mean?

 

[yevaud]

<i>hmmn, lokks like the Universe gets different shapes in different theories.</i><br /><br />Of course. Varying theories over the years have included not only different physical parameters, but differing numbers of dimensions. Euclidian, Yang-Mills, Kaluza-Klein, String, Heterotic String, M-Theory. All have differing "shapes" in higher dimensions. This should not be a surprise.<br /><br />No need to roll eyes at this. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[xmo1]

"We now know that the universe is flat with only a 2% margin of error."<br /><br />WMAP Cosmology 101<br /><br />** We don't do theory. <div class="Discussion_UserSignature"> <p>DenniSys.com</p> </div>

 

[SpeedFreek]

<i>"We now know that the universe is flat with only a 2% margin of error."</i><br /><br />Which means a straight line may indeed be totally straight, but there is still a chance that a straight line is only <i>nearly</i> straight, and that the radius of curvature of the universe is of an order larger than our observable universe.<br /><br />For more information on this, see here:<br /> Extending the WMAP Bound on the Size of the Universe <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>