Is the Universe Truly Infinite? Exploring the Concept of Spatial Infinity

[calios]

guys I am quite interesting when some people talk about flat geometry universe they also relate this to spatially infinite universe..

well i don't fully grasp the idea,
but i try to imagine, when bigbang happened in infinite space, from observation scientist say there is no aether..they think we are in static universe, doesn't talk about boundary.. and later they found redshift and say we are in space expansion with boundary .. but can we say, it may not be the case?
what about we just explode in infinite space? we just thought the space is in expansion..
thank u

 

[Chronos]

In geometrical terms this means the ends of a line with no curvature [i.e., flat] will never meet. In cosmological terms this means you will never return to your departure point no matter how long you travel in one direction. This is not true on earth, for example. You will eventually return to your departure point if you travel long enough in the same direction [due to the curvature of the earth]. Expansion really has nothing to do with the curvature of space. You can still circumnavigate an expanding surface so it has any curvature. Scientists use conic sections to refer to curvature. A flat univese is a slice taken through the axis of the cone. It looks like a 'V'. A positively curved [closed] universe is a slice taken that intersects the axis. It looks like a circle or an ellipse. A negatively curved [open] universe is a slice taken that does not intesect the axis. It looks like a parabola or hyperbola. Both flat and negatively curved universes are considered infinite.

 

[bapowell]

A flat geometry can be bounded. The torus is one such example.

 

[Naty1]

talk about flat geometry universe ...

Well in many respects 'flat' versus 'curved' space [and time] is an idea I don't think many people even considred before Einstein. It's a crazy idea, if you ask me, but it works describing many observations and experimental results. Curved, warped time...what IS that?? It's another story, but you can check 'time dilation' in Wikipedia to get an idea about it.

well i don't fully grasp the idea,

not many do...that's because we don't have everyday experience with such an idea. New perspectives are one thing that makes science so interesting. You get used to seeing a house look smaller in the distance and experience shows you it is really bigger up close.

what about we just explode in infinite space?

while not necessarily impossible, that is not part of the best current scientific thinking.
The theoretical insights we have so far suggest that neither space nor time existed just before the big bang.

Here is a really nice introductory discussion; only five pages, but enough ideas for a lifetime!:

"Misconceptions about the Big Bang"
Baffled by the expansion of the universe? You're not alone.
Even astronomers frequently get it wrong

http://space.mit.edu/~kcooksey/teaching/AY5/MisconceptionsabouttheBigBang_ScientificAmerican.pdf

 

[pmacias]

I understand the fascination with the concept of a spatially infinite universe. However, it is important to note that this is still a theoretical concept and has not been proven or observed in our universe.

The idea of a flat geometry universe does not necessarily mean it is infinite in size. It simply means that the geometry of the universe is flat, rather than curved like a sphere or saddle.

The concept of an infinite universe also raises questions about the nature of space and time. If the universe is truly infinite, then it would suggest that it has always existed and will continue to exist forever. This challenges our current understanding of the beginning and end of the universe.

As for the idea of a boundary, it is still a topic of debate among scientists. Some believe that the universe has a boundary, while others argue that it is constantly expanding without any defined edge. The discovery of redshift and the theory of space expansion do suggest that the universe has a boundary, but it is still a topic of ongoing research.

In terms of the big bang theory, it is important to note that it does not suggest an explosion in the traditional sense. It was a rapid expansion of space and time, and the concept of an infinite universe does not necessarily contradict this.

Overall, the concept of a spatially infinite universe is still a topic of debate and requires further research and evidence to fully understand. As scientists, we must continue to explore and question these ideas in order to gain a better understanding of our universe.