The observable universe is understood as a sphere around the Earth extending 93 billion light years (8.8 *1026 meters) But the problem is we cannot see beyond this due to red shift and we see the cosmic microwave background (CMB). (This is a scientific fudge factor introduced to explain the un-explainable things.) Is the observed universe from earth the same as the real universe. Scientists do not know. So they devised a plan to get rid of all these unknowns. they made a model of the universe with our limited knowledge and tested it. Viola we have a flat expanding universe.
This is like a fairy tale.......
Wiki says:
Many things about the nature of dark energy remain matters of speculation.[12] The evidence for dark energy is indirect but comes from three independent sources:
- Distance measurements and their relation to redshift, which suggest the universe has expanded more in the last half of its life.[13]
- The theoretical need for a type of additional energy that is not matter or dark matter to form the observationally flat universe (absence of any detectable global curvature).
- It can be inferred from measures of large scale wave-patterns of mass density in the universe.
Well this problem came to the scientific world when they calculated the amount of matter in the observed universe. oops only 4%. Where is the rest OMG about 96%. So all the boffins are looking for it and came up with a very good idea. 74% Dark Energy and 32% Dark Matter.
In this I found that how devious the boffins are:
It sounds rather strange that we have no firm idea about what makes up 74% of the universe. It's as though we had explored all the land on the planet Earth and never in all our travels encountered an ocean. But now that we've caught sight of the waves, we want to know what this huge, strange, powerful entity really is.
The strangeness of dark energy is thrilling.
It shows scientists that there is a gap in our knowledge that needs to be filled, beckoning the way toward an unexplored realm of physics. We have before us the evidence that the cosmos may be configured vastly differently than we imagine. Dark energy both signals that we still have a great deal to learn, and shows us that we stand poised for another great leap in our understanding of the universe.
