Astronomy Without A Telescope ? Assumptions ? The current...

Astronomy Without A Telescope ? Assumptions

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The current standard model of the universe, Lambda-Cold Dark Matter, assumes that the universe is expanding in accordance with the geometrical term Lambda ? which represents the cosmological constant used in Einstein?s general relativity. Lambda might be assumed to represent dark energy, a mysterious force driving what we now know to be an accelerating expansion of space-time. Cold dark matter is then assumed to be the scaffolding that underlies the distribution of visible matter at a large scale across the universe.

But to make any reasonable attempt at modelling how the universe is ? and how it unfolded in the past and will unfold in the future ? we first have to assume that it is roughly the same everywhere.

This is sometimes called the Cosmological Principle which states that when viewed on a sufficiently large scale, the properties of the Universe are the same for all observers. This captures two concepts ? that of isotropy, which means that the universe looks roughly the same anywhere you (that is you) look ? and homogeneity, which means the properties of the universe look roughly the same for all observers anywhere they are and anywhere they look. Homogeneity is not something we can expect to ever confirm by observation ? so we must assume that the part of the universe we can directly observe is a fair and representative sample of the rest of the universe.

(via universetoday)

Source: http://moderation.tumblr.com/post/4718327138

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