cosmological principle
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Cosmology Demystified
That has got to be the single strangest post title I’ve ever written. Of all the whacky branches of science out there, cosmology almost takes the cake — second only, I think, to the downright trippy world of quantum mechanics.…
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The Proof in the Afterglow
In 1915, Einstein published his theory of general relativity. This theory predicts that, since gravity works by bending space-time, it also determines the shape of space — and the shape of the universe as a whole. In 1929, Edwin Hubble…
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The Big Bang Theory, Revised
Imagine a time before stars and galaxies existed, before free-floating subatomic particles combined to form the first atoms, before the synthesis of the first atomic nuclei… Wait a second — this sounds familiar! Way back in May, we rewound the…
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Why do Galaxies Exist?
When we look out into the sky, we see a universe filled with galaxies. Galaxies are the second-largest “structure” we’ve covered in depth on this blog. The largest so far have been galaxy clusters, which are just what the name…
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What is the Cosmological Principle?
What if I were to ask you: Are there any unique places in the universe? That is, does any one location in the universe have a special vantage point? Does the universe look different from different locations? You might say…
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From Cold Cloud to Hot Protostar
Paradoxically, stars begin in the galaxy’s coolest places: the dense giant molecular clouds (or GMCs). This is not quite the paradox it seems, as in the beginning, stars require little else but gravity to form. And that’s really quite lucky, because…
