Archive for the ‘Cosmology’ Category

Taming the Multiverse


(UoC) – Sarah Collins:

Professor Stephen Hawking’s final theory on the origin of the universe, which he worked on in collaboration with Professor Thomas Hertog from KU Leuven, has been published in the Journal of High Energy Physics.

“We are not down to a single, unique universe, but our findings imply a significant reduction of the multiverse, to a much smaller range of possible universes.” – Stephen Hawking taming-the-multiverse

Universes arise


Surprising Twist in the Dark Matter Search


(FTB) – Mano Singham:

Astronomers have detected galaxy NGC_1052-DF2 that does not contain any dark matter at all.

So what does this new study imply? That no dark matter exists? If so, how do we explain the observations in every other galaxy? That dark matter does not exist only for this galaxy? Explaining a unique anomaly will be difficult. Or perhaps there are many galaxies like this one and that would require a different theory of dark matter formation and aggregation.

What is likely to happen now is that other astronomers will look at this same galaxy to see if the anomaly holds up while others try to find other galaxies with similar properties while theorists scramble to create new models that could explain either outcome.

Fun times! …

singham 2018/03/31 surprising-twist

NGC 1052-DF2

Phil Plait: What is this galaxy doing without a dark matter halo?

Stephen Hawking’s Scientific Legacy


(Preposterous Universe) – Sean Carroll:

Stephen Hawking is the rare scientist who is also a celebrity and cultural phenomenon. But he is also the rare cultural phenomenon whose celebrity is entirely deserved. His contributions can be characterized very simply: Hawking contributed more to our understanding of gravity than any physicist since Albert Einstein. …

preposterousuniverse stephen-hawkings-scientific-legacy

Stephen Hawking: A Brief History of Time

Why Haven’t We Bumped Into Another Universe Yet?


(Starts With A Bang!) – Ethan Siegel:

The Universe we inhabit is vast, full of matter and energy, and expanding at a tremendous clip. Looking billions of light years away, we can see billions of years into our ancient past, finding evidence of newly-forming planets, stars, and galaxies. We’ve seen so far back that we’ve identified clouds of gas that have never yet formed a single star, and found galaxies from when the Universe was only 3% of its current age. Most spectacularly, we can actually see the leftover glow from the Big Bang, from a time when the Universe was a mere 380,000 years old. Yet in all of this cosmic enormity, we’ve never found evidence that our Universe has bumped into another one in this vast Multiverse. Why not? …

starts-with-a-bang fa15b45b0ce9

Universes arise

The Big Bang May Have Been One of Many


(Atlantic Science) – Natalie Wolchover:

Our universe could be expanding and contracting eternally. …

theatlantic 2018/02 big-bounce

Hubble Extreme Deep Field

Why Is There Something, Rather Than Nothing?


(Preposterous Universe) – Sean Carroll:

It seems natural to ask why the universe exists at all. Modern physics suggests that the universe can exist all by itself as a self-contained system, without anything external to create or sustain it. But there might not be an absolute answer to why it exists. I argue that any attempt to account for the existence of something rather than nothing must ultimately bottom out in a set of brute facts; the universe simply is, without ultimate cause or explanation. …

preposterousuniverse 2018/02/08 why

Universes arise

How Neutrinos Could Solve The Three Greatest Open Questions In Physics


(Starts With A Bang!) – Ethan Siegel:

A detailed look at the Universe reveals that it’s made of matter and not antimatter, that dark matter and dark energy are required, and that we don’t know the origin of any of these mysteries. …

starts-with-a-bang 4a07d7c2aa9f

Detailed Universe

Is the Universe Infinite Or Finite?


(Starts With A Bang!) – Ethan Siegel:

Either possibility offers a tremendous existence, but philosophically, there’s so much more to think about. …

starts-with-a-bang ec032624dd61

Universes arise

Merging Neutron Stars Deliver Deathblow To Dark Matter And Dark Energy Alternatives


(Starts With A Bang!) – Ethan Siegel:

Don’t believe in dark matter or dark energy? Your view of the Universe just got a lot more difficult. …

starts-with-a-bang b5e6d2f44d37

Merging Neutron Stars

Properties of Expanding Universes


(The Conversation) – James Geach:

The PhD thesis of perhaps the world’s most famous living scientist, Professor Stephen Hawking, was recently made publicly available online.

Given the complexity of the topic, “Properties of Expanding Universes,” you might benefit from a summary of its main result. …

Hawking has gone on to make further monumental contributions to cosmology and theoretical physics. Reading his thesis is an insight into an exceptionally creative mind – and the first steps of discovery in what has been a remarkable scientific journey. …

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Big Bang expansion timeline