Astronomy/cosmology questions...

[Buster's Uncle]

  Yeah.  I know of Berz from the Pit, where he's honestly not one of the bad ones IMAO - but he's tres' hardcore on the Libertarian stuff and quite convicted.  Like, I really mean hardcore, but that still tends to leave him almost a sane voice in some of the 'Poly political argument slap-fight threads.

[Buster's Uncle]

Astronomers May Have Spotted a Direct Collapse Black Hole
http://alphacentauri2.info/index.php?topic=18117.0

This struck me as sounding suspiciously like the reporter may not have understood what he was talking about.  So?  Does the article make sense?

[Lorizael]

What seems nonsensical about it?

[Buster's Uncle]

...[furrows brow] I thought black holes of all sizes were supposed to have come out of local fluctuations in the big bang, for one thing.  When did that go away?  Are you telling me that explanation made sense?

[Lorizael]

There's not a lot of good observational evidence for primordial black holes, and you would expect there to be very few large primordial black holes if they exist at all. For black holes that are stellar mass and above, the prevailing theory is that they're the end stage of massive stars post-supernova. But because space is big (and some other problems), assembling stellar mass black holes into supermassive black holes is thought to be a tricky thing; yet we see supermassive black holes very early on in cosmic history, suggesting quite rapid assembly.

[Buster's Uncle]

I don't know why, given, say, an Earth-mass primordial starting out, you could rule out the thing feeding way up, to understate it, with all the mass in the universe still squeezed into say, a 10 light-year sphere at an early point...

[Lorizael]

It's difficult to have an intuition about the early universe because all evidence indicates it was nothing at all like what we see today. The only way to get a handle on it is with a bit of math, so let me demonstrate just with the numbers you provided.

In cosmology, the size of the universe is inversely proportional to its temperature. So with a 10 light-year universe, which is less than a billionth its current size, the temperature would have been something like a billion or 10 billion kelvins. At that temperature, nothing sticks together. Particles (no atoms yet) that collide will annihilate rather than bond. What's more, the universe is at roughly that size for a fraction of a second, because it's expanding incredibly quickly at this stage. So there's simply too little time for any appreciable accretion to occur. The result is that the universe is very smooth for a long, long time.

We know this based on the cosmic microwave background. The CMB has an extremely uniform temperature of almost exactly 2.725 K everywhere we look. That uniform temperature corresponds to uniform density in the early universe. The differences you see in the CMB map are 1 part in 10,000. The big density fluctuations we see today (planets, stars, galaxies, voids, etc.) all came about much later as the very minor early density fluctuations started clumping.

[Spacy]

The only thing faster than the speed of light (that we know of) is Nothing.

Note: nothing is something, but it is still nothing.

Big bang 102.  Big bang 101 is that it is really poorly named - would be better to call it the "everywhere stretch" (stole that one from minutephysics guys). 

[E_T]

According to some conjectures, the matter/energy total amount is "finite", IF and only if, there is an "edge" to the universe.  But if the universe is without bounds, then that balance is infinite...

[ColdWizard]

How bright are the Perseids? At times, I've been tempted to fetch a book at night to see if I could read it from the light pollution and the local paper says to avoid porchlights, streetlights, and such. Assuming it's not cloudy.

[Lorizael]

They vary in brightness depending on how big the meteor is (so brighter ones will be less common than fainter ones), but the brightest meteors will outshine planets. The faintest ones will be dimmer than the most easily visible stars, so you do want to get out somewhere dark to see them. That is, they're talking about this year possibly being particularly strong, with as many as 200 meteors/hour, so you could expect to see a few every minute, but only if you're in an area dark enough to catch them all.

[ColdWizard]

So, like, halfway to Winchester?

Edit: http://www.lightpollutionmap.info/#zoom=9&lat=4706023&lon=-8568392&layers=B0TFFFF

Double edit: WaPo has an article with suggestions, one of which is western Loudoun county, so yes, halfway to Winchester. Merely rates as "Decent". I don't feel like a trip to Shenandoah either.

[Buster's Uncle]

Have Scientists Discovered The Fifth Force Of Nature?
 
Journal link in the article...

[Buster's Uncle]

‘Largest structure in the universe’ undermines fundamental cosmic principles

[E_T]

Did you see the post at WPC, that Arnie put up, about the disccovery of an Earthlike, Goldielocks Zone, Exoplanet around Proxima Centauri (which is ~0.12 ly closer to us than Alpha Centauri)??