Contrabang! #35 Surprising Not Surprising

Astronomers Find A Galaxy Of Unusual Size (G.O.U.S.), And Discover Why It Exists (link)

Above a certain size, spiral galaxies shouldn’t exist. A single major merger — where two galaxies of comparable mass interact to form a larger one — will almost always destroy that spiral structure, producing a giant elliptical instead. The only ultra-large spiral galaxies we typically find are in the process of gravitationally interacting with a neighbor, producing an extended but temporary “grand spiral” structure.

But for every rule, there are remarkable exceptions.

There it is. To cosmologists, rules are not really rules. They are way beyond the point of demanding that their theories explain observations, and can happily discard contradictions as "remarkable exceptions."

The fact that a galaxy this large and massive is so regularly shaped, with such low levels of star formation and so few globular clusters (1600) for its incredible size really does make this a cosmic unicorn.

A cosmic unicorn...what an apt metaphor for a science that has devolved into little more than mysticism and fairy tales.

Did LIGO Just Discover Two Fundamentally Different Types Of Neutron Star Mergers? (link)

No, they didn't, because neutron stars don't exist.

LIGO just announced the second neutron star-neutron star merger ever seen in gravitational waves. It doesn’t match the first.

That they don't match is of little surprise.

Still, the April 25, 2019 signal that showed up in the LIGO Livingston detector — the one that was online at the time — was extremely strong, achieving a detection signal-to-noise significance of 12.9, where 5 is the “gold standard” for a robust detection. The form of the signal was incredibly analogous to what was seen back on August 17, 2019 in both LIGO detectors, but had an inherently greater amplitude, indicating a higher set of masses for both neutron stars, as well as a higher combined mass.

The signal-to-noise numbers are not true measurements, but guesses based on their noise cancelation methods. There are no strong signals seen in the raw data.

The lack of [an accompanying gamma ray] signal appears, on its surface, to suggest something absolutely remarkable. Perhaps lower-mass neutron star mergers produce gamma rays, ejecta, the Universe’s heaviest elements, and a multi-wavelength, long-lasting afterglow. And perhaps, above a certain mass threshold, higher-mass neutron star mergers simply interact and go directly to a black hole, swallowing up all of the matter associated with both stars, producing no heavy elements and emitting no further observable signal at all.

This is an eminent possibility from a theoretical perspective. If two neutron stars merge together and don’t immediately create an event horizon, an enormous, runaway fusion reaction will begin to occur.

I'm not spun up on the intricacies of neutron star merger theory (because it doesn't matter) but it's not clear what sort of fusion could occur. Fusion, as normally understood, is the merger of two separate atomic nuclei into one larger nucleus. How does that apply to the hypothetical neutronium...have they invented new hypothetical physics for that state of matter too?

What falls out of this article is speculation that the reason the more recent neutron star merger detection wasn't accompanied by a gamma ray burst observation is that an event horizon formed too quickly for any signal to escape. So they already have an excuse handy for when the highly touted multisignal messenger search fails to pan out.

The Milky Way Is Gaining New Stars From A Collision That Hasn’t Even Occurred Yet (link)

In the second paragraph, Ethan shares the surprise of the recent discovery of a dense collection of stars discovered in the far fringes of the Milky Way galaxy in the direction of the Magellanic Clouds (emphasis added)

Thanks to the all-sky coverage of ESA’s Gaia satellite — designed to measure properties of stars such as parallax, motion through the sky, stellar colors, etc. — humanity has gained the ability to measure more than a billion stars within about 100,000 light-years of home: almost the entire extent of the Milky Way galaxy. When scientists used this data set to search for new, blue stars, they got quite a surprise: 94,000 light-years away, deep in the galactic halo’s outskirts, a giant collection of young stars was found. It’s the first of its kind, and scientists think they understand why.

A few lines later, he re-emphasizes the rarity of the finding.

Remarkably, all of these factors line up, and this new star cluster really is a finding like nothing ever before.

And yet, just a few lines further, the surprise has already worn off.

It’s no surprise that the gravitational interactions between the Milky Way and each of the Magellanic Clouds would lead to the formation of new stars; the tidal forces between gas-filled objects often triggers new star-formation events.

It's common in the cosmology world to see new observations called surprising, only to soon be explained away as somehow predicted by the standard models. It is less common to see that process unfold in the span of only a few paragraphs!

From the standard gravity-dominated view of the cosmos, the recent observations amount to a "remarkable conclusion that changes the way we think our local galactic neighborhood" because "new gas is already being funneled into the Milky way from satellite galaxies that are still nearly 200,000 light-years away."

From an EU-perspective, it is understood that the Milky Way is related and coupled to the other objects within the local group, and the discovery of plasma flowing between the Milky Way and the Magellanic clouds is little different than the recent (surprising) discoveries of massive current sheaths connecting galaxies over enormous distances.

Ask Ethan: Does A Time-Stopping Paradox Prevent Black Holes From Growing? (link)

A reader asks

[F]or any object falling into a black hole, time slows down upon approach and comes to a standstill as the object reaches the event horizon. Reaching and passing that border would take an infinite amount of time measured by a distant observer… if ‘eating’ matter would take infinite time… how could supermassive black holes come into existence?

Yet another black hole paradox, this one asks how we can observe the growth of black holes when infalling matter will appear forever in suspended animation. From our perspective, once a black hole is formed there is no reason for us to ever observe it grow any larger, thus we could have no evidence of the supermassive black holes alleged to exist at galactic centers.

It sounds like a paradox, but relativity explains how it all really happens.

Ethan's track record of clarifying black hole paradoxes is not stellar. Regular readers may recall that some time ago he offered up the existence of ring singularities to explain the paradox of infinite densities in black holes...but that was the wrong paradox! The ring singularity is a construction meant to explain the infinite angular velocity paradox of black holes. It's hard to keep them all straight! Perhaps he will redeem himself with this newer attempt.

Imagine that we begin with a black hole of one solar mass, that doesn’t rotate, with an event horizon of the exact size that our Sun would be if it collapsed into a Schwarzschild black hole: a sphere of about 3 kilometers in radius. Now, let’s take another one solar mass object — perhaps another star just like our Sun — and let’s allow it to fall in to this black hole.

Never mind...another epic fail. Why does Ethan specify a Schwarzschild black hole, rather than using the term black hole in a more general sense? To convey that he is smart and knows what he's talking about, most likely. (Unfortunately, that doesn't seem to be the case.) The Schwarzschild solution is valid for a universe with only a single, massive body. This can be confirmed easily enough merely by browsing Wikipedia.

This solution pertains when the mass M of one body is overwhelmingly greater than the mass m of the other.

Thus, his hypothetical setup is inherently invalid. There cannot be both a Schwarzschild black hole of one solar mass and another object of one stellar mass. His answer is that once the new mass is at the event horizon, then that is good enough because the event horizon will expand with the addition of the new mass to the system. Perhaps he should re-work the example for a single particle falling in.