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Mixed bag of news and magazine articles relevant to past week

#1
C C Offline
Russia halts Soyuz rocket launches from South America over European sanctions on Ukraine invasion
https://www.space.com/russia-halts-soyuz...nch-guiana

EXCERPTS: The Russian space agency Roscosmos is stopping all Soyuz rocket launches from Europe's spaceport in French Guiana due to European Union sanctions on Russia's invasion of Ukraine.

"In response to EU sanctions against our enterprises, Roscosmos is suspending cooperation with European partners in organizing space launches from the Kourou cosmodrome and withdrawing its personnel, including the consolidated launch crew, from French Guiana," Roscosmos chief Dmitry Rogozin said in a Twitter statement on Saturday (Feb. 26) according to a translation from Russian.

[...] Thierry Breton, the European Commissioner for Space, said Russia's decision to halt Soyuz launches with Europe will not interrupt any services for users of the Galileo satellites or of the E.U.'s Copernicus Earth observation satellite program. "I confirm that this decision has no consequences on the continuity and quality of the Galileo and Copernicus services," Breton said in the statement. "Nor does this decision put the continued development of these infrastructures at risk."

Breton added that the E.U. and its member states are "ready to act decisively" in order to "protect these critical infrastructures in case of aggression," and that it will "continue to develop Ariane 6 and Vega C to ensure Europe's strategic autonomy in the area of launchers." (MORE - missing details)


'Fuzzballs' might be the answer to a decades-old paradox about black holes
https://astronomy.com/news/2022/02/fuzzb...lack-holes

EXCERPT: . . . This problem — called the black hole information paradox — has plagued physics for decades. But theoretical physicist Samir Mathur has proposed a solution: changing the way we think of black holes and picturing them instead as “fuzzballs.”

Based on the traditional picture handed down by the likes of Einstein, “quantum mechanics is violated when you have a black hole,” says Mathur, a professor at The Ohio State University who specializes in black hole physics. “Once you have a situation like that, you actually don’t have a theory of physics.” It’s the job of physicists, he says, to reconcile general relativity, which explains the behavior of big things, and quantum mechanics, which works for the extremely tiny. Mathur believes that the fuzzball theory could do just that... (MORE - missing details)


The dark side of online space disinformation
https://www.science.org/content/article/...nformation

INTRO: Theoretical cosmologist Katie Mack spends a lot of time on Twitter. Mack, at North Carolina State University, joined the platform to talk about science under the moniker “Astro Katie” more than 10 years ago. Since then, her fun and informative posts about space have earned her nearly half a million followers.

Unfortunately, she says, there are many other astronomy-themed Twitter accounts sharing misleading or downright wrong information. From doctored images to sinister conspiracy theories, Mack has seen it all.

Last week, at the annual meeting of AAAS, which publishes Science, Mack discussed space and physics disinformation—and how it can erode trust in science. She sat down with Science to chat about common space falsehoods, how silly pictures can lead to conspiracy theories, and how to spot something fake before you share it.

This interview has been edited for length and clarity... (MORE - the interview)


How did our planet avoid being frozen solid during the early days of our solar system?
https://eos.org/features/the-young-earth...e-cool-sun

INTRO: When Earth was still in its infancy more than 4 billion years ago, it was surrounded by chaos. The planet had nearly been shattered by a giant collision whose debris would go on to form the Moon. The detritus of planet formation was still regularly colliding with the newly reformed Earth. Elsewhere in the solar system, the gas giants were amassing their own satellites and clearing out chunks of rocks that refused to fall in line. And for those first few hundred million years, the Sun was still waking up, with fusion by-products slowly building and causing its core to contract and glow brighter. By the end of the Hadean, when Earth was a meager half a billion years old, the Sun shone at about 75% of its current brightness.

That poses a problem. Not much is known about what was happening on Earth at that time, but what little we do know suggests that there was some amount of liquid water present at or near the surface starting in the Hadean, and there is evidence that life itself began in the Archean (4.0–2.5 billion years ago). If modern Earth were suddenly to receive 25% less sunlight today, it would quickly freeze over, so how did early Earth manage to avoid it for 2 billion years?

For decades this question, dubbed the “faint young Sun paradox” by Carl Sagan and George Mullen in 1972, has been an intriguing research topic for geochronologists, deep-time paleoclimatologists, and astronomers, although the scientists currently working to answer the question prefer to call it not a paradox but just a “regular ol’ problem.” (MORE - details)


Loop quantum gravity: Does space-time come in tiny chunks?
https://www.space.com/loop-quantum-gravi...-quantized

EXCERPT: One of the most annoying things that general relativity and quantum mechanics disagree about is the role that space-time plays in the physics. For quantum mechanics, space-time is just a background, a stage, a floor, a container for all the interesting interactions that make up the physics of the universe. Yes, that stage may bend and warp, and that bending and warping affect the paths of particles — but that's about it. All physics happens "on top" of that background space-time.

Even string theory — the purported "theory of everything" in which all particles and forces are just tiny bits of vibrating strings — assumes the existence of a background space-time to work off of. So that makes it a theory of … almost everything.

For general relativity, however, space-time isn't a background stage for the actors; it is the actor. General relativity doesn't assume a background; it creates it. General relativity is the language of the warping of space-time, and that very warping generates the physics of gravity.

So, in our quest to unite quantum mechanics with gravity, maybe we should take Einstein's theory at face value. If gravity simply is the mechanics of space-time, then to seek a quantum theory of gravity, we really need to seek a quantum theory of space-time. If we can crack that quantization, then by default, we'll end up with a quantum theory of gravity, and the problem will be solved.

This is the approach known as loop quantum gravity. The word "loop" appears in the name because the theory's foundation is based on a rewriting of Einstein's general relativity in terms of lines (instead of points as it's usually done). It doesn't change any of the physics but makes some calculations easier, especially when it comes to quantizing space-time.

What does it mean to quantize space-time? It means there's a fundamental unit, a discrete chunk, of space-timey-ness that sits at some imperceptibly small scale. If you were to zoom in to this screen, the smooth curves and clean edges of the letters would be revealed as a vast number of little squares — pixels.

In much the same way, if you were to zoom in to space-time, you would see that time doesn't advance into the future continuously but in quick little tick-tick-ticks of a discrete clock. When you move, it wouldn't be a smooth motion; it would just consist of stuttering steps from one space-time pixel to another.

The biggest benefit of this quantization of space-time is that singularities simply go away. Singularities appear in Einstein's general relativity as places where densities go infinitely high and gravity becomes infinitely strong. We know that this really means that our understanding of the physics is going off the wall, and that we have no clue as to what's happening deep inside a black hole or at the beginning of the Big Bang, where singularities appear.

In loop quantum gravity, though, those singularities get replaced with really, really tiny chunks of ultradense (and, presumably, ultra-exotic) matter. We would simply banish those singularity demons from our universe and replace them with something understandable... (MORE - missing details)
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#2
Kornee Offline
(Feb 27, 2022 12:16 AM)C C Wrote: 'Fuzzballs' might be the answer to a decades-old paradox about black holes
https://astronomy.com/news/2022/02/fuzzb...lack-holes

EXCERPT: . . . This problem — called the black hole information paradox — has plagued physics for decades. But theoretical physicist Samir Mathur has proposed a solution: changing the way we think of black holes and picturing them instead as “fuzzballs.”

Based on the traditional picture handed down by the likes of Einstein, “quantum mechanics is violated when you have a black hole,” says Mathur, a professor at The Ohio State University who specializes in black hole physics. “Once you have a situation like that, you actually don’t have a theory of physics.” It’s the job of physicists, he says, to reconcile general relativity, which explains the behavior of big things, and quantum mechanics, which works for the extremely tiny. Mathur believes that the fuzzball theory could do just that... (MORE - missing details)

How to explain and characterize a century plus logical error in GR foundations? That has in recent decades morphed, thanks to ill-conceived attempts at 'reconciliation' with QFT, into an endlessly debated 'information paradox' theorist industry? By reexamining whether GR, despite it's to date loudly trumpeted successes, is self-inconsistent at it's core.
Check out Appendix A here:
https://arxiv.org/abs/1606.01417
For quite some time I thought that was the final answer and resolution. For sure it avoids the first order in metric logical failure inherent in GR's Schwarzschild solution.
However, I now believe it is just a superior approximation, exactly valid only in the far field limit. Energy density of gravitational field is imo not incorporated yet. Isotropy of spatial metric is nonetheless a necessarily correct aspect, inherent in Yilmaz (and similar) gravity, but absent in GR.
None of these logical self-consistency issues fazes an industry wedded to GR orthodoxy that, experimentally, continues to be 'good enough'.
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#3
Zinjanthropos Offline
Dumb question but from layman’s perspective: If the singularity that supposedly gave birth to the universe was a fuzz ball then would its particles have lost information from a time prior to the Big Bang or bring all info it had collected with it?

IOW….how could the BB singularity contain universe building information if it didn’t have it already? Where would it get that info?
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#4
Kornee Offline
Exponential metric is manifestly free of any 'event horizon' thus free of any 'singularity' at r = 0.
In fact it has been shown the standard exponential metric has a 'wormhole throat' guaranteeing an automatic fail-safe absence of any 'spacetime singularity':
https://arxiv.org/abs/1805.0378
As per earlier post, the completely self-consistent solution may or may not exhibit such a 'wormhole throat', but in any case will always be event horizon free.
This more or less directly carries over to cosmology. Also, if conservation of information is truly sacrosanct, that alone ensures there cannot ever be a 'singularity' beginning. Implication being some kind of 'bounce' cycling with a perfectly finite minimum sized beginning at each 'bounce'. All current models have difficulties.
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#5
C C Offline
(Feb 27, 2022 03:35 PM)Zinjanthropos Wrote: Dumb question but from layman’s perspective: If the singularity that supposedly gave birth to the universe was a fuzz ball then would its particles have lost information from a time prior to the Big Bang or bring all info it had collected with it?

IOW….how could the BB singularity contain universe building information if it didn’t have it already? Where would it get that info?

Even back when a BB singularity was entertained (see bottom of post for current view), there were technical differences between the latter and a black hole singularity.

But yes, with respect to the so-called "paradox", the issue wouldn't apply to the BB singularity. Information-wise, a black hole has the existing past structure and interactions of the universe -- representationally conveyed by the electromagnetic spectrum -- of which a local region's version of that can be potentially sucked into a BH. But the (now passé) BB singularity wasn't surrounded by a universe with a past/present (i.e.,  no information in that regard to either loose or preserve, sans a Big Bounce situation).

A hypothetical "fuzzball" is apparently a jumble of similarly speculative superstrings which -- along with their extra dimensions -- would supposedly elude a literal singularity status and the problems associated with it (if superstrings existed, were the fundamental units).
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There Was No Big Bang Singularity
https://www.forbes.com/sites/startswitha...9626747d81

EXCERPT: Every time you see a diagram, an article, or a story talking about the "big bang singularity" or any sort of big bang/singularity existing before inflation, know that you're dealing with an outdated method of thinking. The idea of a Big Bang singularity went out the window as soon as we realized we had a different state — that of cosmic inflation — preceding and setting up the early, hot-and-dense state of the Big Bang. There may have been a singularity at the very beginning of space and time, with inflation arising after that, but there's no guarantee. In science, there are the things we can test, measure, predict, and confirm or refute, like an inflationary state giving rise to a hot Big Bang. Everything else? It's nothing more than speculation.
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Surprise: the Big Bang isn’t the beginning of the universe anymore
https://bigthink.com/starts-with-a-bang/...-universe/

EXCERPT: This new picture gives us three important pieces of information about the beginning of the universe that run counter to the traditional story that most of us learned. First, the original notion of the hot Big Bang, where the universe emerged from an infinitely hot, dense, and small singularity — and has been expanding and cooling, full of matter and radiation ever since — is incorrect. The picture is still largely correct, but there’s a cutoff to how far back in time we can extrapolate it.

Second, observations have well established the state that occurred prior to the hot Big Bang: cosmic inflation. Before the hot Big Bang, the early universe underwent a phase of exponential growth, where any preexisting components to the universe were literally “inflated away.” When inflation ended, the universe reheated to a high, but not arbitrarily high, temperature, giving us the hot, dense, and expanding universe that grew into what we inhabit today.

Lastly, and perhaps most importantly, we can no longer speak with any sort of knowledge or confidence as to how — or even whether — the universe itself began. By the very nature of inflation, it wipes out any information that came before the final few moments: where it ended and gave rise to our hot Big Bang. Inflation could have gone on for an eternity, it could have been preceded by some other nonsingular phase, or it could have been preceded by a phase that did emerge from a singularity. Until the day comes where we discover how to extract more information from the universe than presently seems possible, we have no choice but to face our ignorance. The Big Bang still happened a very long time ago, but it wasn’t the beginning we once supposed it to be.
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#6
Syne Offline
(Feb 27, 2022 07:27 PM)C C Wrote: There Was No Big Bang Singularity
https://www.forbes.com/sites/startswitha...9626747d81

EXCERPT: Every time you see a diagram, an article, or a story talking about the "big bang singularity" or any sort of big bang/singularity existing before inflation, know that you're dealing with an outdated method of thinking. The idea of a Big Bang singularity went out the window as soon as we realized we had a different state — that of cosmic inflation — preceding and setting up the early, hot-and-dense state of the Big Bang. There may have been a singularity at the very beginning of space and time, with inflation arising after that, but there's no guarantee. In science, there are the things we can test, measure, predict, and confirm or refute, like an inflationary state giving rise to a hot Big Bang. Everything else? It's nothing more than speculation.
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No, people have just taken to referring to the BB as occurring after inflation instead of before, even though:

The inflationary epoch lasted from 10−36 seconds after the conjectured Big Bang singularity to some time between 10−33 and 10−32 seconds after the singularity.
https://en.wikipedia.org/wiki/Inflation_(cosmology)

After its initial expansion, an event that is by itself often called "the Big Bang", the universe cooled sufficiently to allow the formation of subatomic particles, and later atoms.
https://en.wikipedia.org/wiki/Big_Bang


In no proper definition does the BB only occur after inflation, as inflation is part of the same initial expansion. Every time I read this stuff, it sounds like a crackpot who didn't understand what they were reading.

Yes, we can't attain information prior to inflation, but, at best, that would make assuming there was no singularity just speculative as assuming there was. The problem is that the metric expansion of the universe weighs heavily on the side of the universe getting ever smaller as you move backward in time.
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