[QUOTE=xilman;515284]For those unaware of the law, I framed it around 20 years ago as "Making predictions about how long it will take to perform a calculation in computational number theory carries a great risk of making the predictor appear foolish ". Or words to that effect. I don't think a canonical version has ever been published but I do know that several MF contributors have heard me state it in public --- at Peter Montgomery's tribute colloquium at CWI for instance.[/QUOTE]

Of course your own role in helping to factor RSA129 is another famous example of said "law". Living in the US, I prefer the more general version propounded by late baseball great Yogi Berra, one of America's pre-eminent philosophers: "Making predictions is hard, especially about the future."

Paul, would you be so kind as to post a link to said CWI tribute colloquium?

====================

o [url=https://www.theguardian.com/science/2019/may/01/denisovan-jawbone-discovered-in-tibetan-cave]'Spectacular' jawbone discovery sheds light on ancient Denisovans[/url] | Science | The Guardian -- The Grauniad is propagandistic shite w.r.to their politics/world/national news, but I've always enjoyed their science coverage.
[quote]The 160,000-year-old fossil, comprising a powerful jaw and unusually large teeth, suggests these early relatives would have looked something like the most primitive of the Neanderthals. The discovery also shows that Denisovans lived at extremely high altitude and, through interbreeding, may have passed on gene adaptations for this lifestyle to modern-day Sherpas in the region.
...
The scientists were not able to obtain DNA from the sample, but managed to extract proteins from one of the molars. Proteins, like DNA, could be sequenced and the analysis placed the fossil firmly on the Denisovan branch of the evolutionary tree.

The discovery indicates that Denisovans adapted to high-altitude, low-oxygen environments much earlier than the regional arrival of modern humans about 40,000 years ago.

It also helps explain how present-day Sherpas and some Tibetan populations came to carry a gene of Denisovan origin – presumably acquired through ancient interbreeding – that allows these populations to cope with hypoxia.
...
The paper, published in [i]Nature[/i], is one of the first to use protein analysis to determine an ancient human species and the technique is seen as hugely promising because protein tends to be preserved better than DNA. The team said they were hopeful that further fossils in China would be able to be tested using the method.[/quote]

o [url=https://www.eurasiareview.com/07012019-how-climate-change-caused-the-worlds-first-ever-empire-to-collapse/]How Climate Change Caused The World's First Ever Empire To Collapse[/url] | Eurasia Review. The Akkadian empire of Mesopotamia.
[quote]Now, stalagmite data from Iran sheds new light on the controversy. In a study published in the journal PNAS, led by Oxford palaeoclimatologist Stacy Carolin, colleagues and I provide a very well dated and high resolution record of dust activity between 5,200 and 3,700 years ago. And cave dust from Iran can tell us a surprising amount about climate history elsewhere.

Gol-e-Zard Cave might be several hundred miles to the east of the former Akkadian Empire, but it is directly downwind. As a result, around 90% of the region’s dust originates in the deserts of Syria and Iraq.

That desert dust has a higher concentration of magnesium than the local limestone which forms most of Gol-e-Zard’s stalagmites (the ones which grow upwards from the cave floor). Therefore, the amount of magnesium in the Gol-e-Zard stalagmites can be used as an indicator of dustiness at the surface, with higher magnesium concentrations indicating dustier periods, and by extension drier conditions.

The stalagmites have the additional advantage that they can be dated very precisely using uranium-thorium chronology. Combining these methods, our new study provides a detailed history of dustiness in the area, and identifies two major drought periods which started 4,510 and 4,260 years ago, and lasted 110 and 290 years respectively. The latter event occurs precisely at the time of the Akkadian Empire’s collapse and provides a strong argument that climate change was at least in part responsible.

The collapse was followed by mass migration from north to south which was met with resistance by the local populations. A 180km wall – the “Repeller of the Amorites” – was even built between the Tigris and Euphrates in an effort to control immigration, not unlike some strategies proposed today. The stories of abrupt climate change in the Middle East therefore echo over millennia to the present day.[/quote]

[url=https://www.quantamagazine.org/how-twisted-graphene-became-the-big-thing-in-physics-20190430/]How Twisted Graphene Became the Big Thing in Physics[/url] | Quanta Magazine -- Twisted bilayer graphene, specifically:
[quote]The discovery has been the biggest surprise to hit the solid-state physics field since the 2004 Nobel Prize–winning discovery that an intact sheet of carbon atoms — graphene — could be lifted off a block of graphite with a piece of Scotch tape. And it has ignited a frenzied race among condensed-matter physicists to explore, explain and extend the MIT results, which have since been duplicated in several labs.

The observation of superconductivity has created an unexpected playground for physicists. The practical goals are obvious: to illuminate a path to higher-temperature superconductivity, to inspire new types of devices that might revolutionize electronics, or perhaps even to hasten the arrival of quantum computers. But more subtly, and perhaps more important, the discovery has given scientists a relatively simple platform for exploring exotic quantum effects. “There’s an almost frustrating abundance of riches for studying novel physics in the magic-angle platform,” said Cory Dean, a physicist at Columbia University who was among the first to duplicate the research.
...
Several groups in the U.S. and Europe were soon studying the properties of twisted bilayer graphene, and in 2011, Allan MacDonald, a theoretical physicist at the University of Texas, Austin, urged his colleagues to hunt for interesting behavior at a particular “magic angle.” Like other theorists, MacDonald had focused on how the misalignment of the two sheets creates an angle-dependent moiré pattern — that is, a periodic grid of relatively giant cells, each of which is composed of thousands of graphene crystal cells in the two sheets. But where others had been struggling with the enormous computational complexity of determining how an electron would be affected by the thousands of atoms in a moiré cell, MacDonald hit on a simplifying concept.

He reckoned the moiré cell itself would have one property that varied strictly with rotation angle, more or less independently of the details of the atoms that made it up. That property was a critical one: the amount of energy a free electron in the cell would have to gain or shed to tunnel between the two graphene sheets. That energy difference was usually enough to serve as a barrier to intersheet tunneling. But MacDonald calculated that as the rotation angle narrowed from a larger one, the tunneling energy would shrink, finally disappearing altogether at exactly 1.1 degrees...[/quote]
The comparison with the cuprate-based high-T superconductors in the article is interesting, explains why 30 years after their discovery they have yielded little re. the precise mechanisms involved, and why twisted graphene should make for a vastly superior substrate in this regard.

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[QUOTE=rogue;516147][URL="https://www.cnet.com/news/dark-matter-scientists-observe-the-rarest-event-ever-recorded/"]Dark matter scientists observe the 'rarest event ever recorded'[/URL][/QUOTE]

OK, I know it's journalistic hyerbole, but from the article:
[quote]The research team weren't just holding a magnifying glass over a single xenon atom, hoping to see it decay. In XENON1T [b]there is a nearly unfathomable amount of xenon atoms[/b], thanks to all that liquid xenon, effectively allowing the scientists to "watch" trillions of atoms. While only a small fraction of those are xenon-124, that still provides a good chance of nabbing the physics needle in a haystack. And rather than observing the atoms decaying directly, scientists look for signs of decay -- the X-rays and electrons released when xenon-124 decays.

The collaboration was able to spot 126 such processes over two years, which allowed them to calculate the mindbogglingly long half-life.[/quote]
C'mon, now, "unfathomable", really? These kinds of back-of-envelope calculations are the bread and butter of designers of such experiments. So let's see - roughly guessing liquid Xe has similar density as water, ~1 g/cm^3, each cm^3 has roughly a (mole/124) of atoms, were it pure Xe124. Multiply by 3e6 (grams in "over 7000 pounds", conservatively figured) and divide by the stated half-life and we get (leading multiply by 0.5 since it's called "half life" for a reason) ~0.5*(6e23/124)*3e6/1.8e22 decays per year, which comes out to around 2000 per day. Now Xe124 is ~0.1% of naturally occurring Xenon, so instead we estimate ~2 decays per day, around 10x of what was actually observed, i.e. within an order of magnitude. Hey, that was rather easily fathomed, using concepts any high school science student is expected to master. Why not write the article in a manner which encourages readers to do (or at least follow) such an estimate, rather than put up a stylistic "don't even try to wrap your pretty little head around it" barrier to further thought?

[QUOTE=ewmayer;516190]Why not write the article in a manner which encourages readers to do (or at least follow) such an estimate, rather than put up a stylistic "don't even try to wrap your pretty little head around it" barrier to further thought?[/QUOTE]I'm sure the question was rhetorical and you know the answer, but anyhow, of course the writer doesn't want to make the reader feel dumb because then they'll never come back to [strike]see the ads[/strike] read interesting stuff. And with the trend that being cool means being vague, imprecise and not caring about details just makes matters worse. We will all end up with attention spans so short that we'll not even be able to finish typing sente

:barbie:

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[QUOTE=ewmayer;516190]OK, I know it's journalistic hyerbole, but from the article:

C'mon, now, "unfathomable", really? These kinds of back-of-envelope calculations are the bread and butter of designers of such experiments. So let's see - roughly guessing liquid Xe has similar density as water, ~1 g/cm^3, each cm^3 has roughly a (mole/124) of atoms, were it pure Xe124. Multiply by 3e6 (grams in "over 7000 pounds", conservatively figured) and divide by the stated half-life and we get (leading multiply by 0.5 since it's called "half life" for a reason) ~0.5*(6e23/124)*3e6/1.8e22 decays per year, which comes out to around 2000 per day. Now Xe124 is ~0.1% of naturally occurring Xenon, so instead we estimate ~2 decays per day, around 10x of what was actually observed, i.e. within an order of magnitude. Hey, that was rather easily fathomed, using concepts any high school science student is expected to master. Why not write the article in a manner which encourages readers to do (or at least follow) such an estimate, rather than put up a stylistic "don't even try to wrap your pretty little head around it" barrier to further thought?[/QUOTE]

My high school chem teacher would have had us calculate the number of atoms as follows:

Mass of xenon "over 7000 pounds" I'll call it 3500 kg. Mass of one mole of xenon is 131 grams, or .131 kg. Number of atoms of xenon is then

3500/.131 x 6.02 x 10[sup]23[/sup] = 1.6 x 10[sup]28[/sup] atoms

The isotope fraction is about 10[sup]-3[/sup] and there's probably a fudge factor for the atomic weight of the isotope.

The half-life gives a fraction of ln(2)/(1.8 x 10[sup]22[/sup]) = 3.85 x 10[sup]-23[/sup] of these decaying per year.

So it looks like something in the hundreds to thousands of atoms of the given isotope in the sample decaying per year.

[QUOTE=retina;516192]. We will all end up with attention spans so short that we'll not even be able to finish typing sente[/QUOTE]
Haha, +1. :goodposting:

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[QUOTE=rogue;517403][URL="https://www.inc.com/scott-mautz/super-resilient-people-are-6-times-more-likely-to-do-this-1-thing-according-to-new-research.html?cid=sf01001"]Super-Resilient People Are 6 Times More Likely to Do This 1 Thing, According to New Research[/URL][/QUOTE]That is so click baity.

[QUOTE=Uncwilly;517405]That is so click baity.[/QUOTE]

Ya beat me to it - my reply (and I didn't follow the link) was gonna be "lemme guess - click on this kind of egregious clickbait headline?" I do wonder what they meant by the inane "super resilient" descriptor? Given the special-snowflake-ification of modern society ("How dare you disagree with me? This is a designated Safe Zone!"), I'm guessing having watched the Game of Thrones finale and not thrown oneself off the nearest tall structure in despair, or having "suffered the loss of multiple Facebook friends and nonetheless soldiered on" makes one "super resilient".

(Disclosure: I've only watched the first 2 seasons of GoT, both on cheap used DVDs bought years after said seasons aired. And IMO it was already sucking hard in S2, the level of cheesy-CGI-crapfest-ness had ramped up markedly relative to S1. The hordes-of-scary-white-zombies-from-the-north scene which ended S2 was laughably, just-silly bad.)