a thoughtful web.
wasoxygen  ·  15 days ago  ·  link  ·    ·  parent  ·  post: The Strong Law of Small Numbers
am_Unition  ·  15 days ago  ·  link  ·

Yes, I think my statement needs to be amended to say:

...no known set of functions, mappings, transformations etc. that generates ALL prime numbers.

Edit: Actually I wasn't sure there exists even a single algorithm capable of producing only prime numbers as n -> infinity, even if the results for n below a "really large" were a subset of all primes. But Rowland (from wasoxygen's wiki article above) apparently managed to do exactly that.

Can you imagine being a reviewer for this article? It would be incredibly punishing to go through every problem and substitute increasing n until you saw whether or not it continued to meet the criteria after leaving the "small n" domain. In fact, a reviewer wouldn't do that, they'd write code to do it for them, even in 1988.

bfv  ·  15 days ago  ·  link  ·

Generating all primes is just as easy as testing for primes:

``    import math    def is_prime(n):       for m in range(2,int(math.sqrt(n))+1):            if n%m == 0:                return False        return True    def primes():        n = 2        while True:            if is_prime(n):                yield n            n += 1    for p in primes():``        print p``

it's just that we don't have useful ways to generate primes.

wasoxygen  ·  15 days ago  ·  link  ·

And in 2019, I just entered the phrase "is 4294967297 prime" into a search engine. That level of effort might explain why I only got two out of three of the examples above correct (no better than chance!) before looking at the solutions.

But #1 stumped Fermat too! I didn't know that this problem sparked Euler's interest in number theory, according to "How Euler Did It" (4-page PDF). It was one of the many problems left over from the famous Fermat-Descartes correspondence.

Fermat and Descartes did not like each other very much. In fact, some people describe their relationship as a “feud,” but it seems that Descartes resented Fermat more than Fermat disliked Descartes. They probably never met.

I figured Euler must have scribbled out a lot of long division problems to crack the Fermat number conjecture. But apparently he found a shortcut.

[SPOILER]

Euler’s mentor in St. Petersburg, Christian Goldbach, alerted Euler to the conjecture in 1729. Euler responded almost immediately that he could make no progress on the problem, but by 1732, close to a hundred years after Fermat had originally made the conjecture, Euler had a solution: Fermat was wrong. In Euler’s first paper on number theory [E26] Euler announced that 641 divides 4,294,967,297.... What Euler did not tell us in E26 was how he thought to try to divide 4,294,967,297 by 641. He hadn’t simply been dividing by prime numbers until he got to 641. He had a much better way, but he waited about fifteen years, until E134, to reveal that secret.
wasoxygen  ·  23 days ago  ·  link  ·    ·  parent  ·  post: One day, a mighty oak.

Recipe?

I dunked a healthy-looking acorn in the dirt of a potted plant and kept it watered a while but nothing came up.

johan  ·  23 days ago  ·  link  ·

Disclaimer: I only know this works for European cold-temperate oaks. The Quercus genus has hundreds of species with Mexico having the most species.

I don’t have any direct experience sprouting acorns, but you might have just gotten a dud or, depending on the species, you need to put it in the fridge for a while to mimick the cold period it would experience in nature to wake it from hibernation. Bonus tip for growing your mighty oak a little bit faster: plant it together with a nurse tree of a faster growing species so it gets some competition for light, as well as a bit of protection from the wind. Around here birch or larch are commonly planted together with oak like this, the nurse tree gets removed after a couple of years. This also reduces the risk of multiple trunks, if that’s something you want to avoid.

mk  ·  22 days ago  ·  link  ·

johan is correct. I put it in the fridge for a month.

I am experimenting with other seeds as well.

WanderingEng  ·  22 days ago  ·  link  ·

In the refrigerator dry or wet? When I sprouted apple seeds I put them in the refrigerator in a plastic bag with damp paper towels. They sprouted fine.

mk  ·  16 days ago  ·  link  ·

Wet. I dampened the soil. Funny thing, the leave in there is another plant. I just discovered so when re-potting it. However, the real thing is now sprouting.

WanderingEng  ·  23 days ago  ·  link  ·

I planted some apple seeds which sprouted and then died. Now I have some healthy pepper plants instead. I might buy some pine tree seeds next. They're on my Amazon wish list.

cgod  ·  22 days ago  ·  link  ·

My father was an infamous planter of trees.

He never started any by seed but bought saplings from nurseries. He planted thousands of flowers by seed but never a tree.

Once a year or every other year fifty saplings would show up and he'd get to work, planting a tree anywhere he thought would be nice, peoples yards, empty lots, the park and nature preserves. He did all of this under the cover of night, fueled by whimsy and malt liquor with permission never asked or granted.

The cops came by to tell him to cut it out, people aren't allowed to plant trees on public land or something but knowing it was him and proving it was evidently a crime that they weren't ready to assign a detective over. He never did cut it out.

Anyway, I'm sure pops would tell you to quit screwing around with seeds and carefully pick a few saplings of trees that you love.

WanderingEng  ·  22 days ago  ·  link  ·

I've thought about doing this. There are a few highway interchanges near me that are partially treed but have some open space. I suspect a few trees added here would get ignored and not cut down. One is easily accessible and less than a mile away. I don't really have a place to plant my own trees, so messing around with seeds is a way to experiment in my condo.

I love that your father did this. Those trees will benefit generations.

mk  ·  16 days ago  ·  link  ·

If you put a colored plastic ring around the bottom, workers are more likely to assume the planting wasn't rogue.

steve  ·  22 days ago  ·  link  ·

wasoxygen  ·  38 days ago  ·  link  ·    ·  parent  ·  post: Friday Fun Facts: Deep

It's such a cool name for a place, even if the literal meaning is "snow mountain glacier."

Iceland looks like a great place for fell running, who is up for the Snæfellsjökulshlaupið?

flagamuffin  ·  31 days ago  ·  link  ·

if i recall correctly, 54 was closed for weather, but f570 wasn't for some reason. and it was green up there, even in winter, lot of scrub plants. got out of the car and walked around, found multiple caves within minutes. totally alien landscape.

wasoxygen  ·  40 days ago  ·  link  ·    ·  parent  ·  post: Pubski: December 12, 2018

Paper wallet prepared for office white elephant gift exchange. Just have to remember to load it.

wasoxygen  ·  48 days ago  ·  link  ·    ·  parent  ·  post: SpaceX will Launch a dragon to the ISS at 1:16PM EST TODAY

First time watching the "Countdown Net" alternate camera in the video. It gives a better overall perspective than the vehicle POV cameras, and projects pessimistic parabolas. But the Stage 1 landing video will be interesting too...

francopoli  ·  48 days ago  ·  link  ·

Right as the re-entry burn was going, a part fell off the first stage booster. Once the burn was over, everything went sideways. Booster hit the water. First one of these landings in a while that has failed.

wasoxygen  ·  61 days ago  ·  link  ·    ·  parent  ·  post: Grubski! Thanksgiving edition! What did you cook? Share here.

My mission was to extract water from a machine that would not accept coins.

Foveaux  ·  57 days ago  ·  link  ·

I'm curious about the EARTH water.

wasoxygen  ·  57 days ago  ·  link  ·

The pure and mineral-rich Dutch EARTH Water is bottled at a small water source named Anl'eau. This resource is located in the protected greenzone named "the Hunzedal" in the province of Drenthe. Anl'eau is named as one of the best water sources of Europe by water specialists. The production site is pumping pure spring water from a depth of approximately 150 meters. This groundwater has fallen as rain in the Middle Ages on "the Hondsrug"; at a time when people did not use harmful substances. After a long journey of approximately 1000 years through the ground, the water has absorbed many minerals. The water therefore is of a very good quality.

I got the bottle with the red label (which turned out to be carbonated), once someone told me that the machine would not take cash. I had a €2 coin, but had to use a credit card, and am pleased to find that I was charged only \$2.29, almost exactly matching what Google shows as the exchange rate of €1 = \$1.13.

wasoxygen  ·  77 days ago  ·  link  ·    ·  parent  ·  post: Hubski Race Report: A Foray into Ultrarunning

Great job! That’s a strong finish on what sounds like a tough course.

I like dry feet and have carefully tiptoed across wobbly rocks to avoid getting wet, only to have to wade through a stream minutes later. RDs always seem to downplay the downsides.

So, 50’s done, what’s next?

ButterflyEffect  ·  76 days ago  ·  link  ·

Race Directors are a special breed...I signed up for what will be an incredibly muddy and wet 50k at the end of January, have a 50k in April and another in July, and a 50miler or 100k sometime next year. Getting a mountain trail run in this weekend while the weather is good.

One thing I didn't mention in the article, pinging WanderingEng too, was the emotional aftermath. Maybe you've experienced this too. It was a more of a slow burn instead of an immediate and visceral emotional reaction, over the course of the day or two immediately following the race was...strange. Very calm, increasingly happy about it, increasingly chatty about the race.

WanderingEng  ·  75 days ago  ·  link  ·

I haven't experienced emotion like that. I was struggling at the end of my marathon. But I do find now a year later that I'm still just as proud of doing it as I was then. The long distance is just so difficult it has a totally different emotion.

wasoxygen  ·  88 days ago  ·  link  ·    ·  parent  ·  post: Friday (Fake?) Fun Facts

She is actually French.

tacocat  ·  88 days ago  ·  link  ·

I'm surprised she exists at all

wasoxygen  ·  92 days ago  ·  link  ·    ·  parent  ·  post: US Treasuries Never Wrong - well, not really

Even if your bonds mature in the middle of a recession and you find yourself with cash and few good fixed-income options, at least you made some initial yield, no?

Yes, you're ahead after Year 1 having bought the short-term bond with a higher rate, but now you have to find something to do with your cash for the next nine years, while your alter ego has the reliable income of the ten-year bond. You got more income but less predictability. If your options are poor after one year, you might end up behind over the decade.

I don't understand why the animation plots the yield curve over time against the actual 3-month yield.

This is an animation showing the 3 month US treasury yield (blue line) versus the implied forward yield curve (red). The forward yield is estimated looking at the yields on 3, 6, 9 mo and 1, 2, 3, 5, 7 and 10 year government bonds. The blue highlighted area shows where the yield curve underestimated actual results and the ping highlighted area shows overestimations.

The red line is the yield curve from March 2007, pretty closely matching the official numbers from that month, so I don't see why it's "estimated" or "implied."

The gap between the 5-year rate in March 2007 (about 4.5%) is vertically contrasted with the March 2012 3-month rate (about 0.1%) and the "over-estimated area" between colored red. What is that supposed to represent? Five-year rates are not predictions of what three-month rates will be in five years.

I place 70% confidence that a 10-year US Treasury compared to the 2-year US Treasury will invert sometime within a month of February 2019, and then within 12 months of that inversion we will see the peak of the bull run, and then 6 months from the peak will be a recession.... By the way, that differential today is .22%.

I love a prediction. Can we stipulate treasury.gov as an authorative source? They show rates of 2.92% for a two-year and 3.20% for a ten year T-bill, a gap of 0.28%. I don't know who calls the peak of a bull run, but NBER seems to have say-so over recession dating.

blackbootz  ·  92 days ago  ·  link  ·

+1 for short-term bond demand-decrease explanation.

I think the animated yield curve is "estimated" or "implied" because of the interpolated yields along the line (there isn't a bond between 3 and 6 months, but the line implies there is one).

I, too, don't understand the purpose of the pink and blue shaded regions. I'm trying to wrack my brain because the animator issues economic advisory reports for a team of researchers so there must be a reason, right? I'm wondering if reaching out would be worthwhile, if 2014 is too long ago to remember, or if the animation was outsourced.

I love a prediction. Can we stipulate treasury.gov as an authorative source? They show rates of 2.92% for a two-year and 3.20% for a ten year T-bill, a gap of 0.28%. I don't know who calls the peak of a bull run, but NBER seems to have say-so over recession dating.

Yes, I love a prediction, too. My prediction: inversion of 10-year rates and 2-year rates + or - one month of February 2018, with a peak of the stock market (as measured by Google ticker for S&P 500? I'm open to suggestion) 12 months after with a one month margin of error (so if an inversion occurs in January 2019, a stock market maxima has to occur within December 2019 - February 2020) with an NBER-marked recession within 6 months hence.

I'm tempted to say that a stock market peak has to occur within the following year, rather than within a narrow 3-month band, but the data is pretty strong that the post-inversion stock market peaks occur a healthy amount of time after, so the prediction will stay as such.

wasoxygen  ·  91 days ago  ·  link  ·

I see; the yield curve chart is a smooth estimate of the rates you could imagine getting if terms were offered between the official periods like 6 months, 1, 5, or 10 years.

Per Mr. Laird, the animation is intended to show that today's rates are poor estimators for future rates. I can't imagine why anyone would think they are good estimators. It seems to me that today's 3-month rate is a better guess for the October 2023 3-month rate than today's 5-year rate, if you had to guess.

I wouldn't know where to begin to make such a prediction, so I am impressed by your effort. I will take the cowardly, easy route and predict that at least one of these will NOT happen:

• The 2-year T-bill rate is higher than the 10-year T-bill rate on any day from 1 January 2019 to 31 March 2019.

• If such an inversion occurs, then the S&P 500 Index as reported by Google will have a higher value on at least one of the 365 days before the inversion date, or during days 395 to 760 after the inversion first occurs, than it does at its highest value in the 394 days following the inversion.

• If such an inversion occurs, NBER will add a new business cycle to its list of business cycle reference dates with a "peak" date during the six months following the S&P 500 maximum described above.

My confidence level is 90%, not because I know what I am talking about, but because of the conjunction law.

blackbootz  ·  82 days ago  ·  link  ·

When would be a good check-in date to resolve this? The conceivably-latest point at which my prediction would still hold would be August 2020 (if NBER states a recession started at least as late as February 2020).

wasoxygen  ·  82 days ago  ·  link  ·

I’m free then.

wasoxygen  ·  109 days ago  ·  link  ·    ·  parent  ·  post: THESE TECH COMPANIES WILL NEED MORE WOMEN ON THEIR BOARDS

IMHO we are here for different purposes.

I invite anyone who wants to learn more about the subject to examine the paper you cited in support of the claim that "doubling female participation in board membership increases profits." It says "The results find no impact of board gender quotas on firm performance" in the abstract, and has details about Norway in footnote 9 on page 7.

The paper does not support the claim that increasing female participation in board membership increases profits, rather it describes some correlations, with many qualifications about the uncertainty inherent in this kind of study.

As you have reminded us more than once, correlation does not imply causation.

flagamuffin  ·  108 days ago  ·  link  ·

for the record i think it's hilarious you still talk to him, keep it up, i love it

kleinbl00  ·  109 days ago  ·  link  ·

What purpose are you here for? What purpose do you suppose I'm here for? Because I'll note you responded to my other point here, and have made no response to this one. You could even address my principle point: that female participation on boards is good for the general public. Because that "responsibility of one" vs "responsibility for 13,000" angle, which was my point made to you, is hangin' right there.

Much like the majority of conversations you've ever had where you're directly contradicted.

wasoxygen  ·  146 days ago  ·  link  ·    ·  parent  ·  post: Sci-Fi club no. 36: The Last Question discussion

According to his autobiography In Memory Yet Green, Asimov coined the name in imitation of UNIVAC, an early mainframe computer. Asimov had assumed the name "Univac" denoted a computer with a single vacuum tube (it actually is an acronym for "Universal Automatic Computer"), and on the basis that a computer with many such tubes would be more powerful, called his fictional computer "Multivac". His later short story "The Last Question", however, expands the AC suffix to be "analog computer".

Dyson has other things on his mind.

wasoxygen  ·  210 days ago  ·  link  ·    ·  parent  ·  post: Running the 2018 Charlevoix Marathon

First finish is always a PR, congratulations! What was your longest distance in training?

Getting one done means you can skip the pre-race jitters next time and start off rested. Finishing without swearing you’ll never do it again is also a promising sign. When’s the next one?

SeanBot  ·  210 days ago  ·  link  ·

Thanks! My longest distance was 18 miles which I did 13 days prior to the race on a Sunday. The Sunday before that I did 15, and then the Sunday before that I did 13.9. Besides those runs I was just doing anywhere from 5-10 miles for training and pushing myself as hard as I could each run.

When's the next one?

I think I'm going to do the Detroit half marathon (maybe full) in October and then I'm debating where to do my next full sometime next year. Definitely want to travel, I'm considering Jackson Hole Marathon next year.

wasoxygen  ·  209 days ago  ·  link  ·

Maybe you could get thenewgreen to join you in Detroit. Not many races requre travel documents to run across the border.

If for any reason (for example, emergency, carrying a backpack) you are asked by CBP to identify yourself when crossing the border, you will be expected to present proper identification (WHTI compliant document). CBP actions may delay your re-entry into the U.S. Please note: it is not the intention of CBP to actively or randomly pull runners out of the race to review their documentation.

Please note, the Ambassador Bridge Company and Detroit Windsor Tunnel LLC policy is to prohibit liquids. Runners are discouraged from carrying items on these portions of the course as they may be asked to either inspect or drop them. However, at the end of the day it is up to the runner’s discretion.

SeanBot  ·  131 days ago  ·  link  ·

I tried to get thenewgreen to join me in Detroit but he bailed. Maybe he will join me in the Bahamas for their marathon on January 20. Any of you all are welcome to join as well wasoxygen ButterflyEffect WanderingEng I am registered already and will probably be down there for a week or so getting some diving in. Planning to dive with sharks for the first time.

ButterflyEffect  ·  209 days ago  ·  link  ·

Did you see the runner who was recently detained for crossing the US-Canada border without ID?

wasoxygen  ·  275 days ago  ·  link  ·    ·  parent  ·  post: Doing science right: Have there been previous human civilizations on Earth?

The roughly contemporary architecture at Jericho is devoid of artistic merit or large-scale sculpture, and Çatalhöyük, perhaps the most famous Anatolian Neolithic village, is 2,000 years later.

At present Göbekli Tepe raises more questions for archaeology and prehistory than it answers. It remains unknown how a force large enough to construct, augment, and maintain such a substantial complex was mobilized and compensated or fed in the conditions of pre-sedentary society.

historyarch  ·  273 days ago  ·  link  ·

Klaus Schmidt, who began the excavations, noted similarities in stone tools at Gobeckli Tepe and other sites which was one of his methods for dating. (see: https://www.smithsonianmag.com/history/gobekli-tepe-the-worlds-first-temple-83613665/). Some of the male figures bear similarities to those found elsewhere as well. So clearly, Gobeckli Tepe was not isolated. From the Gobeckli website, the archaeologists date the most recent phase to be 9,600-8,000 BC (see" https://tepetelegrams.wordpress.com/the-research-project/ which also notes the comparison of carved figures). Dating these sites is imprecise but that could indicate only a 500 year gap which may actually be much less if estimates at Gobeckli Tepe and Çatalhöyük are off-- which is a distinct possibility.

Further, much of Gobeckli Tepe is unexcavated so it is risky to draw too many conclusions. It may have been abandoned in 9,000 or even 8,000 BC. There also may be other as yet undiscovered sites that will establish a clear line of development. Jericho and Çatalhöyük suffered devastating destruction in ancient times, there may have been much more sophisticated artistic endeavors that were destroyed, taken away or have yet to be found. Gobeckli Tepe was intentionally buried which likely means more is preserved.

I agree with everyone here that Gobeckli Tepe is fascinating, leaves us with many more questions than answers and may imply a different societal evolution than previously supposed.

wasoxygen  ·  277 days ago  ·  link  ·    ·  parent  ·  post: Everything you ever need to know about how the eye sees colors

Puffin beaks are fluorescent

Unlike humans, birds have always known about the extra colours in the puffin bill. That's because they can see a whole other dimension of hues, said Dunning.

Humans see colours that are a mix of red, blue and green light, he notes, while birds have a fourth colour in the mix — a property called tetrachromatic vision.