Gaia satellite is the one that will map the location of up to a third of the Milky Way to high precision. It’s only been up there a short time but has already been used to find new supernovae, novae and unidentified cataclysmic variables. The last I read it had also identified thousands of cepheids close to the south pole, which includes several from the large Magellanic Cloud, these cepheids are already well known but, being outside the Earth’s atmosphere, Gaia can get a more accurate map of luminosity vs time than is possible from the ground. Previously, Gaia’s predecessor Hipparcos saw about 200 cepheids but, because these are all a long way away (only one closer than 200 light years), it wasn’t able to get enough accuracy to check the cepheid period vs luminosity relationship. The cepheid period vs luminosity relationship is vital to our understanding of the size of the universe, and Gaia will be able to improve on that enormously when it reports back in 2018/2019.

———————————

Some Russian revolution trivia.
“Lenin” had about 160 aliases, of which “Lenin” was only one.
As a young man, Stalin was a bank robber.

———————————

RSA decryption factorisation.

The RSA encoding algorithm relies on the the difficulty of factorising a number that is the product of two large primes.

I can see at least four ways to attack the factorisation.

1) The original primes would be found by generating a random number and then looking to see whether that number is a prime. There are far fewer good random number generators than there are random numbers, so try out random number generators in turn in order try to duplicate either of the primes. That’s most likely the quickest solution, and it it works at all then it will work extremely quickly.

2) The bottom-up method based initially on the sieve of Eratosthenes of trying all possible primes. There are various algorithms known to speed that up. One is the General_number_field_sieve. A conceptually simpler version of that is the http://en.wikipedia.org/wiki/Rational_sieve
The example given is the factorisation of 187. Start by testing factorisation with the smallest primes 2,3,5,7. Then combine powers of these in a funny way to get 2,5,9,56,… Add these in turn to 187 and factorise using 2,3,5,7. Then combine these to get the final factorisation 187 = 11 * 17.

3) The alternative to a bottom-up approach is a top-down approach. In a top-down approach we don’t try one factor at a time, but instead start with all possibilities and whittle them down. For example, 187 ends with 7 and all primes greater than 5 end in 1,3,5, or 7. Because the product ends in 7, the only possibility is that one prime ends in 7 and the other in 1. Then move up to the next digit 87 and limit the possible factors to those whose product ends in 87. Then the next digit etc. I’m using decimal here but the same applies in hexadecimal or binary or any other base.

4) Another top-down approach is to start with the first digits of the number. Suppose we know that 187 is the product of two two-digit primes. The as one prime > 10 the other prime is <= 18, the smallest is 11 so that gives 187 = 11*17. In the RSA algorithm the number of digits of the factor primes is known in advance. For larger numbers we constrain the initial digits of the primes (saving as we progress from one digit to the next).

If I was doing RSA decryption then I’d set up method (1) to try independently. Then I’d apply (3) and (4) to whittle down the possibilities from both ends and then use a sieve on the rest. Challenge: give me a product of two 4-digit primes and I’ll see if I can factorise it by hand.

—————————————-

Saw “The hunger games” on TV last night. It’s not a movie that is easily forgotten.

I’m happy to forget Hunger Games, it was a rubbish movie; the book was better. Not something I’d let a child read.

New Horizons approaches Pluto
http://xkcd.com/1532/

This is a good little article about Pluto, it even has a few things I didn’t know.

7 Wild Myths About Pluto

Myth 1: Pluto was named for the Disney character.
Myth 2: Pluto is tiny.
Myth 3: It’s dark there all the time.
Myth 4: Pluto was once a moon of Neptune.
Myth 5: Pluto is an ice world.
Myth 6: Pluto is airless.
Myth 7: Pluto’s orbit is one of a kind.

More images of Ceres from Dawn released. Some showing new strange features, but as yet none closer than previous “dawn clock”: or close-up of the mysterious bright spots. http://dawn.jpl.nasa.gov/multimedia/images/ceres.html

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NASA TV ran a segment about an amateur rocket firing that looked like an almost perfect duplicate of the Australian one at Enara in Qld. Even the risk of tornado-force winds, layout of gazebos, and crop-watering sprinkler was duplicated. Only differences were they had smaller rockets, fewer wild designs, more Uni student participation, and separate indoors discussion session. Darn it, the Australian one should have been televised too.

mollwollfumble said:

More images of Ceres from Dawn released. Some showing new strange features, but as yet none closer than previous “dawn clock”: or close-up of the mysterious bright spots. http://dawn.jpl.nasa.gov/multimedia/images/ceres.html

————————-

NASA TV ran a segment about an amateur rocket firing that looked like an almost perfect duplicate of the Australian one at Enara in Qld. Even the risk of tornado-force winds, layout of gazebos, and crop-watering sprinkler was duplicated. Only differences were they had smaller rockets, fewer wild designs, more Uni student participation, and separate indoors discussion session. Darn it, the Australian one should have been televised too.

A new computer animated fly-over of Ceres has been released, too. Unfortunately they’ve exaggerated the height of topography by a factor of two, which makes Ceres look smaller than it really is. http://www.universetoday.com/120690/dawn-does-dramatic-fly-over-of-ceres-enters-lower-mapping-orbit-video/

Swap movies. Not what you might think.

SWAP stands for “Sun Watcher with APS detector and Image Processing”, a camera on board the ESA PROBA2 spacecraft.
They release into the public domain a B&W movie a day and also a colour movie each week. This is the current movie of the week.
http://proba2.sidc.be/swap/data/mpg/movies/WeeklyReportMovies/WR260_Mar16_Mar22/weekly_movie_2015_03_16.mp4

PROBA2 follows a sun-synchronous orbit. This means that PROBA2’s orbit will track the terminator, following the dividing line between day and night on earth over the poles.

One of the things that has slowly impinged itself on my consciousness.

How do big telescopes know where to point? I ask because the refraction of light by the Earth’s atmosphere causes deviations in direction of substantial fractions of a degree, which is many hundreds of times larger than the pointing accuracy required. This refraction varies with season, with time of day, and with weather.

In addition, early telescopes needed a huge “mural circle” together with a microscope in order to set telescope position in arc minutes. I can’t see how modern digital control can control the position of that mass of metal sufficiently accurately – digital control goes in fits and starts, never smoothly, consider a stepper motor. The position control hardware on modern large telescopes is tiny.

mollwollfumble said:

One of the things that has slowly impinged itself on my consciousness.

How do big telescopes know where to point? I ask because the refraction of light by the Earth’s atmosphere causes deviations in direction of substantial fractions of a degree, which is many hundreds of times larger than the pointing accuracy required. This refraction varies with season, with time of day, and with weather.

In addition, early telescopes needed a huge “mural circle” together with a microscope in order to set telescope position in arc minutes. I can’t see how modern digital control can control the position of that mass of metal sufficiently accurately – digital control goes in fits and starts, never smoothly, consider a stepper motor. The position control hardware on modern large telescopes is tiny.

Perhaps they use a computer program to extrapolate the positions of stars, planets etc very accurately taking into consideration light refraction. They wouldn’t want to be wasting hours just trying to find a target

mollwollfumble said:

I can’t see how modern digital control can control the position of that mass of metal sufficiently accurately – digital control goes in fits and starts, never smoothly, consider a stepper motor. The position control hardware on modern large telescopes is tiny.

Should be pretty easy.
A common CNC milling machine (one that I saw a few days ago) can accurately and repeatedly position the tool head to 0.001 mm.
Put machinery like that on a longer lever arm and you can have extremely good accuracy.

Spiny Norman said:

mollwollfumble said:

I can’t see how modern digital control can control the position of that mass of metal sufficiently accurately – digital control goes in fits and starts, never smoothly, consider a stepper motor. The position control hardware on modern large telescopes is tiny.

Should be pretty easy.
A common CNC milling machine (one that I saw a few days ago) can accurately and repeatedly position the tool head to 0.001 mm.
Put machinery like that on a longer lever arm and you can have extremely good accuracy.

How did it get that accuracy? When I think of a digital motor … This article outlines the problem http://www.micromo.com/microstepping-myths-and-realities eg. “Simply stated, taking a microstep does not mean the motor will actually move! And if reversing direction is desired a whopping number of microsteps may be needed before movement occurs. That’s because the motor shaft torque must be decremented from whatever positive value it has to a negative value that will have sufficient torque to cause motion in the negative direction.”

Even “Microstepping a 1.8-degree hybrid stepper motor with 256 microsteps per full step” would give 25 arc seconds per microstep. Accurate star positions are measured in micro-arc-seconds (mas). Even without adaptive optics, resolution can be of the order of 1 arc second for a 4 metre telescope.

errors come to play in the mechanical side of things

if a bearing on something is a little loose or has any play whatsoever you introduce accuracy

they probably have an error correcting programme written into things with digital outputs controlling actuators

They work so they must do it somehow

the parkes observatory for example would have big motors driving the dish around, given mechanical wear and the wind moving the dish ever so slightly I suspect digital movements from stepper movements wouldn’t factor into things very much – the dish would be wobbling around continuously from a myriad of other inputs to the dish

they probably just lock on to the target and have a “good enough” approach

Cymek said:

They work so they must do it somehow

Self adjustment is built in.

I mean, what if one spar of the dish is not quite right, flexes when it shouldn’t

then you’ve got expansion of metal with heat and then contraction with cold

if it rains that might happens quickly

wind would try to push a big dish off course

gears also wear so after X thousand hours the gears might not be exactly the same

from an old TAFE course I did I suddenly realised that many of the errors that could be introduced into a system could be removed by programming – I noticed that a robot car that had to perform a series of movements we had programmed in had a dodgy steering system, I then adjusted the programme to account for the dodgy steering (it pulled to the left, so I made a course adjustment by turning the wheels right slightly as it travelled to a set point)

then you have errors in sensors themselves

a sensor should ideally have a linear response (it makes things easier)

but if the sensor doesn’t it means that the response you create to a faulty input will be incorrect too

Would the bigger the surface area of a telescope/dish allow for a bigger margin of error when pointing at a target, to the point were it only has to be somewhat accurate.

Cymek said:

Would the bigger the surface area of a telescope/dish allow for a bigger margin of error when pointing at a target, to the point were it only has to be somewhat accurate.

possible I suppose, but it would be more susceptible to moving around on its own as well without motor input I’d say

[quote=mollwollfumble]How did it get that accuracy? When I think of a digital motor ... This article outlines the problem "http://www.micromo.com/microstepping-myths-and-realities":http://www.micromo.com/microstepping-myths-and-realities eg. "Simply stated, taking a microstep does not mean the motor will actually move! And if reversing direction is desired a whopping number of microsteps may be needed before movement occurs. That’s because the motor shaft torque must be decremented from whatever positive value it has to a negative value that will have sufficient torque to cause motion in the negative direction."[/quote] Make the motor spin at a reasonable speed, but gear it down. Make the gears so they don't have slack when reversing as well. To show how slow & accurate you can make something turn, even with a relatively high rpm motor, check this out ... "T.J. Bivins built what he calls the Slowpoke. It has a 10-in. dia. steel disc that started rotating 6 years ago and will finish its first rotation in about 3.8 billion years. 'It's the only machine I know of that if it worked any better, it would do even less,' jokes Bivins. He says he has assembled the ultimate gear reduction machine. It consists of a glass case with two parallel rows of 8 shafts, each turning a sprocket and all powered by a 120-volt motor. The shaft on the motor turns at 815,000 revolutions per year. Each of 16 sprocket/shaft combinations reduces that speed by factors of 10. It is the final gear reduction that really slows it down by a factor of 300 to 1. ":https://www.farmshow.com/a_article.php?aid=18047

Spiny Norman said:

mollwollfumble said:

How did it get that accuracy? When I think of a digital motor … This article outlines the problem http://www.micromo.com/microstepping-myths-and-realities eg. “Simply stated, taking a microstep does not mean the motor will actually move! And if reversing direction is desired a whopping number of microsteps may be needed before movement occurs. That’s because the motor shaft torque must be decremented from whatever positive value it has to a negative value that will have sufficient torque to cause motion in the negative direction.”

Make the motor spin at a reasonable speed, but gear it down. Make the gears so they don’t have slack when reversing as well.

To show how slow & accurate you can make something turn, even with a relatively high rpm motor, check this out …
“T.J. Bivins built what he calls the Slowpoke. It has a 10-in. dia. steel disc that started rotating 6 years ago and will finish its first rotation in about 3.8 billion years. ‘It’s the only machine I know of that if it worked any better, it would do even less,’ jokes Bivins. He says he has assembled the ultimate gear reduction machine. It consists of a glass case with two parallel rows of 8 shafts, each turning a sprocket and all powered by a 120-volt motor. The shaft on the motor turns at 815,000 revolutions per year. Each of 16 sprocket/shaft combinations reduces that speed by factors of 10. It is the final gear reduction that really slows it down by a factor of 300 to 1.” https://www.farmshow.com/a_article.php?aid=18047

I’m not sure that this is very accurate. Suppose the gears have a typical good clearance of 1 thou. And suppose that the radius is 0.1 metres. One thou is 0.0254 mm. The circumference is 628 mm. 0.0254/628 is 52 arc seconds. That’s not good enough for large telescope pointing. Even the parallax of alpha centauri for example is smaller than that by a factor of 70.

Let’s translate that backlash into years. 0.0254/628 * 3,800,000,000 is 154,000 years. So, once the machine has started, it could take up to 154,000 years for the last gear to even start turning.

mollwollfumble said:

Spiny Norman said:

mollwollfumble said:

How did it get that accuracy? When I think of a digital motor … This article outlines the problem http://www.micromo.com/microstepping-myths-and-realities eg. “Simply stated, taking a microstep does not mean the motor will actually move! And if reversing direction is desired a whopping number of microsteps may be needed before movement occurs. That’s because the motor shaft torque must be decremented from whatever positive value it has to a negative value that will have sufficient torque to cause motion in the negative direction.”

Make the motor spin at a reasonable speed, but gear it down. Make the gears so they don’t have slack when reversing as well.

To show how slow & accurate you can make something turn, even with a relatively high rpm motor, check this out …
“T.J. Bivins built what he calls the Slowpoke. It has a 10-in. dia. steel disc that started rotating 6 years ago and will finish its first rotation in about 3.8 billion years. ‘It’s the only machine I know of that if it worked any better, it would do even less,’ jokes Bivins. He says he has assembled the ultimate gear reduction machine. It consists of a glass case with two parallel rows of 8 shafts, each turning a sprocket and all powered by a 120-volt motor. The shaft on the motor turns at 815,000 revolutions per year. Each of 16 sprocket/shaft combinations reduces that speed by factors of 10. It is the final gear reduction that really slows it down by a factor of 300 to 1.” https://www.farmshow.com/a_article.php?aid=18047

I’m not sure that this is very accurate. Suppose the gears have a typical good clearance of 1 thou. And suppose that the radius is 0.1 metres. One thou is 0.0254 mm. The circumference is 628 mm. 0.0254/628 is 52 arc seconds. That’s not good enough for large telescope pointing. Even the parallax of alpha centauri for example is smaller than that by a factor of 70.

Let’s translate that backlash into years. 0.0254/628 * 3,800,000,000 is 154,000 years. So, once the machine has started, it could take up to 154,000 years for the last gear to even start turning.

No, like i said, use gears that don’t have any backlash.
Something like herringbone gears that have internal springs that provide for zero lash.

I’ve been musing lately about a weird quirk of evolution.

The ability to throw has given humans a great tactical advantage over other species. Not initially for hunting but for initially for keeping competitors and predators away.

So why are humans the only species in the history of evolution to develop the ability to throw? Other animals spit, squirt, pick up rocks and drop rocks, but none has developed the ability to throw them. You can argue “opposable thumb” as much as you like, but consider for example flying. Flying like throwing has an evolutionary survival advantage, with the result that flying has developed at least eight times independently in different animal lineages. It’s far easier for evolution to make physical adaptations for throwing stones than for flying, yet throwing stones hasn’t evolved before. Weird.

I think elephants throw objects with their trunks.

(Thought prompted by elephant trampling item in news)

mollwollfumble said:

I’ve been musing lately about a weird quirk of evolution.

The ability to throw has given humans a great tactical advantage over other species. Not initially for hunting but for initially for keeping competitors and predators away.

So why are humans the only species in the history of evolution to develop the ability to throw? Other animals spit, squirt, pick up rocks and drop rocks, but none has developed the ability to throw them. You can argue “opposable thumb” as much as you like, but consider for example flying. Flying like throwing has an evolutionary survival advantage, with the result that flying has developed at least eight times independently in different animal lineages. It’s far easier for evolution to make physical adaptations for throwing stones than for flying, yet throwing stones hasn’t evolved before. Weird.

probably because they have adapted better ways to get the most suitable prey for them, so throwing is unnecessary

mollwollfumble said:

I’ve been musing lately about a weird quirk of evolution.

The ability to throw has given humans a great tactical advantage over other species. Not initially for hunting but for initially for keeping competitors and predators away.

So why are humans the only species in the history of evolution to develop the ability to throw? Other animals spit, squirt, pick up rocks and drop rocks, but none has developed the ability to throw them. You can argue “opposable thumb” as much as you like, but consider for example flying. Flying like throwing has an evolutionary survival advantage, with the result that flying has developed at least eight times independently in different animal lineages. It’s far easier for evolution to make physical adaptations for throwing stones than for flying, yet throwing stones hasn’t evolved before. Weird.

I started a thread on throwing and evolution a while back..

According to Rod Whiteley, a Senior Research and Education Physiotherapist, skilled throwing has been one of the biggest drivers of the evolutionary success of humans. A number of researchers believe that throwing is important and over many years has shaped us significantly as humans.

http://www.abc.net.au/radionational/programs/ockhamsrazor/throwing-and-human-evolution/5759974

mollwollfumble said:

I’ve been musing lately about a weird quirk of evolution.

The ability to throw has given humans a great tactical advantage over other species. Not initially for hunting but for initially for keeping competitors and predators away.

So why are humans the only species in the history of evolution to develop the ability to throw? Other animals spit, squirt, pick up rocks and drop rocks, but none has developed the ability to throw them. You can argue “opposable thumb” as much as you like, but consider for example flying. Flying like throwing has an evolutionary survival advantage, with the result that flying has developed at least eight times independently in different animal lineages. It’s far easier for evolution to make physical adaptations for throwing stones than for flying, yet throwing stones hasn’t evolved before. Weird.

Chimpanzees throw things.

some spiders throw a web.

roughbarked said:

some spiders throw a web.

Humans also throw a tantrum & chuck a wobbly.

Tamb said:

roughbarked said:

some spiders throw a web.

Humans also throw a tantrum & chuck a wobbly.

;)

boomerangs.

roughbarked said:

mollwollfumble said:

I’ve been musing lately about a weird quirk of evolution.

The ability to throw has given humans a great tactical advantage over other species. Not initially for hunting but for initially for keeping competitors and predators away.

So why are humans the only species in the history of evolution to develop the ability to throw? Other animals spit, squirt, pick up rocks and drop rocks, but none has developed the ability to throw them. You can argue “opposable thumb” as much as you like, but consider for example flying. Flying like throwing has an evolutionary survival advantage, with the result that flying has developed at least eight times independently in different animal lineages. It’s far easier for evolution to make physical adaptations for throwing stones than for flying, yet throwing stones hasn’t evolved before. Weird.

Chimpanzees throw things.

so do orang utans and gorillas. Ring tailed lemurs throw things.. actually they throw ‘scents’ using their tail (ok that’s more wafting, forget that) though none of this throwing is for food sources, technically it’s tantrum throwing.

However, some spider throw their web nets, frogs and chameleons throw their tongues out to capture their food. Crows and ravens throw things on the round to ‘crack’ them (turtles)

Arts said:

roughbarked said:

mollwollfumble said:

I’ve been musing lately about a weird quirk of evolution.

The ability to throw has given humans a great tactical advantage over other species. Not initially for hunting but for initially for keeping competitors and predators away.

So why are humans the only species in the history of evolution to develop the ability to throw? Other animals spit, squirt, pick up rocks and drop rocks, but none has developed the ability to throw them. You can argue “opposable thumb” as much as you like, but consider for example flying. Flying like throwing has an evolutionary survival advantage, with the result that flying has developed at least eight times independently in different animal lineages. It’s far easier for evolution to make physical adaptations for throwing stones than for flying, yet throwing stones hasn’t evolved before. Weird.

Chimpanzees throw things.

so do orang utans and gorillas. Ring tailed lemurs throw things.. actually they throw ‘scents’ using their tail (ok that’s more wafting, forget that) though none of this throwing is for food sources, technically it’s tantrum throwing.

However, some spider throw their web nets, frogs and chameleons throw their tongues out to capture their food. Crows and ravens throw things on the round to ‘crack’ them (turtles)

I’m sure that the birds simply drop them from a great height rather than toss them at a target, though thrushes do carry a snail to a rock and bash it on the rock.

However, some spider throw their web nets

net casting spiders, if these are the ones you mean, don’t actually throw their net.

ChrispenEvan said:

However, some spider throw their web nets

net casting spiders, if these are the ones you mean, don’t actually throw their net.

more like, drop it?

no, not drop it either. they hold it in their forelegs (and four legs do the holding) and stretch it out while falling on the prey and ensnare it.

roughbarked said:

ChrispenEvan said:

However, some spider throw their web nets

net casting spiders, if these are the ones you mean, don’t actually throw their net.

more like, drop it?

some of them hold it and do a classic cartoon capture.. I was sure there was one that threw it… doco memories

mollwollfumble said:

I’ve been musing lately about a weird quirk of evolution.

The ability to throw has given humans a great tactical advantage over other species. Not initially for hunting but for initially for keeping competitors and predators away.

So why are humans the only species in the history of evolution to develop the ability to throw? Other animals spit, squirt, pick up rocks and drop rocks, but none has developed the ability to throw them. You can argue “opposable thumb” as much as you like, but consider for example flying. Flying like throwing has an evolutionary survival advantage, with the result that flying has developed at least eight times independently in different animal lineages. It’s far easier for evolution to make physical adaptations for throwing stones than for flying, yet throwing stones hasn’t evolved before. Weird.

Good question, and I don’t think any of the answers so far adequately answer it.

My best answer is that perhaps throwing things sufficiently fast and accurately to be of any use is much more difficult than we realise.

Arts said:

roughbarked said:

ChrispenEvan said:

However, some spider throw their web nets

net casting spiders, if these are the ones you mean, don’t actually throw their net.

more like, drop it?

some of them hold it and do a classic cartoon capture.. I was sure there was one that threw it… doco memories

Yeah, I have a memory of David Attenborough show, in back of head. I’d like to watch that again.

maybe our throwing ability increased at the same rate as our ability to brachiate decreased?

The Rev Dodgson said:

My best answer is that perhaps throwing things sufficiently fast and accurately to be of any use is much more difficult than we realise.

Well, most of us find that out when we try to play cricket or any other sport that requires such things.

A chameleon can throw its tounge very accurately. Methinks that sight and the brain capacity have a lot to do with it as well.

A chameleon can throw its tounge…

its what?

throwing effectively is a learned skill. Sure a kid can throw, but without instruction it’s misdirected and ungainly. To throw to hunt you have to learn it and gain strength.

ChrispenEvan said:

A chameleon can throw its tounge…

its what?

well its tongue then.

roughbarked said:

The Rev Dodgson said:

My best answer is that perhaps throwing things sufficiently fast and accurately to be of any use is much more difficult than we realise.

Well, most of us find that out when we try to play cricket or any other sport that requires such things.

The ability to throw to where the target will be not where it is at the moment of release may be a factor.

roughbarked said:

A chameleon can throw its tounge very accurately. Methinks that sight and the brain capacity have a lot to do with it as well.

That’s not throwing, it’s hitting.

Tamb said:

roughbarked said:

The Rev Dodgson said:

My best answer is that perhaps throwing things sufficiently fast and accurately to be of any use is much more difficult than we realise.

Well, most of us find that out when we try to play cricket or any other sport that requires such things.

The ability to throw to where the target will be not where it is at the moment of release may be a factor.

To be sure that this is something we learnmed from attempting to be killers.

learned?

Tamb said:

roughbarked said:

A chameleon can throw its tounge very accurately. Methinks that sight and the brain capacity have a lot to do with it as well.

That’s not throwing, it’s hitting.

Like a king hit? One punch law?

golden eagles ‘throw’ baby mountain goats off the side of the mountain to kill them. Ok technically it’s dropping, but they drag the goat to the edge and push it off..

orcas throw their prey into the air to stun and kill

Arts said:

orcas throw their prey into the air to stun and kill

Technically it is flipping.

an interesting article about humans throwing…

http://www.abc.net.au/radionational/programs/ockhamsrazor/beta-nav/how-throwing-helped-humans-conquer-the-world/5776230

roughbarked said:

Arts said:

orcas throw their prey into the air to stun and kill

Technically it is flipping.

Though all this stuff does imply that the brain knows that if a seal is tossed in the air, it cannot swim away and must fall back to earth and that if opened jaws are placed where it will predictably fall, wins at least a majority of times, makes it all worth the effort.

Arts said:

an interesting article about humans throwing…

http://www.abc.net.au/radionational/programs/ockhamsrazor/beta-nav/how-throwing-helped-humans-conquer-the-world/5776230

It’s striking that humans are the only species that can skilfully and forcefully throw. If you have been caught unawares in front of a chimp enclosure, you and your poo-covered clothes might well disagree, but while chimps’ aim is reasonable, they don’t throw with great velocity. Typically it’s an underarm ‘fling’ and certainly nothing like the skilled forceful over-arm throw you would see during javelin at the Olympics, or from the pitcher’s mound at Fenway Park.

Chimpanzees can stand up and throw over-arm, but even with training, these creatures, who are far stronger than us, can only throw at about 30 kilometres per hour —about as well as a five-year-old human can do with five minutes of training. Twelve-year-olds will throw at triple that speed, and the fastest recorded human throws are five times this, at over 160 kilometres per hour.

well, there ya go everything else is punching, or wafting, or hurling or dropping

monkeys throw stuff at each other

yes it is an evolutionary advantage – people are taught to stand still in the face of an aggressive dog for example – yet the real solution is to either fake a throw at the dog or throw something across its path. in Syria we were visiting a ruin and I was looking at something when I heard my name being called , spinning around with cat like reflexes I spied my significant other being chased by a very large dog. I quickly sized up a stone and threw it between the dog and the significant other – at which the dog turned tail and ran away.

dogs have evolved to know when someone is throwing something at them – I’ve had aggressive Alsatians turn tail and run away in the past

Arts said:

an interesting article about humans throwing…

http://www.abc.net.au/radionational/programs/ockhamsrazor/beta-nav/how-throwing-helped-humans-conquer-the-world/5776230

Which context shows that humans took the art of throwing and packed it down a rifle breech.

yes the evolution of throwing is flying, shooting, firing artillery rounds and space travel

a satellite is simply an object hurled into orbit

Arts said:

Arts said:

an interesting article about humans throwing…

http://www.abc.net.au/radionational/programs/ockhamsrazor/beta-nav/how-throwing-helped-humans-conquer-the-world/5776230

It’s striking that humans are the only species that can skilfully and forcefully throw. If you have been caught unawares in front of a chimp enclosure, you and your poo-covered clothes might well disagree, but while chimps’ aim is reasonable, they don’t throw with great velocity. Typically it’s an underarm ‘fling’ and certainly nothing like the skilled forceful over-arm throw you would see during javelin at the Olympics, or from the pitcher’s mound at Fenway Park.

Chimpanzees can stand up and throw over-arm, but even with training, these creatures, who are far stronger than us, can only throw at about 30 kilometres per hour —about as well as a five-year-old human can do with five minutes of training. Twelve-year-olds will throw at triple that speed, and the fastest recorded human throws are five times this, at over 160 kilometres per hour.

well, there ya go everything else is punching, or wafting, or hurling or dropping

Throwing is as much about developed two legged stature as it is having arms used for something else.

The Rev Dodgson said:

My best answer is that perhaps throwing things sufficiently fast and accurately to be of any use is much more difficult than we realise.

Other primates have brute strength while humans have fine motor skills

Witty Rejoinder said:

The Rev Dodgson said:

My best answer is that perhaps throwing things sufficiently fast and accurately to be of any use is much more difficult than we realise.

Other primates have brute strength while humans have fine motor skills

Have you ever tried building something that can support you and all your children, from spider webs?

as I kid I used to be involved with plum fights , thousands of juicy rotting plums laying idly around

we turned up at a pub one day and realised that the wooden fort where much younger kids were playing on was also surrounded by plums

we separated into two teams that crouched behind the wooden stockades

the other kids clears off – the plum fight was raging, you’d stay low and move quickly when not covered lest you cop it in the head from a plum

I realised that the wood had small gaps between the palings , if thrown fast enough the fruit would make it through the gap. I saw someone’s grinnimg face come into the gap and I stood and hurled a juicy plum at the gap where upon it exploded as it hit the gap spraying itself on the other side

roughbarked said:

Have you ever tried building something that can support you and all your children, from spider webs?

Not that I recall.

wookiemeister said:

a satellite is simply an object hurled into orbit

Pushed into orbit.

Witty Rejoinder said:

roughbarked said:

Have you ever tried building something that can support you and all your children, from spider webs?

Not that I recall.

Are your motor skills good enough to spin silk?

roughbarked said:

Are your motor skills good enough to spin silk?

With my arse?

at primary school it snowed heavily one year

the older kids were separated from us by a set of bars and also with a height advantage

I watched as two older girls stood giggling as they had just thrown these snowballs straight into some kids face

I was stood at the furthest end of the yard and quickly gathered some snow into a perfect ball

hefting it and judging the weight and distance I watched silently – watching to see if my targets would stay put – they were still laughing at this kid crying

I threw the snowball into the air and it sailed in this perfect curve and hit one of the bars at face height infront of the targets , if they had been clever they would have stood back

the snowball exploded into their faces – I didn’t see them near the fence again

Witty Rejoinder said:

roughbarked said:

Are your motor skills good enough to spin silk?

With my arse?

That wasn’t what I meant and you know it.

roughbarked said:

Witty Rejoinder said:

roughbarked said:

Are your motor skills good enough to spin silk?

With my arse?

That wasn’t what I meant and you know it.

Humans spin silk all the time.

wookiemeister said:

at primary school it snowed heavily one year

the older kids were separated from us by a set of bars and also with a height advantage

I watched as two older girls stood giggling as they had just thrown these snowballs straight into some kids face

I was stood at the furthest end of the yard and quickly gathered some snow into a perfect ball

hefting it and judging the weight and distance I watched silently – watching to see if my targets would stay put – they were still laughing at this kid crying

I threw the snowball into the air and it sailed in this perfect curve and hit one of the bars at face height infront of the targets , if they had been clever they would have stood back

the snowball exploded into their faces – I didn’t see them near the fence again

In indoor cricket, I had a ball that would lob high and slow. Some batsmen would flay at it while others stupidly stood aside thinking it would go to the keeper only to see it land on top of the bails. Those that flayed at it either missed or if they connected, usually hit a catch back to the bowler, er\\\ me

roughbarked said:

That wasn’t what I meant and you know it.

So you’re not talking about spiders? My comments was about the strength versus fine motor skills of primates; not other animals.

Tamb said:

roughbarked said:

Witty Rejoinder said:

With my arse?

That wasn’t what I meant and you know it.

Humans spin silk all the time.

Some do, yes. The rest spin shit.

Witty Rejoinder said:

roughbarked said:

That wasn’t what I meant and you know it.

So you’re not talking about spiders? My comments was about the strength versus fine motor skills of primates; not other animals.

OK, then let’s see you toss a few green leaves up a tree somewhere and sleep on it.

roughbarked said:

Tamb said:

roughbarked said:

That wasn’t what I meant and you know it.

Humans spin silk all the time.

Some do, yes. The rest spin shit.

So a spin doctor would be a proctologist?

Tamb said:

roughbarked said:

Tamb said:

Humans spin silk all the time.

Some do, yes. The rest spin shit.

So a spin doctor would be a proctologist?

well done.

was playing softball once started whacking these balls high and far. finally the fielders were split into closer or far.

the only way they could get me out was when someone I knew in the distance broke two fingers catching the ball

roughbarked said:

Tamb said:

roughbarked said:

Some do, yes. The rest spin shit.

So a spin doctor would be a proctologist?

well done.

Thogh more likely the faecesless men.

roughbarked said:

OK, then let’s see you toss a few green leaves up a tree somewhere and sleep on it.

I’m pretty sure I could fashion a functioning sleeping nest from leaves and branches.

Witty Rejoinder said:

roughbarked said:

OK, then let’s see you toss a few green leaves up a tree somewhere and sleep on it.

I’m pretty sure I could fashion a functioning sleeping nest from leaves and branches.

Yeah but you aren’t a gorilla, though indeed you are a primate.

i see this thread is starting to go to shit.

ChrispenEvan said:

i see this thread is starting to go to shit.

SNAFU.

SNAFU.

a pyramid in egypt.

ChrispenEvan said:

i see this thread is starting to go to shit.

It is all the tossers in it. ;)

Anyway, a number of plants throw their seeds.

ChrispenEvan said:

SNAFU.

a pyramid in egypt.

A novel by some geezer.

In indoor cricket, I had a ball that would lob high and slow. Some batsmen would flay at it while others stupidly stood aside thinking it would go to the keeper only to see it land on top of the bails.

no ball!

ChrispenEvan said:

In indoor cricket, I had a ball that would lob high and slow. Some batsmen would flay at it while others stupidly stood aside thinking it would go to the keeper only to see it land on top of the bails.

no ball!

The umpires always put up their finger. I had a hat trick off the first three balls of the game.

umpire was shit then.

Snafu, a toy also known as Screwball Scramble

ChrispenEvan said:

umpire was shit then.

more than one umpire. If you weren’t there then you are imagining something different from what I’ve described.

i know exactly the ball you describe.

when I’m making a nest I usually hawk up some flem and bones, it acts as a glue holding the sticks together

phlegm

ChrispenEvan said:

i know exactly the ball you describe.

Have you umpired indoor cricket?

no. but i have played 2-3 seasons a year for 14 years. plus outdoor cricket. seen everything.

umpired outdoor cricket.

in those days chrispen was the hard man of cricket , legend has it he gave Richie a black eye

ChrispenEvan said:

no. but i have played 2-3 seasons a year for 14 years. plus outdoor cricket. seen everything.

OK. Anyway, as I said, the umpires let me get away with it on numerous occasions. The hat trick off the first three balls were all catches. the first two back to me, the third when he tried to put the ball somewhere else, went straight to another fielder.

best was 5 in a row. all bowled. felt sorry for him so i bowled the sixth so he had a chance of hitting it.

ChrispenEvan said:

umpired outdoor cricket.

Well, if they take a swing at it and miss and it hits the stumps or if they step forward, raise their bat then step out of the way of the ball which comes past dropping below shoulder height?

roughbarked said:

ChrispenEvan said:

no. but i have played 2-3 seasons a year for 14 years. plus outdoor cricket. seen everything.

OK. Anyway, as I said, the umpires let me get away with it on numerous occasions. The hat trick off the first three balls were all catches. the first two back to me, the third when he tried to put the ball somewhere else, went straight to another fielder.

I used to do a slow, slower ball that would get up above the batsmans eyes but bounce around his feet. Usually after he’d already taken a swing .

if the ball passes over shoulder height of the batter at the crease and in their normal batting stance then it is a no ball. high and slow has to do that. the faster the ball the flatter the trajectory. to hit on top of the bails then it must have passed the batter above the shoulder. unless they are 2m tall.

ChrispenEvan said:

if the ball passes over shoulder height of the batter at the crease and in their normal batting stance then it is a no ball. high and slow has to do that. the faster the ball the flatter the trajectory. to hit on top of the bails then it must have passed the batter above the shoulder. unless they are 2m tall.

None of my balls passed above the shoulder. Most of them did land at the batsmans feet. The odd one did hit the top of the stumps.

roughbarked said:

ChrispenEvan said:

if the ball passes over shoulder height of the batter at the crease and in their normal batting stance then it is a no ball. high and slow has to do that. the faster the ball the flatter the trajectory. to hit on top of the bails then it must have passed the batter above the shoulder. unless they are 2m tall.

None of my balls passed above the shoulder. Most of them did land at the batsmans feet. The odd one did hit the top of the stumps.

Some batsmen slaughtered my bowling.

… would go to the keeper only to see it land on top of the bails.

a full toss. if it bounced at the batter’s feet then it wouldn’t land on top of the bails.

please keep your story straight.

ChrispenEvan said:

… would go to the keeper only to see it land on top of the bails.

a full toss. if it bounced at the batter’s feet then it wouldn’t land on top of the bails.

please keep your story straight.

I said it was a ball. There are lots of balls bowled more than one.

and i was discussing that ball not the others.

ChrispenEvan said:

and i was discussing that ball not the others.

and the umpires gave it out.

like i said, shit umpire.

ChrispenEvan said:

like i said, shit umpire.

Well, that part wasn’t my worry. ;)

mollwollfumble said:

I’ve been musing lately about a weird quirk of evolution.

The ability to throw has given humans a great tactical advantage over other species. Not initially for hunting but for initially for keeping competitors and predators away.

So why are humans the only species in the history of evolution to develop the ability to throw? Other animals spit, squirt, pick up rocks and drop rocks, but none has developed the ability to throw them. You can argue “opposable thumb” as much as you like, but consider for example flying. Flying like throwing has an evolutionary survival advantage, with the result that flying has developed at least eight times independently in different animal lineages. It’s far easier for evolution to make physical adaptations for throwing stones than for flying, yet throwing stones hasn’t evolved before. Weird.

The rest have big teeth.

Conclusion
It has been proposed (Young, 2002) that the earliest hominid specialization was aggressive throwing and clubbing, and that this behaviour increased reproductive success during a prolonged period, driving natural selection that progressively improved its effectiveness. If these assertions are correct, the evolution of the human hand should provide evidence of this process in its anatomical structure.

The fossil record indicates that adaptation for throwing and clubbing began to influence hand structure at or very near the origin of the hominid lineage and continued for millions of years thereafter. During this prolonged period of evolution, the hand underwent a profound remodelling that increasingly adapted it for grasping spheroids in a manner that allows precise control of release and for gripping clubhandles with strength sufficient to withstand a violent impact. Two unique human handgrips were thereby produced. Called the ‘power’ and ‘precision’ grips by Napier (1956) who identified and described them, they can also be referred to as clubbing and throwing grips on the basis of their evolutionary origins.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1571064/