Oxenfurt lecture hall

[Elegast7]

A psychologist conducted an intelligence test. His subjects were a physicist, a chemist, and an engineer. He gave each a red rubber ball and told them, "Tell me the mass of this red rubber ball."

The physicist measured the circumference and oblateness of the ball to determine its volume, dropped it from a height and measured the rebound, deduced the density of the rubber, and computed the mass from the volume and density.

The chemist submerged the ball in a graduated cylinder and used Archimedes' Principle to compute the mass.

The engineer took out his red rubber ball catalog and looked up the mass.

I heared that one, but it was a little bit different. The version I heard was between a physicist, an engineer and a mathematician instead of a chemist.

Both examples of the engineer and the physicist were about the same. The difference was that the mathmatician would calculate the solution only using his mind and formulas whereas the physicist would device an experiment.
And calculating the mass with the Archimedes's principle is actually pure physics. But it is ofcourse up to you which version you prefer.

Spoiler

A mathematician, a physicist, and an engineer are all tasked with determining the properties of a red rubber ball.

The mathematician derives a formula based on the size of the ball and the material that the ball is made of and the answers that his solution yields are the different properties of the ball.

The physicist performs a series of tests on the red rubber ball and uses the results from his experiments to determine the properties.

The engineer whips out his book of "red rubber balls" and writes down what he finds.

 

[GuyNwah]

I heared that one, but it was a little bit different. The version I heard was between a physicist, an engineer and a mathematician instead of a chemist.

Both examples of the engineer and the physicist were about the same. The difference was that the mathmatician would calculate the solution only using his mind and formulas whereas the physicist would device an experiment.
And calculating the mass with the Archimedes's principle is actually pure physics. But it is ofcourse up to you which version you prefer.

I know a few other variations, too, but the engineer's act of looking it up in a list of objects designed by other engineers was the point here

 

[Elegast7]

I know a few other variations, too, but the engineer's act of looking it up in a list of objects designed by other engineers was the point here

Sure, tbh I never fully understood the joke. What is different about the engineer then the others that make him look up the answer. Is it that they cooperate more? Are they more lazy, smarter?

 

[Gilrond-i-Virdan]

@rohirrim: I think the point of the joke is that engineers attempt to optimize the solution. I.e. find an effective way to solve the problem. While pure scientists don't necessarily care about optimization.

 

[GuyNwah]

Sure, tbh I never fully understood the joke. What is different about the engineer then the others that make him look up the answer. Is it that they cooperate more? Are they more lazy, smarter?

Not really. The key insight is that the red rubber ball is a manufactured object. If it's manufactured, it's also catalogued and sold on the foundation of specifications in the catalogue.

 

[gedierond]

There quite a few of those jokes. I remember a couple from my university days, although they are referred to different scientists rather than engineers.


A chemist, physicist and a mathematician survive a plane crash and end up marooned on a desert island. They try to find food and only find a can of beans, so they try to come up with a way to open it.

The physicist says: "Applying enough force we should be able to pry the can open.". Picking up a rock from the floor, he adds: "Estimating the weight of this rock and the resistance of the can I could find the height from which the rock should be dropped in order to open the can. Then it´s simply a matter of finding a tree or a cliff tall enough."

The chemist says: "If we scratch the tin layer covering the can, the iron inside will be exposed. Then, the salty water of the sea will provide an excellent medium for the metal to corrode quickly, making it easier to pry the can open".

The mathematician asks the others for some time alone. After a couple of hours he returns and says: "I´ve found the perfect way to do it!! It´s failproof!". "Well, please do tell us!", the others say. To which the mathematician replies: "First, let´s assume we have a can opener..."

 

[Veleda.980]

Hey @veleda,

If you want to share some of your knowledge with us you're welcome to!

I once took a linguistics graduate course and was kind of fascinated at how phonological analysis uses formal systems to describe transformations and derivations. This has allowed some linguists to trace these changes and map them historically and geographically, leading to strong theories of migration and cultural exchanges. Can literature be used as a similar tool?

Absolutely. Textual criticism is vital to dating documents and establishing authorship.

My area is Germanic languages so there isn't a lot to work with prior to the Middle Ages, but some of it is pretty interesting. Based on proto-Germanic fragments, there seems to have been an influx of seafaring terminology from an as-yet-to-be-identified culture. It fuels speculation that the Norsemen may have learned seafaring from someone, the Phoenicians perhaps? Highly speculative, but fun to contemplate.

 

[Mataresa]

Walking on toes vs walking on the whole foot

Interestingly enough while talking with me littlest nephew a few months back, we were talking about horses, and he asked why they had an extra joint in their hind legs. Explained to him that they didn't, that like most mammals they ran on their toes, and their hooves were toenails. Showed him on me dog as well and he asked why we don't run on us toes like other mammals, got to admit I had no idea why. Wonder if we did at one point, natural high heel.

I checked that one earlier - from a quick check on the research, apparently humans, the other great apes and bears are the only main groups of animals that walk heel-first, and it's apparently more energy-efficient.

And, that research then leads to the second question, which is "so if it's more energy efficient to walk heel-first, and our feet are designed that way, why do runners touch ground with the balls of their feet first?". The official, scientific answer is apparently "We have no fucking idea".

That's right; there's much we don't understand about bipedal gait, the selective advantages it conferred on our ancestors, and the efficiency of different gaits. Running gait, where the balls of the feet take weight and the Achilles tendon acts as a spring, gets more stable and efficient at fast cadences, something like 180 per minute in experienced runners. Bears, humans, and other great apes don't need to move that way most of the time, so, well, we don't.

We do know that running in heels is not only uncomfortable but inefficient: it negates the energy storage capacity of the Achilles tendon and the foot by preventing them from stretching and flexing. It might have a lesser detriment when riding or fencing, because the spring action is more in the thighs and gluteals. But it surely can't help.

Maybe this is a good question for the Oxenfurt dons.

Maybe we have some biologists or anthropoligists or anything that could shed some more light on this.

I was always under the impression, that we used our whole foot because in ancient times we liked to use our feet to grab things similiar to our hand or like apes do, be it for climbing or maybe even tools while being seated down. But as we started to walk predominantly upright, we lost that ability in favour of having a safer footing to stand on and to have to balance less. I have never heard of that being more energy efficient than just running on your toes though and I would like to hear an explanation for that. I always thought, that we were comparitively worse runners to other animals on two feet, exactly because we didn't just walk on our toes. Also while walking we might use our heels, but I am pretty sure that while running, we mostly run on our toes as well.
Well all of these things are just my guessing and understanding, so none of that is actually supported by any actual scientific data, just what I think.

 

[dragonbird]

Source of the "more efficient" and "only humans, bears, great apes", for reference.
http://www.unews.utah.edu/old/p/012710-3.html

 

[Mataresa]

From the article:

Relative to other mammals, humans are economical walkers but not economical runners.

Fits with my impression.

 

[GuyNwah]

I would think it is rather different, for two reasons.

First, humans are actually rather good runners -- not for top speed, where four legs and a long, flexible back are decisive -- but for distance, where efficiency is important. Humans much slower than a horse or a deer can still run the animal down, with endurance, patience, and cooperation.

Second, the anatomy of human lower legs and feet is distinctive: human feet are not that much like those of the other great apes or bears, and no other has the long, elastic Achilles tendon. Simply put, our feet are an exquisitely developed device for efficient bipedal walking, though it cost us much of the ability to grasp or climb that the other great apes retain.

Walking and running have different physiology. In walking, your foot stores energy as it comes down heel-first. It flattens out like a leaf spring, then releases that energy in forward motion as you shift your weight to the ball. ("Flat feet" is the condition of having lost that springy arch, which is why it is so painful and makes walking so difficult.)

Running works differently: now the long, elastic Achilles tendon and the large gastrocnemius (calf) muscle become important. The entire lower leg and foot become an energy development, storage, and release machine. The running gait and pace allow the lower leg and foot to function as a larger and more powerful spring than the foot alone. That's how elite long-distance runners make it look so effortless. But it only works that way at a running pace; try running in slow motion.

Science Daily, Human gait adapted for efficient walking...
New Scientist, Achilles tendon is key

 

[gedierond]

Next time I see one of my biologist friends, I´ll try to remember asking them about this. It´s a very interesting subject (as is every evolutionary analysis on human physiology, IMO).

 

[NorthernXY.291]

From the article:

Relative to other mammals, humans are economical walkers but not economical runners.

Fits with my impression.

No, there are still tribes in Africa that basically run their prey down and kill it from exhaustion. Humans aren't designed for speed, we're designed to cover large distances. Not quoting all of Guy N'wah, but same thing is somewhat true for the kangaroo (also a special bone), they become for efficient hoppers that faster they hop thanks to their Achilles. I find it interesting the backbones of "prey" like a deer, yet predators have a more elastic/bendable spine. Check out a video of a cheetah running after a gazelle and watch their spines.


One thing I like doing is constructing the logical form for magical beasts to live, die or move around. Much like why silver would be so deadly (scientifically), the optimum shape of a dragon or griffin so it could fly, without just explaining it with magic. Loved it when I read that CDPR used some of the form of a greyhound dog for the shape of their dragon, because that's what I've always thought.

 

[Mataresa]

I think, these should have been posted here:

Numerical systems are positional, which means each digit's value is calculated with respect to its position. Take for instance the number 123, in "decimal system" or base 10. It's value can be expressed as 3*10^0 + 2*10^1 + 1*10^2 = 3*1 + 2*10 + 1*100 = 3 + 20 + 100. Right?

So other numerical systems use other "bases". For instance, base "2" or binary uses 2 symbols, usually 0 and 1. This means a binary number's decimal value can be calculated in the same way, but using powers of 2. For instance the binary number 1010 = 1*2^3 + 0*2^2 + 1*2^1 + 0*2^0 = 1*8 + 0*4 + 1*2 + 0*1 = 10. Another example: a numerical system that uses sixteen digits is called hexadecimal, and since we only have symbols for one digit numbers (0 through 9) alphabet letters are used in this way: A = 10, B = 11, ... F = 15. Therefore the hexadecimal number AF1 can be converted to its decimal value in the same way: 10*16^2 + 15*16^1 + 1*16^0 = 10*256 + 15*16 + 1 = 2801.

So using base 17.73 the number 666 is roughly the same as 1998: 6*17.73^2 + 6*17.73^1 + 6*17.73^0 = 6*314.3529 + 6*17.73 + 6 = 1998.4974. And since we're counting page numbers, I say it is page 1998.

You asked which numerical system, now you know it

I'm somewhat confused about bases which aren't natural numbers. Isn't the number of used digits supposed to be equal to the base? So what does it mean to have 17.73 digits then? Usually symbolic (digital) translates into natural.

It reminds me the story about some kid who was solving a math word problem which was something about that 3 diggers could dig a ditch in 1 day, and the question was how many diggers would it take to dig a ditch in 2. The kid was thoroughly perplexed trying to imagine 1½ diggers digging a ditch ;D

That's because in practice (as far as I know) there is no such thing as a numerical system based on 17.73 You are right, it would use up to that amount of digits but then again you can always define half units or whatever fraction you prefer. In theory it was useful as a way to relate 666 to 1998. You are welcome to find more applications!

Most digital hardware is based on discreet numbers to simplify measuring continuous physical events (such as potential). But i suppose a complex enough system could read an array of states including variations of 1% Again, worst case scenario, you define a physical state composed of ten or one hundred discreet substates. As far as I know this would be completely useless, overly complicated and only intended for geeky fun



You... don't think numbers are fun? I mean, of course they aren't!

Some interesting math that's fun to read ;D

https://math.stackexchange.com/ques...nning-math-concepts-which-are-easy-to-explain

Since we have so many cat pics lets throw in some more math. This is meta-mathematics so no calculation involved.

What number is larger than infinity? What size is infinity? We know there is an infinite amount of Natural numbers (0,1,...,infinity). But how many numbers with decimal expansion are there between two natural numbers, such as 0 and 1? 0.1, 0.01, 0.001, etc. Also an infinite amount of numbers. So how can both sets, natural and real, have an infinite amount of numbers when one is clearly larger than the other?

Georg Cantor's approach is very clever. If we have a set such as {1,2,3}, how many combinations of elements from this set can we make? Let's see. {emptyset}, {1}, {2}, {3}, {1,2}, {1,3}, {2,3} and {1,2,3}. That's 8 subsets. If we put them all together { {emptyset}, {1}, {2}, {3}, {1,2}, {1,3}, {2,3}, {1,2,3} } this is called the power set of {1,2,3}, and it has 8 elements as you can see. For larger sets, say sets with n elements, the size (called cardinality) of their power set is 2^n. In the previous example, n = 3 and therefore 2^3 = 8 is the size of its power set. So what happens when we estimate the size of the power set of the Natural numbers? That'd be 2^(infinity). And for any positive value of n, 2^n is necessarily greater than n. So there must be a number that is larger than the size of the set of natural numbers!

This number was named Aleph-null or Aleph-zero by Cantor, and its value is necessarily greater than the "infinity" of the natural numbers as 2 raised to the power of infinity is greater than infinity This also led to the better understanding of transfinite numbers (larger than infinity).

Since these numbers are just so damn big, substracting 1 shouldn't really matter, right? This leads to very amusing drinking songs like:

"Aleph-null bottles of beer on the wall, Aleph-null bottles of beer, Take one down, and pass it around, Aleph-null bottles of beer on the wall" (repeat).

On a slightly related subject. How can the physical universe (and events in it) be fully described? As a continuum, or as a countable set? For instance, if you assume that all can be enumerated by elementary particles - it can be viewed a countable set. From the point of view of mysics for instance, all the universe and its interactions can be described with "names", i.e. symbolic information which is a countable set too. I.e. imagine an enormous computer which can perform infinite computations of all of those interactions.

Maths is fun.

 

[Lieste]

There quite a few of those jokes. I remember a couple from my university days, although they are referred to different scientists rather than engineers.


A chemist, physicist and a mathematician survive a plane crash and end up marooned on a desert island. They try to find food and only find a can of beans, so they try to come up with a way to open it.

The physicist says: "Applying enough force we should be able to pry the can open.". Picking up a rock from the floor, he adds: "Estimating the weight of this rock and the resistance of the can I could find the height from which the rock should be dropped in order to open the can. Then it´s simply a matter of finding a tree or a cliff tall enough."

The chemist says: "If we scratch the tin layer covering the can, the iron inside will be exposed. Then, the salty water of the sea will provide an excellent medium for the metal to corrode quickly, making it easier to pry the can open".

The mathematician asks the others for some time alone. After a couple of hours he returns and says: "I´ve found the perfect way to do it!! It´s failproof!". "Well, please do tell us!", the others say. To which the mathematician replies: "First, let´s assume we have a can opener..."

The "right" way is to dent the sidewall of the tin and then to flex it back and forth at the dent. After a very short time the metal fails and you can tear the top off the tin off.

 

[Lieste]

Maybe we have some biologists or anthropoligists or anything that could shed some more light on this.

I was always under the impression, that we used our whole foot because in ancient times we liked to use our feet to grab things similiar to our hand or like apes do, be it for climbing or maybe even tools while being seated down. But as we started to walk predominantly upright, we lost that ability in favour of having a safer footing to stand on and to have to balance less. I have never heard of that being more energy efficient than just running on your toes though and I would like to hear an explanation for that. I always thought, that we were comparitively worse runners to other animals on two feet, exactly because we didn't just walk on our toes. Also while walking we might use our heels, but I am pretty sure that while running, we mostly run on our toes as well.
Well all of these things are just my guessing and understanding, so none of that is actually supported by any actual scientific data, just what I think.

The 'run on toes' thing is mostly a myth. There is little difference between the performance of endurance runners using a forefoot strike and a heel strike. The predominant difference may be shock reduction and a reduction in overuse injury by adding more flexion, but for moderate distances there probably isn't much in it.

As running speed increases the body lean forward tend to make a bent foreleg a requirement to 'fit' everything in without excessive body rise on each stride, and then the toe strike becomes geometrically more natural, but for endurance performance the body is much more upright (though there is a forward lean in efficient running).

In sprinting we run on our toes, using the forefoot both in landing and power parts of each stride.
In endurance running we run using the whole foot. Some land on the heel, before planting the whole foot and then pushing off the forefoot, while others land on the forefoot, plant the whole foot and then push off again from the forefoot.
Walking... tends to use the heel, whole foot and then forefoot for the push off, but it is possible to walk landing the whole foot or the forefoot instead. This may be speed dependent - I know I strongly wear the heels of my shoes, but I am a very fast walker with a long stride for my height, and therefore need the heel strike for increasing the stride length in the absence of a flight phase.

 

[Mataresa]

Read about the idea of the interestless money system two days ago (https://en.wikipedia.org/wiki/Freiwirtschaft German article is much more expansive). Plus seems to be, that the rich don't get richer by just letting their money "work" for themselves, but downsides are that you need to enforce the usage, since it would be more profitable for wealthy people to not use it.
Are there any economists or more proficient people than me around, that could state their opinions on this system?

 

[GuyNwah]

Read about the idea of the interestless money system two days ago (https://en.wikipedia.org/wiki/Freiwirtschaft German article is much more expansive). Plus seems to be, that the rich don't get richer by just letting their money "work" for themselves, but downsides are that you need to enforce the usage, since it would be more profitable for wealthy people to not use it.
Are there any economists or more proficient people than me around, that could state their opinions on this system?

The Freigeld leg of this system appears to depend on efficient markets, in which the prices of goods adjust rapidly and accurately to reflect supply and demand.

Efficient markets are a standard and common economic assumption. The problem is, real markets are almost never efficient. In fact, the more active a market (and full information and immediate access should guarantee efficiency, right?), the more it tends, not toward efficiency, but to insanity.

Real markets have supply problems, recession traps, bull stampedes, bear raids, speculative bubbles (from tulips and South Sea ventures to dot-coms and securitized mortgages), and these lead not to efficiency and stability at all but rather booms and busts.

 

[Mataresa]

Can someone give me a link to data about the spread of languages and percentages of immigrants by country for the US? Trying to find some data.

 

[GuyNwah]

Can someone give me a link to data about the spread of languages and percentages of immigrants by country for the US? Trying to find some data.

The US keeps a very detailed collection of census data, including language and ancestry, and broken down by regions as fine as individual school districts. Census data are updated every 10 years; community surveys are updated annually. Best to browse online at

http://factfinder.census.gov/faces/nav/jsf/pages/index.xhtml

The statistics list 108 ancestries; I've had a harder time finding statistics by individual native language, but it's in there somewhere.

There are other local sources, too. For example, Los Angeles, which is a ginormous salmagundi of a city, has at least 224 languages people use at home and 92 used at school. See http://www.laalmanac.com/LA/la10b.htm and http://www.laalmanac.com/population/po47.htm