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Ray Tracing

This lesson is from Rick Matthews, Professor of Physics, Wake Forest University.

Lesson 1, convex lens
The object is far from the lens.

Convex Lens ray tracing GIF

 

Lesson 2, convex lens
The object is near the lens.

Convex Lens ray tracing GIF Object near lens

The rules for concave lenses, are similar:

A horizontal ray is refracted outward, as if emanating from the near focal point.

A ray that strikes the middle of the lens continues in a straight line.

A ray coming from the object, far from the far focal point, will leave the lens horizontal.

Lesson 3, concave lens.
Note that object placement has little effect on the nature of the image.
The rays diverge.

Concave Lens ray tracing GIF

__________________________

In every case:

if the rays leaving the lens actually intersect then the image is real.

If the rays leaving the lens diverge then someone looking back through the lens
would see a virtual image:
Your mind would extrapolate where you think the image should be,
even though one isn’t really there, as shown below with the dotted lines.

concave-lens

image from Giancoli Physics, 6th edition

http://users.wfu.edu/matthews/courses/tutorials/RayTrace/RayTracing.html

 

PhET Electric circuit lab

An electronics kit in your computer! Build circuits with resistors, light bulbs, batteries, and switches. Take measurements with the realistic ammeter and voltmeter. View the circuit as a schematic diagram, or switch to a life-like view.

Learning Goals

  • Discuss basic electricity relationships.
  • Build circuits from schematic drawings.
  • Use an ammeter and voltmeter to take readings in circuits.
  • Provide reasoning to explain the measurements and relationships in circuits.
  • Discuss basic electricity relationships in series and parallel circuits.
  • Provide reasoning to explain the measurements in circuits.
  • Determine the resistance of common objects in the “Grab Bag.”

PhET circuit construction

PhET Circuit construction kit lab!

Start with “grab a wire” – Pull a “wire” onto the screen.

Add resistors, at least one battery, a lightbulb and a switch.

Move the elements close together, so they connect.

If you need to break 2 pieces apart, right click at the location, and choose ‘split junction’

a) Create a series circuit with one light bulb that you can turn on/off.

Click ‘voltmeter’ and a virtual voltmeter appears on the screen. Move the voltmeter’s leads.

When the switch is off

  1) measure the voltage across the bulb : _____

  2) measure the voltage across the battery: _____

Then with the switch on, do this again.

b) Create a parallel circuit with 2 bulbs that you can turn on/off

Click ‘voltmeter’ and a virtual voltmeter appears on the screen. Move the voltmeter’s leads.

When the switch is off

  1) measure the voltage across bulb A : _____

  2) measure the voltage across bulb B : _____

  3) measure the voltage across the battery: _____

Then with the switch on, do this again.

Geekiness and autism: Is there a connection?

02:58 PM ET
Geekiness and autism: Is there a connection?
Elizabeth Landau

http://geekout.blogs.cnn.com/2012/04/23/geekiness-and-autism-is-there-a-connection/

Laura Nagle loves physics. She peruses scientific papers for her own enjoyment, and she can sometimes work out the answers to cosmological mysteries in her head when she watches documentaries about the universe. She has read, in her estimation, about 12,000 books.

You might say Nagle, 58, is a geek. But if you knew that she also has had severe problems communicating with others throughout her life, and had trouble in school because she’s not “well-rounded,” you might guess that she also has autism.

“I find that physics, engineering – these things speak to my heart, and I see details, relationships and patterns that most people don’t,” says Nagle, who lives near Flagstaff, Arizona.

Nagle’s experience speaks to a pervasive stereotype in popular culture that people with high-functioning autism – a form of which is called Asperger’s syndrome – are geeks.

As with most generalizations, it excludes a vast swath of people on the autism spectrum who don’t fit it – plenty have interests or talents in the arts or literature, and don’t care at all about traditionally geeky pursuits such as computers, science and technology.

But it’s worth looking at why this image of the geek with autism has emerged, and exploring the realities of how autism and talent intertwine. Understanding the condition better is ever more important as the number of people with autism rises. The main signs and symptoms of the condition are communication problems, poor social interactions and repetitive behaviors.

Just last month, the Centers for Disease Control and Prevention announced that an estimated one in 88 children in the United States have an autism spectrum disorder. A person who has high-functioning autism and did not have a childhood delay in cognitive or language development would get a diagnosis of Asperger’s syndrome, although this distinction is likely to disappear in the next edition of the Diagnostic and Statistical Manual of Mental Disorders, the standard classification of mental disorders used by mental health professionals in the United States.

Diagnosing genius

While more and more American children are found to have an autism spectrum disorder, speculation has abounded about brilliant historical figures and fictional characters having it, too.

Albert Einstein and Isaac Newton, both fundamental in shaping the way we understand the universe, had characteristics of Asperger’s, researchers have postulated.

Then there’s TV – take Sheldon Cooper, a character from “The Big Bang Theory.” (Although the show’s writers have said that the character does not have Asperger’s syndrome, actor Jim Parsons told Variety that he views his role as in line with the condition.) And people with Asperger’s have connected with the quirky behaviors of Dr. House from “House, M.D.” and Temperance “Bones” Brennan of “Bones,” although these characters have not received formal diagnoses. (For that matter, another doctor on “House, M.D.” once concluded that House is simply a jerk.)

All of these characters seem obsessed with scientific inquiry, but they struggle with effective communication or maintaining relationships. (Not to mention Abed from “Community” – he’s got an encyclopedic knowledge of science fiction, but asked in a recent episode, “Is this a social cue?”)

“[Viewers] could look at any of these characters who are ostensibly Aspies, and they could think that we have no passion because sometimes our language doesn’t seem to convey deep emotions, and we are doing things that most people do not seem to find inspiring of passion,” Nagle said.

And Nagle doesn’t mind that the public associates genius characters with autism – to her, they represent an idea she’s passionate about: That there’s room in this world for everyone, regardless of their quirks and social deficits.

“You get this idea that even if Sheldon is not a party guy, even if Sheldon is not the guy you’d want to have trying to repair your car, that maybe it’s important to have a theoretical physicist or two,” she said.

Others say the stereotype of the Asperger’s scientific genius is unfortunate; that it overshadows the fact that many people with high-functioning autism have talents in arts and literature instead, says Teresa Bolick, a licensed psychologist who specializes in neurodevelopmental disorders. And some are not geniuses per se, they are simply fixated on specific interests.

In other words, not all smart people have Asperger’s, and not all people with Asperger’s have great talents. The diagnosis requires that the person have some kind of social impairment – for instance, lack of eye contact, and not being able to interpret facial expressions, gestures and figurative speech. So a physics genius who gets along well with everyone may well not have autism.

A genetic basis for both scientific talent and autism?

There may still be an underlying connection between scientific talents and autism, however.

More study is needed to back up this theory, but one hypothesis is that geeks and people with autism are linked genetically. British autism expert Simon Baron-Cohen and colleagues published a study in 1997 suggesting that fathers and grandfathers of children with autism were more likely to work in the field of engineering, compared with fathers and grandfathers of neurotypical children.

The researchers are expanding upon their study to see if people who are good at computers and science are generally more likely to have a child with autism.

“One possibility is that the very same genes that give rise to autism, in a less severe combination, might also be giving rise to talent in the general population,” said Baron-Cohen, who is a first cousin of the comedian and actor Sacha.

A larger combination of those genes could give rise to more severe forms of autism, Baron-Cohen speculated. And it could be that people who carry those genes, being similar in personality and interests, have a greater likelihood of marrying each other.

“If you were to get rid of all the autism genetics, there would be no more Silicon Valley,” Temple Grandin, a best-selling author and professor of animal science at Colorado State University, who has autism, said in a TED talk in 2010.

Although these ideas have gained traction, they aren’t based on proven scientific facts; further research is necessary to support these conclusions.

And keep in mind that as awareness grows about autism, doctors have realized that intellectual disability in autism is nowhere near 70%, as was previously thought – it’s only around 30%, Dr. Gary Goldstein, president of the Kennedy Krieger Institute, told CNN.

A darker side of the stereotype

Meanwhile, the false notion that all people with high-functioning autism are talented in the sciences persists culturally – and that may have a detrimental effect on parents.

“Many of us in the autism community, with official diagnoses, are often asked ‘What’s your special science ability?’ says Christopher Scott Wyatt, assistant professor of English at Robert Morris University. “I say, ‘I teach poetry.’ ”

When speaking about autism, Wyatt, who has high-functioning autism, often fields questions from parents of children on the spectrum who wonder when they will see a math or science ability come through. The answer is: Many children don’t have it. The stereotype of the geek with autism has this downside of making parents concerned if their children with the condition don’t excel at science.

“It leads to assumptions of magical abilities,” he said. “They’re expected to have traits they don’t have.”

Gretchen Leary, 26, of Boston, has Asperger’s syndrome and, like Wyatt, her passion is for writing, not the physical sciences. She also has other narrowly focused interests, such as Latin and marine biology. But although she’s not a tech geek per se, her job involves data entry and other repetitive tasks that appeal to her cravings for order and familiarity. See her iReport

Nagle also has particularities about things that are familiar – if you want to kick her out of a room, “paint it lavender,” she says.

So what is the difference between being a geek and having Asperger’s?

Experts are quick to point out that autism is a medical diagnosis, and “geek” is not – of course.

And in order to receive a diagnosis, a person must see a doctor, probably because he or she is suffering in some way. Being a geek is a cultural description, not a medical condition.

People with high-functioning autism may become depressed because they are failing at relationships or jobs, or anxious because of their social interactions. They may have severe difficulties communicating with other people that have led to troubles at home or the workplace. Leary says she’s had many misunderstandings with her spouse and still has more trouble with face-to-face communication than via phone.

Sensitivity to light and noise, another common feature of autism, has also been problematic for Leary. These sensory issues can also interfere with children’s socialization. Crowded, bright places like shopping malls, where young people often hang out, can feel overwhelming and isolate those who don’t want to be there, said Bolick, the psychologist.

Underlying the interests of many people with Asperger’s is a fascination with systems, Baron-Cohen said. Sometimes, that can be advantageous and could help start careers, such as in software engineering or physics. But sometimes, people who have autism fixate on activities that do not have immediate practical applications – for instance, collecting coffee cups.

“Many folks with Asperger’s are able to give remarkable attention to whatever problem they’re interested in,” Bolick said.

Turning a disability around

In some cases, people on the autism spectrum have talents or interests that could become part of a profession, but they’re not thinking in those terms.

“For many people with autism, the reason why they have their obsessions is not because of financial gain. They’re doing it because of intrinsic motivation,” Baron-Cohen said. “The idea that they could make it useful may not even occur to them.”

Wyatt, for example, writes a lot but doesn’t publish. “My wife keeps saying, ‘You should send this to someone,’ but why?” he says.

One man with Asperger’s whom Baron-Cohen met had a desire to understand changes in weather patterns. He’d go out into his garden at midnight every night to measure temperature, wind speed and other related weather factors. He wasn’t trying to use the information like a meteorologist; he just wanted to know.

Similarly, a young patient of Bolick’s would diligently do his homework but not turn it in. When she asked him about it, he stood straight up and said, “I don’t do my homework to get good grades. I do my homework to learn.”

But this problem of not finding practical uses for interests varies widely; some people with autism are markedly driven to achieve, and do. Other times, success is hindered by difficulty in planning and organizing, another common feature of autism spectrum disorders. These are areas that teachers and coaches can help with, Bolick said. Grandin has also spoken out about the need for these mentors to help people with autism develop their talents and use their interests in meaningful ways.

And organizations are starting to take note of certain strengths that a person with high-functioning autism might bring. The nonprofit Aspiritech, based in Highland Park ,Illinois, provides opportunities for people on the Asperger’s spectrum to become software testers, a profession that harnesses their “attention to detail, precision, an affinity for repetitive tasks, outstanding technology skills.”

“This is the kind of disability which could be turned around, so that something that seems to be interfering with the person’s life could transform their life,” Baron-Cohen said. “The obsessions could be a stepping stone or a passport into more opportunities.”

Toward a better future for the next generation

Doug Sparling, 52, of Kansas City, Missouri, chose his job in software engineering because of his Asperger’s. Human interaction, especially when working on a project closely with a partner, can trigger anxiety for him. But he loves electronics, logic and solving problems.

In information technology, he can follow those passions while largely having the solitude he wants. He works more than 40 hours a week, but on a flexible schedule, and works from home a lot.

“Coding is something I get ‘lost’ in, it’s a world where I lose track of time,” he said in an e-mail.

Sparling is married with four children, including a 23-year-old stepson and a 12-year-old son with Asperger’s.

Nagle’s story is different. If she’d had supportive, encouraging teachers, coaches or advocates, Nagle believes, she would have turned her passion for physics into a career, too.

During her second year of college, a counselor told her that her grant would be cut and her work-study hours cut in half. And instead of questioning it or investigating other scholarship opportunities, she quit school and began one of many jobs she didn’t enjoy.

She has worked in architecture and structural engineering, but never finished college. She now lives in a mobile home provided to her. She is heavily involved in autism advocacy and is working on a documentary to be released this year.

When Nagle gives talks about autism, she tells her audience she hopes that none of the young people with autism today end up like herself.

She says: “I don’t want them being 58 years old, homeless [if not for] favors, not able to take care of their teeth, and looking back on lives in which they haven’t accomplished what they could have accomplished.”

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This website is educational. Materials within it are being used in accord with the Fair Use doctrine, as defined by United States law. §107. Limitations on Exclusive Rights: Fair Use
Notwithstanding the provisions of section 106, the fair use of a copyrighted work, including such use by reproduction in copies or phone records or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright. In determining whether the use made of a work in any particular case is a fair use, the factors to be considered shall include:
the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
the nature of the copyrighted work;
the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
the effect of the use upon the potential market for or value of the copyrighted work. (added pub. l 94-553, Title I, 101, Oct 19, 1976, 90 Stat 2546)

Genetic link between autism and prodigy

from A genetic link between autism and prodigy? By Renee Morad
The Daily Dose, Ozy.Com, Mar 15, 2017

Ohio State University psychologist Joanne Ruthsatz, author of The Prodigy’s Cousin, once tested a child prodigy’s IQ. In the middle of her assessment, the child asked for a break at McDonald’s. As they were eating, the child genius’s autistic cousin walked in, and the coincidence made Ruthsatz wonder: What are the chances of having a child prodigy and an autistic child in the same family?

The question motivated her to find some answers. So she went on to study prodigies who reached a professional level before age 10. After examining their DNA, and those of their families, she discovered that half of prodigies had an autistic relative as close as a grandparent or niece. She also found that both the prodigies and their autistic relatives seemed to have evidence of a genetic mutation or mutations on the short arm of chromosome 1 that was not shared by their neurotypical relatives. The two also shared some characteristics.

We caught up with Ruthsatz to talk about how her findings might help answer questions about autism. Our condensed and edited conversation follows.

HOW MIGHT THE LINK BETWEEN PRODIGY AND AUTISM HELP US BETTER UNDERSTAND BOTH TRAITS?

Ruthsatz: Well, if we could find how they are different from their neurotypical relatives, that would lead the way to better medicine for autism. What we’re looking for is a genetic marker that prodigies have that their neurotypical or autistic relatives do not have. More than 50 percent of children who are prodigies have autistic first or second relatives. That’s way too much. It’s a big marker, a big flag. Now we’re working to find out where the difference is, since we know where the similarity is.

WHAT STRENGTHS DID YOU FIND AMONG PRODIGIES WHO EXCEL IN MATH AND SCIENCE?

This group had huge visual-spatial skills. They were able to see visually and report the difference, telling exactly how to get from point A to point B and, miraculously, whether it was northeast, left, right or so on. I didn’t cue them; they just knew. But artistic prodigies were below average on this skill. Some of the artistic prodigies couldn’t have told me left from right.

WHAT DID THE MUSIC GENIUSES EXCEL IN?

The music prodigies had the strongest memories. In fact, all music geniuses had a score above 99 percent on working memory. They had significantly better working memories than the other types of prodigies.

WHEN YOU COMPARED PRODIGIES AND THOSE WITH AUTISM, WHAT SIMILARITIES DID YOU FIND?

They all have an obsession in something, or what we’d call a “rage to master” in prodigies. They both have strong working memories. They all usually come from families that have engineers or scientists or professors. Well, not all of them, but more than you’d expect. Some come from very normal families, some working-class — and many have autistic relatives.

YOU UNCOVERED EVIDENCE THAT PRODIGIES HAVE A VERY EXTREME SENSE OF EMPATHY. CAN YOU EXPLAIN?

One of the prodigies started a charity that raised $8 million for children with neuro diseases. He was so in tune with these patients that he used to play little concerts for them in the hospital, and his efforts got bigger and bigger. He raised a lot of money for research. Another one focused on feeding starving children. They are very sensitive to the human condition. Now, with autistic individuals, there’s this misunderstanding that they don’t care, but I think they care so much that they don’t know what to do with it — they’re super sensitive.

WHAT DO YOU FIND MOST INTERESTING ABOUT CHILD GENIUSES?

They are just so extremely rare, and we’re almost seeing an evolution in genetic research that shows that as the world goes on, the gene pool changes. You can go back to Mozart, and he certainly had an autistic background, but we’re finding that more and more. I think we’re seeing an evolution of extreme talent.

WHAT DO YOU SUSPECT YOUR LATEST RESEARCH MIGHT LEAD TO?

We are hoping to arrive at the prodigy gene that allows all the deficits in autism to be put at bay, letting the talent shine through. We think it’s going to be one or two genes. We don’t think they will be massive genes that are different. We think it’s going to be a moderator that lets prodigies be social and live their lives functionally where autistic savants cannot … and finding that difference might lead to better medicine for people with autism.

______________________________________

This website is educational. Materials within it are being used in accord with the Fair Use doctrine, as defined by United States law. §107. Limitations on Exclusive Rights: Fair Use

Notwithstanding the provisions of section 106, the fair use of a copyrighted work, including such use by reproduction in copies or phone records or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright. In determining whether the use made of a work in any particular case is a fair use, the factors to be considered shall include:

the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
the nature of the copyrighted work;
the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
the effect of the use upon the potential market for or value of the copyrighted work. (added pub. l 94-553, Title I, 101, Oct 19, 1976, 90 Stat 2546)

AI assignment

On a separate sheet of paper please answer these questions (or fill in the blanks)

AI – readings

1. AI is intelligence exhibited by machines. It doesn’t mean that ____________ .

2. What does it mean for a computer to be intelligent?

3. People can do more than solve problems: we are aware, sentient, sapient, and conscious. What does it mean for someone to be sapient?

4. What does it mean for someone to be sentient?

5. Some AI problems have successfully been solved. People are so used to them that we often don’t even call them AI.  You may already be using some AIs in your own life. List & clearly describe two examples of these AIs.

6. There is a field of computer science called “philosophy of artificial intelligence.” List 2 of the questions that field is working to answer.

7. How are strong and weak AIs different?

8. In our resource, look at the 2 articles we link to “How to Help Self-Driving Cars Make Ethical Decisions”, or “What Will It Take to Build a Virtuous AI?” Summarize the first article, in your own words, in 3 well-written paragraphs. Summarize the second article for homework.

 

Chicken or the egg

Which came first, the chicken or the egg?

At first glance, this seems like a reasonable question. But most questions have hidden assumptions, and this question has tons of them. And as it turns out, most of the assumptions are incorrect – meaning that the question – as it is usually asked or understood – is actually meaningless.

The question assumes that (a) chickens and eggs have existed continuously, without change, for a long period of time (b) that chickens (vaguely defined!) lay eggs (also vaguely defined!), and (c) that eggs hatch into chickens.

Problem? None of these assumptions are true. They only appear to be true because people only look at chickens and eggs over a very short period of time (perhaps weeks, a year, or when reading books, thinking back over the last 5000 years.)

But birds and their ancestors have been continuously changing for millions of years – and so has the way that their ancestors reproduced. The first chickens… may not even have been chickens, but rather some other form of bird that no longer exists.  And those earlier birds are descendants of a branch of the dinosaur family tree; and those early dinosaurs are a branch of the reptile family tree.  And over very long, deep periods of time, the way that these organisms reproduced has actually changed!

In fact, the first eggs developed millions of years before anything we even know as birds existed.

chicken or the egg

Vapor cones and mach cones

A vapor cone, also known as shock collar or shock egg, is a visible cloud of condensed water which can sometimes form around an object moving at high speed through moist air, for example an aircraft flying at transonic speeds.

FA-18 Hornet breaking sound barrier July 1999 US Navy

When the localized air pressure around the object drops, so does the air temperature. If the temperature drops below the saturation temperature a cloud forms.

prandtl glauert vapor cloud Mach
In the case of aircraft, the cloud is caused by supersonic expansion fans decreasing the air pressure, density and temperature below the dew point. Then pressure, density and temperature suddenly increase across the stern shock wave associated with a return to subsonic flow behind the aircraft. Since the local Mach number is not uniform over the aircraft, parts of the aircraft may be supersonic while others remain subsonic — a flight regime called transonic flight.


 

A vapor cone is caused by the formation of so-called ‘Prandtl–Meyer’ expansion fans, which temporarily decrease the air pressure, density and temperature below the air’s dew point. It is not the same thing as the Mach Cone (which is an invisible pressure front), but the two often occur in tandem, allowing us to pretend that we have just seen the sound barrier broken. In this incredible clip of a Boeing F/A-18 Hornet flying at a height of 25 feet, you can see both the Vapor Cone and evidence of the Mach Cone on the surface of the water…

http://physicsfootnotes.com/vapor-cone-versus-mach-cone/