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The Harriss spiral is constructed from rectangles in the ratio of the plastic number (1.3247…), in a similar way to how a Fibonacci spiral is created from rectangles in the related golden ratio (1.6180…). These plastic rectangles can be split into two smaller plastic rectangles, leaving a square. Recursively splitting the rectangles, and drawing curves in the squares gives this fractal spiral.0
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An open letter to Gov. Scott Walker: stop perpetuating the myth of the lazy professor
When you say we should work harder, I hear two things: 1) we aren’t working hard, and 2) we don’t think we have to. Professors seem like an easy target. We have good job security, we’re paid well, we often come from privileged backgrounds. We appear to have little to do but teach a class for a few hours a week, and we have extended vacations. It’s easy to see us as cloistered in the Ivory Tower, without much experience with the “real world†and the concerns of average folks.The picture I’ve painted for you is incomplete, though.0 -
The whiteness of newly fallen snow is, of course, one of its primary defining characteristics, so it’s tempting to just say that, you know, that’s the way snow is. But it’s actually a pretty good question, because snow is really just frozen water, and frozen water tends to be transparent0
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A teaser. For the setup, go to the link.
…In each case the rolling coin has made one complete rotation. But the red arc at the top is half the length of the red line at the bottom. Why?I have a more physics-y than a formal math-y explanation of why, which I will post soon.
————
OK, here's my answer.
In the rolling case, all you have is rotation. On rotation gives you 2*pi, so it rolls one circumference.
But in the other case you have rotation and revolution (spin and also orbital motion). Going halfway around the coin gives you an equal contribution of each, so the amount of spin only requires pi rotation, and it rolls half of the circumference. If the coin's point of contact never changed, it would still do a rotation over the course of its revolution. If the orientation stayed fixed, the point of contact would make a complete trip around the coin.
A related example of this is the moon. If viewed from an external inertial frame (where the distant stars appear to be fixed), the moon rotates around the earth every ~4 weeks. But since it's tidally locked and always has the same part facing the earth, it also rotates once about its axis.
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[youtube:https://www.youtube.com/watch?x-yt-ts=1422579428&x-yt-cl=85114404&v=CmjeCchGRQo]
Gav shows you how insanely quick the inside of a DSLR camera moves when it takes a picture, by filming it at 10,000 fps.…Camera filmed is a Canon 7D.This video is a good demonstration of how a rolling shutter works.Shot with a Phantom Flex at 10,000fps0 -
(yay! internet finally restored!)
Why 50 million smart meters still haven’t fixed America’s energy habits
The upshot: Right now, smart meters aren’t waking Americans up and making them conscious of their energy use — because they aren’t being paired with what behavioral research shows us is needed for that to happen.This is the story of why the smart meter revolution has, thus far, fallen short — and how we can better use one of the most pivotal innovations in the electricity sphere to save energy, cut greenhouse gas emissions and save a lot of money.I can vouch for the notion of immediate feedback being an important component to changing behavior — something that's discussed in the article. My new-ish car tells me my instantaneous gas efficiency and reminds me of things that I know but would not necessarily be thinking about, such as how wasteful it is to romp on the gas when speeding up, or how hitting the brakes means you are bleeding away your kinetic energy as heat. So it's modified how I drive — smaller accelerations. Less gas when speeding up and coasting to slow down, when it's appropriate to do so. So I can see how this would work for home energy use, too.
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Sodium's explosive secrets revealed
The explosion, say Pavel Jungwirth and his collaborators at the Czech Academy of Sciences in Prague, is not merely a consequence of the ignition of the hydrogen gas that the alkali metals release from water. That may happen eventually, but it begins as something far stranger: a rapid exodus of electrons followed by explosion of the metal driven by electrical repulsion.Neat. It's not the hydrogen reacting with air that causes the alkali to explode. That reaction doesn't cause more surface area to be created as the reaction unfolds, so it can't "accelerate"
Video in the link, including slow-motion views of the explosion.
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Let there be light! Celebrating the theory of electromagnetism
There was also another controversy raging at the time, concerning the nature of light. It was known that light travelled through space with a finite speed, rather than leaping instantaneously from its source to our eyes.But no-one knew, a century-and-a-half ago, what light was actually made of.Most physicists agreed it travelled through space as a wave but they didn’t know what these light waves were made of, and they didn’t know how they got from one place to another. Maxwell was about to solve all these mysteries.0 -
Having some internet issues at home, so here's some bookshelf porn
21 Stunning Bookshelves You’ll Want for Your Home
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A plaque will be placed in Swansea's Grove Place to commemorate the 19th Century scientist Sir William Grove.Sir William, was the founder of the Swansea Literary and Philosophical Society, and managed to combine a legal career with several important scientific achievements. In particular he anticipated the conservation of energy and was a pioneer of fuel cell technology. He was the first to produce electrical energy by combining hydrogen and oxygen in 1842, a technology that went on to supply water and electricity for space missions.
Just another example of a Welsh person having done great things for the world.
Links
William Robert Grove, Wikipedia.
Blue plaque for Swansea scientist Sir William Grove, BBC News.
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A couple of science stories that don't quite count as science because the results have never been duplicated.
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[youtube:https://www.youtube.com/watch?v=tC13_BkDieU]
As the video warns, magnets like these are potentially very dangerous.
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Mathematically Precise Kinetic Sculptures and Transformable Objects by John Edmark
I was a tad confused at first, because to me "kinetic sculpture" refers to those systems where balls are continually moving about on various tracks in a closed system. But these are rather nice, too.
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Having two pictures of the exact same lightning bolt lets you do something pretty amazing; reconstruct its path in 3D. In this case because the precise location and elevation of the photographers isn't known this is slightly more art than science, but it is still fun!1
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I haven't done much fist-shaking from the porch recently, but here's to changing that. Today's curmudgeonly two-fer have one thing in common: overselling the product, in a way. The thing is, I don't think they need the false advertising, whether it's on purpose or owing to some comprehension gap. Ignore the rant if you wish, and just enjoy the technology/math-based artistry of these pieces.
Fascinating 3D-Printed Fibonacci Zoetrope Sculptures
These 3d-printed zoetrope sculptures were designed by John Edmark, and they only animate when filmed under a strobe light or with the help of a camera with an extremely short shutter speed.… just like any other object would. Maybe it's just me, but this sounds like the author is implying this is special to this particular class of structures — it's not. That's just how the strobe effect works.
Marvellous rube goldberg mechanical lightswitch covers
These are wonderful. But having a few gears doesn't turn it in to a Rube Goldberg device; it's not just a matter of being slightly more complex than it needs to be — in this case, mostly by adding one layer of complexity. There are no chain reactions and no diversity of mechanism, two hallmarks of such devices.
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In my research on electromagnetism, I have understood that magnetism is forces created by moving charges and felt by moving charges. An electric current is a model of continuous flow of uncountable electrons moving in the same direction. This scheme seems benign but when I applied it to the Universe, I find in it a surprisingly judicious approach to solve the mystery of dark matter.
Please read the article at
Magnetism and dark matter http://pengkuanem.blogspot.com/2015/01/magnetism-and-dark-matter.html
or
https://www.academia.edu/10183169/Magnetism_and_dark_matter
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How to write your first scientific paper
First advice is to take it seriously. Science isn't science unless you communicate your results to other people. You don't just write papers because you need some items on your publication list or your project report, but to tell your colleagues what you have been doing and what are the results. You will have to convince them to spend some time of their life trying to retrace your thoughts, and you should make this as pleasant for them as possible.Lots of good stuff here. Make sure you know something about the journal to which you are submitting, too. Details vary — this ties in with the "pick a level of discussion and stick with it."
Bee also mentions that students often write as part of a group. Feedback from colleagues is important and usually makes for a better paper. My advice is drop the ego and be receptive to criticism. And hope that you work with people who will give you honest feedback (a situation I have been fortunate to be in for many years)
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Yup, a Climate Change Denier Will Oversee NASA. What Could Possibly Go Wrong?
This is very worrisome. NASA is one of the key scientific agencies studying global warming and climate change. A good fraction of NASA’s annual budget goes to Earth-observing satellites critical in looking at various factors of climate change (like the recently launched OCO-2, which monitors CO2).This is as close to the analogy of putting the fox in charge of the hen house that there is. It would be as ludicrous as putting the rabidly anti-science Sen. James Inhofe (R-Oklahoma) in charge of the committee that oversees the Environmental Protection Agency.Oh, wait.0 -
[youtube:https://www.youtube.com/watch?v=ZuvK-od647c]
Really good explanation of quantum entanglement and how Bell's inequality rules out local hidden variables.
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An Open Letter to Neil deGrasse Tyson
I mean, what the hell is that? I’ve been staring at this for a while, and really can’t find an angle from which it doesn’t look insulting to a whole bunch of people who don’t deserve your scorn. Are you trying to say that bad teachers are so common that every good student has had to work around them? That only bad teachers give A’s? That no student is so good that a good teacher would give them all A’s?My most charitable interpretation is that a poor teacher is an obstacle — perhaps a student would not be as motivated, the student might have the conflict of misinformation from the teacher vs. knowledge gained elsewhere, or things like that, which could trip him/her up. A good teacher might not have so much heavy lifting to do with a talented student. But I'm working here — even considering the character limit of twitter, this seems like a dig at teachers.
As long as I'm piling on, Tyson hit another sour note recently, IMO. There's also the one about unhackable systems, which is the sort of thing that happens to everyone from time to time, I guess: you aren't familiar with the gory details, so you assume the hidden part is also the trivial part. It's almost like saying "let's build a perpetual motion machine to make some energy" (though I am unsure if they are impossible at the same level — does "unhackable" run into some fundamental problem, or is it just so hard to do that it's transactionally impossible? I don't know)
The larger point is that Tyson has a huge audience, and with great power comes great responsibility, as the saying goes. Most of the stuff he does is very good, but the mistakes have a large impact as well.
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Figuring otu when ignoring air resistance is a bad approximation.
When Does the Air Resistance Force Make a Difference?
With only the gravitational force, the object has a constant acceleration and the motion is fairly simple to model.However, objects on the surface of the Earth usually have an air resistance force on them also. When can we ignore this extra force and when is it important?0 -
Some quotes from the physicist Steven Weinberg that seem to be topical to the recent events in France:
"I have a friend — or had a friend, now dead — Abdus Salam, a very devout Muslim, who was trying to bring science into the universities in the Gulf states and he told me that he had a terrible time because, although they were very receptive to technology, they felt that science would be a corrosive to religious belief, and they were worried about it... and damn it, I think they were right. It is corrosive of religious belief, and it's a good thing too."
"There are those whose views about religion are not very different from my own, but who nevertheless feel that we should try to damp down the conflict, that we should compromise it. … I respect their views and I understand their motives, and I don't condemn them, but I'm not having it. To me, the conflict between science and religion is more important than these issues of science education or even environmentalism. I think the world needs to wake up from its long nightmare of religious belief; and anything that we scientists can do to weaken the hold of religion should be done, and may in fact be our greatest contribution to civilization."
Today these religious fanatics are murdering satirical cartoonists. I would not be surprised if in the future they turned their attentions to attacking intelligent atheists who express themselves as eloquently as Steven Weinberg does.
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What Feynman is presenting in the video is an atheist's version of the story of Adam and Eve and the Tree of Knowledge. Feynman's banana is analogous to the fruit of the Tree of Knowledge, which is more typically depicted as an apple.
And as an atheist, Feynman rejects the version of man's origins presented in Genesis, but rather considers man to be a close relative and a descendant of the apes. Plucking a banana from its tree is like obtaining one additional bit of understanding of "the ultimate laws of physics".
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Blog post: swansont: I'm Syndrome, Your Nemesis!
in SFN Blogs
Posted
Stop Blowhard Syndrome
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