Wisconsin student not impressed with the flipped classroom

March 22, 2015 Leave a comment

A student at University of Wisconsin weighs in on the “flipped classroom” in his school’s newspaper:

“The fact of the matter is that flipped lectures do not work. Video lectures alone cannot possibly replace traditional lectures because in order to create the most effective teaching environment, the professor must be able to have physical interactions with the student body as a whole. The professor must be able to read his audience while teaching the material, so that he can tell if his students are comprehending the information he is presenting. It is no question that the best professors are those who are able to sense a lack of understanding in his or her students, no matter the size of the class, and then make corrections to his or her teaching style as needed. When the professor is teaching to an inanimate camera instead of actual students, he or she essentially destroys the final step in the communication process: feedback.”

– Phillip Michaelson, “Flipped Lectures: Do not pay thousands of dollars on glorified Khan Academy Lectures.” The Badger Herald, 13 March 2015 [link].

Categories: Education

Spring break without doing physics or math problems can lower your IQ

March 14, 2015 Comments off

Spring break is arriving for most students across the country. They may wish to keep in mind Telegraph’s curious report on the research of Professor Siegfried Lehrl at University of Erlangen on the ill-effects of vacation on mental acuity:

“‘Fourteen days of complete rest can be enough to bring your IQ down by 20 points – more than the difference between a bright and an average student,’ says Prof Lehrl. ‘Vocabulary shrinks, and we even detect personality changes.’

“So how can you negate the nightmare effects of your dream vacation? According to Prof Lehrl, you should exercise your brain on holiday for at least 10 minutes a day by playing an intellectually stimulating game (chess or Scrabble, for instance), mitigate inactivity with regular long walks, rehydrate constantly – and chew lots of gum. Gum? ‘The part of the brainstem that keeps us alert is constantly stimulated by chewing, as a result of which the attention level rises, as does the flow of blood to the brain.”

– Michael Hewitt. “Sun, sea and shrinking brain power.” The Telegraph, 15 August 2011 [link]

Comment: Hard to believe such things. Nevertheless, it is probably beneficial to keep up at least some reading and problem solving over an extended holiday. Forgot your books and class notes and don’t know what to do? Try reading online Feynman’s Lectures on Physics. Or you can just chew gum, but that’s not as fun.

Categories: Education

Visualizing gauge unification with high-scale thresholds

March 11, 2015 Comments off

Released: Sebastian A.R. Ellis, James D. Wells. Visualizing gauge unification with high-scale thresholds. arXiv:1502.01362.

Abstract: Tests of gauge coupling unification require knowledge of thresholds between the weak scale and the high scale of unification. If these scales are far separated, as is the case in most unification scenarios considered in the literature, the task can be factorized into IR and UV analyses. We advocate “Δλplots” as an efficient IR analysis projected to the high scale. The data from these plots gives an immediate qualitative guide to the size of threshold corrections needed at the high scale (e.g., the indices of high-scale representations) and provides precise quantitative data needed to test the viability of hypothesized high-scale unification theories. Such an approach shows more clearly the reasonable prospects of non-supersymmetric grand unification in large rank groups, and also shows the low summed values of high-scale threshold corrections required for supersymmetric unification. The latter may imply tuned cancellations of high-scale thresholds in theories based on weak-scale supersymmetry. For that reason we view non-supersymmetric unification to be just as viable as supersymmetric unification when confining ourselves only to the question of reasonable high-scale threshold corrections needed for exact unification. We illustrate these features for a non-supersymmetric SO(10) graund unified theory and a supersymmetric SU(5) theory.

Categories: Physics

All explanations end with ‘it just does’

February 22, 2015 Comments off

It is rather obvious but it is helpful to remind ourselves periodically that explanations only go so deep before hitting a wall, as Emmett explains:

“When we make the statement hedged about with so many qualifications it might be argued that we are making it a necessary statement by putting the necessity in; that we are saying in effect that if the wire is of such a kind that the other end will move when I pull this end, then if nothing happens to prevent it going so the other end will move when I pull this end, then if nothing happens to prevent it doing so the other end will move when I pull this. “We can couch the statement in such a form that it carries with it necessity or theoretical certainty, but the events which are being described are the events of experience. The fact that, usually, if we pull one end of a wire the other end moves is derived from experience and it is a fact which we come to see and absorb very early in life. As soon as we start touching or seeing material objects we experience events similar to this. And to the question Why it should happen no answer seems possible except that it just does. It is to events of this kind, the simplest sort of link in the chain of cause and effect, that all chains can be reduced and in terms of which they can all be explained. “When we are investigating or analysing we want to postpone for as long as possible the answer ‘It just does — it’s a fact of experience — look around you and see.’ And indeed one of the main points of an investigation, of asking a ‘why’ or ‘how’ question, is to discover more intermediate links. But the answer ‘It just does’ is bound to come eventually.”

– E.R. Emmett. Handbook of Logic. Totowa, NJ: Littlefield, Adams & Co, 1967.

Categories: Philosophy

Admit more Classics majors to Physics PhD programs?

February 15, 2015 Comments off

Tony Leggett won the 2003 Nobel Prize in physics for his work on superfluid helium-3. Rebecca Tan interviewed him during his visit to Singapore last month:

Tan: “You took a rather unusual path to a career in physics, doing your first undergraduate degree at Oxford in classic philosophy, known colloquially as the Greats. If you could go back in time, what career advice would you give to your 17-year-old self?”

Leggett: “Do the same, I have no regrets at all. Had I gone into physics initially, I would have missed the enormous intellectual benefits I would have gotten out of my Greats education.”

– R. Tan. “A Word to Young Physicists in Asia.” Asian Scientist (2 Feb 2015) [link].

Comment: Unfortunately the world is different now. Leggett describes in this interview how he was able to go into physics based on one individual seeing some promise in him despite having almost zero background. This was at Oxford in 1959. It is very unlikely that anything like that could happen today.

The implicit question that arises from Leggett’s response is whether we are greatly losing out as a field by not letting more come into the fold from alternative backgrounds. Smart people with different perspectives make a better and more energetic community overall. Who wouldn’t want to see what Lionel Trilling, or Maya Angelou or Edward Said would have produced if they had become physicists?


Categories: Education

Cicero on cosmology in Roman antiquity

February 8, 2015 Comments off

Cicero in about 50 BCE explaining the heavens:

“The universe is held together by nine concentric spheres. The outermost sphere is heaven itself, and it includes and embraces all the rest. For it is the Supreme God in person, enclosing and comprehending everything that exists, that is to say all the stars which are fixed in the sky yet rotate upon their eternal courses. Within this outermost sphere are eight others. Seven of them contain the planets — a single one in each sphere, all moving in the contrary direction to the great movement of heaven itself. The next sphere to the outermost is occupied by the orb which people on earth name after Saturn. Below Saturn shines the brilliant light of Jupiter, which is benign and healthful to mankind. Then comes the star we call Mars, red and terrible to men upon earth.

“Next, almost midway between heaven and earth, blazes the Sun. He is the prince, lord and ruler of all the other worlds, the mind and guiding principle of the entire universe, so gigantic in size that everything, everywhere, is pervaded and drenched by his light. In attendance upon the Sun are Venus and Mercury, each in its own orbit; and the lowest sphere of all contains the Moon, which takes its light, as it revolves, from the rays of the sun. Above the Moon there is nothing which is not eternal, but beneath that level everything is mortal and transient (except only for the souls in human beings, which are a gift to mankind from the gods). For there below the Moon is the earth, the ninth and lowest of the spheres, lying at the centre of the universe. The earth remains fixed and without motion; all things are drawn to it, because the natural force of gravity pulls them down.”

– Cicero. “The Dream of Scipio,” in Cicero: On the Good Life. Penguin, 1971.

Comment: This passage was originally written by Cicero sometime between 54 BCE and 51 BCE. The “Dream of Scipio” is in the last volume of his six volume set entitled On the State. Much of those six volumes is lost to us now. However, we do know that the device Cicero used was that of a conversation between Scipio Africanus the younger and others. The passage above is Scipio Africanus the elder coming in a dream to explain the heavens. It is a nice summary of what Romans of antiquity knew and thought of astronomy and cosmology.  Of course, Cicero got much of this from the Greeks, but he had to synthesize sources and make decisions, especially on the ordering of the planets and the Sun (he sided with Pythagorus over Plato). Presumably he consulted with others as well, and it is fair to say that this is likely to be the Roman view of the cosmos in approximately 50 BCE.

“Atlas bearing the heavens” http://www.aip.org

Categories: Cosmology

Longhand writing better than laptop for note taking

February 3, 2015 Comments off

“In three studies, we found that students who took notes on laptops performed worse on conceptual questions than students who took notes longhand. We show that whereas taking more notes can be beneficial, laptop note takers’ tendency to transcript lectures verbatim rather than processing information and reframing it in their own words is detrimental to learning.”

– P.A. Mueller, D.M. Oppenheimer. “The Pen is Mightier Than the Keyboard: Advantages of Longhand Over Laptop Note Taking,” Psychological Science vol. 25, 1159-1168 (2014) [link].

Comment: The implication is that the slowness of writing requires the brain to process lots of information into a smaller number of words that the student must come up with him/herself, thereby requiring more engagement with the material while being presented. Makes sense to me. It should also be noted that this is a study about today’s students who are much more used to the computer than to writing. The results would be obvious for people of my age, who grew up with more longhand writing, but I presume it was less obvious to researchers that the result would stand for the very young. I hope that means spiral ring notebooks will be around forever.

Categories: Education

Athenodorus teaches Roman Emperor Claudius how to write well

February 1, 2015 Comments off

Robert Graves channeling the 12-year-old future Roman emperor Claudius describing his lessons on writing and communicating effectively:

“Athenodorus told me [Claudius], the very first day of his tutorship, that he proposed to teach me not facts which I could pick up anywhere for myself, but the proper presentation of facts. And this he did. One day, for example, he asked me, kindly enough, why I was so excited; I seemed unable to concentrate on my task. I told him that I had just seen a huge draft of recruits parading on Mars Field under Augustus’s inspection before being sent off to Germany, where war had recently broken out again.

“‘Well,’ said Athenodorus, still in the same kindly voice, ‘since this is so much on your mind that you can’t appreciate the beauties of Hesiod, Hesiod can wait until tomorrow. After all, he’s waited seven hundred years or more, so he won’t grudge us another day. And meanwhile, suppose you were to sit down and take your tablets and write me a letter, a short account of all that you saw on Mars Field; as if I had been five years absent from Rome and you were sending me a letter across the sea, say to my home in Tarsus. That would keep your restless hands employed and be good practice too.’

“So I gladly scribbled away on the wax, and then we read the letter through for faults of spelling and composition. I was forced to admit that I had told both too little and too much, and had also put my facts in the wrong order. The passage describing the lamentations of the mothers and sweethearts of the young soldiers, and how the crowd rushed to the bridgehead for a final cheer of the departing column, should have come last, not first. And I need not have mentioned that the cavalry had horses; people took that for granted. And I had twice put in the incident of Augustus’s charger stumbling; once was enough if the horse only stumbled once. And what Postumus had told me, as we were going home, about the religious practices of the Jews, was interesting, but did not belong here because the recruits were Italians, not Jews. Besides at Tarsus he would probably have more opportunities of studying Jewish customs than Postumus had at Rome. On the other hand, I had not mentioned several things that he would have been interested to hear – how many recruits there were in the parade, how far advanced their military training was, to what garrison town they were being sent, whether they looked glad or sorry to go, what Augustus said to them in his speech.

“Three days later Athenodorus made me write out a description of a brawl between a sailor and a clothes dealer which we had watched together that day as we were walking in the rag-market; and I did much better. He first applied this discipline to my writing, then to my declamations, and finally to my general conversation with him. He took endless pains with me, and gradually I grew less scatter-brained, for he never let any careless, irrelevant, or inexact phrase of mine pass without comment.”

– Robert Graves. I, Claudius. Penguin Books: London, 1986.

Comment: These are very good lessons on writing scientific papers as well. Among the writing sins implied above, repetition and getting side-tracked off the main argument are perhaps scientists’ biggest writing sins. However, repetition is often viewed as a good technique to emphasize the main points of the paper. Claudius, or rather Robert Graves, would disagree.

Categories: Education

BICEP2/Keck and Planck joint analysis casts doubts on detection of gravitational radiation from inflation

January 31, 2015 Comments off

From the conclusions section of joint analysis paper released last night by the BICEP2/Keck Array and Planck collaborations:

“The final result is expressed as a likelihood curve for r, and yields an upper limit r < 0.12 at 95% confidence. The median limit in the lensed-ΛCDM+noise+dust simulations is r < 0.075. It is interesting to compare this latter to dust-free simulations using only BICEP2/Keck where the median limit is r < 0.03—the difference represents the limitation due to noise in the Planck maps, when marginalizing over dust. The r constraint curve peaks at r = 0.05 but disfavors zero only by a factor of 2.5. This is expected by chance 8% of the time, as confirmed in simulations of a dust-only model. We emphasize that this significance is too low to be interpreted as a detection of primordial B-modes.”

– P.A.R. et al. (BICEP2/Keck and Planck Collaborations), “A Joint Analysis of BICEP2/Keck Array and Planck Data.” January 30, 2015 [pdf].

Comment: Unfortunately the excitement was short lived over the earlier claim by the BICEP2 collaboration of gravitational radiation effects on early universe microwave background radiation. This was a prediction of inflation theories, although the size of the effect is unknown (“model dependent”). The current result suggests that galactic dust, which mimics the signal but is of little cosmological significance, was larger than BICEP2 originally thought. Non-zero B modes and inflation theories are not disproved by this new result quoted above, but the exciting prospect of finding evidence for them is not supported either.

The BBC has a short, popular article on this latest development here for those not technically versed on the subject but wish to know about this important result.

Categories: Cosmology

Difference between a cathedral and a physics lab?

January 29, 2015 Comments off

“What have we been doing all the centuries but trying to call God back to the mountain, or, failing that, raise a peep out of anything that isn’t us? What is the difference between a cathedral and a physics lab? Are they not both saying: Hello?”

– Annie Dillard. Teaching a Stone to Talk. Harper Perennial, 1992.

Comment: It is often remarked that physics and mathematics are dreary subjects that are impersonal and lonely. Humans are a social species, who crave contact, discussion, gossip, and interactions of all kinds with people. History, psychology, social science, medicine, and law are all fields that “make sense” from this perspective.  What drives the physical scientist and the mathematician? It is a craving to discover the “other” — that which is greater and more enduring than us weak humans.

Categories: Physics

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