Category Archives: Physics

Float Like a Butterfly, Sting Like a Mantis Shrimp

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How mantis shrimps deliver armour-shattering punches without breaking their fists

The smashers deliver the fastest punch of any animal. As the club unfurls, its acceleration is 10,000 times greater than gravity. Moving through water, it reaches a top speed of 50 miles per hour. It creates a pressure wave that boils the water in front of it, creating flashes of light (shrimpoluminescene – no, really) and immensely destructive bubbles. The club reaches its target in just three thousandths of a second, and strikes with the force of a rifle bullet. Against such punches, even the best armour eventually fails.
But the mantis shrimp’s club doesn’t fail. It can deliver blow after punishing blow, breaking apart its prey without breaking apart itself.

Move Along at c; Nothing to See Here

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MINOS reports new measurement of neutrino velocity

[T]he new MINOS study significantly reduces the systematic errors of its earlier work with detailed measurements of the behavior of the experiment’s GPS timing system, improved understanding of the delays of electronic components at every stage of the MINOS detectors and the use of upgraded timing equipment, designed and implemented with the assistance of the National Institute of Science and Technology and the United States Naval Observatory.

Applying these improved understandings, the MINOS collaboration measures a neutrino arrival time for travel between Fermilab and Soudan, Minn., that is consistent with the expected travel time at the speed of light. The difference between the measured and calculated times is -15 ± 31 nanoseconds, indicating no observable effect.

Gotta include the plug for the home team.

From The Far Side to Jurassic Park to Reality

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Driving without a Blind Spot May Be Closer Than It Appears

It’s not hard to make a curved mirror that gives a wider field of view – no blind spot – but at the cost of visual distortion and making objects appear smaller and farther away.

Hicks’s driver’s side mirror has a field of view of about 45 degrees, compared to 15 to 17 degrees of view in a flat driver’s side mirror. Unlike in simple curved mirrors that can squash the perceived shape of objects and make straight lines appear curved, in Hicks’s mirror the visual distortions of shapes and straight lines are barely detectable.

(Yeah, I know that the “objects are closer than they appear” gags were on the passenger side, which does have a curved mirror)

Kind of a Drag

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Cloudy, with almost no chance of Venus, ended up being the weather yesterday. I did manage a glimpse through a telescope, during one of the brief interludes when the clouds thinned. I also snapped this, with my transit/eclipse glasses covering my iPad camera lens

A somewhat pixelated Venus might be that dark blotch in the upper left, just inside the rim. Maybe. It was taken about the right time for it to be there, I think. But it might just be part of the cloud.

We had an OK turnout and it was fun talking to people, play with some of the other kids and I even got a chance to tour our 26″ telescope, which I had not previously visited.

The Twinkie Offense and Defense

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Meet the Twinkie of particle physics: the muon.

The muon is the sponge cake of elementary particles. It’s plump, basic, easy to mass-produce and disappears quickly—much like a Twinkie.

The rebuttal

Second, despite our relatively long lifespan, we are nothing like a Twinkie, which seems to have an infinite shelf life.

Much like Wonder Bread, the Twinkie’s expiration date is “You should live so long”

I Only Saw Her Shadow

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What did the 1882 Transit of Venus look like?

The last [transit] before 2004 was in 1882, recent enough that photography was being used in astronomy. And it so happens that astronomers at Mt. Hamilton in California were able to take a series of 147 (!) images of the transit, 140 of which were used to make this amazing video

Today’s the day! Hoping it’s clear in the late afternoon, because we’re having a family and friends shindig at work, and we don’t want to disappoint.

These Are Rights, not Commandments

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The Physicists’ Bill of Rights

We hold these postulates to be intuitively obvious, that all physicists are born equal, to a first approximation, and are endowed by their creator with certain discrete privileges, among them a mean rest life, n degrees of freedom, and the following rights which are invariant under all linear transformations

There’s actually a few of these “rights” that I think should earn a slap to anyone exercising them, but I’m just going to assume the author was thinking of string theorists and not worry too much.

Within Epsilon of the Truth

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Excellent Approximations and Lying to Children

[I]t’s true that Euclidian geometry is only a special case of the mroe general geometry of spacetime. But it’s an amazingly good approximation to any situation you will ever encounter. Which is why we teach it to children– because it’s vastly simpler, and the cases where it doesn’t work are very far from everyday experience.

The post on which this comment is based seems to propose doing things the hard way — why teach non-Euclidean geometry without having the foundation in Euclidean geometry. Do you really want to teach that kinetic energy is \((gamma -1)mc^2\)   and, perhaps more importantly, do you want to derive how you got that, rather than going with the Newtonian approximation that’s going to hold as long as you are limited to everyday speeds?

Physics curricula aren’t perfect — I think e.g. the Bohr model can do more harm than good — but then again that’s not really an example of a model that’s approximately correct. The suggestion that we abandon teaching classical physics and instead we dive into quantum and relativistic topics (starting with lasers at Eight O’clock on day 1) means explaining the details while simultaneously trying to get across basic ideas like forces and energy. I think that’s a lot to ask a student to digest.