Science stories

[Rincewind]

Much of the science that permeates into the wider media does so due to some attention grabbing feature or implication. Some of this is good and some of it is little better than wild speculation for the purposes of garnering attention. However A thread where people could point to such stories might be useful.

I was sparked by the following story about the fossil evidence of a ancient bird thouht to be a distant relative of modern ducks and geese with a 5 metre wingspan and a toothy beak which graced the skies 50 million years ago.

A popular news item can be read here

http://www.scientificblogging.com/ne...had_bony_teeth

The abstract of the original article can be read here and those with access to the journal content can link to the full-text

http://www3.interscience.wiley.com/j...22208/abstract

Given the history of geese at Chesschat, the thought of a 5 metre relative of the goose will probably make people glad they were not living 50 million years ago when these gargantuan geese might have (literally) eaten them for breakfast.

[Rincewind]

Here is another recent story on some old rocks (possibly the oldest found) from Quebec.

http://www.sciencedaily.com/releases...0925144624.htm

Again the full text cannot be accessed with subscription however the abstract is here

http://www.sciencemag.org/cgi/conten.../321/5897/1828

And a podcast of an interview with the first author (McGill PhD candidate Jonathan O'Neil) is here

http://www.sciencemag.org/cgi/conten.../5897/1828/DC2

Gives some insights into the scientific methods of geology and geochronology used in dating these specimens.

[Rincewind]

A group of mathematicians at UCLA have claimed to have found the first prime with more than 1 million digits

http://www.latimes.com/news/science/...,2746766.story

There wont be anything published on this in the science literature right away but assuming they are right, then they will get a $100,000 prize for the discovery.

More info here

http://www.math.ucla.edu/~edson/prime/

Including this...

Even though I work for the Mathematics Department, I'm a System Administrator, not a Mathematician!

[Capablanca-Fan]

This was discussed on another thread.

There are two main supports for this myth:

1. Old window panes were thicker at the bottom, implying that glass had slowly flowed under gravity
2. The atomic arrangement of a glass has long-range disorder that looks very like a snapshot of a liquid's arrangement, while true solids have an orderly (periodic) arrangement. So a glass is really just an extremely slowed-down liquid with very high viscosity.

But (1) is based on the faulty assumption that window panes were uniform in thickness. However, old planes were made from a now obsolete manufacturing process: spinning semi-molten glass, which produced a sheet which was thicker at one end. Glaziers normally found it easier to lay a pane with the thicker end at the bottom. I.e. the glass didn't flow into place, but was in place from the beginning. To demonstrate this further, there are panes where the thicker edge is NOT at the bottom.

(2) is actually a sort of "no true Scotsman" fallacy, defining a solid as having a periodic arrangement. But this is actually a definition of a type of solid: a crystal. In reality, in solids, the atoms vibrate about equilibrium positions, while in liquids there is limited translational freedom—on this level, a glass is definitely solid.

That a glass is not a liquid is shown by the fact of an easily measurable phase transition between the two. However, a glass transition is a second-order phase change, i.e. the second derivatives of the Gibbs function that are discontinuous at the transition temp, e.g. heat capacity, compressibility, volume expansion. A liquid-to-crystal transition is first order, i.e. the first derivatives of the Gibbs function (e.g. entropy, volume) are discontinuous at the transition temp.

There is an operational definition of a glass transition temp Tg where the viscosity of the exceeds 10^13 N s /m^2. About 50 K below that, the viscosity would be so large (if we were to grant the liquid claim for a moment)that there would be hardly a flow of an atomic diameter even in the evolutionary age of the universe, which would not allow for window panes to sink.

Another problem with the "super-viscous liquid" claim is that there is a thermodynamic basis for glass transition, so it's not just a relaxation effect of increasing liquid's viscosity to an arbitrarily high level. In 1948, Walter Kauzmann discovered the "Kauzman paradox": as a liquid cools, its entropy drops faster than that of its corresponding crystal. Supercooling is certainly possible, where the liquid stays molten even below the freezing point, but if it continues indefinitely, then at a certain temperature (Kauzmann Temperature) its entropy would drop below that of the crystal with the same enthalpy. This would violate the Third Law of Thermodynamics. Thus there must be a phase change before this, involving a calorimetric ideal glass transition temperature T0c.

The observed glass transition temperature Tg depends on how fast the cooling is, but is similar to T0c and approaches T0c as dT/dt → 0.

[Rincewind]

1. Old window panes were thicker at the bottom, implying that glass had slowly flowed under gravity

I agree the flowing of glass seems to be apocryphal. Though there has be evidence of very slow flowing liquids such as the long running Pitch Drop Experiment, which incidentally won an Ig-noble prize.

1. The atomic arrangement of a glass has long-range disorder that looks very like a snapshot of a liquid's arrangement, while true solids have an orderly (periodic) arrangement. So a glass is really just an extremely slowed-down liquid with very high viscosity.

However, this point seems to be more a question of semantics than anything else. By the standard definitions of solids and liquids you would expect there to be a standard transition temperature and latent energy. I appreciate the point you make about the second-order discontinuity but that would seem to indicate there is something different about glass. Furthermore, you said that Tg depends on the rate of cooling which would seem to be different than what one expects for uncontroversial solids.

Therefore, my approach would to be cautious and say glass and standard pressure and temperature appears to be a solid for most everyday mechanical applications. However, to me the phase change properties seem to indicate that, as a phase, glass is neither solid nor liquid.

[Capablanca-Fan]

I agree the flowing of glass seems to be apocryphal. Though there has be evidence of very slow flowing liquids such as the long running Pitch Drop Experiment, which incidentally won an Ig-noble prize.

That's an interesting one and good pic there, and close to home too! Polymers and colloids can have viscosity that changes with shear stress (thixotropy).

Globular molecules, such can form orientationally disordered solids or plastic crystals. Here, there is a first-order phase transition to a normal orientationally ordered solid where there is fairly free rotation, with a much greater entropy decrease than solidification. There is also an orientational glass transition that's second order, especially favoured when there are strong intermolecular forces.

Liquid crystals comprise rod-shaped molecules and have a number of phases, but unlike globular molecules, they are not my area.

However, this point seems to be more a question of semantics than anything else. By the standard definitions of solids and liquids you would expect there to be a standard transition temperature and latent energy. I appreciate the point you make about the second-order discontinuity but that would seem to indicate there is something different about glass. Furthermore, you said that Tg depends on the rate of cooling which would seem to be different than what one expects for uncontroversial solids.

Yes, there is something different about glass and crystals, but this is consistent with glasses being a type of solid, and certainly not just a liquid that's even more viscous than pitch.

Therefore, my approach would to be cautious and say glass and standard pressure and temperature appears to be a solid for most everyday mechanical applications.

Yes, that's fair.

However, to me the phase change properties seem to indicate that, as a phase, glass is neither solid nor liquid.

Or else it is a solid that's different from the crystalline solids most often studied.

[Rincewind]

Isn't the greatest power the power to be invisible?

Invisibility cloak 'step closer'

[Rincewind]

A common theme of science stories (perhaps more so in Australia than elsewhere) is the species once thought extinct is found. The media seems to have such an appetite for these stories that even species once thought extinct in this specific region is rediscovered. Whether the newly discovered population has evaded notice or remigrated back to a previously occupied range is not usualy explored.

Anyway, here is a recent example of this sort of story...

Student finds 'extinct' desert mouse

[Kevin Bonham]

A common theme of science stories (perhaps more so in Australia than elsewhere) is the species once thought extinct is found. The media seems to have such an appetite for these stories that even species once thought extinct in this specific region is rediscovered. Whether the newly discovered population has evaded notice or remigrated back to a previously occupied range is not usualy explored.

The attention on these rediscoveries is frequently an artefact of state threatened species listings. A species that hasn't been seen for ages in a particular state will often be formally listed as extinct from that state, although it is alive elsewhere including close to the border of that state.

Another artefact of state threatened species listings is that a secure species can become considered threatened in a state (and hence receive conservation attention) although the species as a whole is completely secure. Unless the population in question is disjunct or occurring at a genuine (ie habitat or climatic) range extremity then the value of conserving these kinds of populations is dubious.

There was some similar discussion about my rediscovery of an orchid that was listed presumed extinct in Tasmania (but not nationally) earlier this year - but the one remaining Victorian population that was still attributed to that species was only attributed to it on the assumption that the original "Tasmanian" collections were actually from somewhere else. By finding the species exactly where Hooker had said it was in 1840 I did a slight bit of damage to that assumption.

[Kevin Bonham]

Here is a refereed article (PDF LINK) about a 2003 Western Australian range extension for the mouse in question. The authors document that the mouse seems to have contracted its range historically but may now be expanding again.

Incidentally, the only news report Google News found giving the celebrity mouse's scientific name was one from Russia.

[Rincewind]

The following story is very interesting. A female shark with no contact with male sharks giving birth.

Virgin shark gives birth

That study can be accessed here

http://www3.interscience.wiley.com/j...32430/abstract

[Desmond]

Maybe god gave up and decided that while man was created in his image, sharks would just have to do as the shephards of his garden. Did 3 wise octopuseses show us?

[Kevin Bonham]

New extinct New Zealand penguin found using DNA

The gist of this is that a previously unknown penguin, the Waitaha Penguin (Megadyptes waitaha Boessenkool et al., 2008) has been split from subfossil material previously thought to be the currently present Yellow-Eyed Penguin.

It appears that the Waitaha Penguin was entirely exterminated by Polynesian settlers and then the Yellow-Eyed Penguin expanded into its range to fill the niche left by the demise of its close relative.

[Capablanca-Fan]

The lobster trap is supposed to be a funnel where lobsters crawl in for the bair and can't crawl out. Hence they are trapped until they are ready to be fished out.

But video footage a few years ago showed that they crawl in and out as they please. The only ones caught are those with the bad luck to be in the "trap" just as it's pulled out.

As an article in the University of New Hampshire’s online magazine put it:

‘[A] mere 6 percent of the lobsters who entered were caught, largely because they had the bad luck to be in the trap when it was hauled up. Instead of a Crustacean Hotel where the lobsters would “check in and never check out”, the lobster trap works more like a 24-hour roadhouse where the patrons are generally free to leave—usually through the supposedly one-way entrance.’

[Capablanca-Fan]

Many explanations of bird and airplane flight involve the Bernoulli Effect, in which faster flow of a fluid decreases the pressure (derived from conservation of energy: kinetic energy + potential energy must be the same at all points of a steady-state flow). So the story goes that the curvier top surface of the wing means a greater distance for air to travel per unit time, so greater speed, so lower pressure than on the bottom of the wing, so lift results.

But the numbers are far too small, and this explanation will not explain airplanes flying upside down. More recent studies emphasize Newton’s 3rd Law. Once there is a turning in the flow, then there will be a force on the object doing it. There are two reasons that forward motion causes the wings to deflect air downwards: first, the wings are slanted slightly upwards into the air stream (a positive ‘angle of attack’); second, the Coanda Effect, where a fluid follows the curve of the surface, which from the upper surface points downwards. The fact of a downdraft can be shown easily by standing under helicopter blades in motion, since they are basically rotating wings. ‘The lift of a wing is proportional to the amount of air diverted down times the vertical velocity of that air.’ See Anderson, D. and Eberhardt, S., A Physical Description of Flight, and Understanding Flight, McGraw–Hill, 2001; for more on this intuitive understanding of flight, that also allows rough estimates of lift.

Prof. Andy McIntosh of Leeds Uni in the UK teaches his aerodynamics students the ‘mathematical aerodynamics explanation’ that allows lift to be calculated accurately: that fundamentally lift is due to circulation (technical term for the turning of the flow), which will generate lift by reaction. The flow leaves the trailing edge of a real wing smoothly (the Kutta condition) which invokes circulation. Lift is given by l = ρvg, where l = lift per unit of wingspan, ρ = density, v = velocity, g = circulation strength (the Kutta–Zhukovsky theorem).