What does this mean? Are McDonald’s burgers made out of undigestible material, meaning you can eat as many as you want and not get fat? Or are they a miraculous, non-spoiling food source that could feed hungry millions in places without access to fresh produce or refrigeration?

Well, J. Kenji López-Alt of the Burger Lab has found a more mundane yet scientific answer, by comparing spoilage of a McDonald’s Quarter Pounder with a homemade control burger using good, honest, all-natural ingredients. Both burgers ended up with pretty much the same lack of mould or visible rot.

The main reason seems to be that the burgers in question are small enough to quickly dehydrate when left out on the kitchen bench. Together with the fact that the burger patties are essentially sterilised in the cooking process, they lack both starting mould spores and the environment in which to grow them.

This was further verified by sealing a McDonald’s burger in a plastic bag, which caused it to grow mould just like that loaf of supermarket bread you’ve left for too long.

The moral of the story? Don’t believe everything you see on the internet, at least not without thinking about what it actully means. And one demonstration on YouTube is not the same as a controlled experiment…

For the proper study, with control burgers and everything, head on over to the Burger Lab at Serious Eats.

Let me explain. (And let me also apologise for my attempted pun, which I blame on summer brain deactivation.)

An ice cream headache, also known as brain freeze or cold stimulus headache, or, if you want to get really fancy, sphenopalatine ganglioneuralgia, is the pain you get when something very cold touches the roof of your mouth.

It is supposedly the most common cause of head pain; at least, according to the seminal 1988 textbook Headache, by Dr Neil H. Raskin. Although, Dr Raskin also found it was more common in migraine sufferers, with 93% of them experiencing it compared to 31% of a control group (see the reassuringly titled article by Joseph Hulihan in the British Medical Journal, “Ice cream headache: no need for abstinence” [PDF 159 KB]).

The pain appears to start in blood vessels in the mouth or sinuses, which rapidly contract when cooled and then dilate again when they rewarm. It’s then transmitted to the brain by either the trigeminal, glossopharyngeal or vagus nerve (opinions are divided on the culprit).

The trigeminal nerve, shown in yellow, carries signals between the brain and most parts of the face. The glossopharyngeal and vagus nerves, not shown, largely serve the throat and chest, respectively. (Gray's Anatomy of the Human Body, 20th edition)

The problem is that each of these nerves serves many other parts of the head – like the forehead in the case of the trigeminal, or the membrane around the brain for the glossopharyngeal – and the brain misinterprets the signals as coming from one of these other areas. This is a phenomenon known as referred pain, which can also be experienced in heart attacks when people feel pain in the neck, shoulders or back instead of the chest.

There are a few treatments recommended for ice cream headaches, like tilting your head back, pressing your tongue against the roof or your mouth or drinking a warm drink. But for most people they’ll go away themselves some time between 20 seconds and 5 minutes – although for an unfortunate few they’ve been known to trigger migraines.

But as I mentioned before, it’s also the main drawback for a newly “discovered” method athletes can use to stave off overheating. Drinking “ice slurry” – basically slurpies – allows people to run for longer in hot weather and endure a higher body temperature, compared to those who only have a cool drink (Siegel R, Maté J, Brearley MB, Watson G, Nosaka K & Laursen PB 2010, “Ice slurry ingestion increases core temperature capacity and running time in the heat”, Medicine & Science in Sports & Exercise, vol. 42, no. 4, pp. 717-725, doi:10.1249/MSS.0b013e3181bf257a).

More recent follow-up research by the same group compared the ice slurry with full body immersion in cold water. Both methods were just as effective in increasing running time, but the slurpies were rather more convenient (Siegel R, Maté J, Watson G, Nosaka K & Laursen PB 2012, “Pre-cooling with ice slurry ingestion leads to similar run times to exhaustion in the heat as cold water immersion”, Journal of Sports Sciences, vol. 30, no. 2, pp. 155-165, doi:10.1080/02640414.2011.625968).

The one problem? 6 out of the 8 participants in the trial suffered from brain freeze.

Which just goes to show that even the most benign, natural-sounding treatments – or in this case, performance-enhancing drugs – can have unfortunate side effects. But still, remember that title from the British Medical Journal: “no need for abstinence”.

Browsing The Age website today, I came across the following link to an article in their Executive Style section:

The article itself gives a reasonable precis of the report which it’s quoting (Kim JH, Malhotra R, Chiampas G, d’Hemecourt P, Troyanos C, Cianca J, Smith RN, Wang TJ, Roberts WO, Thompson PD, & Baggish AL 2012, “Cardiac arrest during long-distance running races”, New England Journal of Medicine, no. 366, pp, 130-140, doi:10.1056/NEJMoa1106468).

Specifically, it repeats the article’s main conclusions, which are:

Marathons and half-marathons are associated with a low overall risk of cardiac arrest and sudden death. Cardiac arrest, most commonly attributable to hypertrophic cardiomyopathy or atherosclerotic coronary disease, occurs primarily among male marathon participants; the incidence rate in this group increased during the past decade.

That increase there being due to the greater number of people participating in marathons and half-marathons.

My concern is of course the sensationalist headline, which tries to emphasise the fear that running is in fact dangerous. A message somewhat at odds with the media releases from the institutions where the research was based, being the Massachusetts General Hospital and Harvard University. Their stories were, respectively, Participating in marathons, half-marathons not found to increase risk of cardiac arrest and Good news for marathoners.

What have we learned here? I can think of at least two things:

1. Never treat a newspaper headline as an accurate summary of scientific research; always read the actual story carefully, or preferably track down the original article.
2. Whatever you may think of the paper itself, don’t assume newspaper websites are a reputable news source.

Here in Melbourne it’s been a sweltering start to the new year, hitting 40 degrees on 2 January. Of course, you can’t blame isolated spells of hot weather on climate change alone, as temperatures will always fluctuate around long-term changes in the mean (although extremes, particularly on the hot end, are expected to become more frequent).

But still, even though we’re all familiar with the tabloid notion that winter disproves global warming, the readers of the Herald Sun seem convinced that summer makes a good counter-argument too:

At last, summer. It used to go for months, now we get weeks. “Climategate” sure exposed the frauds.
(Note: it’s January)

It’s summer, not climate change. We’ve had 40 degree days every year for years.

One day of 40 degrees … it’s nothing out of the ordinary. Deal with it like people have for years.

The most at-risk are the pensioners who can’t afford their electricity bills. The carbon tax will only make things worse. Global warming is a scam … 40 degrees is not unusual.

And my favourite:

We’re told this is the hottest start to summer in over 100 years. Does that mean it has been hotter in the past – before airconditioning and maybe even before global warming?

Yes, I know I should find something better to read – but give me a break, I’m on holiday!

Regular coverage will resume shortly…

That question is, surprisingly, hotly debated. It all started in 2008 when Sabine Begall and colleagues from Germany and the Czech Republic found, using Google Earth, that cows tend to align themselves north-south along the Earth’s magnetic field (Begall S, Červený J, Neef J, Vojtěch O & Burda H 2008, “Magnetic alignment in grazing and resting cattle and deer”, Proceedings of the National Academy of Sciences, vol. 105, no. 36, pp. 13451-13455, doi:10.1073/pnas.0803650105).

It's actually rather difficult to find suitable herds of cattle on Google Maps, given that they're mostly found in rural areas where the photo resolution is poorer. The cows pictured here are near the 12 Apostles in Victoria, and don't have any obvious consistency in their alignment- the pattern was actually found in the statistics of 8,510 cows (click to embiggen).

The obvious question to ask is whether the alignment is due to environmental conditions. However, the researchers claimed they could rule this out: the behaviour of cattle under heat stress or when basking in the sun is well known, and not seen in the cows studied; also, the varying local wind patterns didn’t match the orientations (interestingly, although the wisdom accumulated by farmers over thousands of years was sufficient to rule out these environmental causes, no one had ever noticed the north-south alignment before).

For comparison, they also looked at “beds”, or body prints left in snow by red deer and roe deer. These were even more highly correlated along north-south alignment, and being created at night were clearly unrelated to the position of the sun. (Additionally, although the satellite photos of cows weren’t high enough resolution to see the actual direction they’re pointing, i.e. if it’s north or south, the deer beds showed that they face north when resting.)

Perhaps the clincher though is that at high latitudes, where there’s a big difference between magnetic and geographic north, the cows and deer were much more aligned to the magnetic.

So how do they do it? Is it because beef is so high in iron?

Actually, the mechanism that animals use to detect magnetic fields – a skill known as magnetoreception - is still largely unknown. But it has been studied more in some animals than others.

Birds, for instance, are known for their navigational abilities, and they have a few features sensitive to magnetic fields. They have a region in their upper beak that is known to contain magnetite (Fe₃O₄); also, their eyes use the light-sensitive protein cryptochrome, which is affected by magnetism, so they may be able to “see” magnetic fields.

We might even share this ability: human sinuses have been found to contain magnetite, and the cryptochrome in our eyes is also potentially magneto-sensitive (see Baker RR, Mather JG & Kennaugh JH 1983, “Magnetic bones in human sinuses”, Nature 301, pp. 78-80, doi:10.1038/301078a0 and Foley LE, Gegear RJ & Reppert SM 2011, “Human cryptochrome exhibits light-dependent magnetosensitivity”, Nature Communications 2, doi:10.1038/ncomms1364).

It’s actually with humans that the whole cow compass affair started: Sabine Begall had been studying naked mole rats, which always sleep on the south side of their burrows, and she got to wondering whether sleeping humans also had a preference.

Begall tried using Google Earth to examine campsites to see if there was a pattern, but it turned out to be very hard to see which way people were sleeping in tents. But cows were much more visible, and they indeed showed a pattern.

However, not everyone agrees. In January 2011 another Czech team did their own analysis of satellite photos of cows across Europe, and found no alignment (Hert J, Jelinek L, Pekarek L & Pavlicek A 2011, “No alignment of cattle along geomagnetic field lines found”, Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology, vol. 197, no. 6, pp. 677-682, doi:10.1007/s00359-011-0628-7).

But it doesn’t end there. In November, Begall’s team published a response, in which they re-analysed the same photos. They claim that the second study had used a different statistical technique and included a lot of “noise” in their data, including poor quality photos, pastures on slopes and herds near power lines, which supposedly disrupt the magnetic effect  (see Begall S, Burda H, Červený J, Gerter O, Neef-Weisse J & Němec P 2011, “Further support for the alignment of cattle along magnetic field lines: reply to Hert et al.” Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology, vol. 197, no. 12, pp. 1127-1133, doi:10.1007/s00359-011-0674-1).

So the great magnetic cow controversy rages on. But the original question is still unanswered: what about humans?

This is a topic waiting to be solved, perhaps with better quality satellite photos, or by choosing suitable locations: people lying on beach towels are much easier to see, but the beach is a possible confounding factor.

Or maybe like the deer, we need to examine campgrounds up close, or even just go down to the local park at lunchtime and see which way people are lying. It could be a fun summer research project!

Despite this, I can’t help wondering if we’re missing an obvious piece of the puzzle: dark matter and dark energy together account for about 96% of the total mass of the universe.

So if everything we can see and experiment on is a mere 4% of all that there is, is there any wonder it doesn’t make sense?

Okay then, do we know anything at all about what dark matter may be? Well, for a long time the leading candidates have been either MACHOs or WIMPs. Yes, those are the actual names.

MACHO stands for Massive Astrophysical Compact Halo Object, and it basically refers to clumps of normal matter that sit in the “haloes” around galaxies, but for some reason can’t be seen. They could be objects like planets, brown dwarfs (unignited stars) or even black holes.

Although MACHOs don’t emit enough light for us to see, they can be detected by gravitational microlensing, which is when their gravitational fields bend the light rays from distant stars when they pass in front of them.

Unfortunately, although surveys of gravitational microlensing have found MACHOs, there’s not enough of them to account for the universe’s missing mass.

So we turn to the other option: WIMPs, or Weakly Interacting Massive Particles. These are a postulated type of subatomic particle that only interacts via gravity and maybe the weak nuclear force.

This means they would have properties similar to neutrinos (i.e. very hard to detect), only heavier (hence the “massive”). And that’s why we haven’t yet been able to create them or detect them on Earth.

However we do have some indications they exist, from observing collisions between galaxies like in the famous Bullet Cluster (pictured).

The so-called Bullet Cluster, formed from the collision of two galaxies, as captured by NASA's Hubble Space Telescope and Chandra X-ray Observatory. Ordinary matter, shown in pink, has been distorted into a bullet shape by the collision, whereas the clusters of dark matter, shown in blue, appear to have passed straight through. This supports the theory that dark matter particles only interact by the force of gravity. (Image from NASA)

In these collisions, we see matter like hot gas piling up in the middle, but the centres of mass of the colliding galaxies – presumably made out of dark matter – pass straight through. This suggests that the dark matter is something that doesn’t interact much at all, like WIMPs.

Lately though, there have been some intriguing signals suggesting we’re getting closer to actually detecting these dark matter particles. Experiments like CRESST and DAMA in Gran Sasso (the same underground lab that detected those pesky neutrinos) have seen hints of WIMPs  colliding with nuclei.

And most recently, the balloon-borne experiment ARCADE has seen a radio signal coming from space that could be the result of WIMPs colliding with each other to produce pairs of electrons and positrons (Fornengo N, Lineros R, Regis M & Taoso M 2011, “A dark matter interpretation for the ARCADE excess?”, arXiv:1108.0569v1).

These are all very small, very early results, so we have to be careful not to jump to conclusions. But when we’re contemplating the universe and trying to come up with a “theory of everything”, we really shouldn’t ignore the other 96% we can’t see.

Striga asiatica or witchweed, a parasitic plant, the seeds of which germinate in the roots of their host when triggered by the hormone strigolactone - hence the name (image by Florida Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org, via Wikimedia Commons)

Levels of strigolactone increase when light or nutrients are limited, which is a good time to grow taller than your neighbours, or to quickly reproduce before the food runs out (by inhibiting side-shoots, more energy is available for making flowers and seeds for reproduction).

Conversely, when nutrients are plentiful strigolactone levels fall, the plant grows bushy and is able to take advantage of its environment.

Now a follow up paper has revealed that strigolactone helps plants grow tall in another way: by making their stem thicker and stronger and so able to support the weight. It does this in response to signals issued by another hormone, auxin (Agusti J, Herolda S, Schwarz M, Pablo Sancheza, Ljung K, Dun EA, Brewer PB, Beveridge CA, Sieberer T, Sehr EM & Greb T, “Strigolactone signaling is required for auxin-dependent stimulation of secondary growth in plants”, Proceedings of the National Academy of Sciences, published online 28 November 2011, doi:10.1073/pnas.1111902108).

Strigolactone also seems to encourage growth in other areas too, like tiny hairs on the roots needed to extract nutrients from the soil and encourage the growth of symbiotic fungi.

Of course, like anything it comes with negative effects too: presence of strigolactone in the root systems seems to stimulate the germination of seeds of some parasitic weeds, like those of the genus Striga (from which strigolactone gets its name).

It could also be used by foresters to make plantation trees grow faster with straighter trunks, which probably counts as a positive for both us and the plants; until the whole chopping down thing, of course. Despite their signalling hormones, the trees are a little quiet about whether it’s good or bad overall.

Here are some links to go with our recent radio broadcasts. Or, you can download the podcasts, for our shows from 3 November 2011 (25:54 min / 12 MB) and 10 November 2011 (28:09 min / 26 MB).

• Analysis of corporate ownership networks shows that out of 43,060 transnational companies, only 147 of them – mostly banks – control 40% of the wealth. Read more in New Scientist, or see the entire paper in the arXiv database.
• Protesting about this risks exposure to pepper spray, or Oleoresin Capsicum, which uses the chemical capsaicin ((CH₃)₂CHCH=CH(CH₂)₄CONHCH₂C₆H₃-4-(OH)-3-(OCH₃)), extracted from chilli peppers, to cause eye and skin irritation. Read about its health effects in Investigative Opthalmology and Visual Science and the North Carolina Medical Journal, or see treatment recommendations from Melbourne’s Royal Children’s Hospital.
• The Berkeley Earth Surface Temperature study, partly composed of and funded by climate change sceptics, has performed a massive re-analysis of global land temperature records and verified that yes, the world really is warming.
• Aside from being real, climate change seems to have caused Australian seaweed species to move between 50 and 200 km south, risking the habitat of many other species that depend on them. Read more at ABC Science, or see the paper in Current Biology.
• In more extinction news, Tasmanian devils are currently threatened by a contagious cancer, which seems to spread due to their genetic similarity. Hope is held for a small, genetically different and mostly disease-free population in the northwest of the state, research into which has won a team of scientists the 2011 Eureka Prize for Environmental Research (also see their paper in Conservation Biology). Although the recent discovery of devils with facial tumour disease in even that remote area has increased concern for this unique species.
• (A good friend of ours, John Cook of Skeptical Science, was also awarded the 2011 Eureka Prize for Advancement of Climate Change Knowledge. Congratulations John!)
• Speaking of genetic diversity, research on the Sandy Island mouse has shown that polygamous females produce more viable embryos. See the paper in Ecology Letters, or read more at the University of Western Australia.
• Finally, to space. Three recent discoveries have shed new light on how solar systems like ours form: there’s a planet called LkCa 15b, 473 light years away, which has been discovered in the process of forming; water seen in the planet-forming disk around the young star TW Hydrae (175 light years away) supports the theory that it collects around grains of dust to make comets, which then deposit the water on planets like Earth; and photos of the asteroid Lutetia, taken by the European Space Agency’s Rosetta probe, suggest that, at around 3.6 billion years old it’s a relic of the early Solar System, and have given clues to its formation.

Have you missed any other shows? Catch up on our old episodes!

Appropriately for our pre-Halloween theme, it’s Ghostbusters (1984), directed by Ivan Reitman (see, I told you he’d be back), and starring Bill Murray, Dan Aykroyd, Sigourney Weaver, Harold Ramis, Rick Moranis, Annie Potts, etc.

It might not sound like it, but I believe this is a great movie for science. To quote:

But is there any real science in Ghostbusters? Well, there are the proton packs, those portable particle accelerators they wore on their backs – remember “don’t cross the streams”?

Of course, they’re not terribly accurate – a real world proton accelerator (like, say, the Large Hadron Collider) would be far too big to carry on your back – but what’s really interesting is what they seem to do, which is to contain “negatively charged ectoplasmic entities”. Which, considering positive electrical charges attract negative charges, kind of makes sense.

That’s if you assume that these “ectoplasmic entities” are negatively charged; presumably they’re negative because they’re bad, in some way.

Ectoplasm, though, is a term first used in 1883 to describe a material supposedly excreted from the orifices of mediums in the Victorian era. You can see “ectoplasm” in a lot of spirit photographs from the time (needless to say, they were hoaxes, and mediums tend not to do that these days).

Another Victorian-era innovation referenced in the movie is the actual practice of ghostbusting, or “ghost hunting“. It’s still very popular today; perhaps too popular, as apparently police forces in the United Kingdom are being inundated with nuisance Freedom of Information requests from ghost hunters looking for any reports containing supernatural terms. Although there were far more complaints about ghost hunters than actual sightings of ghosts in at least one report, from Dyfed-Owes Police in Wales (PDF 30 KB).

Seemingly influenced by the movie is not only the concept of ghostbusting, but also the techniques they use. Many modern ghost hunters carry electromagnetic field detectors, very similar to the devices used by Dr Egon Spendler.

Why would people think ghosts generate electromagnetic fields? Considering ghosts could at best be described as “unknown to science”, it seems strange to use such a specific scientific technique. Although, ghost hunters do at least claim they find strong electric or magnetic fields in haunted locations…

Is it just the movie’s influence, or is something else going on? Could they be extrapolating from the fact that living organisms produce electromagnetic fields?

Intriguingly, there have been counter-suggestions that it could run the other way: that electromagnetic fields may cause people to see ghosts.

It’s been long known that strong electric or magnetic fields can cause people to see flashes of light, or phosphenes (PDF 8.4 MB). But even further than that, Canadian psychologist Michael Persinger claims that low-level magnetic fields applied to the temporal lobes of the brain can cause people to sense a mysterious presence, or even experience religious ecstasy. He’s even invented a device to generate this effect, called the God Helmet.

Persinger’s claims are very controversial, with critics saying that the power of suggestion, as well as prior susceptibility and beliefs, have far more to do with whether people experience any unexplained sensations under the influence of the God Helmet. At least, this seemed to be the case with the ‘Haunt’ Project, which attempted to use both electromagnetic fields and infrasonic (low frequency) sound to cause people to sense a ghostly presence (it didn’t work).

So perhaps a more likely explanation for the use of electromagnetic field detectors is that they’re essentially another data collecting device to take with you when hunting ghosts. And the more types of data you collect – preferably by using high-tech equipment that’s easy to misinterpret – the more likely it is that you’ll find something unusual purely by chance.

And when you’re casting a wide net for anomalies, anything you find takes on significance, no matter how random. Which is a mistake you often find in pseudoscience.

Still, it’s all very entertaining, and I’m possibly being too harsh on the ghost hunters. Maybe I should back off: they’re pseudoscientists.

Our first film was not so accurate, but let’s see if we do better with Moon (2009), directed by Duncan Jones, aka Zowie Bowie, and starring almost solely Sam Rockwell.

This is one of those annoying movies with a twist, so I can’t say too much about what happens (although recent research has shown that spoilers can actually make stories better). But suffice to say it’s about a guy (Sam Rockwell) living on the Moon, with only a computerised Kevin Spacey for company.

He’s there to mine for helium-3, an isotope that has one less neutron than the more common helium-4 (which has two neutrons and two protons in its nucleus. Helium-3 still has the two protons and hence the same chemical properties, but lacking a second neutron it has a lower atomic weight).

Helium-3 has been suggested as a possible fuel for nuclear fusion: two helium-3 nuclei can combine to create one helium-4 nucleus and two protons, as well as a whole lot of energy. It’s also used in neutron detectors and to achieve extremely low temperatures in cryogenics.

The trouble is that helium-3 is extremely rare, about 1/10,000th the abundance of helium-4, or around 7.2 parts per trillion in the atmosphere. In fact, most of the helium-3 used on Earth is manufactured.

However, the situation on the Moon is more promising. The lunar regolith, or dirt, may contain up to 50 parts per billion on some parts of the surface. As a result, mining the Moon for helium-3 is a potentially lucrative industry, and it seems to be one of the main reasons the various spacefaring nations are once more interested in lunar exploration.

So, for an interesting depiction of this potential future industry – with a fascinating psychological twist – check out the movie Moon.

Or if you want to try helium-3 mining for yourself, have a go at the Helium-3 Space Game on YourDiscovery.com.