Science Podcasts

Naked Scientists episode

Sun, 19th Apr 2009

Science Questions and Answers

This week, we find out how a giant parachute could help avoid satellite collisions, why the schizophrenic brain can't see a popular optical illusion and discover that all octopodes (or octopuses?) are poisonous!  Plus, we take on your science questions, discussing cycling on the moon, electric fences and couples getting tazered together.  In Kitchen Science, we make a sprinkler from a spinning straw!

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In this edition of Naked Scientists

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  • 23:00 - Why do you see speckles when you sneeze?

    Why if you sneeze in the dark when you open your eyes again (apparently it’s impossible for you to sneeze with your eyes shut) why do I see white speckles in front of my eyes?

  • 27:33 - Why do planets spin in a particular direction?

    What determines the initial rotation of stellar cosmic objects? If you look at the sun it’s rotating, if you look at the planets going round the sun, they’re all rotating. What makes them decide what rotation to rotate in the first place?



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Dear Scientists.. I am listening to your programme via Secondlife..I would like to ask a question.. can you tell us why musquito's and other insects often swirl underneath a tree in circles, during summer? Saphira, Sun, 19th Apr 2009

Is it bad to drink boiled water that has been left to for a while (e.g. 48 hours after it was boiled) compared to drinking it sooner? Chemistry4me, Tue, 21st Apr 2009

That is amazing!
After watching a few times I was going crazy trying to suppress it! Arrhhh!!

Here you can have the back of Einstein's head following you everywhere! Chemistry4me, Wed, 22nd Apr 2009

During the show, when talking about the hollow mask illusion, something Chris said caught my attention:

I am a casual cannabis smoker, and I tend to smoke 1 to 2 joints a day - I find it relaxing and a great help through an extremely high pressure career. I had seen this illusion many years ago (before I started smoking cannabis) and I saw the effect of the illusion back then. I thought it odd that cannabis would definitely result in me losing the ability to see the effect, so I tried it before smoking any cannabis (partially as a control, but also to see if any long term effects had resulted) and the effect was still there, and still impossible to suppress. I then smoked a joint, and still, the effect was there and impossible to suppress. I was surprised at the off-the-cuff mention of this apparent "fact", in particular seeing as he linked it to cannabis causing schizophrenia. Just a few weeks earlier, there was a discussion on the show about the possibility that schizophrenics may be more likely to smoke cannabis rather than cannabis being the cause of schizophrenia, yet Chris said this as though that research was forgotten. DrSmokesaBit, Wed, 29th Apr 2009

I don't think Chris was suggesting that cannabis does cause schizophrenia, more that it's another link in addition to the existing epidemiological links.  It's very possible still that schizophrenia sufferers are more likely to smoke cannabis, rather than cannabis being a causal agent.  The research to suggest causation has not been done as far as I know.

Also, Chris was reporting on a study in which they referenced the fact that smoking cannabis can lead to the hollow mask effect going away.  I'm not sure under what conditions (such as doseages) but these are the journals they cite (not sure if these will be available to you, but you should at least be able to find an abstract):

Emrich et al., 1991 H.M. Emrich, M.M. Weber, A. Wendl, J. Zihi, L. von Meyer and W. Hanisch, Reduced binocular depth inversion as an indicator of cannabis-induced censorship impairment, Pharmacol. Biochem. Behav. 40 (1991), pp. 689–690.

Emrich et al., 1997 H.M. Emrich, F.M. Leweke and U. Schneider, Towards a cannabinoid hypothesis of schizophrenia: cognitive impairments due to a dysregulation of the endogenous cannabinoid system, Pharmacol. Biochem. Behav. 56 (1997), pp. 803–807.

Semple et al., 2003 D.M. Semple, F. Ramsden and A.M. McIntosh, Reduced binocular depth inversion in regular cannabis users, Pharmacol. Biochem. Behav. 75 (2003), pp. 789–793.

Leweke et al., 1999 F.M. Leweke, U. Schneider, M. Thies, T.F. Münte and H.M. Emrich, Effects of synthetic Δ9-tetrahydrocannabinol on binocular depth inversion of natural and artificial objects in man, Psychopharmacology 142 (1999), pp. 230–235.

Leweke et al., 2000 F.M. Leweke, U. Schneider, M. Radwan, E. Schmidt and H.M. Emrich, Different effects of nabilone and cannabidol on binocular depth inversion in man, Pharmacol. Biochem. Behav. 66 (2000), pp. 175–181.

The original paper is also available here. BRValsler, Wed, 29th Apr 2009

Cannabis research always interests me and I take particular care when reading papers written about its effects as they may well be biased one way or another depending on who funded or requested the research - it tends to be a touchy subject. My interest in it has led me to perform a number of small self-experiments such as IQ and memory tests, and the results (albeit in relatively "casual" scientific experiments) have shown the effects to be far less intoxicating than some "research" would have you believe. IQ tests have produced the same results (within a reasonable mean deviation) when using cannabis as when not. I also tend to produce a high level of creativity after smoking cannabis. Of course, these tests are rather unscientific, and I wouldn't take them as more than the anecdotal curiosities that they are.

The articles you mentioned do indeed look interesting, unfortunately I don't have a subscription so I can't see the articles (and despite promises from my university, they never did grant me the "alumni" access they said I would have  ). One of the papers makes reference to a "strong cannabis-induced impairment of binocular depth inversion" due to "cannabis-induced “psychedelic states”" which sounds like a fairly strong dose (though without reading the paper itself, that is purely conjecture) - my understanding of alcohol (which is not based on personal experience as I do not drink) is that it too causes vision impairment, in particular to depth perception. I saw brief mention of "alcohol withdrawal" in one of the abstracts, but no direct mention of the effects of inebriation - I am wondering if the same effect would be produced? DrSmokesaBit, Wed, 29th Apr 2009

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