Dr Karl On Triplej

It's a Marine Science Special! Professor Emma Johnson joins Dr Karl and Zan Rowe to help answer your ocean-based science questions.

Why do op shops all smell the same? Why can't we use 3D printers to print organs? Is there any benefit to avoiding gluten?

Does forcing a smile really make you happier? Why do certain notes or chords have emotional responses? Is urine good for helping lemon trees grow?

How does addiction work? Why were dinosaurs so big? Does stress shorten your life?

Why does my partner get a runny nose, after eating a hot dinner? Why is urine actually yellow? Could space possibly be a sphere?

Why do people get tired when driving? Is it possible to drive a fast car upside-down in a long, circular tunnel? Are your chances of surviving a car accident better if you are asleep and you're body is limp?

Why do people rock from side-to-side when they sleep? Plus: are humans the only mammal that suffers morning sickness during pregnancy?; and why can cat fur have different colours along the length of each strand of hair?

Why is it considered a good thing to urinate on lemon trees? Plus: can birth marks be hereditary?; and why do yellow sunglasses make daylight appear brighter?

What happens if you swallow chewing gum? Plus: can a woman's tastebuds change during and after pregnancy?; and can drinking milk cause osteoporosis?

Why does crockery seem to randomly explode? Plus: Is it possible to be allergic to only male furry animals?; and a caller reports the results of his and his partner's female ejaculation tests.

As part of triplej's 'sex week', Dr Karl and Zan Rowe take talkback questions ranging from female 'squirting' to male morning glories and having sex during pregnancy.

When using earbud-style headphones, why does the music's pitch seem lower when they're removed? Is there a way to reduce the effects of jet-lag?Why is it when you are extremely tired that trivial things seem very funny?

Why does your head seem to spin when you lie down if drunk? What are the differences between various cookwares and are any types dangerous? What happens to bullets that are fired into the air?

Previous 'Mornings' presenters drop by to share their favourite Dr Karl moments from the last 30 years on triplej. Plus: Karl's favourite organ; his first comments on radio re-enacted; and the five most-common science questions asked by listeners.

In a special triplej listener talkback, Zan Rowe and Dr Karl discuss the link between mental illness and marijuana use with psychiatrist Dr Matthew Large, from the University of New South Wales.

Does cold storage affect how food metabolises and germinates? Plus: why do some people's eyes squeak when they rub them?; and why can some people make their ears 'crack' when they press them?

Do snipers need to take in to account the Coriolis effect when taking a shot? Plus: what happens if you pee on an electric fence?; and can babies breathe underwater?

Why do some mobile phones ring when they are switched off? And why do many women crave chocolate just before their periods?

Why do wasps survive being frozen? If black is a shade of light, then how does a projector recreate it? Why does cold air clear a foggy windscreen better than warm air?

Do microwave ovens block mobile phone reception? Will vinegar sooth sunburn? How can you 'pop' a yawn?