Ask the Naked Scientists PODCAST

Chris Smith answers science questions from the public. Does the rate of nail growth differ between men and women? What are the advantages of a nose swab over a mouth swab? What could improve the connectivity of my remote? Accounting for the rotation of Earth, does a plane flying from London to Cape Town fly in a straight line? How does a colour printer work? Like this podcast? Please help us by supporting the Naked Scientists

Do statins affect your Vitamin D production? Why do we have leap years? Which came first, the chicken or the egg? Could we live on the moon of Titan? Did COVID come from a lab? What aspects of science can we still now answer? Could popping a pimple on your face kill you? How does wireless charging work? Dr Chris Smith and Clarence Ford have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

Chris Smith answers another sample of enquiries from across the scientific spectrum: What might have caused my beetle infestation? Why do so many cultures describe an afterlife? What's the medical explanation for 'cracking the seal?' How do lions identify cubs that aren't theirs? If the Earth stopped rotating, would we feel it? Will hydrogen combustion engines be efficient? Like this podcast? Please help us by supporting the Naked Scientists

Dr Chris Smith answers listener questions including, how can we communicate science better? How much distance do we travel through space each second? Why might I feel stomach pain when I'm hungry and I take a cold drink? What causes people to feel sleepy when they're near a pregnant woman? Why do we enter planes on the left rather than the right? Like this podcast? Please help us by supporting the Naked Scientists

Why might chilli cause an upset stomach? How does a boomerang work? What's the difference between 50Hz and 60Hz of energy? Why does Saturn have a hexagon? Are stars moving away from us? How do we know how large underground oil deposits are? Why aren't cameras as good as out eyes? Do mosquitoes prefer certain people? Dr Chris Smith and Clarence Ford have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

Why kind of gas is in a gas giant planet? Can you do anything about sleepwalking? What causes stutters and speech impediments? Does blowing out birthday candles spread germs onto the cake? Why don't we feel the wind from moving through space? What are shooting stars? Why don't we have strangers with identical DNA? Dr Chris Smith and Clarence Ford have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

This week, a Christmas surprise in Dr Chris's tree that he'd rather not have brought home; should I drink water from aircon machines or even vehicle exhausts, will coffee make me live longer, is the flag planted during the Moon landing still there, what's the scientific basis of itching, which planets don't have a moon, and what makes mosquitoes prefer me to other people? Dr Chris and Talk Radio 702's Relebogile Mabotja take on your science questions... Like this podcast? Please help us by supporting the Naked Scientists

What is the science of a midlife crisis? Can you store stainless steel in the fridge? Where do flies go in the winter? Could you make food directly from soil? Do the sun and the moon change positions in the winter? Why does the mouth generate saliva? How do worms get into your body? Dr Chris Smith and Relebogile Mabotja have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

Dr Chris and Clarence Ford take on listener questions. This time they include, is intelligence more nature or nurture? Is time travel possible? Could time travellers be walking among us? Are Tibetan monks really capable of levitating? Why do I feel down during the holidays? What are the differences between lab grown and mined diamonds? What are weeds and why do they always grow where they shouldn't? Like this podcast? Please help us by supporting the Naked Scientists

Does COVID damage your brain? Why do moths have 'dust' on their wings? Where did the oldest plants come from? Is it better to sleep on your side or your back? Who is the top dog in a pack when humans aren't around? What is your pineal gland for? Why would stomach ulcers cause headaches? Dr Chris Smith and Clarence Ford have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

Does alcohol burn off during cooking, why people put their principles in front of their own life and freedom, what causes ageing and can gene editing be used to reverse it, and is curiosity genetic across species? And does Dr Chris believe in God? Relebogile Mabotja and Dr Chris Smith have the answers to the questions you're asking! Like this podcast? Please help us by supporting the Naked Scientists

Dr Chris takes more listener questions. This week, they include: Why do the sun and the moon appear the same size during a lunar eclipse? How long does it take bowel movements to return to normal after a colostomy? Can you prick a balloon without popping it? Is an enlarged heart dangerous? Do wild horses suffer without having their hooves maintained? Like this podcast? Please help us by supporting the Naked Scientists

What is our water carbon footprint? Does microwaving food destroy the nutritional value? Why do golf balls have dimples? Should we be desalinating water? Why are breastfed babies less likely to become obese? How did we calculate a dog year? Why do we always look at something that we're told not to? What is intermittent fasting? Dr Chris Smith and Clarence Ford have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

Does prior infection or vaccine protect better against COVID? How do you know when something is wrong with your bowels? What is the difference between old and new vaccines? What effect does grapefruit have on taking mediaction? What are the chemical markers that someone is pregnant? Chris Smith and Relebogile Mabotja have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

Why do animals dream? Why do weird dreams feel so normal? Do ovulating people have more vivid dreams? Why might someone stop dreaming? Will ChatGPT replace The Naked Scientists? What is deja vu? Why is so much money being invested into AI? Can sunflowers absorb radioactive waste? Is the Mexican alien real? Dr Chris Smith and Clarence Ford have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

How does colour blindness work? How do we know what other planets are made of? Why might a red dye suddenly disappear? Why don't you feel the velocity of a plane for the whole flight? Do mobile phones in crowded spaces expose us to anything dangerous? What causes testicular torsion? How do you avoid getting rats in your car? Where did humans come from? Dr Chris Smith and Clarence Ford have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

Dr Chris Smith tackles the impressive array of questions from listeners. What gives non Newtonian liquids their special properties? Could wearing socks in bed increase the risk of having a stroke? Do Inuits not experience dental decay? Why can't we remember when we fall asleep? And what makes certain foods traditional breakfast items? Like this podcast? Please help us by supporting the Naked Scientists

Should you drink re-boiled water? How do bees know who to attack? Should we just leave the deep sea alone? Why do some countries drive on the left? What causes fire? Why do we need the toilet as soon as we get home? Why is there a fridge light and not a freezer light? Why does the moon move in the sky? Dr Chris Smith and Clarence Ford have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

How do we fuel cars more sustainably? What causes morning sickness during pregnancy? Why does California have a sunny Christmas? Why are some smells able to summon powerful memories? Why can I hear fluid flowing when I move my neck? Is premature ejaculation nature's way of hastening reproduction? And what's the physics behind why stars twinkle? Dr Chris Smith and Clarence Ford have the answers... Like this podcast? Please help us by supporting the Naked Scientists

What is causing climate change? Does pumping out oil leave a hole behind in the Earth? What does an Adam's apple do? What causes temperature differences from day to day? How does throat singing work? What would happen to Twitter's data if it collapsed? What is the spring tide, and why is it dangerous? Dr Chris Smith and Clarence Ford have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

How do flysprays work, and are they harmful for humans? What's "muscle memory" and where are these memories stored? Why do disinfectants "only" kill 99.9% of germs? How do I cleanse domestic rainwater tanks to kill microbes? How does freefall - as described by orbiting astronauts - work? If I let my pet cobra go, will it survive in the wild? What's the basis of sweating, and why do some people sweat more than others? Dr Chris Smith and CapeTalk's Clarence Ford have the answers... Like this podcast? Please help us by supporting the Naked Scientists

This week,?What makes an appendix burst? Why do we blush??Do carrots really improve our eyesight? What other foods can we eat to regenerate our organs? Can lions survive on seafood? Can studying the arts impact on my health? And why do some flowers only release their scents at night, a how? Dr Chris Smith and Clarence Ford have the answers... Like this podcast? Please help us by supporting the Naked Scientists

What are hiccups and what's the medical term for the phenomenon? How far to the horizon and why does it always appear to be at eye-level? What are lectins and are they harmful? What is pulmonary fibrosis, why does it happen and can it be cured? Why do bright lights make spots on my vision, and why does the colour change when I close my eyes? And as a 65 year old in good health and with 4 Covid-19 vaccines and one mild SARS-CoV-2 infection, do I need another Covid-19 booster?? Like this podcast? Please help us by supporting the Naked Scientists

Why do we always find cockroaches on their back? How does medicine know where it hurts? Why do we dream? Why is the Earth still so hot? What came first, the chicken or the egg? Why did Chernobyl explode? How much energy does a seed need to grow? Can we work out how much energy there is in the world? Why do most of us look different? Chris Smith and Clarence Ford answer questions from the students of the International School of Cape Town... Like this podcast? Please help us by supporting the Naked Scientists

What makes the brain age? Why don't ice skaters get dizzy? Do we have two sets of DNA? Where does all of the burned fuel go? Do dogs get headaches? Why are dogs so good at pattern recognition? Does someone carrying a donor egg provide any of the child's DNA? Would watering your lawn increase the chance of rain? Dr Chris Smith and Amy MacIver have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

Why do we teach kids nursery rhymes? How do we know how anatomically modern humans populated the world? What is cataract surgery, how is cataract surgery performed, and is there an upper age limit? Is most human behaviour innate, or learned? Why does water boiled in a microwave sometimes explode when you add sugar or coffee? Join Dr Chris and TalkRadio 702's Relebogile Mabotja to find out... Like this podcast? Please help us by supporting the Naked Scientists

Does flash photography harm baby's eyesight? What is ocular myasthenia gravis? Can having a disease give you an advantage against another disease? Why are soldiers so prone to PTSD? Why is it so difficult to predict the weather? What does it mean to be double-jointed? Are we susceptible to certain rhythms? Why is water so important? Like this podcast? Please help us by supporting the Naked Scientists

Is carbonated water better for you than still water? Why are some dogs scared of fireworks, and being touched? Is there a cure for tinnitus? Do energy drinks actually give you energy? Why does the second cup of tea never taste as good as the first? What is electronic data? What is a melanoma? Dr Chris Smith and Clarence Ford have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

Chris answers an eclectic crop of science questions including: why do we appear to have superhuman strength in high stress situations? Are science and religion at odds with one another? What's the cause of grid outages and blackouts? Will identical twins die of the same illness/disease? Why are manufactured goods so prone to breaking despite technological advancements? Are coal mines on the verge of becoming obsolete? Why do we hold our heads in exasperation? Like this podcast? Please help us by supporting the Naked Scientists

What role do cockroaches play in our ecosystem? What would happen if all of Earth's gases combined? Why is the universe expanding? What is the most flammable gas? Why does the Earth look flat from the ground? How does the brain co-ordinate the body? How were the pyramids built so long ago? What happens to our body during a heart attack? In this 'Classroom Edition' of Ask The Naked Scientists, Dr Chris Smith and are answering the questions set by pupils at John Graham Primary School... Like this podcast? Please help us by supporting the Naked Scientists

When is the next comet? What is past the milky way? Which animals have been sent into space? Did the moon come before the Earth? What lifts up the moon? What are all the dents in the moon? How did the moon form? How do we know how old the Earth is? Why are Neptune and Uranus blue? Why is the sun the only star we can see in the daytime? How fast do you need to go to escape a black hole? Is there other life in the universe? In this 'Classroom Edition' of Ask The Naked Scientists, Dr Chris Smith, Clarence Ford are answering the questions set by pupils at Parow East Primary School... Like this podcast? Please help us by supporting the Naked Scientists

Why is nearly everyone right handed? How do genetically modified crops work? Why do some animals bob their head as they walk? How did stem cells restore people's sight? Why are people so hesitant to use CRISPR? How big are Qatar's air conditioners? Why doesn't honey go off? Dr Chris Smith and Clarence Ford have all the answers... Like this podcast? Please help us by supporting the Naked Scientists

Neanderthal genetics and what DNA can tell us about ancient societies, no evidence for telekinesis, whether low blood pressure is a bad thing, the reason why humans cry, human DNA diversity in Africa and beyond. Also, do I get drunk quicker after "Sober October", can a team of cyclists solve the energy crisis, is Earth gaining or losing mass, will nature eventually deal with invasive species, and are electric cars a good thing? Dr Chris and Clarence Ford have the answers... Like this podcast? Please help us by supporting the Naked Scientists

Why are bad habits so hard to drop? Are we in a new industrial revolution? Why don't islands have snakes? How do drugs know where to go? Would fireworks work on Mars? Which foods cause inflammation? Why can't we harness power from. The Earth's magnetic field? How does sepsis get into the body? Should you avoid steroids? Do masks affect learning development in children? Dr Chris and Clarence Ford have the answers... Like this podcast? Please help us by supporting the Naked Scientists

Why is Pluto not considered a planet anymore? What is the possibility of there being more than one universe? Why do birds not get electrocuted when they stand on electrical wires? Is the universe finite or infinite? If it is finite, what is it expanding into? What is the actual measurement of a lightyear? How do meteors form? Why do birds fly in formation? Like this podcast? Please help us by supporting the Naked Scientists

What's the difference between mist and fog? Would 1 kilometre on our orbit make the difference between life and death on Earth? How do washing powders get clothes clean? How does sunlight and seawater lighten hair? How deafening was the Big Bang? Will rainwater wash clothes better than tapwater? Why does water issuing from a tap when you first turn it on, look white with tiny bubbles? Why doesn't Super Glue go hard in the tube? Are gravitational waves audible? Like this podcast? Please help us by supporting the Naked Scientists

Could we slow down light to see backwards in time? Why does the moon appear not to rotate? Why don't some melting icebergs lead to sea level rise? What are the problems with Newtonian physics? Do acupuncture and fish therapy work? Are supplements a scam? How did our solar system form? Does light therapy work? Lester Kiewit and Dr Chris have the answers... Like this podcast? Please help us by supporting the Naked Scientists

How do we know that white light contains every colour? Why does time only move forward? Why aren't birds electrocuted by power lines? How do aeroplanes manage to stay airbourne? Why can't different species reproduce? How do X-Rays work? Why do antibiotics work against bacteria, but not viruses? Lester Kiewit and Dr Chris have the answers... Like this podcast? Please help us by supporting the Naked Scientists

Can the James Webb telescope see the origins of the Universe? Does freezing your jeans remove stains and preserve the colour? What are the effects of tumours in the adrenal glands? How many people have ever lived on Earth? Does a drink stop a cramp? Will the James Webb Telescope unlock new physics for us? Why is AM frequency affected by power lines? Lester Kiewit and Dr Chris have the answers... Like this podcast? Please help us by supporting the Naked Scientists

Consumption of energy in the brain; the role of my adam's apple; seed anatomy; why there are so many planets; body components that suck oxygen from the air; NASA predicts the number of stars in our universe; why do flowers bloom in spring; measuring the milky way; the chemical properties of bromine; pursuing the origns of life; if the moon isn't cheese, what is it made of? Dr Chris Smith joins 567 Cape Talk's Lester Kiewit to talk the answers through... Like this podcast? Please help us by supporting the Naked Scientists

Soap on the bathroom mirror with a hot shower running; sedatives acting unusually; coffee reduces tiredness but also provides a lick of energy; does a glass of sherry warm you up on a cold night; how do you contract shingles; asian flush; water density experiment for you to try at home; is the conflict in Ukraine speeding up climate change. Dr Chris Smith joins 567 Cape Talk's Lester Kiewit to talk the answers through... Like this podcast? Please help us by supporting the Naked Scientists

The Platinum Jubilee; aerodynamics and physics of tailgating vehicles; why planets and the moon are all in the same orbital plane; how ants lead their nest-mates to a food source; animal extinction; how light can reveal what something is made of; do transplant recipients inherit genetic diseases from their donors; and would someone with an arm transplant leave a different DNA fingerprint with their new hand? Dr Chris Smith joins 567 Cape Talk's Lester Kiewit to talk the answers through... Like this podcast? Please help us by supporting the Naked Scientists

What are stars made of? How do ants breathe? How does a person catch chickenpox? Why are sunsets and sunrises red? What are planets made of? How many bones in a human body? How do Earthquakes occur? IF the Earth's round, why don't we fall off? Why doesn't sand dissolve? How does a bird fly? This week Lester and Dr Chris are with the kids at the AKA snapshot study group to find out what they want to know... Like this podcast? Please help us by supporting the Naked Scientists

Shortages of cooking oil, risks of being hit by lightning and can lightning travel through your plumbing; why boats have round portholes; what's the memory capacity of a human brain; can we measure happiness; do animals feel happy and sad like we do; what gives farts their unique characteristics, and why do stars twinkle? Lester and Dr Chris have the answers... Like this podcast? Please help us by supporting the Naked Scientists

Why do some animals sleep standing up? And do fish sleep? Why are elderly voices higher pitched than younger voices? Why does the outside temperature drop just before the sunrise? Why do I feel pain in my ears during a plane takeoff, and why does chewing gum help? Do cats and dogs recognise their siblings? Why is yawning contagious? Do dogs get depressed? And why doesn't our own snoring wake us up? Dr Chris and Abongile Nzelenzele have the answers... Like this podcast? Please help us by supporting the Naked Scientists

Can trees produce more than 1 type of fruit? Why do some flowers only have a scent at night? What makes fruit taste sweet? How does the Google search engine work? How do motorcycle tyres grip the road? How are some children geniuses? What is myasthenia gravis? What's the difference between a sickness, a disease, an illness, an affliction, a malaise and a disorder? How does reverse swing work on a cricket ball? And how do tides work? Dr Chris Smith and Lester Kiewit have the answers... Like this podcast? Please help us by supporting the Naked Scientists

Why are humans still born with bits we don't need - will evolution do away with them? Did an onion make me cry less because it was cold from the fridge? Do animals get diabetes like humans do? What is the physics of a rainbow? Where does lightning come from? What did cloning Dolly the Sheep mean for me? And is Covid-19 nature redressing the balance? Dr Chris Smith and Relebogile Mabotja have the answers... Like this podcast? Please help us by supporting the Naked Scientists

Nominative determinism; can cold showers ward off coughs and flu; what's von Willebrand's Disease; if smoking causes cancer how does it cure salmon; why can some people roll their tongues; what's "Agent Orange"; in television, how does a green screen work; do crocodiles age more slowly than we do; what is Helicobacter pylori? Chris and Lester have the answers... Like this podcast? Please help us by supporting the Naked Scientists

Is it better to keep the tank topped up to full, or should I drive around on half empty: what's better for my car and fuel consumption? Why might althletes take an ice bath after exercise? If I go out with wet hair, will I really catch a cold, or is that a myth? Do babies sleep better in a cooler room? What's the difference between an electrical blackout and a brownout? Is the expensive face cream better than the cheaper one? Lester Kiewit and Dr Chris have the answers... Like this podcast? Please help us by supporting the Naked Scientists

What happens, genetically, when a black and a white human partner have children? And if a pair of genetically identical twins marries another pair of identical twins, are their kids genetically brothers and sisters? Do birds have ears? And if you lose one of your special senses, do other senses strengthen to compensate? What's the reason for human handedness? And does a blood transfusion recipient carry the genes of the blood donor? Dr Chris has the answers... Like this podcast? Please help us by supporting the Naked Scientists

Why does my kiddie object to wearing shoes? What is spacetime and how does time dilation work? What is entanglement, otherwise known as spooky action at a distance? Are my feet ageing faster than my head? When a person dies, does their energy pass into their offspring? How does hyperloop technology work? Relebogile Mabotja and Dr Chris Smith have the answers... Like this podcast? Please help us by supporting the Naked Scientists

How does the James Webb Space Telescope work, and what will it reveal to us? How do spring and neap tides work, and what determines the times of tides? What causes hot flushes and night sweats? And why park the James Webb Space Telescope out in space - why not on the dark side of the moon? Lester Kiewit and Dr Chris Smith are back in action! Like this podcast? Please help us by supporting the Naked Scientists

Why cockroaches invariably are found dead on their backs; what happens to old and previous Covid-19 variants; why do I see myself differently in photographs compared with when I look in the mirror; how do chickens produce eggs; what powers deep space probes; why do some people snore, especially after a few drinks; and why is yawning contagious? Dr Chris Smith and Lester Kiewit have the solutions! Like this podcast? Please help us by supporting the Naked Scientists

Why, after a dose of Covid-19, am I left with a new taste sensation resembling rotten onions? Why does bleached hair look blond, not white, and does salt water decolour the hair of surfers? How do I get rid of unwanted facial hair? Why is the hole my dog digs bigger than the dirt or sand that came out of it!? Why do mosquitoes prefer me to my wife? Does lighting a match do away with the smell of poo? Dr Chris and Lester Kiewit have the answers... Like this podcast? Please help us by supporting the Naked Scientists

What boils fastest, a glass or plastic kettle? Do animals adapt to their surroundings? Why do I feel sleepy when I take a trip to the coast? What's an itch? Why can I hear my husband snoring, but not me doing it myself? Can we artificially insert memories into the brain? Why do the colour of the sea vary in different locations? Why is entropy not a force? What is in it for a virus? Like this podcast? Please help us by supporting the Naked Scientists

This week, what's the bottom line on sanitising surfaces against Covid-19? Why, wonders Lester, am I so sluggish for the first few hours of the day? And can you train your chronotype to be a better morning person? Does it make a difference if you sleep on your left or your right? Why is gambling addictive and is addiction a genetic trait? Can pornography be addictive? And will resorting to apps like Google Maps impact my sense of direction? Join Dr Chris Smith and Lester Kiewit for the answers... Like this podcast? Please help us by supporting the Naked Scientists

The chemistry of fireworks, can I safely eat one year old Christmas cake, why we don't fall out of bed at night, what the Universe is expanding into, the reason we have to remove laptops from bags at airports, why the spinal cord won't spontanteously regenerate, sleep apps, and the science of forgetfulness all go under Lester and Dr Chris's microscope for analysis this week! Like this podcast? Please help us by supporting the Naked Scientists

This week we join young learners at Christel House school who ask us about the duration of immunity to Covid-19 post-vaccine and post-infection. Also, menstrual synchrony and whether it's fact or fiction, craniofacial abnormalities and the developing baby, the threat humans face from Artificial Intelligence (AI), why we're conscious and why we sleep. Dr Chris Smith and Lester Kiewit have the answers... Like this podcast? Please help us by supporting the Naked Scientists

What gases are present in lava? What happens when hot magma meets cold water in the sea? How different is an animal's brain to my own? How much of my intelligence is down to genes, and how much is the environment in which I grew up? Do photons weigh anything? Is there a cancer pandemic? And will a spoon in the neck of the bottle keep champagne fizzy? Dr Chris and Lester Kiewit tackle your burning questions... Like this podcast? Please help us by supporting the Naked Scientists

This week, James Croll and Mulitun Milankovic's contributions to planetary climate cycles; what it takes to knock a planet off-axis; where do clouds falling off Table Mountain go; does a discharged battery weigh less than a charged battery; the cheese reaction and bad dreams; why some foods go through undigested; why are planets round; birds recognising their own flocks; Captain Kirk heads to space; is a bad smell potentially infectious? Lester Kiewit and Dr Chris have the answers... Like this podcast? Please help us by supporting the Naked Scientists

This week, where Vitamin D comes from, if lab-grown protein is vegan-friendly, how mammals evolved to dive deep underwater, how genes can be used to track evolution, how chillies create a burning sensation in the mouth, whether feet change shape as we age, what makes a battery rechargeable, and why tropical seas tend to be blue and clear. Dr Chris Smith and Lester Kiewit have the answers... Like this podcast? Please help us by supporting the Naked Scientists

This week it's time to join another local school to answer their burning science questions including can we bring back extinct species from the dead; is the Universe infinite; can we replace cells and tissues in the body; will science solve Alzheimer's Disease; are humans getting taller; how do viruses like Covid-19 evolve and change; why do black holes matter; and, an easy one to finish on: what's consciousness!? Like this podcast? Please help us by supporting the Naked Scientists

What causes r-rolling difficulties otherwise known as rhotacism? Also, why do we have to stay still in an MRI scanner, why is calcium a metal, what makes water hard and how does a water softener work, what is the impact of a caesarian birth on health and why, what's the reason dementia affects short but not long term memory, and how does gravity work? Join Lester and Dr Chris for the answers to this week's crop of questions... Like this podcast? Please help us by supporting the Naked Scientists

This week we ask whether we're about to start spoiling other planets with our space forays, if there is antimatter in the human body, what causes cluster headaches, whether microwaving can ripen avocado, what causes long-sight, how atomic clocks operate, the basis of entropy and thermodynamics, why heat wipes out a magnet, and whether cleaning surfaces is a good idea for combating Covid-19... Like this podcast? Please help us by supporting the Naked Scientists

Is there such a thing as a true circle? Can two light rays collide with one another? What makes the sky look blue? Have aliens ever visited Earth? Will time travel ever be possible? What's the perfect pH for seed germination? Would a truck full of birds weigh less if all the birds took off? What's at the bottom of a black hole? Why is poo brown despite the fact we all eat different foods? This week the questions for Dr Chris come from the kids at Gaia Waldorf School, and they're very hard! Like this podcast? Please help us by supporting the Naked Scientists

Why do I shiver when I wee? How does carbon dating work? What can I not tickle myself - is that similar to why I mind my own farts less than someone else's? Does breath-holding block tickle sensations? How does "the cloud" work in computing? Why are sunsets red, and what is the green flash? Why would a telegraph pole by the road vibrate of its own accord? Dr Chris and Lester have the solutions! Like this podcast? Please help us by supporting the Naked Scientists

Can you be allergic to one part of an animal but not another? What's the point of dreaming? What happened before the Big Bang? What's in wine that causes hangovers, and is this an allergic reaction? Are we seeing into the past when we detect light from far away in space? Why does driving through a long tunnel or across a bridge make me feel giddy? Lester and Dr Chris make your head spin with the answers! Like this podcast? Please help us by supporting the Naked Scientists

How do African animals withstand extreme cold in the Kalahari? Does the data we're all generating and storing weigh anything? How does relativity relate to the real world? Why do we run Olympic races in the direction we do? Is the ozone hole disappearing now? Were left handers less able to defend themselves back in history? Is a germinating seed making new matter? And will volcanoes eventually empty the Earth of magma? Lester and Chris have the answers... Like this podcast? Please help us by supporting the Naked Scientists

Why do some forms of heater seem to warm a room up faster? What's the different between Alzheimer's Disease and dementia? Are aluminium cooking utensils a risk factor for Alzheimer's? Can magic mushrooms control dementia, or other mood disorders? How do we know what's inside the Earth, and did we collide with another planet during Earth's past? Are microwaves a risk for cancer? Is there a limit to human Olympic performance? Like this podcast? Please help us by supporting the Naked Scientists

In this week's show, recorded before the Euro 2021 final, Dr Chris explains why Inuits survive on polar fare with impunity but Shackleton's crew developed nutritional deficiency when they were stuck in the Antarctic. Also, why laser beams are bad for goalkeepers, if energy drinks are dangerous, why squinting sharpens vision, if there humans with better senses than average, and what is meant by the percentage chance of rain? Like this podcast? Please help us by supporting the Naked Scientists