Snworld

Why aren’t our Solar System’s planets and moons made from the same material? the solar system formed from the collapse of a molecular cloud consisting mostly of hydrogen, but also containing heavier elements. As the cloud collapsed, its central region began to heat up until eventually the hot ‘proto-sun’ was formed. the planets formed by the accretion of material from within this cloud. due to their high boiling points, only metals and silicates could exist in solid form in the hot, inner regions of the early solar system. More volatile elements either remained gaseous or were blown away by the sun’s energy. since this heavy material existed mainly in the inner regions of the solar system, the planets that formed there are small and rocky. in the cold outer reaches of the solar system, compounds with low melting points could remain in solid form. these ices were also much more abundant than the heavier elements. the outer planets were therefore able to grow much larger, and he...

Why do we go red in the face when embarrassed? Humans seem to be the only animals to show embarrassment, and Charles darwin called blushing “the most peculiar and most human of all expressions”. A 2009 study by dutch psychologists found that we are more likely to give people a second chance if they blush when they betray us. the ability to blush acts as a signal that you are sensitive to the social rule you have just broken. Psychopaths, on the other hand, do not blush at all.

Could direct air capture prevent climate change ? direct air capture (dAC) is an appealing way to tackle climate change: just pass ambient air over chemicals that absorb the Co2 driving global warming, and then use or store the Co2. dAC differs from the better-known carbon capture and storage (CCs) in that it can be done anywhere, not just at big sources of Co2 such as power stations. it’s more effective than natural Co2 ‘scrubbing’ using trees and plants, and can be performed where the Co2 is most easily stored or re-used. unlike CCs at power stations, dAC must be effective at removing the far more dilute Co2 in ambient air. this demands special equipment and chemicals, plus renewable energy sources producing zero Co2. that has led to grave doubts about the economic viability of dAC. For now, it remains an intriguing but impractical remedy for global warming. 

How do we know when something is wet?  our skin contains lots of nerve endings that respond to different stimuli. there are receptors for touch, vibration, heat, cold and pain – but not for wetness. water is such a ubiquitous component of all living cells that it would be difficult for a nerve cell to avoid firing constantly in response to its own composition. instead, wetness seems to be a property that our nervous system learns to recognise, based on a mixture of cold, pressure and texture. A 2014 study at Loughborough university found that hairy skin is more sensitive to wetness than smooth skin, which may be because hairy skin has more temperature sensitive nerve endings. when you are born, you don’t feel wet or dry, you just feel cold or warm. over time we learn that the feeling of cold cloth sticking to our skin means that we’ve sat on a wet park bench.

Why do different countries use different mains voltages? the biggest disparity is between the usA on 110V and most of the rest of the world on 230V. America’s lower voltage goes all the way back to thomas edison, who introduced direct current (dC) mains electricity at 110V. edison’s rival nikola tesla showed that long power lines transmitted alternating current (AC) more efficiently than dC. His AC approach won out, but he stuck with edison’s 110V. But by the time electrification spread to europe early in the 20th Century, lamps had filaments that could give out more light and handle greater power loads. so the Berliner elektrizitätswerke company in Germany established 230V as the standard. 

Why do snakes have slits for pupils? Vertical pupils are an adaptation for ambush hunting. A 2010 study at sydney university found that of 127 Australian snake species, the ones that ambushed their prey by night had vertical pupils, while those that actively chased down prey in the day had round pupils. the constriction of round pupils helps distant prey stay in focus, but it also lets in less light. Vertical pupils improve vision across a wider range of light levels, and enable the animal to detect horizontal movement more effectively. it’s also possible that vertical pupils are more camouflaged, since they break up the round outline of the eye

Why does it feel good to scratch? studies using funCtionAL magnetic resonance imaging (fMri) have shown that scratching causes patterns of brain activity that are associated with pleasure and reward. this effect is strongest when you do the scratching yourself and when you are actually scratching an itch, rather than just an arbitrary patch of skin. But contrary to what you might expect, or might have read elsewhere, there’s no clear evidence that this pleasure comes from a release of endorphins – it happens purely in your brain and spine. this mechanism may have evolved to encourage us to dislodge skin parasites. All the evidence suggests that it’s a very ancient response, because all vertebrates scratch themselves – even fish! 

Is it best to charge your mobile battery from empty or half-full? nickel-based batteries were blighted by the ‘memory effect’, and would lose capacity unless regularly discharged completely. Most phones nowadays have lithium batteries, and these do not suffer from the memory effect. in fact, it is good for them if you top the batteries up rather than deplete them completely. therefore, it’s best to charge your phone from half-full. 

Can germs survive on a bar of soap? Yes. when you wash your hands, you  transfer a thin film of bacteria, skin flakes and oils to the bar of soap. A 2006 study of 32 dental clinics found bacteria growing on the soap in all of them – after all, standard soap doesn’t kill bacteria, it just dislodges them. A 1988 study found that washing your hands with a dirty bar of soap doesn’t transfer any of the germs onto your hands – but then the study was conducted by a us soap manufacturer.