It’s good to be writing again! I took an accidental sabbatical after Pokémon X and Y entered my life in the new year and found it required excessive amounts of playing before I was sated. So I’m back with some (hopefully) solid ideas in mind, but for now I thought I’d ease us in with some quick-fire science questions, each answered in 150 words or less.
1) Why do pigeons do the head-bobbing thing when they walk?
The movements of a pigeon walking along follows a two-stage cycle: 1) the head quickly thrusts forward and 2) the head remains stationary relative to the surroundings as the body continues to walk underneath it, giving the illusion of a slow backwards motion.
A static head interspersed with rapid movements is much better for scanning for slow prowling of cats and foxes than a constantly moving head. We actually have a similar trick – when our eyes shift from one direction to another, we become temporarily blind to prevent motion blur. This is why you’ll never see your own eyes move in a mirror. Source.
2) What colour is a mirror?
Despite being whatever colour is being reflected into your eye at any given moment, a mirror is also very slightly green. A perfect mirror would 100% reflect all light that hit it and not absorb any. However studying the spectrum of absorbance shows that real mirrors do absorb tiny amounts of the light which hits them, but the colour which is absorbed the least is green. This can actually be seen pretty easily using a mirror tunnel. Just by putting two mirrors parallel to each other creating a tunnel of light bouncing back and forth “forever”, you see how before it disappears completely, the distinctly green tinge can be seen. Source.
3) Why do chillies feel hot?
Chillies contain a molecule called capsaicin (pronounced like an upturning boat) which bind to and activate a receptor called TRPV1 on pain-detecting nerves whose normal job it is to send a message to the brain telling you that your mouth may well be on fire, or least very hot. In response, blood vessels in your face dilate, turning you bright red and you start sweating loads to reduce the “heat”. You also receive a pain signal asking you not to try anything like that again, please. Capsaicin is not soluble in water so downing a glass won’t help much, but it is lipid soluble, so yoghurt or milk make the effect ease off pretty quickly. Source.
4) Why do spiders’ legs curl up tight when they die?
Our limb muscles come in antagonistic pairs of flexors and extensors – bicep contraction moves your forearm up, tricep contraction brings it down again. Spiders do it rather differently – they have flexors capable to pulling their legs down and in towards them, but no extensors. Moving the leg up and out again instead requires controlled hydraulic pressure using fluid from their bloodstream.
When a spider dies, the fluid settles and the legs naturally reset to the most tightly curled up position. Once rigor mortis of the flexor muscles sets in, the eerie effect gets locked into place, no matter how the spider is oriented. Source.
5) Why hasn’t the asteroid belt formed a planet?
4.6 billion years ago, clouds of gas and dust surrounding our new sun began colliding and aggregating into the planets we are familiar with today – all except a belt of small rocks between Mars and Jupiter that never managed to form a planet of their own.
The rocks in this region were prevented from naturally convalescing by the overbearing mass of Jupiter. The huge gravitational influence of the gas giant perturbed them so much that they’d smash together and shatter rather than gently clumping together.
Furthermore, there are certain regions which resonate with Jupiter’s gravity, giving them so much extra energy that they get flung out of the main belt forever. 99.9% of the original mass of the asteroid belt was quickly lost this way so that there’s now only enough matter to fill a small fraction of our Moon, let alone create a planet. Source.
6) Why is steak red and chicken breast white?
Steak is a slab of cow muscle which in life required a steady supply of oxygen over long periods of time. This requirement called for high concentrations of myoglobin, an oxygen-binding protein with a strong red colour. When you place the steak on a hot pan, the myoglobin structure falls apart and loses its oxygen – changing from red to brown in appearance.
Chicken breast muscles are used only for flight (or “flight”) and their oxygen consumption is brief and occasional, but urgent. Myoglobin can’t deliver the oxygen quick enough in this case, so it’s present only in very small quantities, giving raw chicken a glassy pink appearance instead. Source.
7) Why do metals feel colder than plastic or wood at room temperature?
Our bodies are pretty rubbish at detecting absolute temperatures, capable only of making comparisons in the form of “is this thing hotter or colder than the last thing I touched?”.
If you hold a metal object and a wood object at the same time, your body is likely to insist that the metal feels colder although a thermometer will tell you they are objectively the same temperature. The metal is a good heat conductor and will carry the heat away from your warm hand much more efficiently. Your body interprets this as cold. The wood is a heat insulator so the part of the wood you are touching will soon warm up to the same temperature of your hand, and the “cold” sensation is never felt. The difference in thermal conduction is also why wooden spoons are highly recommended over metal ones when cooking! Source.
8) How deep have we dug into Earth and why haven’t we gone further?
The furthest into the Earth we’ve ever gone is all of 12.262 km or 7.62 miles, courtesy of the Kola Superdeep Borehole in Russia. This took us down a third of the way through the crust to the mantle – the primary goal of scientific drilling.
The main issue is lack of funding; a mission to drill down under the ocean floor where the crust is much thinner was cancelled for this very reason. So we have the odd scenario where we have an active probe going strong and communicating with us from 19 billion km away but travelling even a half-marathon’s distance downwards is too much for us. It seems space and the near-infinite scope of unknowns captures most people’s imaginations a lot more than geology which really affects the cashflow. Source.
9) Why does chopping onions make me cry?
Because you’re weak. But also because of an enzyme called LFS or lacrymatory-factor synthase – which can be translated as “enzyme which makes a thing that makes you cry”. LFS converts naturally occurring and harmless sulphated amino acids into a rather nasty irritant, but it’s normally tucked up safely in special cell compartments. Chopping up the onion breaks open the cells and releases particles containing LFS into the surroundings. Enzymes work slower when chilled which is why keeping onions in the fridge can help prevent the tears and LFS is destroyed completely by sufficient heat which is why you stop crying once the onion is cooked. Source.
10) Why do men have nipples?
Because women are the default sex. A new human embryo begins laying down its body plans under the assumption that it will be a female. Only once the Y chromosome is activated later in development do the deviations needed to create a male body plan take place. The only changes that were naturally selected for are those that gave men an advantage in health or reproductive success – everything else stays the same by default. Clearly reproductive organs fall into the first category, but nipples in men remain perfectly benign. So there was simply no reason for them to be weeded out by natural selection, and they remain the unmagnificent chest decorations in menfolk across the world. Source.
Got any science questions you want me to try and answer in 150 words or less? Let me know!