Know It All

He's got an answer for everything, week 5

What’s the probability of winning a tenner on the National Lottery? - Sik, Gills
You’ve got a 1 in 56.6 chance of winning £10 in the main Lotto draw. If you played every week from July 2010, you should have won £10 by September 2011. You’ll have spent £57 for the privilege, so will be £47 out of pocket. Of the money you spent, £6.84 will go to the government, as the lottery is the only form of gambling that’s still taxed, and £15.96 will go to good causes. 

How does science explain deja vu? - Emma, Alum Chine
Didn’t I answer this last week? No? Ok. Deja vu is a miscommunication in your brain. Your current experience should be stored as a short-term memory, but is wrongly stored as a long-term memory. This then makes you think it also happened at some unspecified time in the past. Deja vu is always vague rather than specific. It’s “I think this happened before”, rather than “I know this happened before, on 5 Jan 2002”. Such vague feelings explain why people wrongly believe they’re psychic. They have deja vu, then have a flawed memory that they’ve experienced, imagined or dreamt the situation happening before. As always, the scientific explanation is infinitely more fascinating than the pseudoscientific construction. Deja vu is a minor flaw in the way our brains work that has affected 70% of people. It opens up questions about our perception of reality, whether our misunderstood memories affect our understanding of the world, and whether this fuels what we think of and how we interact with other people. These deep philosophical questions are much more exciting than star signs. Unless you’re a Virgo, of course.

Why when walking home do you become increasingly desperate for the toilet the closer you get to your front door? - Eli, Hull
It’s quite simple really: the longer it takes you to get home, the more time urine has had to work its way through your system. When your need to wee weighs heavy on your mind, it’s also going to weigh heavy on your bladder. Think of anything except waterfalls. When your front door is in sight, you can also subconsciously relax, making your ultimate release feel closer. However, these two minor psychological factors are nothing compared to the fact that your bladder is simply filling up more and more. When you finally let it all gush out, it might feel like the final scenes of Indiana Jones and the Temple of Doom, with the great wave of water shooting through the tunnels, but it’s a mere drop in the ocean. Speaking of which, if everyone in the world peed in the ocean at once, the sea level would only rise 4.98 nanometres. Urea (the waste product present in urine) is also excreted by sweating, so it’s a myth that swimming pools have a colour-changing chemical in them to detect urine. Probably best not to put that to the test if you’re on the top diving board.


What gun fires bullets the furthest? How far do bullets go before they start dropping? What level of wind does it take to deviate a bullet? - Roy, Hove
A McMillan Tac-50 sniper rifle, as fired by Canada’s Corporal Rob Furlong, killed someone from a record 2.43km (1.51 miles) away, in Afghanistan in 2002. The stated maximum effective range of the Tac-50 is 2km, beyond which its accuracy can’t be depended upon. At about 3.5km, the bullets drop below fatal velocity, and after about 7km they’ll come to a stop altogether. Gravity acts upon bullets the instant they leave the gun and all wind speeds will alter the bullet’s course, albeit imperceptibly at low levels. At a range of 350m, a 32km (20mph) crosswind will move a bullet about 40cm (16in). The greater the range, the slower the bullet, so the greater the deviation. If all that sounds impressive, it’s nothing compared to the railguns that the US Navy are working on: they’ll be able to hit a 5m target from 370km (230 miles) away. If those pesky buildings, trees and hills weren’t in the way, you could shoot someone in Durham whilst sat in London. Hopefully by the time the technology is perfected in 2025, we’ll have finally realised that war is not the answer.

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