The atmosphere applies a pressure of about 100 000 N to every square metre on Earth’s surface. We take this pressure for granted because we have the same amount of pressure pushing out. But what happens when the pressure of the atmosphere is applied to an object with no outward pressure? It implodes. In spectacular fashion.

Scientific research has shown that heterosexual males and females find members of the opposite sex more attractive when they wear the colour red. This is a subconscious preference that seems to have some evolutionary basis. We attempted to replicate these findings in Sydney but our methods were much less controlled and the results achieved were not statistically significant.

Scientists have recently discovered nanodiamonds in the flames of ordinary candles. They are produced at a rate of about 1.5 million per second. Unfortunately they are also burned up at this rate and released into the atmosphere as carbon dioxide. Still this finding may prove useful in the ongoing search for economical ways to produce diamonds.

When pressure is applied to ice, its melting point is reduced so it turns to water. When the pressure is removed, however, it turns back into ice. This process is called ‘regelation.’ Big thanks to Art of Ice Sculptures http://www.icesculpture.com.au who donated the beautiful block of ice.

In Sydney, ice melts because it is warm out in the middle of the day (even in winter). This creates a layer of water on top that certainly makes it slippery. But should it be slippery at night or in a cold northern climate where the air temperature is below zero? Yes, because the pressure your skates apply to the ice actually lowers its melting point allowing you to glide along a thin layer of water.

Animation in this video is courtesy of VisChem (TM), Copyright 1995, Roy Tasker

For a more complete picture of the mechanisms involved in making ice slippery, check out this great article: http://lptms.u-psud.fr/membres/trizac/Ens/L3FIP/Ice.pdf

One of the most common physics misconceptions is that an unbalanced force causes constant motion. In truth, an unbalanced force leads to changes in motion – accelerations.

The Earth spins on its axis, completing a full revolution every day. By why does it do this? One of the most common misconceptions in physics is the belief that constant motion requires a constant force. So many people believe there must be some force in the Earth (e.g. gravity, centrifugal force) that keeps it spinning. In truth, no force is required because a fundamental property of mass is that it maintains its state of motion in the absence of external forces. This property is called inertia.

Everything is not as it first appears. This simple plastic ball looks purple until you swing it in a circle and reveal its true nature. Inside are three light emitting diodes (LEDs), which are red, green and blue. They turn on and off in sequence very quickly. When still, the ball appears purple because your eyes and brain don’t ‘refresh’ quickly enough to perceive the changing colours. However, when swung in a circle, the ball changes colours at different locations so the colours don’t merge with each other and the ball’s true nature is revealed. Now let’s not think too carefully about how this illusion is conveyed through video (because the camera doesn’t refresh quickly enough to perceive the colours changing either – so you have no hope of seeing it on YouTube even frame by frame).

One might wonder, if exercise takes energy, why haven’t people evolved to no longer need exercise? My theory is that it’s because exercise has always been there and it was potentially useful. The energy was spent anyway, and since it was a constant, the body found uses for it, rather than evolving new mechanisms to accomplish all the things that exercise does for us.

I like the analogy of an ancient, thousand year old city with a river running though it. Over time, the inhabitants would develop many uses for the river and come to depend on it. They might wash themselves, their clothes, transport goods, catch fish, irrigate, siphon water energy and so many other things from that river.

Now, imagine that river suddenly dries up. The city would be in very bad shape as they are not adapted to the absence of the river. The city may dwindle as people die and migrate, though over some long period of time, the remaining inhabitants may adapt to new practices to thrive without the benefits of the river.

I think exercise with humans is much like this. Exercise has always been there, but has suddenly (rather abrupt, relative to the long evolutionary timeline) stopped, and therefore all those physiological and mental mechanisms that had made use of exercise are now suffering.

Will humans ever evolve to need less exercise? Perhaps. I would guess that some of that has happened already – that some individuals are healthier despite lack of exercise whereas others need more. I also suspect there could be more people tolerant of lack of sleep, slavery, clothing and other characteristics of civilization than existed in the stone age.

However, when you talk about any kind of human evolution, the evolutionary game has gotten very strange and complex with governmental, medical, societal changes and complexities that have arisen over the last century. The genes that perpetuate the most now may be way different than did as recent as the late 1800’s. Evolution is now so subject to ever-changing societal intervention that it blows the conventional Darwinian stereotypes of “survival of the fittest” out of the water, as “poorly fit” individuals are medically, culturally or governmentally enabled to reproduced at greater rates than they would have ever in human history.

When we touch something that is hot or cold, what are we actually sensing? Is it the temperature of the object, or the rate at which heat flows between the object and our hand?