QandA

Q&A Tabs

Phlegm is the mucous secretion of the respiratory passages. The cilia cells that line these passages are continually driving the phlegm upward to the throat, where it triggers the swallow reflex...

Lobsters and other shellfish have harmful bacteria naturally present in their flesh. Once the lobster is dead, these bacteria can rapidly multiply and release toxins that may not be destroyed by...

While a coin toss is regarded as random, it spins in a predictable way. In 2008, a team from the Technical University of Łódź, Poland, analysed the mechanics of a coin tumbling in the air. The...

Mammals remove excess nitrogen from their bodies by converting it to a dilute solution of urea, stored in the bladder. Birds convert nitrogen to uric acid instead: this is metabolically more...

It depends on how high (or low) you set the bar of fluency. Ziad Fazah, born in Liberia, brought up in Beirut and now living in Brazil, claims to be the world's greatest living polyglot, with...

All female mammals have a clitoris, the sole purpose of which is to react to sexual stimulation, and presumably this stimulation has evolved to be pleasurable for most species. But establishing...

To create a sound, we have to set matter - whether it's a gas like air, a liquid or even a solid material - in regular motion, creating a wave of specific frequencies, which we hear as a sound of...

Mirrors don’t reverse left and right either – that’s just our interpretation of what happens. Your reflection in the mirror is actually reversed front to back – if you have...

Discovered by an American student named Gary Flandro in the mid-1960s, the slingshot manoeuvre usually involves spacecraft briefly 'coat-tailing' a planet orbiting the Sun, extracting some of the...

The ice disappears because the wind blows away water molecules that have evaporated or 'sublimed' from the ice, so the ice slowly shrinks in size. The molecules that escape are those with the...

Recent Q&A...

While a coin toss is regarded as random, it spins in a predictable way. In 2008, a team from the Technical University of Łódź, Poland, analysed the mechanics of a coin tumbling in the air. The...

Probably a bit like giraffes. We can’t be sure because reproductive organs don’t fossilise, and no fossils of dinosaurs caught in the act have ever been found. We don’t even know...

It is not entirely clear why Saturn possesses rings. Astronomers have developed three theories of their formation. They could have formed from material left over from the formation of the planet...

They may wish to fit in by imitating others, feel constrained by being observed, become excited by the noise and actions of the crowd, or may respond to local conditions and culture.

An odd...

Lots of insects hide in burrows and only emerge at night, or use camouflage to avoid detection. But, more than any other group of animals, insects are also masters of the opposite strategy called...

By changing the way we perceive the world. For example, in experiments in which people looked at smiley or sad face icons, the music they were listening to affected what they saw. Even a neutral...

This is because our estimates of time depend on how much we remember, and more memories are laid down in an emergency. Experiments have investigated this. In one case volunteers fell back into a...

The main ozone-depleting gases are chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). The Montreal Protocol, which came into force in 1989, lists 56 CFCs and 34 HCFCs, and production...

A potentially hazardous asteroid (PHA) is an asteroid whose orbit comes nearer than 0.05AU (about 7.5 million km) to the Earth and whose brightness implies a size of the order of about 100m across...

Physicists have determined that there is a lower limit to the temperature scale called ‘absolute zero’. It occurs at –273.15°C (or –459.67°F). No matter how much...