MYTHBUSTERS WHAT CAUSES A SONIC BOOM?

COLLAGEN IN YOUR COFFEE: DOES IT ACTUALLY MAKE YOUR SKIN BETTER?

In the 1990s, everyone who watched Friends wanted Jennifer Aniston’s haircut. Now, she’s hoping that we’ll all want to copy her morning cuppa: a coffee with a spoonful of her collagen supplement stirred in. But is there any scientific support for the claim that the supplement will “promote a youthful appearance”?

Collagen is one of the most abundant proteins in the body. It plays a role in building cells for skin, hair and nails, and as connective tissue in cartilage, muscle, and tendons. Studies have shown collagen’s effectiveness in reducing symptoms of arthritis, repairing tendons and ligaments, and as a scaffold for growing tissues for testing in the laboratory.

The production of collagen is ramped up during childhood and puberty, but as we reach our late-➤0s, our ability to replenish collagen starts to decline. The main cells that synthesise collagen for the skin are called fibroblasts and they’re sensitive to damage from sunlight and air pollution. The decline of collagen has been suggested as a main cause of wrinkles, with one study finding an 80-year-old’s collagen production is decreased by 7› per cent compared with a young adult’s.

So can collagen supplements stave off wrinkles, sagging skin and brown spots, as their sellers claim? Technically, collagen supplements – whether they’re taken as pills, mixed up from a powder, or drunk as a hydrogel shot – contain a slightly different form of collagen to that made in our bodies. This is because pure collagen would be hard for us to digest. To put collagen into a supplement, it is therefore partially broken down in a process called hydrolysis. The result, hydrolysed collagen, can be consumed and digested safely.

But does it work? A review of 19 available studies, with a combined total of more than 1,000 participants, found that hydrolysed collagen supplements were effective in reducing the appearance of skin ageing, if taken for at least 90 days. However, the same review cautioned that the individual studies could’ve been limited by their small numbers of participants. They also pointed out that these studies are often funded, at least in part, by the companies that manufacture the supplements. The authors conclude that claims by sellers, and their supporters, “surpass any evidence currently proven in the literature.”

While some have said that the temperature of your beverage could diminish the benefits of collagen supplements, the limited amount of research available suggests you’d need much higher temperatures than that of your morning mocha – 1›0°C at least – to begin breaking down collagen into something unusable by your body.

When an aircraft is flying below the speed of sound, sound waves ripple and spread out in front of and behind the plane. This contributes to the rumble and roar you hear when a plane is flying overhead. Of course, these waves are invisible, but we see something similar with slow-moving boats on calm water, when you can see gentle undulations of the bow and stern waves created by the boat’s hull.

For the plane, the sound waves are spreading out from the aircraft at the speed of sound, which is about 1,200km/h (750mph). If the plane accelerates to the speed of sound or faster, then the sound waves can no longer move fast enough to get out of the way of the aircraft. The waves bunch up and combine to form a shock wave. This then trails behind the aircraft in a V-shape. Something similar is seen for the boat on water. When that craft speeds up and gets faster than the speed of the water waves, then V-shaped white water is seen trailing behind the boat.

For the aircraft, the shock wave is what causes the loud, thundering sonic boom. It’s happening all the time, but for people on the ground, they only hear it once when the wake passes over them. Occasionally a double bang is heard, because two wakes are created, one by the aircraft nose and the other by the tail.

NASA is currently researching how to make a quieter sonic boom. They are doing this by shaping the supersonic aircraft so the wake created by the plane is less pronounced, meaning the boom is more muffled, making a ‘whoomph’ rather than a ‘bang’.