While many scientific myths have innocent or well-meaning origins — like the promotion of healthy eating, or over-simplified metaphors — the fact is that they’re just plain wrong. Popularised misinformation irritates scientists to no end, so I asked a bunch of experts to get things off their chest and set the record straight on myths they get tired of addressing.
“Black holes are like cosmic vacuum cleaners.”
Dr Abhijeet Borkar, University of Cologne
"Besides the fact that they both have mass and therefore a gravitational field, black holes have very little in common with vacuum cleaners. Although black holes do ‘clean up’ the gas and dust around them, and it does end up in a small confined space, this phenomenon is in no way associated with suction.
"If you were sufficiently far away from a black hole, it would be no different to being that same distance away from any other object with the same mass. For example, if our Sun suddenly turned into a black hole, there would not be any effect on the orbits of any planets of the Solar system. They would continue to go around the now-turned-black-hole Sun the same way they normally do. This is due to Newton’s law of gravitation and Gauss’ law of gravity, which dictate that the gravitational force you can feel from an object is dependent on that object’s mass and your distance from it – it doesn’t matter what the object is made of.
"Although stars can form a stable orbit which they can follow for millions of years, particles of gas and dust don’t have the same speed as each other. When these particles go around a body, there are collisions between the particles, which cause them to lose angular momentum and fall slowly towards the centre of their orbit. This reduction in the momentum of the gas particles is not really a phenomenon strictly associated with black holes, so much as any body with mass, be it a star, a planet or a black hole.
"It’s only as one moves closer to the black hole that things start to get interesting. Within 10 Schwarzschild radii (a distance that varies based on the mass of the black hole), there are no stable orbits and everything — not just gas and dust, but stars and planets too — will quickly fall into the black hole.
"This is just to say that all the usual fear-mongering associated with black holes ('How long until we’re all sucked into one?!') is completely unrealistic. The immediate influence of the supermassive black hole in the centre of our galaxy does not extend beyond a few dozen light-years. Stable orbits around black holes can continue in their paths for billions of years, so we’re in no danger of falling into one any time soon."
“Quitting sugar is good for your health.”
Emma Beckett (BBiomedSc (Hons), GDipClinEpi, MScMgt), University of Newcastle
"While numerous sparkle-toothed and rippling celebrities may boast the benefits of quitting sugar, the reality is that eliminating sugar from your diet is logistically impossible. Not only that, but the idea of using one macronutrient as a global scapegoat for poor health is a vastly unhelpful message when it comes to nutritional education.
"The myth that sugar is the root of all evil likely stems from the faulty assumption that if too much sugar is bad for us, then no sugar at all must be good for us! It’s true that cutting down on added and refined sugar in your diet is a good thing, but quitting sugar completely would require the elimination of grains, fruits and vegetables — and you being grossly malnourished as a consequence.
"Not only would quitting sugar be a far-from-healthy option to choose, many ‘sugar-free’ recipes aren’t actually free from sugar. Replacing the traditional cane sugar in a muffin recipe with agave syrup or honey may sound healthy — but these sugar ‘substitutes’ still contain sugar. Unfortunately, the trend of righteous eating can make people think that natural-sounding foods are healthier, when in reality they aren’t. This trend has made people vulnerable to the marketing techniques used to sell the idea of a ‘sugar-free lifestyle,’ popularised by people like Sarah Wilson, who is not an accredited practicing dietician or registered nutritionist.
"In short, the only people benefitting from the ‘quitting sugar’ movement are the people selling the recipe books."
“People with a dominant left-brain are more logical and those with a dominant right-brain are more creative.”
Dr Justin Bourke, BSc/BE, PhD, MIEAust, MIEEE, St Vincent’s Hospital, Melbourne
"Certain brain regions are responsible for processing information around particular tasks, some of which are specific to one hemisphere. For instance, movement of the right side of the body is controlled by the left hemisphere and vice versa, and the dominant language region is in the left hemisphere for around 95% of right-handed people and around 70% of left-handed people. The brain is extraordinarily complex, with the dominant language region able to swap sides if it is damaged early enough in development.
"So, while it’s true that certain regions of the brain are responsible for processing information around particular tasks, there is no evidence that dominance in logical or creative thinking is linked to stronger left or right brain networking activity.
"Indeed, a recent study from the University of Utah used a form of fMRI imaging to investigate networking in both hemispheres of over 1,000 people, and found no evidence to support the ‘left-brain, logical; right-brain, creative’ theory.
"It may well be that this particular myth has roots in the days of phrenology, where the lumps and bumps of a person’s skull were correlated with personality traits, and on occasion, used to determine criminality of individuals. In reality, we all have creative and logical processing, some just fall more toward one than that other. In any case, this myth may be popular as it gives people a construct with which to describe their personality and their approach to life, and that might not be a bad thing."