Additional Product Features Author s. David Bradley has worked in science communication for more than 20 years. He has written for 'New Scientist', the 'Telegraph', the 'Guardian' and many other publications, as well as contributing to and editing books including 'The Bedside Book of Science' He has won awards for his writing and blogging, including 'Daily Telegraph' Science Writer of the Year.
He tweets as sciencebase and has over 15, followers. He lives in Cambridge, England, with his wife.
Deceived Wisdom: Why What You Thought Was Right Is Wrong - David Bradley - Google книги
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The blade of their skates in contact with the surface is about 3 millimetres in width and about mm long. The force pressing down on the ice is 75 kg multiplied by gravity, which has a value of 9. The Newton is named after Sir Isaac Newton, who never did sit under an apple tree and discover gravity when an apple from said tree fell on his head. He invented that tale merely to publicise his book. Think of him as the original spin doctor. We now see that Newtons 75 multiplied by 9.
To calculate the pressure we need to know the area of the blade in metres. The pressure is the force, Newtons, divided by this area, 1,, Newtons per metres squared, or Pascals. Named for French scientist Blaise Pascal who never told tales of falling apples, but did invent a mechanical calculator when he was 19 years old in That value for the pressure being applied through the skate to the ice sounds enormous. And, in some senses it is: it is about twelve times the value of atmospheric pressure.
This pressure is about ten times too small to melt ice. The skater would have to apply a pressure of times atmospheric pressure to do that and to apply that amount of pressure would have to weigh ten times as much as a normal ice skater, and so be about kg. You might be wondering whether the pressure could be in- creased by sharpening the blades. After all, dividing the force of a 75 kg skater by a smaller number would mean a bigger pressure. Regardless, the effect would be to lower the freezing point of the ice by a few tenths of a degree.
Given that most ice rinks freeze their ice to well below 0 Celsius, this would have little impact. The ice will stay solid.
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There are theories about the water molecules at the surface and how they are not being held as tightly in the solid ice as those within the frozen solid. There are also ideas about defects in the structure of ice that might allow some water molecules to become loose and so enter the liquid state. It might be that the steel of the blade some- how grabs these loose water molecules and promotes melting as more and more water molecules loosen their grip on the ice to form that thin slippery layer of water below the skate.
Either way, this has nothing to do with the pressure applied. One property that quickly becomes apparent to anyone new to ice skating, however, is that when you land on the ice with a bump and struggle back to your feet, your body heat allows the frozen particles of ice to quickly revert to the liquid state … leaving you with a soggy behind. The Science: Applying pressure to ice lowers its freezing point, which means it will melt to form liquid water above a certain temperature. The Deceived Wisdom: Recycling is a waste of time and energy.
E nergy — Those opposed to recycling often attest that it takes more energy and resources and produces more of the greenhouse gas carbon dioxide to collect, process and recycle glass, paper, metal and plastic. This is dangerously misleading Deceived Wisdom. Mining metal ores, running oil wells and converting crude oil into plastics, felling trees and pulping wood all use far more energy than the relatively simple collection and processing of waste products.
Glass — Only a fraction of glass bottles can be recycled into new containers. Colourless glass works well but unfortunately, brown and green bottles are less easy to recycle, producing low-quality recycled products. This might sound like the glass is wasted, but production of virgin glass is an energy-intensive process, as is the production of cement; both also release vast quantities of carbon dioxide.
By using waste glass aggregates and concrete the need for fresh raw materials for those applications can be reduced. The glass is recycled, just not into new bottles. Plastics — Today some recycling centres have highly so- phisticated sorting systems that use laser-guided conveyors and air-jet systems to separate the different plastics in a stream of shredded mixed waste. Crossed laser beams scan the plastics and a spectrometer reads their chemical signature, much as a checkout laser scanner scans the barcode on the items from your shopping trolley.
A puff of air is then sent from the ap- propriate jet to send each shard of plastic into the appropriate hopper. As this technology gets cheaper and more widespread the ability to extract different plastics from household and in- dustrial waste will become greater and less plastic will be sent to landfill or wasted. Aluminium — Until very recently, aluminium was consid- ered a precious metal, so expensive was its extraction and pro- duction. Indeed, the statue of Eros in Piccadilly Circus, Lon- don, is aluminium as is the cap on the top of the needle-shaped Washington Monument, in D.
Such was the esteem with which this metal was once held. Indeed, the cost of making al- uminium during the nineteenth century made it more expen- sive than gold. Despite electricity being relatively cheap, the energy costs and environmental impact of strip-mining bauxite and extract- ing the metal is very high. A quick calculation shows this to be the case: melting aluminium requires less than kilojoules of energy per kilogram of metal.
Breaking down aluminium oxide from bauxite uses about 80 times as much energy. Paper — Paper is made by pressing wet, pulped fibres of cellu- lose from wood, sugar cane or grasses into sheets and then dry- ing. Only about one third of the trees harvested each year are used to make paper; the majority are used in manufac- turing wooden products, in construction and other areas.
Organic matter — Until recently organic waste was sim- ply landfilled and the methane gas released by its rotting un- derground vented or burned. But many recycling and com- posting centres can now accept all kitchen and garden waste and process it into useful compost.edutoursport.com/libraries/2020-07-04/2047.php
2 Vital Steps to Avoid Deception
It is Deceived Wisdom that once buried in landfill, waste materials are gone forever. The Science: We may not be reducing our consumption, but there are many effective ways to reuse products and materials and once they are beyond that, they can be recycled. Any good wine waiter knows that such an affectation is a pointless act and has no ef- fect on boosting the body, improving the bouquet or removing any bitter aftertaste of the wine. A good red wine will taste fine, provided it is not too cold, even if the cork is removed just be- fore it is poured and quaffed. What the good sommelier also knows is that sometimes a less than adequate red wine can be improved.
This is done not by simply opening the bottle but by pouring quickly it into another container, a decanter, for instance. Waterhouse explains that it takes at least a day for these natu- ral chemicals to be broken down. Unfortunately, if you leave a bottle of wine to breathe for that length of time not only will your guests have broken down and departed but bacteria, known as acetobacter, will have invaded the wine and started to convert the alcohol content to acetic acid, or vinegar.
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As to the idea that a wine becomes smoother over the course of a meal — that is more down to your taste buds and nose than anything in the wine changing chemically. As to the evaporation of malodorous compounds, these are rare in modern winemaking. This com- pound is harmless in the quantities present in a corked wine, but it makes the drink unpalatable. White wines have little tannin content and the fruity aromas that often accompany them are usually due to volatile com- pounds in the wine. Decanting a bottle of white wine will ensure that some of this volatile content is lost and the wine will lose much of the bouquet the wine maker hoped you would experience if it is not drunk immediately it is opened.
The same sad loss will happen if the wine is warm or allowed to become warm once it has been opened. One more piece of Deceived Wisdom about red wine… there are endless claims that red wine contains some kind of medical panacea, whether it is the antioxidant compound res- veratrol or one of countless other natural chemicals found in the drink. Certainly, wine contains lots of natural chemicals: one of them is ethanol, which we usually refer to as alcohol.
Any marginal benefits of antioxidants or other health-giving compounds in wine are cancelled out many times over by the presence of ethanol, which despite our enthusiasm for drink- ing it is a toxic chemical. Scientific studies from around the world show that more than half of all alcohol-related deaths are due to heart disease, cancer or liver damage.
So much for the red wine panacea. The Science: The surface area exposed to the atmosphere by removing the cork or unscrewing the cap from a bottle is far too small to allow any significant exchange of gases with the liquid. A Stradivarius violin is often associated with super- lative excellence by players, composers and conductors. The sound, they say is exquisite and cannot be reproduced by the most beautifully crafted modern instrument.
There are numerous theories as to why a Stradivarius can produce such a beautiful musical timbre. The design and shape of the violins and craftsmanship used in their creation are considered the most important factors, but there are theo- ries in support of others. Others have suggested that the sound might even be linked to the preservatives used at the time to kill woodworm and prevent moulds forming in the wood.
There is one theory that says he used wood from ancient churches and that this endowed his violins with an almost spiritual quality. Unfortunately, researchers in Europe have smashed that notion too, demonstrating that there really was no secret sauce in the varnish. They took microscopic samples of varnish from five Stradivarius violins and carried out a highly sophis- ticated chemical analysis. The instruments were made at dif- ferent times during a thirty-year period. The analysis revealed that the varnishes contain materials, such as oils and pigments, used widely in decorative arts and paintings of the period.
The researchers found no unknown ingredients, no mineral or fossil resin layer as had been suggested by others.