Food for Climate Skeptics
“The frigid winter now ending may be, unhappily, no fluke. The warming trend that had dominated world climate during most of the years since 1880 appears to have come to an end. Murray Mitchell, Jr., of the U.S. Weather Bureau reported that mean annual temperatures have dropped in both Northern and Southern hemispheres by 0.2 degree Fahrenheit since the early 1940s. In many areas climatic conditions have already returned to those that prevailed in the 1920s. The downturn has allayed fears about the ‘greenhouse effect,’ in which a rising concentration of carbon dioxide in the atmosphere, due to increased use of fossil fuels, was supposed to be trapping more and more solar energy. But the reasons for the cooling are unknown.”
Daytime temperatures had fallen during the 1940s and 1950s as an aerosol haze created by industrial pollution reflected sunlight.
“If a future experiment should demonstrate that antiparticles have a negative gravitational mass, it will deliver a mortal blow to the entire relativistic theory of gravity by disproving the principle of equivalence.
An antiapple might fall up in a true gravitational field, but it could hardly do so in Einstein’s accelerated spaceship. If it did, an outside observer would see it moving at twice the acceleration of the ship, with no force at all acting on it. The discovery of antigravity would thus force upon us a choice between Newton’s law of inertia and Einstein’s equivalence principle. The author earnestly hopes that this will not come to pass. —George Gamow”
Full article is at www.ScientificAmerican.com/mar2011/gamow
Concrete for Construction
“About fifteen years ago serious attempts were made to combine steel and concrete by molding the one into the other in such a way that the resulting product would possess a high resistance not merely to compressive but to bending and tensional stresses. A vast amount of experimental work was done, out of which has sprung our modern reinforced concrete. Not only is concrete found to be available for practically every form of construction [see illustration at left] which hitherto has been built in brick or stone, but it has now invaded the field which was supposed to be peculiarly reserved for iron and steel.”
Atmosphere of Venus
“Venus is nearly as large as the earth and, as it is much nearer the sun, its temperature must be higher than that of the earth. The average temperature is estimated to be about 140 degrees F. Various phenomena appear to indicate that the planet is surrounded by a comparatively dense and cloudy atmosphere which, indeed, is apparently seen as a luminous border, in the transits of Venus over the sun’s disk, which occur once or twice in a century. This dense atmosphere strongly reflects the sun’s rays and thus prevents the surface of the planet from attaining a temperature too elevated for highly organized life. The planet would be regarded as habitable.”
Drudgery of the Needle
“At the present moment some 650,000 females are employed in the United Kingdom as milliners, dressmakers, seamstresses and shirtmakers; and their labor being manual, they are, on an average, the most enslaved, most dependent, and most unhappy of the industrial classes. Half a million sewing machines are much needed amongst them. Their introduction would double their wages. Nor is there any danger that this market for female labor will be overcrowded, at least for several generations. Men must eventually resign the monotonous drudgery of hand-sewing to machines that are wrought or attended to by women. Three fourths of the journeymen and apprentice tailors now in Great Britain—50,000 able-bodied men—could well be spared to man the navy, or engage in some more suitable employment than handling the needle.”
Fun with Sparks
“In some of the furnace-heated houses of this city, the air is so dry that it is a common amusement of the children to light the gas by a spark of electricity from their fingers. By rubbing the feet along the carpet the body becomes so charged with the electric fluid, that, on approaching the finger to the gas-burner, a spark is drawn forth sufficient to light the gas.”