Science Misconceptions 6/7/20

Science by Richard Bleil

Benjamin Franklin discovered electricity. Or, did he? Actually, electricity was discovered by the first human to see lightening. Or get shocked by an electric eel. Or who felt the first jolt of static electricity. No, electricity had been known for many years before Benjamin Franklin’s famous 1759 experiment. In fact, the term “electricity” was coined by William Gilbert around 1600.

No, Benjamin Franklin’s experiment wasn’t intended as one of discovery so much as one of invention. Franklin was very interested in fire. He invented a series of tubes for fireplaces to improve efficiency of its ability to heat homes, and invented the first fire brigade (the goal of which was to actually rush into fires to remove and save as many personal items as possible rather than putting the fire out). In a time when a single house fire could take out an entire community, lightening striking buildings and setting them on fire was a real problem. Benjamin actually invented an electrical insulator and flew the kite experiment to prove that it actually worked. He tied his insulator near one end of the kite, with the famous key dangling down. Flying the kite in the lightning storm, he couldn’t feel the electricity through the insulator. To prove that he should have been feeling electricity, he touched the key and got an electrical shock, proof positive that the kite and string were conducting electricity, but his insulator was not. He used this insulator to create the first lightning rod, to be struck by lightning and conduct the electricity safely to ground without touching the house and preventing fires.

Thomas Edison invented the light bulb. Not. Well, kind of. The first electric light as actually created by Humphry Davy in 1802. The electricity was passed through carbon, making it produce light. This was the “Electric Arc Lamp”. Very expensive and dangerous, requiring a very high voltage, the electric arc lamp wasn’t terribly practical for home use. Passing electricity though pieces of metal until they become sufficiently hot and they will glow. This is the first filament, but metals are prone to oxidation even without being excessively heated so they didn’t last long. Again, luminescence, but not practical.

What Thomas Edison invented was the first practical light bulb. Others had the idea of encasing the filaments in glass vacuums but with limited success. Edison tried a variety of techniques to make the light bulb practical, and to last long enough for household use. Edison put the filament in a glass bulb, and vacuumed out the air not once but twice, no doubt with two different powered pumps. This is done in modern instrumentation requiring extremely high vacuums. See, the most powerful pumps aren’t efficient at pumping out the bulk of the air, so these instruments rely on a “rouging pump” to get most of the air out, and a “turbo pump” to finish the job. It’s like the booster rockets and the secondary rockets to launch ships into space.
By creating a sufficiently high vacuum, Edison actually created a light bulb with a filament that lasted long enough to be practical for household use.

Sir Isaac Newton invented gravity. This is totally true. Before Newton, things just floated around haphazardly. It was complete chaos. Seriously, he…well, no, he didn’t invent gravity. He didn’t even really discover it. The first human to never fall off of the earth discovered gravity. The famous story is the apple falling from the tree and hitting Newton in the head, to which Newton replied “OUCH! What the h…” well, the story is a little bit different from that. But do we honestly believe nobody was hit in the head with a falling object before Newton?

No, Newton developed a “thought experiment” around the belief that heavier objects fell faster than lighter ones. He imagined two masses, a heavy one and a light one, falling free from air resistance. In his mind, the heavier object fell faster. Then he imagined tying the two masses together and asked how fast they would fall. He realized that the two masses together weighed more than the heavier mass and so should fall faster. But, it’s also true that the slower falling lighter mass should act as a “drag” on the heavier mass so together they would fall faster than the small, but slower than the heavier mass. Both of these answers would be correct if heavier masses indeed fell faster, but of course it is impossible for both to be correct. Therefore, the original assumption, the assumption that heavier masses fall faster than lighter ones, must be wrong. He basically showed that all masses fall at the same rate regardless of mass. From this observation, he created his laws of motion, known today as the “Newtonian Laws” which is the foundation of classical physics.

History is rich with misconceptions of science and discovery. It’s a fascinating to me to track down the true stories behind these misconceptions.

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