Random Facts

From time to time, as a curious person, I enroll into searches for answers to questions that intrigue me. Below are the result of those researches.

As new questions (and new answers) arise, I’ll update this page.

  • What makes the rain smell like rain?
    Short answer: It depends. If you’re talking about the smell that can be perceived right before it rains, this smell comes from ozone, which is produced by ionized gases in the atmosphere and by lightnings.
    But, if you’re talking about the smell that can be perceived while and after it rains, called petrichor, this smell comes from a blend of things: first, by oils that are secreted by plants into the soil during dry periods; second, by Geosmin, a compound that is released by some bacterias that are found when they die in soil; and, finally, by ozone again. When drops of rain hit the ground, these three elements are released into the air.
    Long answer: Check these texts on Smithsonian Magazine and BBC, as well as Wikipedia’s article about petrichor.
  • Why does everything taste bad after you brush your teeth?
    Short answer: This is due to sodium lauryl ether sulfate (SLES)/sodium lauryl sulfate (SLS), both surfactants added to create foam and make the paste more spreadable, which alters how our tastebuds perceive some tastes.
    Long answer: Read these articles from Mental Floss and Colgate.
  • Why does my voice sound so different when it is recorded and played back?
    Short answer: It’s because normally, when you hear your own voice, its sound reaches the inner ear both through the external auditory canal and through bone conduction (through your skull). But, when you hear a recording of your voice, the sound is received only through the external auditory canal, which normally results in the perception of a higher pitched voice (but that’s how everybody really perceives your voice).
    Long answer: Read these articles from Scientific American and Mental Floss.
  • Why do people feel pleasure in enduring the pain of eating pepper?
    Short answer: the pain that we get for eating pepper is due to the presence of capsaicin, a substance that exists in peppers for the purpose of preventing predators (mainly mammals) of eating them without spreading their seeds (birds, for example, aren’t sensitive to capsaicin).
    Some people says that eating pepper has an “addictive effect”, which makes these people eat pepper with more frequency and in increasingly higher doses/stronger peppers. The main reason for this “voluntary masochism” probably is the fact that eating chili peppers makes the body release endorphins in response to the pain, so eating peppers would be a safe way of thrill seeking and achieving a kind of a “runner’s high”.
    Long answer: Read this article by Washington Post and watch this video from How Stuff Works.
  • Why do we yawn?
    Short answer: There are some physiological hypotheses: that it removes “bad air” from the lungs and increase oxygen circulation in the brain; that it’s responsible for the regulation of vigilance and increase of brain arousal level; that (unlike the previous hypothesis) it’s responsible for the decrease of brain wakefulness; that it regulates the brain temperature; that it’s a “defence reflex” of the ear to equalize air pressure in the middle ear with outside air pressure; or that it’s a combination of all the previous options.
    Also, there are some social/communication hypothesis too: that it is triggered by drowsiness, boredom, hunger, or mild psychological stress; that it has some impact on the behavioural organization of a social group; that its contagiousness depends on how empathetic the people involved are to each other or in the hierarchical relation between them. These hypothesis have the best experimental evidence among all propositions on the function of yawning.
    Long answer: For a much more in depth analysis of the hypothesis, read the article Why do we yawn?.