A couple of interesting scientific stories are making the rounds today, and worth a little physics and general science commentary. The first reminds us just how incredibly limited our sensory perceptions are in telling us about the world, by forcing us to imagine how it may look to animals whose perceptions are slightly different. The second reminds us just how little we know about our own planet.
Nothing about quantum physics today, but … wait, everything is made using quantum physics… — Could you imagine getting a dog to sit absolutely still, while fully awake and listening to voices, for as much as 8 minutes? Researchers trained dogs to do it, then put them in an MRI [Magnetic Resonance Imaging] machine to … Read more
Welcome 2014! And quite a start to the year, with a cold snap that rivals anything we’ve seen in two decades. I don’t remember cold like this since the horrid winter of 1994, when the Northeastern U.S. saw snowstorms and extreme cold that alternated back and forth for weeks. Of course, when I was a child in the 1970s, such chills happened a lot more often; I remember a number of New England mornings where I awoke to a thermometer reading of -20ºFahrenheit (-29ºCelsius) [244 Kelvin].
The scariest negative temperature numbers that one hears about from the media are associated with the “wind chill”, which is a number that is supposed to measure how cold the air “feels” to your skin. But “wind chill” is a rather subjective and controversial measure — there’s no unique way to define it, since you’ll feel differently depending on how much exposed skin you have, on your body weight, on your age and conditioning, etc. By contrast, the temperature measured by a thermometer is defined independent of how humans feel, and experts agree on what it is and means. Oh sure, people use different scales to measure it: Fahrenheit (F), Centigrade or Celsius (C), and Kelvin (K). But the differences are no more than the distinction between meters and feet, or between kilograms and pounds; it’s straightforward, if a bit annoying, to convert from one to the other.
So everyone agrees the temperature is and feels extremely cold, But is it, from the point of nature, really that much colder than usual? To say it another way: it was 84ºF (29ºC) in southern Florida yesterday. How much warmer is that than the -40ºF (-40ºC) that was registered in the cold Minnesota morning?
Well, you might first think: wow, it’s a difference of 124ºF (69ºC), which sounds like a huge difference. But is it really so huge?
For general readership Evolution really happens in nature: we know this from the frightening rate at which bacterial species, faced with our most powerful antibiotics, manage to find ways around them. More precisely, a certain amount of natural variability and accidental mutations within bacterial populations, and the huge rate at which bacteria reproduce themselves (a … Read more