42 Comments
Posted February 9th, 2013 in Science. Tags: Climate, Diagrams, Graphics, Introductory-Science, No Equations, Pedagogy, Physics.
Before the Industrial Revolution in the 1800s, the concentration of carbon dioxide (CO2) in the atmosphere was about 280 parts per million (ppm). This means that for every million molecules in the atmosphere, about 280 of them were CO2.
However, climate.nasa.gov shows that we’ve burned so much coal and oil that atmospheric CO2 is now approaching 400 ppm. It hasn’t been this high for millions of years. The last time Earth’s atmosphere had this much CO2, our species (and many others) hadn’t yet evolved. (more…)
3 Comments
Posted October 17th, 2010 in Math. Tags: Graphics, Introductory-Science, No Equations, Quickie.
Dr. Benoît B. Mandelbrot passed away last Thursday at the age of 85. He’s best known for coining the term “fractal,” so it might be appropriate to remember him by looking at some pictures of the Mandelbrot set. He discovered this hauntingly beautiful fractal shape while exploring the mathematics of imaginary numbers. His discovery inspired generations of scientists and mathematicians, some of whom have recently found a 3D version that they call a Mandelbulb. (more…)
5 Comments
Posted November 11th, 2008 in Math. Tags: Graphics, Introductory-Science, No Equations, Quickie.
I’ve found stereograms entrancing ever since I first managed to “see” one. If you can’t see them, try viewing these images on one of those shiny new LCD monitors and focus on your own reflection. Be sure the monitor is perfectly level, and your head is perfectly vertical. Then use your peripheral vision to search the image for a hint of 3D structure but keep your face in focus. With any luck the image should simply pop into view. (Unless your eyes point in slightly different directions… right?).
These images fascinate me because they’re essentially tricking my binocular vision into hallucinating objects when I look “through” a pattern of (almost) random noise. I used to make my own stereograms using (more…)
45 Comments
Posted December 4th, 2008 in Astronomy. Tags: Graphics, Introductory-Science, No Equations, Physics, Pseudoscience, Quickie.
This is what you get if you take a photo of the Moon every night for a month, then make a movie out of those pictures. The Moon’s phases aren’t surprising, but the Moon also appears to grow and shrink as it orbits the Earth. This happens because the Moon’s orbit is slightly elliptical; its distance to the Earth varies by about 10%.
Also, the Moon appears to “wobble” from left to right. That’s because the Earth’s gravity pulls harder on the Moon the closer it is to the Earth, so the Moon travels faster in its orbit when it’s closer to the Earth. The Moon’s rotation rate matches its average orbital speed (which is why we only see one face of the Moon), but its orbital speed varies during the orbit while its rotation rate remains fixed, so the Moon appears to wobble from left to right.
2009-08-10 Update: I’ve noticed that many people arrive at this article by googling moon wobbles. All the other sites on the first page claim that “moon wobbles” are responsible for explosions, mass-murder, earthquakes, terrorism, etc. Sadly, I need to emphasize that the wobbling I’m describing can’t possibly result in these kinds of ludicrous effects.
