This post will be rather short because I’m in the middle of finals. Of course, if you follow me regularly, you also know that I’ve posted rather a lot this week. When I’m exhausted from studying, it’s much easier to write in short bursts, which might explain all the short posts recently. While reading this article, I recently found the following video, in which a fan of My Little Pony: Friendship Is Magic demonstrates the physics impossibilities in a few scenes of his favorite show. Let’s watch it, and then I’ll explain why I showed it to you. (A
Science And Math
explanatory articles on physics and math
Science And Math / Uncategorized
An Update on Kiera Wilmot
I recently posted about the plight of a teenager in Florida, Kiera Wilmot, who performed a science experiment which went badly. No one was hurt and no property was damaged, but she’s been expelled and she’s facing felony charges. The case has been getting a lot of media attention, which is a really good thing, I think. Here’s some more reading material if you’re interested. DNLee has posted twice on the issue on her Scientific American blog. Both posts are eloquent, enraged, and worth reading. You can find them here and here. There’s also some discussion about what caused
Computer Related / Discrete Math / Mathematics / etc.
R.I.P. Kenneth Appel
Imagine that you’re a stingy cartographer and that you want to make a colored map of the united states. Because you’re stingy, you want to avoid spending money on ink. You have to color the map so that no two adjacent states are the same color—otherwise you wouldn’t be able to tell them apart! If you want to buy the fewest colored pens possible, how many colors must you use to make your map? Very early on, mathematicians guessed that the answer was four colors. However, no one could prove it. An example map is in the tittle figure,
Geometry / Mathematics / Physics / etc.
Stuff From Shape — Kaluza-Klein Theory
There is geometry in the humming of the strings. There is music in the spacing of the spheres. ~Pythagoras When Albert Einstein and David Hilbert published the theory of general relativity, they weren’t just proposing a new theory of gravity. They were proposing a new way of thinking. In general relativity, gravity isn’t a force. Instead, it’s a natural consequence of the shape of the universe. Force comes from stuff. Matter pushes and pulls on other matter. A proton may need to use its electric field to attract an electron, but the field is a property of the proton.
Physics / Relativity / Science And Math
More on General and Special Relativity
Last time, I answered some questions from readers Ms. C and Mr. A on special and general relativity. Mr. A asked some very deep follow-up questions, so I thought I’d share them. Mr. A asks: I believe you already answered what I had intended to be my follow-up question: spacetime curvature accounts for the acceleration of an object already in motion; but why does a body at rest being to move (e.g. why doesn’t a stationary object hover in the air until someone touches it)? If I understand you’re post correctly, Einstein would say that there is no such thing as being at absolute rest —
Physics / Relativity / Science And Math
Rock Me, Einstein — Some Questions on Special and General Relativity
In 1905 Albert discovered Relativity, in 1906 he invented Rock and Roll ~Yahoo Serious In the last week or two, I’ve gotten several excellent questions on special and general relativity. I’d like to devote this week’s post to presenting and answering those questions. For the sake of anonymity, I will call the people who asked the questions Ms. C and Mr. A. I hope you enjoy! A Question on Special Relativity The first question is by Ms. C, who asked: I’ve read your article “The Speed of Light is Constant.” I’ve… got a question on the speed of light
cosmology / Geometry / Mathematics / etc.
Receding Horizons: Dark Energy and the Expanding Universe
Astronomy compels the soul to look upwards and lead us from this world to another. ~Plato The history of astronomy is a history of receding horizons. ~Edwin Powell Hubble Last week, I discussed the possible shapes our universe could take. I offhandedly mentioned that not only is the universe expanding, but that that expansion is accelerating. We attribute this expansion to a mysterious phenomenon we call dark energy. This week, I want to explore the history of this idea and the beautiful experiments that tell us all is not as it seems. The Static Universe and Einstein’s Greatest Blunder
cosmology / Geometry / Mathematics / etc.
For There We Are Captured—The Geometry of Spacetime
All about me there are angles— strange angles that have no counterparts on the earth. I am desperately afraid. ~Frank Belknap Long, The Hounds of Tindalos Whoever…proves his point and demonstrates the prime truth geometrically should be believed by all the world, for there we are captured. ~Albrecht Durer I was recently asked: What does it mean when we say spacetime is “curved” or “flat?” The answer lies in the interface between differential geometry and physics. This is the latest in many articles I’ve written on Einstein’s relativity, so you might want to check out my series on faster-than-light
Condensed Matter / Physics / Quantum Mechanics / etc.
How Things Work: The Field Effect Transistor
I don’t know how to do this on a small scale in a practical way, but I do know that computing machines are very large; they fill rooms. Why can’t we make them very small, make them of little wires, little elements – and by little, I mean little. ~Richard Feynman (1959) As of 2012, the highest transistor count in a commercially available CPU is over 2.5 billion transistors. ~Wikipedia In my article on quantum tunneling, I mistakenly claimed that diodes and transistors made use of this phenomenon. In an effort to correct my mistake, I’m going to explain
cosmology / Physics / Science And Math
What Is Time? A Simple Explanation
Mastery is achieved when “telling time” becomes “telling time what to do.” ~“Telling Time” This week I’m trying something a little different. I heard about a contest where the goal was to explain time in terms an eleven-year-old could understand. While I didn’t make the contest deadline, I thought I’d share my attempt with you all. What Is Time? What is time? Scientists often think of time as a direction you can travel in. Just as we can move up, down, left, or right in space, we can move in time. Something is wrong with this comparison, though. When