Imagine Magazine - Johns Hopkins - September/October 2011 - (Page 16)

PHYSiCS: although physics is one of the oldest academic disciplines, it’s a ﬁeld students in physics explain that discovery isn’t just about ﬁnding answers; it’s about using those answers to ask the next question. BRinging STaR PoWeR To eaRTH by lUc Peterson There’s more to the universe than solids, liquids, and gases. Much more. In fact, over 99% of visible matter is something else entirely. If you take a solid, like ice, and heat it up, it will melt into a liquid, like water. Keep heating the liquid and it will boil into a gas. If you keep heating the gas, it will eventually get so hot that the gas’s electrons separate from their atoms, turning the gas into a soup of positive and negative charges. This soup is called plasma, the fourth state of matter. Plasma is the most common form of visible matter. The sun is made of plasma, as are all the stars and galaxies. Lightning, fire, and the glowing gases inside fluorescent light bulbs are all plasma. Plasma is everywhere. Inside the core of the sun, the plasma, which is mostly hydrogen, exists at temperatures of several million degrees and densities 150 times that of water. Normally two hydrogen atoms, both positively charged, repel each other. If the atoms are hot enough, though, they can collide and stick together, creating a new element. In the sun, four hydrogen atoms combine into a helium atom. But if you were to weigh the helium and compare its mass to the hydrogen, you’d find that some mass has disappeared! Of course, this mass isn’t actually missing. It has instead been converted into energy, according to one of the most famous equations of physics: Einstein’s E=mc2. Creating energy by turning light elements into heavier ones is known as nuclear fusion. Someday, fusion might power human civilization. Since fusion works by converting hydrogen into helium, our fuel THe neXT geneRaTion that is only becoming more fertile for discovery. Below, four graduate 16 imagine Sept/Oct 2011 SHUTTErSTOCK, VECTOrSTOCK

Table of Contents for the Digital Edition of Imagine Magazine - Johns Hopkins - September/October 2011

Imagine Magazine - Johns Hopkins - September/October 2011
Contents
Big Picture
In My Own Words
Physics Is…
Making the Team
Nuclear by Nature
Physics: The Next Generation
Telescopic Views
Exploring the Mysterious Lives of Stars
Around the Universe in Three Weeks
Selected Opportunities & Resources
Book Buddies
Meeting the (Economics) Challenge
Off the Shelf
Word Wise
Exploring Career Options
One Step Ahead
Planning Ahead for College
Students Review
Creative Minds Imagine
Mark Your Calendar
Knossos Games

Imagine Magazine - Johns Hopkins - September/October 2011