Teacher resources and professional development across the curriculum

Teacher professional development and classroom resources across the curriculum

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The Smoking Gun of Cosmic Inflation

Physics_cosmic inflationYoung Alvy Singer got it partially right.The main character in the Woody Allen film Annie Hall explained why he gave up doing his homework: “Well, the universe is everything, and if it’s expanding, someday it will break apart and that would be the end of everything!”

The Harvard-Smithsonian Center for Astrophysics recently announced that the BICEP2 collaboration (its research partnership with Caltech/JPL, Stanford/SLAC, and UMinn) had observable evidence to prove how this expansion got started from the point of the Big Bang: through cosmic inflation.  “These results are not only a smoking gun for inflation, they also tell us when inflation took place and how powerful the process was,” said Harvard theorist Avi Loeb. Physics for the 21st Century at Learner.org provides explanatory text, images, and video to help you make sense of the discovery and the theories that led to it.

Start by looking at the text for unit 4 on String Theory to understand how cosmic inflation is responsible for the structure of the universe as it is today.

Short of running backwards the movie of all time, the Cosmic Microwave Background, or CMB, is the best link to the first moments of the development of matter. The CMB is the detection of the relic gas radiating from the Big Bang. Astrophysicists also have been able to find in their data the finger prints of gravitational waves, which are described as ripples in space-time. Dr. Nergis Mavalvala of MIT explains the relation of gravitational waves to today’s astronomy. Watch the segment of the video Gravity, beginning at 14:30 through 16:21, to learn about how these waves are propagated.

The final unit looks in on the work of two astrophysicists, Robert Kirshner and David Spergel, both trying to determine the cause of the acceleration of the expansion of the universe and whether there may be an end to it. Their chief suspect is Dark Energy. Their research may assuage Alvy Singer’s concern about the universe ultimately breaking apart.

Teaching Newton’s Laws of Motion



Newton’s laws of motion were written more than 300 years ago and they are still in force.  But how do you teach them so they have impact on students, who often seem inert?

First you must ask yourself the question: Is Newton’s work still relevant in today’s high-tech world? For many years, physicists have been scratching their collective heads about how gravity can exist alongside of the other three forces of nature (electromagnetic, strong nuclear, and weak nuclear forces) because it is many factors weaker than the other forces — the 98-pound weakling at the beach, if you will.

Physicists at the University of Washington’s Eot-Wash lab are testing Newton’s Inverse Square Law at extremely minute distances, less than a hair’s width. In the program “Gravity” from Physics for the 21st Century, you’ll see their experiments and what they have learned. This law defines the force bodies have on each other at various distances. It gives students a glimpse into long-standing physics puzzles and the people working on them.

Students can test their understanding of the 2nd and 3rd laws by observing automobile collisions. You don’t have to go to the street corner and wait for two cars to crash, you can go to Learner.org’s student interactive Amusement Park Physics in the bumper cars section of the virtual park.  The bumper cars provide collisions between moving cars and cars at rest, with drivers of various masses. Students can predict the resulting motion after the collision and perhaps become more aware drivers in the future. (One can always hope.)

Newton’s laws of motion are explained with tabletop demonstrations that use CDs, balloons, eggs, and other common objects in workshop 7 of the Science in Focus: Force and Motion. Advance the video slider to about 29 minutes into the VOD at where you will also learn about how great thinkers from before Aristotle to Newton pondered the questions of the nature of forces and motion acting on objects.

Or you can visit Newton and Galileo in their studies as they work on their theories, in The Mechanical Universe…and Beyond program 6, “Newton’s Laws,” and get a feel for the times of both scientists whose names are synonymous with motion today.

These approaches to teaching Newton’s laws should give your students many ways to think about Newton’s simple and elegant set of rules for all matter.