Here is a great article since you guys are learning about rotational motion.
Keeping with Dan's subject let stay with astronomy and how the earth spins or should I say wobbles.
As young student, is there any physics research you would like to do if given the opportunity.
The direction of Earth’s axis is not fixed, but instead wobbles by a tiny fraction of a degree. Astronomers track this change by continuously monitoring the position of distant quasars in the sky. But now Ulrich Schreiber of the Technical University of Munich and his colleagues, reporting in Physical Review Letters, have, for the first time, measured the wobble in a lab with a ring laser.
A ring laser is basically a laser cavity that has been bent around into a square or triangle loop, with mirrors at each corner. Laser light will travel around the ring in both directions. However, if the ring is rotating, then light moving in the same direction will have farther to go to complete a loop than light moving in the opposite direction. This travel difference causes a measurable frequency shift between the counterpropagating beams.
Ring laser gyroscopes are commonly used in aircraft, but the systems typically are not stable enough with respect to environmental fluctuations to measure the long-period changes in the Earth’s axis. To address this instability, the authors constructed a 4 -meter by 4 -meter square ring—the “Gross Ring”—out of zerodur, a ceramic glass with very low thermal expansion. Using data from spring 2010, the team extracted the signal of the dominant Chandler wobble, which is a 435 -day free oscillation of the Earth due to pressure fluctuations at the sea floor and wind activities around the Earth. This shows that ring lasers could provide an alternative to costly astronomical methods of studying the Earth’s rotation. – Michael Schirber
As a marine science major I feel that this extremely important for future research with changes in climate, global warming, and how scientists use the rotational wobble to more accurately do research. Besides the cost being much less, what else can benefit from this new discover?
ReplyDeleteI understand the idea of the ring laser, the way the laser is bounced around in a circular (or square-like) shape but I don't understand how its rotating tells us anything. How are we able to determine for example the "signal of the dominant Chandler wobble" or "long period changes in the Earth's axis"? I don't see how any fluxuations in its rotations can tell us anything.
ReplyDelete~Rebekah Clayton