Orange Lutheran’s AP Physics class to publish scientific paper on Hubble Parameter
Published March 20, 2008
Orange Lutheran’s AP Physics students will soon be published authors of a scientific paper. The class, taught by Rob LaPointe, was recently asked by the Society for Astronomical Sciences (SAS) to present its research on the Hubble parameter at its upcoming annual conference and in print in the SAS Journal.
The proportionality between velocity and distance of astronomical objects is called the Hubble Constant, or Hubble parameter, and has been known within an approximate range for decades. But scientists don’t usually settle for approximate ranges, and so they—and now Orange Lutheran’s physics students—have been trying to determine the parameter with greater and greater precision. Since the reciprocal of the Hubble parameter is the age of the universe (otherwise known as Hubble Time), knowing the precise value of the parameter is of great interest to the scientists who study the stars.
The students are using observational data recorded at LaPointe’s home observatory in the San Bernardino Mountains to measure how fast other galaxies are moving away from our own Milky Way galaxy. They will then use those measurements to further refine the Hubble parameter.
Cosmology tells us that the universe is expanding, which means that virtually all galaxies outside our own (except our closest neighbors) are moving away from us at speeds that increase in proportion to their distance from us. For example, Galaxy A (10 billion light years away) will be moving much faster than Galaxy B (only 1 billion light years away), so the light from Galaxy A will be much more redshifted than the light from B. In fact, light from the creation of the universe, which scientists believe to be about 13.7 billion years ago, is shifted so much across the spectrum that today it is invisible to the naked eye, and can be detected only as microwave radiation.
(Light from galaxies that are moving away from us appears redder to us than to an observer moving at the same speed as the galaxy. Since the speed of light is constant and cannot change, regardless of the emitting object’s own velocity, the wavelength of the light is lengthened, causing the light to shift towards the red end of the spectrum.)