Wednesday, 25 July 2001: Currently I am assisting in some data entry of the daily system status reports. Besides constituting a daily record, this information goes into a database so that trends in the behavior of any of about 150 different components or readings can be identified.

Otherwise I have done some more reading, some practice on some computer skills, and some efforts at calculations involving some special cases of relativity. (Did you know that because of relativistic space-time curvature, the Earth's diameter is 4 millimeters longer than it should be? If you did, you didn't tell me.)

An interesting tidbit from this week for all you skeptics: general relativity has practical applications in the GPS system. The Global Positioning System satellites must make corrections for the effects of relativity. If this were not done, the system would not provide the accurate location information that soldiers, pilots, and other GPS users rely on.

So far we have had two presentations this week:

• -- Dr. Joe Giaime described some aspects of seismic isolation yesterday. This is the means of configuring the various components of LIGO so that extremely small ground vibrations do not interfere with efforts to measure gravitational waves. The presentation clarified the current issues of low frequency seismic noise at this site, so stay tuned as I compile details on this.
• -- Dr. Joe Romano (one of the UT-B professors) gave a presentation today on detecting gravitational waves from gamma ray bursts. Gamma ray bursts are an especially mysterious astronomical phenomena. They are short (less than a second to a few minutes) bursts of gamma radiation (higher energy than x-rays) apparently coming from objects far beyond our galaxy. Astronomers have yet to determine exactly what produces them. Dr. Romano gave some background, then discussed how statistical methods could be used with data from LIGO to indicate whether or not the sources of bursts also produce gravitational waves. This is an example of an area where gravitational wave detectors could eventually provide information that so far is unavailable to astronomers.

Last Saturday I went with several others students from LIGO to an alligator farm in Hammond. This farm is among the largest in the United States with thousands of alligators and turtles at any given time. The pond with large alligators was said to hold 250. Some we saw were over 3 meters long.

We have had late afternoon-evening thunderstorms on several days, including one right now.

Image credits: Wm. Robert Johnston, © 2001 (top); LIGO-Livingston, 2001 (bottom).

© 2001 by Wm. Robert Johnston.
Last modified 1 August 2001.
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