Philosophical Society of Washington

Minutes of the 2341st Meeting

President Larry Millstein called the 2341st meeting of the Society to order on January 23, 2015 at 8:04 pm. He announced the order of business, noted the deaths of long-time members John Wood and Robert Fristrom, announced new members, and reported the results of the General Committee election. The previous meeting's minutes were read and approved. The President presented a summary of the 16th meeting of the Society on December 2, 1871, noting that papers on the existence of the aether and Encke's Comet had been presented. President Millstein then introduced the speaker for the evening, John Mather, the co-recipient of the 2006 Noble Prize in Physics. His lecture was entitled, "Grasping the Universe: Telescopes to See Almost Forever."

Dr. Mather introduced his lecture by noting that his interest in telescopes began as a child, and he said he is still thinking about how to make bigger and better ones. The first part of his lecture was, accordingly, a summary of the history of telescope design and astronomy in general, beginning with Leonardo's and Galileo's work on telescope design and Galileo's lunar sketches. He discussed the work of Hale, Goddard, Lemaître, and Jansky, who built a radio antenna and detected signals from the center of the Milky Way in 1928. Dr. Mather remarked that we keep making equipment and discovering what we did not expect; equipment made the discoveries possible.

Other discoveries continued: Edwin Hubble showing that the universe is expanding; Alpher and Herman predicting the cosmic background radiation and its temperature; the Lovell Radio Telescope detecting quasars and verifying gravitational lensing. And then NASA was founded in 1958, with Dr. Mather specifically noting that the constituting legislation included public outreach in NASA's mission. The moon program was launched in 1962 with NASA's James Webb planning the missions and budget.

Additional discoveries followed: Penzias and Wilson discovering the cosmic background radiation in 1964; the Ryle Telescope cataloging quasars; the 300-foot Green Bank Telescope detecting pulsars with millisecond periods, and recently the 1000-foot Arecibo Telescope, mapping the Venusian surface and observing pulsar exoplanets, Mercury, and the lakes on Titan.

From 1984 to 1994, the Cosmic Background Explorer (COBE) measured the cosmic background radiation. It was a beautiful fit to the blackbody spectrum curve. The radiation, though, is not perfectly uniform, as it has hot and cold spots, that differ by 30 microKelvins. Hawking called this the greatest discovery in the history of science because it "proved" the expanding theory of the universe. (Dr. Mather was the co-recipient of the Nobel Prize in 2006 for this work on the cosmic background radiation.) Subsequently, the Wilkinson Microwave Anisotropy Probe produced an even higher-resolution map. Dr. Mather noted that all of this has been possible because of equipment and that the engineers deserve much of the credit.

In the next part of his lecture, Dr. Mather discussed the work of existing and to-be-built large telescopes and the future ahead. He discussed ALMA (the Atacama Large Millimeter Array) which recently took a picture of a solar system, 450 light-years away, in the early stages of its formation. The Square Kilometer Array is in construction in South Africa and Australia. There are also the Twin Keck telescopes in Hawaii and the four "Very Large Telescopes" in Chile, all in the eight to ten meter range. Larger telescopes of 25 meters and more are also under construction.

Dr. Mather then discussed the Hubble Space Telescope, which will celebrate its 25th anniversary this year, and showed images illustrating its important discoveries. Hubble's successor, the James Webb Space Telescope, is planned to be launched in 2018. Dr. Mather showed a video of the complicated engineering marvel that is the JWST.

Dr. Mather then talked about the future. Dark energy and other ideas like it will most probably be addressed by using computer simulations. Scientists cannot build equipment to observe such things, but instead will use tools to imagine it, benefiting from ever-expanding computing power.

Dr. Mather then overviewed techniques, technologies, and ideas still in the development and trial stages. For example, to detect exoplanets, he presented ideas such as focusing with diffraction gratings, the "Starshade" proposal, and the proposed New Worlds Telescope. Dr. Mather closed his lecture by noting that human space travel is a problem, as humans are fragile; but robots are getting smarter and tougher. Longer-range travel with humans will, in his opinion, not be easy.

After the question and answer period, President Millstein thanked the speaker, made the usual housekeeping announcements, and invited guests to join the Society. At 10:01 p.m., President Millstein adjourned the 2341st meeting of the Society to the social hour.

Attendance: 175
The weather: Rainy
The temperature: 2°C

Respectfully submitted,

Zeynep Dilli
External Communications Director & Recording Secretary

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