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Arlie Petters: Expert Q&A

On July 30, 2007, Duke University physicist Arlie Petters answered questions about his life growing up in Belize and about his work on gravitational lensing, a phenomenon of deep space.


[Editor's note: Several viewers sent e-mail inquiring how they could help support Arlie Petters' efforts to improve math and science education in Belize, such as the following:]

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Q: I hardly watch TV but was watching your show when I saw a profile of Arlie Petters. I was in Dangriga, Belize a couple of years ago and found it one of the most impoverished places I ever visited. I would like to know if there is contact information for Dr. Petters, since I would like to contribute my very limited resources to help the place out, if I could. Thanks for any assistance you can give me. Wanda Gough, Addison, Texas

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Q: Where/how can we send monetary donations to the Petters Research Institute? Didrik Thede, Baltimore, Maryland

Arlie Petters: Dear Wanda and Didrik,
Thank you for your willingness to assist our institute financially with its efforts. Please use International U.S. Postal money orders made out to "Petters Research Institute" and mail to:

Professor Arlie Petters

Duke University
Department of Mathematics
Science Drive
Durham, NC 27708-0320

Currently, we are soliciting funds to help students with full or partial tuition scholarships, textbook scholarships, and after-school prep classes for the next PSE (national exam) in mathematics. However, if you prefer to assist in another way, please let us know.

Unless you indicate that the donation is anonymous, we shall put your name on our Web site as a donor.

Q: What suggestions would you have for teaching elementary school children mathematics? Anonymous

Petters: One of the major challenges in teaching kids is that they typically have a short attention span. So for children in elementary school, it is important to teach them mathematics through a lot of activities—reciting, clapping, singing, hands-on experiments, etc. In many ways, the teacher should be an engaging "entertainer."

Q: What do you think can be done in the U.S. to improve K-12 math and science education? Are there programs in particular states that you think are working well currently? Jason Lewis, Boston, Massachusetts

Petters: Dear Jason,
I believe that the first step is for policy makers to acknowledge that it takes more effort to do well in mathematics and science. This means that more resources have to be put into the teaching of those subjects in K-12—e.g., proper training of teachers, availability of the best technological learning tools, rewards for excellence at both the teacher and student levels, etc. And perhaps most importantly, the relevance of mathematics and science to real-world problems has to be stressed throughout a student's entire educational career.

Q: As a former Peace Corps volunteer in Dangriga (1985 to 1987), I was very pleased to see your segment on NOVA and glad to hear of the educational progress being made there thanks to your efforts. When I left Belize there was a proposal to build a new school out near the water plant—did it get built and staffed? Did you happen to know Victor Williams from the Ag. Station? He and I worked on the bees of Stann Creek. Lowell Baltz, Darby, Montana

Petters: Dear Lowell,
I am glad to hear that you volunteered in Dangriga. Yes, a new pre-school was built near the water tower, and it is doing quite well. I don't know Mr. Williams, but I might recognize him by face. If your travel brings you to Dangriga again, please look us up:

Q: How have your experiences been trying to lend your knowledge and expertise to your native country? Patti, Belize

Petters: Dear Patti,
I have enjoyed the experience interacting with our young people. When it comes to issues connected to national development, particularly with education reform and the introduction of new industries, one has to work harder to stay out of "the politics." This is quite natural, though, when there are new initiatives with a potential for major economic growth. All in all, I keep my focus on servicing the people.

Q: Einstein often alluded to God to make explanations of the unexplainable but seemed scared of scientific ridicule if he acknowledged the existence of a Creator, Sustainer, and Law-giver of universal order. Do you acknowledge the existence of such a ONE? (I also was born in Belize.) Thank you! Mike Alamilla, Newmarket, Ontario, Canada

Petters: Dear Mike,
I believe in the existence of God. Each day I pray and thank God for each moment of life. I have no tension between this belief and utilizing the scientific method in my day-to-day research.

Q: Were your fellow Belize countrymen and family offended when Dr. [Neil deGrasse] Tyson introduced you as an African-American? Cynthia DaneshFar, Dallas, Texas

Petters: Dear Cynthia,
No one mentioned the issue to me nor did my relatives and friends. A lot of Belizeans from my generation immigrated to the U.S. when we were in our early teens and became U.S. citizens. Naturally, we became part of the African-American community and endorsed the efforts to improve the community. So I believe that most Belizeans understand our dual role.

Q: Has there been a formulation of the three main theories of physics—relativity, quantum mechanics, and string theory? Joe Bertke, Fort Lauderdale, Florida

Petters: Dear Joe,
The best candidates out there for trying to bring together general relativity and quantum mechanics are models like string theory, braneworld gravity, etc. However, the major challenge is for these theories to make testable predictions.

Q: Does Dr. Petters have a family (wife and kids)? Anonymous

Petters: I am married, though no children yet. I want lots of kids!

Q: In your opinion, could tired light answer most of the observations interpreted as the expansion of the universe? John Shannon, Lowell Observatory, Flagstaff, Arizona

Petters: Dear John,
I would apply Occam's razor in this case, namely, if there is a simple explanation already for a given phenomenon and this explanation already fits quite well with all known data, then there is no need to consider a more complex, different theory to explain the phenomenon. One of the challenges facing the theory of tired light (in which light loses energy as it travels over vast distances) is that its loss of energy would cause changes in objects that are not consistent with observational data. See the critique by Dr. Edward Wright:

Q: How much innovation do you feel the children seem to be receptive to in your village social environment compared to, say, Belmopan or Mexico City? I happen to carry a fascination with Belize. Thank you. Henry Rutgers, Emeryville, California

Petters: Dear Henry,
About two weeks ago, we ran a computer assembly course for kids from 11 to 19 years old. About 102 of them took the course, and they came from every district in the country. They had a fantastic time and wanted more. I believe that kids in Mexico would have a similar reaction.

Q: I enjoyed the NOVA scienceNOW segment on your work. My question relates to Earth-based imaging of the cosmos with optical instruments such as orbiting telescopes. Would these images be affected by gravitational lensing? Are we truly imaging the distant objects as they would actually appear "up close and personal?" If lensing does affect the light from distant objects, how do we compensate for such affects when imaging? George Grigonis, Feasterville, Pennsylvania

Petters: Dear George,
I am glad that you enjoyed the segment. Yes, the Hubble Space Telescope has found a lot of gravitational lensing effects such as multiple images of the same background source. One is imaging the object up close and, in many cases, the object (e.g., quasar) is so far away that it would not be resolved without the presence of a gravitational lens.

In general, gravitational lensing would cause distortions in the shape of the object as well as shift its position. However, there are models one assumes as representing the shape, etc. of the unlensed source. In fact, the nature of the unlensed source is often inferred by comparison to similar objects that are not lensed.

Q: Does your work touch on the "braneworld" gravity model, which brings up the idea of a fourth dimension of space? Sheena Cooke, St. Louis, Missouri

Petters: Dear Sheena,
Yes. Charles Keeton and I worked out a way of detecting braneworld black holes using their gravitational action on light. These black holes would create ripples in the energy spectrum of the light that are similar to the ripples created by a pebble dropped in a pond.

Q: Could the new CERN collider possibly create miniature black holes? If so, would they potentially be dangerous? Also, what would their creation in such a setting tell physicists? Anonymous

Petters: It is difficult to create tiny black holes. If the Large Hadron Collider (LHC) does generate such objects, they would evaporate almost instantly. Their existence would then be inferred only from the radiation they produce, called Hawking radiation, so they pose no danger.

The type of tiny black holes in the work by Dr. Keeton and myself are actually so massive that they cannot be generated by the LHC. These black holes, though tiny, have the mass of asteroids. Despite this, back-of-the-envelope calculations show that they would likely pass through the Earth with only a subtle impact on atoms. So, again, nothing to worry about. If a tiny braneworld black hole is found, then it would support the hypothesis that physical space has more than three dimensions.

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