Quantoken asked what's new with the observed cosmic strings - his or her personal theory is that CSL-1 "was really just bird shit causing the original telescope to record a slightly distorted image".
The next debater immediately pointed out a new article astro-ph/0503120:
The article first of all confirms that there are no cosmic strings seen in the microwave background whose tension would exceed a certain bound and whose velocity is smaller than 0.7c or so. Then they focus on the neighborhood of CSL-1, the double galaxy conjectured to be a result of gravitational lensing by a cosmic string. Yes, they use the same coordinates from Mark Jackson that I published in the previous blog article.The result?
- They observe the discontinuity of the microwave background temperature near the cosmic string with *2 sigma* significance which may or may not be a sign of the cosmic string. The whole CSL-1 double galaxy fits into one pixel of WMAP or so, so they have to use 4 pixels around, and the precision is not great. PLANCK is expected to be twice as sensitive. The cosmic string would have to move by velocity higher than 0.94c to fit the data.
On Thursday, Henry Tye was giving a nice talk at the Duality Seminar about the cosmic strings. It included a lot of new interesting information about the simulation of cosmic string networks, about the WMAP - cosmic string relation described above, and so forth. He also said that the number of cosmic strings from an Abelian i.e. U(1) Higgs model in the visible Universe should be 40 plus minus a few. If it's not fourty, the strings must be strings from string theory, some people say! ;-)
Many well-known physicists - like Cumrun Vafa, Hiroshi Ooguri, Juan Maldacena (who was speaking at MIT which I unfortunately missed), Henry Tye, Jacques Distler (interesting visitors, aren't they?!) - discussed the nature of the Hartle-Hawking state. Incidentally, one of the results is that Jacques' viewpoint that the conformal factor makes Euclidean quantum gravity inconsistent was largerly debunked, if Jacques allows me to say. We seemed to agree that the problems can't survive in anti de Sitter space where the things seem to work, and it has also been explained that the reason why it works is not because of the negative cosmological constant term (one would in fact need a positive cosmological constant if this term should be able to cure the unboundedness of the action from below).
Now we returned from the dinner with the speaker at Sushi Cafe (Hirosi, Henry, Jacques were the more senior people). The debates were very interesting - cosmology, string theory, outsourcing of string theorists to India, increasing capacity of memory chips, microprocessors, hard disks, and so forth.
Larry Summers and the physicists
Also, before the dinner, between 6:15 pm and 7:00 pm, Larry Summers debated roughly 100+ physicists in the physics library. Lisa Randall introduced the president - and I think that she was pretty balanced. Everyone I talked to has been satisfied with Summers' answers, and everyone said he was nice and so on. No doubt, a hypothetical dissatisfaction with the president is partially another example of the science wars - the disagreement between hard sciences on one side and soft sciences on the other side; of course, economics is counted as a hard science, especially in Larry's edition.
Let me mention several highlights. Someone was asking whom should a student or scholar try to contact if she or he faces some grievances or discrimination of any kind - someone outside the "political hierarchy" of the school. Summers explained that there exists the ombudsperson at Harvard. An instant vote proposed by Summers immediately revealed that 2/3 of the people did not know that the ombudsperson existed (I was among the ignorant two thirds). Another girl who spoke afterwards showed that even the important people at Harvard did not know that the ombudsperson existed.
Although Summers has said many sentences that were more politically correct and polite than informative ;-), he also stated many important things that were not affected by PC. He defined his vision of Harvard and sciences at Harvard, and he insisted that the policies must be effective, Harvard must be the leader, and other schools will undoubtedly follow this instutution every time Harvard invents something that works (Yale's support of the students from poor families is a recent example). Other questions led Summers to explain how the hiring decisions are made; how the support of the poorer scholars and those with children is working now and how it will work in the future.
At the end, Summers has pointed out that the men (and women) who attended the meeting are likely to be a part of the solution. In other words, the likely parts of the problem are those who did not attend. The last thing I have to mention - and the relation of this sentence with the previous sentences is purely coincidental if any - is that Dan Fisher did not attend. ;-)