General relativity includes a dynamical spacetime, so it is difficult to see how to identify the conserved energy and momentum. Noether's theorem allows these quantities to be determined from a Lagrangian with translation invariance, but general covariance makes translation invariance into something of a gauge symmetry. The energy and momentum derived within general relativity by Noether's presecriptions do not make a real tensor for this reason. Einstein argued that this is true for fundamental reasons, because the gravitational field could be made to vanish by a choice of coordinates. He maintained that the non-covariant energy momentum pseudotensor was in fact the best description of the energy momentum distribution in a gravitational field. This approach has been echoed by Lev Landau and Evgeny Lifshitz, and others, and has become standard. The use of non-covariant objects like pseudotensors was heavily criticized in 1917 by Erwin Schrodinger and others. 

Question: "Which of the scientists believed non-covariant energy momentum pseudotensor was the best description of energy momentum in a gravitational field?"

OPTIONS:
- no
- yes

Answer: "Erwin Schrodinger"

Response: no
After more than a year of effort, attorneys with Northwest Justice Project earlier this week told 25 families in a mobile home park here that they can keep their homes and no longer need to fear eviction. The East Wenatchee City Council has entered into an Interlocal Agreement with the Wenatchee Housing Authority authorizing the Authority to purchase and maintain the Mobile Park Plaza mobile home park. Located just north of the Wenatchee Valley Mall, the park had been threatened with closure for more than a year. "We cannot say enough about how relieved we are that this is over," said Manuel Luna, one of the residents of Mobile Park Plaza. "We were afraid that no solution would be found, and that our families would have no place to go. We are very grateful for the help of our attorneys. Without them, we would not have saved our homes. We are also thankful for the help of the Housing Authority, the City Council and Mayor Steve Lacy." Formerly owned by local businessman Dan Jennings, Mobile Park Plaza had been home to 45 low-income families, many of them Latino farm workers. In October 2000 Jennings gave the park residents notice of his intent to close the park effective November 30, 2001. While some park residents decided to move, others, including 25 families, organized an informal association to relocate or save their homes. Unable to afford private legal counsel, the families asked for help from legal services attorneys at the Northwest Justice Project and Columbia Legal Services. In the succeeding months, these attorneys worked with representatives of the Greater Wenatchee Housing Authority, the state Office of Community Development, Chelan County, the City of East Wenatchee, state legislators, Jennings and others to secure funding and find a solution. "There seemed to be a never-ending set of obstacles," said Patrick Pleas, an attorney with Northwest Justice Project. "Mr. Jennings had financial considerations, the City had growth and economic development considerations, and the State and Housing Authority had their own concerns. Thankfully, hard work and good will from all parties allowed us to find a solution that works for everyone." Northwest Justice Project and Columbia Legal Services are non-profit organizations that provide civil legal assistance to low-income individuals and families throughout Washington state. Members of the state's Access to Justice Network, these organizations work with thousands of volunteer attorneys to ensure that justice is available to those who face critical legal problems and can't afford private legal counsel. 

Question: "How many families left the Mobile Park Plaza before the fight to stay was organized?"

Response: "At least 20"
OPTIONS:
- no
- yes

A: no
According to the radar reconstruction, American 77 reemerged as a primary target on Indianapolis Center radar scopes at 9:05, east of its last known position. The target remained in Indianapolis Center's airspace for another six minutes, then crossed into the western portion of Washington Center's airspace at 9:10. As Indianapolis Center continued searching for the aircraft, two managers and the controller responsible for American 77 looked to the west and southwest along the flight's projected path, not east-where the aircraft was now heading. Managers did not instruct other controllers at Indianapolis Center to turn on their primary radar coverage to join in the search for American 77. In sum, Indianapolis Center never saw Flight 77 turn around. By the time it reappeared in primary radar coverage, controllers had either stopped looking for the aircraft because they thought it had crashed or were looking toward the west. Although the Command Center learned Flight 77 was missing, neither it nor FAA headquarters issued an all points bulletin to surrounding centers to search for primary radar targets. American 77 traveled undetected for 36 minutes on a course heading due east for Washington, D.C. By 9:25, FAA's Herndon Command Center and FAA headquarters knew two aircraft had crashed into the World Trade Center. They knew American 77 was lost. At least some FAA officials in Boston Center and the New England Region knew that a hijacker on board American 11 had said "we have some planes." Concerns over the safety of other aircraft began to mount. A manager at the Herndon Command Center asked FAA headquarters if they wanted to order a "nationwide ground stop." While this was being discussed by executives at FAA headquarters, the Command Center ordered one at 9:25. The Command Center kept looking for American 77. At 9:21, it advised the Dulles terminal control facility, and Dulles urged its controllers to look for primary targets. At 9:32, they found one. Several of the Dulles controllers "observed a primary radar target tracking eastbound at a high rate of speed" and notified Reagan National Airport. FAA personnel at both Reagan National and Dulles airports notified the Secret Service. 

Question: "By 9:25, FAA's Herndon Command Center and FAA headquarters knew two aircraft had crashed into the World Trade Center and they knew what was missing?"

OPTIONS:
- no
- yes

Answer: "Flight 77"

Response:
yes