Detailed Instructions: In this task, you need to write an incorrect answer to the given question. Along with the question, you are also given the correct answer(s) and the associated paragraph. An incorrect answer should be closely related to the content of the paragraph and/or the question but will not truthfully answer the question. Your incorrect answers should be similar to the given correct answer such that it will pose a challenge for students to distinguish the two. A good incorrect answer should prevent those who skip the paragraph from answering the question. The incorrect answer should not be trivial, in the sense that they should not be easily eliminated without reading the paragraph.
Q: Paragraph- Sent 1: General relativity includes a dynamical spacetime, so it is difficult to see how to identify the conserved energy and momentum.
Sent 2: 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.
Sent 3: The energy and momentum derived within general relativity by Noether's presecriptions do not make a real tensor for this reason.
Sent 4: Einstein argued that this is true for fundamental reasons, because the gravitational field could be made to vanish by a choice of coordinates.
Sent 5: He maintained that the non-covariant energy momentum pseudotensor was in fact the best description of the energy momentum distribution in a gravitational field.
Sent 6: This approach has been echoed by Lev Landau and Evgeny Lifshitz, and others, and has become standard.
Sent 7: The use of non-covariant objects like pseudotensors was heavily criticized in 1917 by Erwin Schrodinger and others. 
Question: When did the standard approach to energy momentum become criticized?.
A:
1971.