EINSTEIN RESPONDS TO A STUDENT, EXPLAINING A CENTRAL TENET OF RELATIVITY.
The schoolboy David Cumberland had answered a test question saying that vertical lines are parallel; his answer, however, was marked as incorrect by his teacher on the grounds that the lines would converge at the earth's center. After Cumberland insisted he was correct, the teacher made a deal with him: if he could find an authority that would support his claim, his grade would be changed.
Cumberland, apparently quite an enterprising young student, wrote to Einstein asking if vertical lines are indeed parallel and Einstein, in the present letter, responded, using relativity theory to provide support for the student’s test answer:
October 28, 1950
Mr. David Cumberland
924 S.E. 2nd Str.
Fort Lauderdale, FL
The concept “vertical” has meaning only with respect to the earth and cannot be used beyond that context. But there is the other concept, lines vertical to an euclidian plane. Those lines are parallel.
[signed] A. Einstein
One of the central components of relativity is that our understanding of space and time is subject to the relevant frame of reference. In this letter, Einstein uses relativity - namely a shift in the frame of reference - to prove that boy’s answer can be interpreted to be correct.
Upon showing his teacher Einstein’s letter, the boy’s grade was indeed raised.
One 8.5x11 inch sheet of Institute for Advanced Study letterhead. Usual folds; some water spots to page, not affecting text.
A WONDERFUL LETTER SHOWING A VERY HUMAN SIDE OF EINSTEIN AND EXPLAINING A BASIC CONCEPT OF RELATIVITY.
Price: $20,000 .