ANNALS ANNALES - Academia Oamenilor de Stiinta din Romania

42 Mărgărit Pavelescu
5. THE GENERAL THEORY OF RELATIVITY
Even before he left the patent office in 1907, AE began work on extending and
generalizing the theory of relativity by trying to imbed the gravitation theory. The
special theory of relativity is consistent with the laws of electricity and magnetism, but
it is not compatible with the Newtonian law of gravitation.
This law says that if distribution of matter in a space region is changing, this change
has to be felt instantaneously in the universe. It results no only that it would be
possible to radiate signals faster than speed of light (fact not allowed by special
theory of relativity), but in order to understand what does it mean ―instantaneously‖ it
would be need to appeal to the concept of absolute or universal time at which the
special theory of relativity renounced in the favour of the personal time AE was aware
of it still from 1907 but only in the 1911 arrived to think seriously to it. He began by
enunciating the principle of equivalence, a postulate that gravitational fields are
equivalent to accelerations of the frame of reference.
For example, people in a moving elevator cannot, in principle, decide whether the
force that acts on them is caused by gravitation or by a constant acceleration of the
elevator. When he came back to Zurich in 1912 he has had an inspiration moment
when he understood that this equivalence could be valid of the space-time geometry
would be curve not plate how it was considered till then!
His extraordinary idea was that mass and energy would contort the space-time in a
way that must be determined [2], [3]. Together with Grossman [2], AE studied the
theory of curve surfaces that was developed by mathematician Riemann. But this did
not think at a space more than three dimensions.
AE understood that space-time has to be curved and this is a system with four
dimensions. AE and Grossmman have written a paper from which come out that the
gravitational forces are the expression of the fact the space-time is curve. But owing
to en error of AE they could not find the equations that make the connection between
the curve of space-time and the mass and energy.
AE continued his work to Berlin and in 1915 after a long discussion with David
Hilbert, he could find the right equations. Interesting is the fact that David Hilbert
himself came off to find the correct equations a few days ago than AE, but he
recognized that the paternity of idea belongs to AE [3].
The new theory of space-time has received the name of general theory of relativity in
order to make it different of special theory of relativity that did not imbed the effects of
gravitation.
It is incomparable more difficult than previous one, owing to the mathematical
complexity introduced by tensorial algebra and Riemannian geometry. There is belief
that in époque only 10 scientists have understood the new theory.
By the contrary, the special theory of relativity can be understood by any student
from the Physics Faculty with an adequate education. It has to be said that before to
have success, the general theory of relativity was strong denied by scientific
community from Germany.
Such, at a moment it appeared a book signed by 100 authors in which the theory was
complete negated. When AE has heard about it, he declared: ―I am right, because if
not, it would be sufficient only one author!‖.
The full general theory of relativity was not published until 1916.