My first #textbook
Recently, I published my first textbook: "Variational approach to gravity physics: from Newton to Einstein and beyond", by Springer.
The title speaks for itself: this book deals also with General Relativity, which cannot be too surprising. A significant part of my daily work, in fact, is about this subject, be it in the form of using it, as in the Gaia mission, or in that of testing it, with dedicated experiments like the proposed AGP mission.
Obviously, I am trained for this job, but this does not mean that I understand everything about general relativity. This brings us to the origin of this book which, as like as that of many other books, I suspect, is rooted in the many unanswered questions left from the university courses, and in the difficulty to find a book that could fit my personal view of this subject.
One of the things that I always found so difficult to accept was the apparently unbridgeable gap between Newtonian gravity and relativistic gravity. Intuitive concepts like forces, masses, accelerations on one side then... everything is overturned and changes to a geometric interpretation coming, apparently, from nowhere.
A giant leap for a poor physics student, with nothing in between!
When you grasp the concepts of relativistic gravity, however, there is always the reassuring discovery that, by requiring the compatibility with Newtonian physics at slow speeds in weak gravity fields, also this strange world have some connection with the previous, familiar one.
It looks like, after having decided to jump on the other side of a ravine, when on the other side you realize that a small invisible bridge connects the two ends. So why in the world did you decide to make the jump in the first time? It requires an act of faith like that in "Indiana Jones and the Last Crusade". But it's... disturbing.
Then you remember classical mechanics as presented in the Lagrangian approach, with the quite reasonable principle of least action. And that general relativity can be shown also in such framework. But usually the Lagrangian/Hamiltonian, that is the variational approach, in undergraduate courses is presented only for the equations of motion, whereas in relativistic equations you used it also for the field equations. So... maybe... it can work on the "Newtonian side" as well, mmm... let's try... yes!
In the meantime, you realize that this approach and its evolution from Newton to Einstein (and beyond) can be easily understood in terms of a parallel evolution of the three fundamental principles of covariamce, relativity, and equivalence. And while you realize that Physics is all about a model built with the right mathematical tools, you can also bargain an additional grasp on why the apparent difficulty of transiting from the Euclidean geometry to the differential geometry of relativistic physics it's a matter of convenience.
I believe that it was Albert Einstein who said that "If you can't explain it simply, you don't understand it enough." I hope I was able, in this book, to explain it simply enough for undergraduate students.
For more information: http://www.springer.com/gp/book/9783319512099
The title speaks for itself: this book deals also with General Relativity, which cannot be too surprising. A significant part of my daily work, in fact, is about this subject, be it in the form of using it, as in the Gaia mission, or in that of testing it, with dedicated experiments like the proposed AGP mission.
Obviously, I am trained for this job, but this does not mean that I understand everything about general relativity. This brings us to the origin of this book which, as like as that of many other books, I suspect, is rooted in the many unanswered questions left from the university courses, and in the difficulty to find a book that could fit my personal view of this subject.
One of the things that I always found so difficult to accept was the apparently unbridgeable gap between Newtonian gravity and relativistic gravity. Intuitive concepts like forces, masses, accelerations on one side then... everything is overturned and changes to a geometric interpretation coming, apparently, from nowhere.
A giant leap for a poor physics student, with nothing in between!
When you grasp the concepts of relativistic gravity, however, there is always the reassuring discovery that, by requiring the compatibility with Newtonian physics at slow speeds in weak gravity fields, also this strange world have some connection with the previous, familiar one.
It looks like, after having decided to jump on the other side of a ravine, when on the other side you realize that a small invisible bridge connects the two ends. So why in the world did you decide to make the jump in the first time? It requires an act of faith like that in "Indiana Jones and the Last Crusade". But it's... disturbing.
Then you remember classical mechanics as presented in the Lagrangian approach, with the quite reasonable principle of least action. And that general relativity can be shown also in such framework. But usually the Lagrangian/Hamiltonian, that is the variational approach, in undergraduate courses is presented only for the equations of motion, whereas in relativistic equations you used it also for the field equations. So... maybe... it can work on the "Newtonian side" as well, mmm... let's try... yes!
In the meantime, you realize that this approach and its evolution from Newton to Einstein (and beyond) can be easily understood in terms of a parallel evolution of the three fundamental principles of covariamce, relativity, and equivalence. And while you realize that Physics is all about a model built with the right mathematical tools, you can also bargain an additional grasp on why the apparent difficulty of transiting from the Euclidean geometry to the differential geometry of relativistic physics it's a matter of convenience.
I believe that it was Albert Einstein who said that "If you can't explain it simply, you don't understand it enough." I hope I was able, in this book, to explain it simply enough for undergraduate students.
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