## lördag 15 februari 2014

### New View of Motion under Gravitation vs Einstein's View

Stephen Hawking: The happiest experience of my life testing General Relativity in free fall under the illusion of zero gravitational force.

If we compare the New View of Motion under Gravitation presented in recent posts with Einstein's General Relativity, we find

New View:
1. gravitational potential $\phi (x,t)$ primordial,
2. matter with density $\rho (x,t)$ from $\phi (x,t)$ by $\rho (x,t) =\Delta\phi (x,t)$: action local in space and time,
3. gravitational free fall motion along trajectory $x(t)$ from $\phi$ by $\ddot x(t)=-\nabla\phi (x(t),t)$,
4. $\rho\nabla\phi$ gravitational force,
5. Newton's 2nd law $\rho\ddot x= - \rho\nabla\phi$ consequence of 3.
6. Equivalence Principle consequence of 3.
7. definition of non-gravitational force $F\equiv \rho\ddot x + \rho\nabla\phi$,
8. Euclidean space coordinate $x$ specified up to translation with constant velocity,
9. $\dot x =\frac{dx}{dt}$ derivative with respect to universal time differential $dt$,
10. gravitational potential satisfies evolution equation: $\Delta\dot\phi +\nabla\cdot (u\Delta\phi )=0$, where $u(x(t),t)=\dot x(t)$ is velocity.
General Relativity:
• Equivalence principle ad hoc assumption: gravitational force = inertial force,
• matter distribution primordial,
• curved space-time from matter distribution: action at distance,
• motion as free fall along geodesic in curved space time under zero gravitational force,
• non-zero gravitational force illusion because gravitational force = inertial force.
The New View starts from gravitational potential and gravitational force as primordial and ends with matter by action local in space and motion as reality. Newton's 2nd law and the Equivalence principle are consequences of the New View and not ad hoc assumptions. The coordinate system is Euclidean without rotation since centrifugal forces are missing in 3, and with origin and translation at constant velocity free to choose. One such system is determined by the fixed stars, assuming no rotation of the visible Universe. Notice that a free fall trajectory $x(t)$ is immaterial and thus exists as solution to $\ddot x(t)=-\nabla\phi (x(t),t)$ also in vacuum where $\Delta\phi (x(t),t)=0$.  The evolution equation for $\phi$ then express that matter moves along immaterial free fall trajectories. No medium for propagation of gravitational forces is required, because all action is local and trajectories are immaterial.
Free fall trajectories could be used to locally define curved coordinate systems, but reason to do so lacking.

General Relativity starts from matter creating curved space-time by action at distance gearing motion and ends with gravitational force as illusion. Einstein was led to General Relativity from the idea of extending Special Relativity with zero gravitation to the case non-zero gravitation by changing the coordinate system to give the illusion of zero gravitation. The Equivalence principle as ad hoc assumption serves to identify gravitational force with inertial force. Einstein based his physics on thought experiments with people being stuck in elevators in free fall.  Einstein put the emphasis on the choice of coordinate system, as if real physics could depend on the coordinates chosen to describe physics.

Einstein thus developed a gravitational theory based on an idea that gravitation is illusion. No wonder if  General Relativity is also only illusion and not physics.

Recall that Einstein fell in love with the idea of gravitational force as illusion, viewing it as the happiest thought of my life:
• The gravitational field has only a relative existence... Because for an observer freely falling from the roof of a house -at least in his immediate surroundings - there exists no gravitational field.
Einstein's example shows the consequences of falling in love too much with an idea, in particular with an idea that serves your preconceived agenda.

Recall that modern theoretical physics is paralyzed by the incompatibility of general relativity with quantum mechanics, but physicists thoroughly trained to confess to the dogma of general relativity are unable to get out of the dead-lock. And so the happiest thought of Einstein's life has brought death to physics, in accordance with the logic of tragedy.

Occasionally you may hear a famous physicist like Feynman confessing: I still can't see how Einstein thought of general relativity, while media like Times sells copies by propagating big mystery physics:
• Even now scientists marvel at the daring of general relativity.
• But the great physicist (Einstein) was also engagingly simple, trading ties and socks for mothy sweaters and sweatshirts.
• He tossed off pithy aphorisms ("Science is a wonderful thing if one does not have to earn one's living at it") and playful doggerel as easily as equations.
• Viewing the hoopla over him with humorous detachment, he variously referred to himself as the Jewish saint or artist's model.
• He was a cartoonist's dream come true.