In the rotating frame where you are at rest and the universe is spinning, there is a centrifugal force on the rest of the universe trying to tear it apart. But there is also a Coriolis force that is twice as large. That Coriolis force is strong enough to cancel the centrifugal (that's one factor of one) and enough to provide the centripetal acceleration to keep the contents of the universe in orbit around your head (that's the other factor of one).WCOLtd said:How come when I spin around, the universe doesn't fly apart as if its rotating around me? Why is my frame of reference that I am at rest and its the universe spinning around me not valid?
As @jbriggs444 mentioned, it is a perfectly valid frame, it is just non-inertial. If you are using the right kind of mathematical objects, called "tensors", then you can write the laws of physics the exact same way in inertial and in non-inertial frames. However, most of the high-school and undergraduate physics that you will see does not use tensors. So in those math classes the laws of physics look quite a bit different in inertial and non-inertial frames.WCOLtd said:How come when I spin around, the universe doesn't fly apart as if its rotating around me? Why is my frame of reference that I am at rest and its the universe spinning around me not valid?
Roughly speaking, that accelerometers at rest measure 0 acceleration. To get more detailed would probably go beyond a B thread.WCOLtd said:What defines the inertial frame?
That is the way most people feel, but Nature doesn't care about our apriori strong affinities.WCOLtd said:It seems to me from an apriori perspective that Mach's Principle is so strong. That's why I have a strong affinity to it.
Mach's Principle is a concept in physics proposed by Austrian physicist Ernst Mach. It suggests that the inertia of an object is determined by the distribution of all the matter in the universe. In other words, the rotation and motion of an object are dependent on the rest of the mass in the universe.
Mach's Principle explains the rotation of the universe around us by stating that the mass and inertia of our local reference frame (Earth and its surroundings) are influenced by the distribution of matter in the rest of the universe. This means that the rotation of the universe around us is a result of the inertia of all the mass in the universe.
Mach's Principle is still a topic of debate among physicists. Some argue that it is not a fundamental principle, but rather a consequence of other physical laws. Others believe that it is a crucial concept for understanding the nature of gravity and the structure of the universe.
There is currently no direct evidence that supports Mach's Principle. However, it is consistent with Einstein's theory of general relativity and has been used to explain certain observations, such as the rotation of galaxies and the cosmic microwave background. Additionally, some scientists believe that the principle is necessary to reconcile the laws of physics with the observed structure of the universe.
Mach's Principle is often compared and contrasted with other theories of gravity, such as Newton's theory of gravity and Einstein's theory of general relativity. While it shares some similarities with these theories, it also has some crucial differences, particularly in its emphasis on the role of the universe as a whole in determining the motion of objects. Further research and experimentation are needed to fully understand the relationship between Mach's Principle and other theories of gravity.