Replies

I never got to finish that previous conversation.Here it is:

Sir, I am afriad you don't understand GR correctly. While Einstein was indeed influenced by Mach's ideas, GR is not really a Machian theory, though it predicts some effects that are reminiscent of Machian ideas (like dragging of inertial frames). One can find some books that say that GR is Machian, but the general consensus is that it is not. In GR, uniform motion is relative, but accelerated motion is absolute --- just as in Newtonian physics. The question of whether something is rotating or not is an ABSOLUTE question with one and only one correct answer. Yes, one can go to a frame in which a rotating object looks like it is not rotating --- however, such a frame is not an inertial frame; more specificly, it is a rotating frame. And one can tell that it is so by looking at the "fictitious forces" that appear in that frame. It is absurd to say that the whole universe could be rotating about an axis that goes through the earth. Distant stars could only be kept in circular orbits about such an axis by some centripital force directed toward that axis. Here the people like Sungenis will babble about dragging of inertial frames. They say that the distant matter going around will drag the stars around the axis. Not so. Not least of the problems with this idea is that one cannot write down a global rotating coordinate system, since the time coordinate lines would become superluminal at some finite (and not so large) distance. To put it another way, if all the stars go around the earth every 24 hours, then stars more than a light-year away would be going faster than light. But all this is nonsense anyway. Anyone who has a solid grasp of GR knows that in it accelerated motion is an ABSOLUTE concept. Finally, let me say that I actually do research in areas that require GR. I have refereed papers for journals such as Classical and Quantum Gravity. As I said, I teach GR at the graduate level --- do you?

17 posted on 10/11/2005 6:58:42 AM PDT by smpb (smb)

I agree, there is some controversy as to whether GR is Machian. I should have stated that it contained Einstein's interpertation of Mach.

Still in GR there are no fictitous forces in rotation. They become real forces as described by Thirring, Barbour and Berlotti, Bondi, etc. Einstein invented GR specifically so he could relativize rotation (a shortcoming of SR). When you reduce to the approximation of a Post-Newtonian formulation, then you are more SR-like, but as a general principle, rotation is relative in GR.

As to the point at which velocities of the stars become superluminal, this is the Schwartzchild radius, and Bondi has demonstrated that a shell of matter at this radius represents the effect of the rest of the universe. This lends support to Thirring, Barbour Berlotti, etc.

This also lends support to the ideas that aether theory can reproduce many relativistic effects (i.e, frame dragging). It tends to reduce GR to a more local action as it is usually described. Aether theories, especially with graviton type gravity tend to be more local in action also, while Mach's principle is more universal. Never the less, the matter at the farther reaches of the universe do have an effect at the earth, it is just a matter of how to represent it.

Mark

Re 28: To put it another way, if all the stars go around the earth every 24 hours, then stars more than a light-year away would be going faster than light. But all this is nonsense anyway. Anyone who has a solid grasp of GR knows that in it accelerated motion is an ABSOLUTE concept.

"But all of this is nonsense anyway." A dismissal by assertion.

It is not a valid argument to question the motivation of the proponent--the truth of the proposition is independent of motivation. But....

When an idea is presented that attempts to overturn 300+ years of observations and serious human thought and when that idea is advanced to show that the Roman Catholic Church "has always been right in all theological and moral aspects", one may wonder what is going on here. Their motivation is NOT to provide a better understanding of our life and universe, but to promote a religious agenda.

The authors see the overthrow of heliocentrism as a moral crusade. Their objective is show an "ABSOLUTE" truth to bolster their faith in their notion of God and a Christian 'revealed truth', as 'proof' that Hindu and Buddhist and secular understandings are dead wrong. They offer a particularly weird manifestation of fundamentalism.

Mark, You are talking nonsense. Rotation is not relative in GR. Period.

By the way, Robert Bennett told me, when I pressed him, that he does not believe in either special or general relativity! I can send you the e-mail where he said this to me. Bennett talks (as you do) about the Lense-Thirring effect and the dragging of inertial frames, but the Lense-Thirring effect is something that exists in General Relativity and not in Newtonian physics. Yet Bennett says he believes in Newtonian physics and not General Relativity. He totally inconsistent!
He rejects GR and then appeals to a GR effect.

I just looked you up in the ISI database and find that no one named M.J. Wyatt has ever published a research paper in physics. There is an M.J. Wyatt who has published a few papers in engineering. What are your credentials for arguing about General Relativity with someone who has taught graduate courses in it at a major university? (In fact I am teaching it again next fall.) You have what some people call Chutzpah. Look, fellah. I do this stuff for a living. Do you also tell brain surgeons and airline pilots about the technicalities of their fields? Sorry to be harsh, but God is not served by his followers speaking nonsense.

Bennett is an ignoramus when it comes to physics and Sungenis is a bigger one. Sungenis wrote some brilliant theological works (like "Not by Faith Alone") but he is now dabbling in things he knows zippo about. He still obviously has the fundamentalist idea of every man his own Pope, except that instead of rejecting 2,000 years of Church Tradition, as he used to do as a fundamentalist, he now rejects 400 years of well established physics. Just as he used to think he could figure out the whole Bible on his own without the aid of Tradition, so now he thinks he can figure out the physical universe on his own without knowing what theoretical physicists have been up to for the last 400 years. Chutzpah to the nth degree.