Good Relativity Q&As

[Nesti (Mark)]

A Gravity Probe B link.

Beyond questions about observable phenomenon, there are quite a few questions directed toward the core of existence. Correctly, Dr. Sten Odenwald has addressed them honestly, we really don't know.

A lot of good, simple questions. A lot of good straight answers.

http://einstein.stanford.edu/content...ity/qanda.html

[bojan]

Mark, thanks for this link, it is very interesting.
All our "anti-relativists" should read what's there very carefully :-)
And others, of course.. including me :-)

[Robh (Rob)]

Thanks Mark,

Excellent resource.
It's going to take a while to get through these!

Regards, Rob

[Nesti (Mark)]

My pleasure gentlemen.

Sorry to do this to you, but, while pondering the meaning of special and general relativity, have a think about the core of gravity, mass, matter...everything!

“In this way, Einstein’s gravity can easily be looked upon as a fictitious force; in that the force itself is applied to spacetime and not the objects within spacetime. Whereas Newtonian gravity states that objects apply the force of gravitation between masses; which is direct. In this simple way, we can now see that gravitation is not the force itself, but the outcome of mass applying an influence on spacetime. So if we now apply this information to the unification idea, we see that there may be an issue in attempting to unify the equations which describe our three particle forces (strong, weak and electromagnetic), with equations describing a ‘secondary affect’, gravitation. And although this concept has been well understood for some time, the simple fact that we really do not understand why or how mass exerts influence over spacetime is a good reason to suggest that unification won’t happen unless we can answer the how and why questions in the first place... It becomes a somewhat complex issue to visualize, however, there is something very important worth pondering, as it is at the very heart of gravitation and perhaps relates to the construction of reality itself. If all the laws are constant and consistent throughout the universe, and through the activity of gravitation, mass can be moved whilst in uniform motion – a change observed from a separate frame of reference, brought about from the presence of matter and the subsequent warping (negative divergence) of spacetime - then what does the warping, where does the energy come from? Einstein side-stepped this issue, by stipulating that there is no absolute space or time in which we can measure relative aspects against, but gravitation is a field, and if so, a field held within what then? This is precisely where Einstein proclaimed the importance of the synchronization of the clocks comes into play, as it provides a way-out of the logic labyrinth. Also, how the metric changes at each point is spacetime, it is a though spacetime knows how much mass is there in the first place, as well as the density. The metric specifies how much spacetime needs to bend at any given distance and Einstein did incorporate conservation into the metric (Einstein tensors include the Ricci tensors by Gregorio Ricci-Curbastro, which in turn, include the Bianchi identity which defines conservation), but here again we must recognize that mathematics is only a language used in order to describe a physical process, it is not the process itself. I’ll give you an example; Einstein’s formulas for relativity consist of many parts, each representing different functions, such as the Christoffel symbols (Elwin Bruno Christoffel’s work on tensors), these provide a means of inserting forces into spacetime, without being affected by any changing curvature, and the derivatives, which calculate how the curvature must change according to the metric. These are all amazing mathematical structures, but they are no more gravity than these words are your understanding of them; mathematics is a descriptive language, it is not a physical act. So could it be, that at the fundamental level, some hidden energetic process exists, which coordinates both the bending of spacetime and the unaccountable quantum behavior as we will soon see, and might that mechanism be involved with other mystery processes? Some of the most recent theories are taking into account that spatial dimensions are perhaps another manifestation of energy (beyond that of a stress-energy tensor and mass-energy content), and in the same manner that energy can be converted to matter and back again, so too could spatial dimensions be enfolding and unfolding energy into matter.”

[astroron (Ron)]

Thanks Mark I just read some of the answers and my head hurts

[Chippy (Nick)]

Thanks for the link!

[sjastro]

Interesting Mark including the links.

Originally Posted by Nesti

“In this way, Einstein’s gravity can easily be looked upon as a fictitious force; in that the force itself is applied to spacetime and not the objects within spacetime. Whereas Newtonian gravity states that objects apply the force of gravitation between masses; which is direct. In this simple way, we can now see that gravitation is not the force itself, but the outcome of mass applying an influence on spacetime.

Spacetime is an extension of Newtonian gravitational potental which defines the gravitational field.

Both concepts relate to how a particle (object) interacts with a gravitational field.
The force is applied to the particle, the outcome is spacetime or gravitational potential.

..........a change observed from a separate frame of reference, brought about from the presence of matter and the subsequent warping (negative divergence) of spacetime - then what does the warping, where does the energy come from?

In a gravitational field the particles travel on geodesic paths which define the equation of motion. Since the particles move in inertial frames where the sum of the external forces equals zero, why is energy required for warping?

The question has much more relevance for spacetime expansion. Before it was discovered the Universe was expanding at an accelerating rate, expansion was considered an inertia effect requiring no external forces or energy.

Now that expansion is found to be accelerating the "where is the energy coming from" is pertinent.

I’ll give you an example; Einstein’s formulas for relativity consist of many parts, each representing different functions, such as the Christoffel symbols (Elwin Bruno Christoffel’s work on tensors), these provide a means of inserting forces into spacetime, without being affected by any changing curvature, and the derivatives, which calculate how the curvature must change according to the metric.

The equation of motion of a particle on a geodesic path involves the sum of real and fictitious forces. Since the frame is inertial the sum equals zero. The real force contributes to accelerating the particle through the field, the "fictitious" forces are the terms which contain the Christoffel symbols.

If you change the curvature, you change the metric which in turn changes the equation of motion.

These are all amazing mathematical structures, but they are no more gravity than these words are your understanding of them; mathematics is a descriptive language, it is not a physical act.

The scientists who mathematically developed Quantum Mechanics would be turning over in their graves.

Regards

Steven

[Nesti (Mark)]

sjastro yeah, LOL.

I found it r-e-a-l-l-y interesting that Einstein used Hendrick Lorentz and George FitzGerald's 'Local Time' - which came from the study of Albert Michelson and Edward Morley's work on electromagnetism - to formulate Special Relativity within a common time frame with which to provide some reference, and later he did similar in General Relativity. However, once formulated, he then abolished its’ notion altogether, presenting the argument that there is no absolute (universal) time with which we can measure against, nor fixed space. So this now goes all the way back to Galileo's principle of relativity, where he discusses uniform motion is relative, and that there is no absolute and well-defined state of rest.

So, use intuitive and logical processes to establish an absolute space and time, then formulate a theory which uses approprate transformations, then abolish the notion of absolute space and time to make your theory a self fulfilling prophecy.

Sorry if I've created confusion by dragging in SR to demonstrate a point.

You've gotta admit, that's pretty tricky!

[Nesti (Mark)]

Originally Posted by sjastro

Interesting Mark including the links.

The scientists who mathematically developed Quantum Mechanics would be turning over in their graves.

Regards

Steven

ROFLMAO - perhaps they should have thought twice about supporting Renormalization ???!!!

As my tutor once said "fiddling with the math isn't science".

Cheers
Mark

[Enchilada]

Originally Posted by Nesti

ROFLMAO - perhaps they should have thought twice about supporting Renormalization ???!!!

Sorry, I do fail to see the humour. Maybe you should look into a bit more detail of why Kenneth G. Wilson at CalTech discovery (and possible applications) in 1982 actually won him the Nobel Prize in Physics.
It was his innovative method of statistical physics was a major advancement and solved the problem of the so-called Kondo effect regarding electrical resistance against temperature approaching absolute zero. Another is the behaviour of liquid Helium at very low temperatures I.e. Climbing up the container walls. He also solved several of the problems in quantum mechanic fields - one being actually being ; what does renormalization mean?

[Nesti (Mark)]

End of thread for me. The risk of catching 'Swine Flu' is too great.