
BurtJordaan » April 25th, 2017, 9:34 am wrote:And in a nonmath fashion, if at all possible.
vivian maxine » 25 Apr 2017, 23:17 wrote:Truth to tell, though, I don't think it's so much that I do not understand it as that I do not believe much of it. Can those be the same thing?
mitchellmckain » 25 Apr 2017, 21:33 wrote:The idea that one should start with GR rather than SR is bizarre in the extreme to me. SR is basic to so many subjects and the mathematics is simple algebra.
BurtJordaan » 25 Apr 2017, 17:34 wrote:I will leave it here and invite opinions on the main topic, before going deeper into what the isotropy of space, spacetime structure, and their visualization aids might mean.

BurtJordaan » April 26th, 2017, 7:57 am wrote:vivian maxine » 25 Apr 2017, 23:17 wrote:Truth to tell, though, I don't think it's so much that I do not understand it as that I do not believe much of it. Can those be the same thing?
Maybe. People that understand it mostly believe relativity, not because it is dogma, but because experiments support it. Understanding the theory to some degree makes it a lot easier to understand the experiments.
BurtJordaan » April 26th, 2017, 8:27 am wrote:mitchellmckain » 25 Apr 2017, 21:33 wrote:The idea that one should start with GR rather than SR is bizarre in the extreme to me. SR is basic to so many subjects and the mathematics is simple algebra.
The problem as I see it, is that the present system may work for formal students, but it apparently has a very low yield for the informal student. The majority of our members seem to (relativistically) belong to the latter group.
Is there a better way for them?
someguy1 » 26 Apr 2017, 05:48 wrote:BurtJordaan » April 25th, 2017, 9:34 am wrote:And in a nonmath fashion, if at all possible.
But that's the essence of the problem. Physics is inherently mathematical. Intuitive or qualitative explanations are bound to be insufficient.
Dave_Oblad » 26 Apr 2017, 21:17 wrote:So we have a Lab in a flat even Space Continuum (no outside gravity). When the Lab is NOT being accelerated, the continuum blowing through us is steady and consistent (isotropic).
someguy1 » April 25th, 2017, 10:48 pm wrote:BurtJordaan » April 25th, 2017, 9:34 am wrote:And in a nonmath fashion, if at all possible.
Perhaps that's the source of the difficulty.
People want a qualitative or intuitive grasp of a subject that is inherently mathematical. Any qualitative explanation of relativity is not relativity itself.
Classical physics is the same. What is Newtonian gravity without math? "Matter attracts other matter." You can't do any better than that. To understand Newton's theory of gravity you must say, "Matter attracts other matter with a force equal to the product of their masses divided by the square of the distance between their centers, all of that times a constant." Or in the compact math notation, .
There is philosophical significance to this. Modern physics  that is, our best theories about the nature of the world  can not be understood without advanced math. And math is hard. Differential geometry, the math behind relativity, is an upper division or graduate level course for math majors. Tensor calculus and lots of it.
What does it mean that our very understanding of the world depends on being able to work with advanced math? Isn't that unfair to everyone else? Are the poets and artists not allowed to know how the world works? Why is that?
These are important questions.
We know from quantum theory that sometimes the ONLY thing you have is the math, and everyone argues about the intuitive meaning of the equations. Now that's mysterious!!
But that's the essence of the problem. Physics is inherently mathematical. Intuitive or qualitative explanations are bound to be insufficient.
Jorrie wrote:Hi Dave, from the above, can I assume that you reckon the "continuum blowing through us ... steady and consistent (isotropic)" is not detectable? That we cannot know how fast it is blowing through us or in which direction? That its 'blowing through' does not change the path of light beams, or the laser distance measurement in any direction?
Even SR is something where I learned more from my independent studies than in the classroom.

Dave_Oblad » 27 Apr 2017, 19:53 wrote:Ok, hope that wasn't too much detail.. pretty simple actually.
BurtJordaan » 26 Apr 2017, 19:00 wrote:Now let us stop the rocket's burn, so that you become weightless again. Repeat the same laser experiment and you should not be surprised to find that the isotropy of the space inside the lab has been restored. All six sides will again be at exactly the same distance from you than what they were before the rocket blast. This is the essence of the isotropy of space. There is more to it, but for now, this is nothing new. Einstein, Newton and Galileo would all have agreed with us. Or would they?

hyksos » April 27th, 2017, 3:51 pm wrote:
The early development of SR was actually extrapolating on electromagnetism as given by Maxwell's Equations. Maxwells equations are sinequanon for electromagnetism in physics. Well ... they are if all the magnets and wires involved are bolted to the laboratory desk. If you start moving around with magnets on moving platforms, and maybe even someone with a battery is moving along with said platform, Maxwell's equations break down.. and break down hard. This dirty secret is what Lorentz knew about, and where he enters stage left into this drama.
jocular wrote:As to the OP I have learned nearly all that I know of GR from forums such as this supplemented with reading around the subject in a loose way.
Hyksos wrote: What Einstein produced was a theory that contained no Aether at all, fully covariant, and mathematically consistent. The only remaining question was whether our universe acts that way or not.
Robert B. Laughlin, Nobel Laureate in Physics, endowed chair in physics, Stanford University, had this to say about ether in contemporary theoretical physics:
It is ironic that Einstein's most creative work, the general theory of relativity, should boil down to conceptualizing space as a medium when his original premise [in special relativity] was that no such medium existed [..] The word 'ether' has extremely negative connotations in theoretical physics because of its past association with opposition to relativity. This is unfortunate because, stripped of these connotations, it rather nicely captures the way most physicists actually think about the vacuum. . . . Relativity actually says nothing about the existence or nonexistence of matter pervading the universe, only that any such matter must have relativistic symmetry. [..] It turns out that such matter exists. About the time relativity was becoming accepted, studies of radioactivity began showing that the empty vacuum of space had spectroscopic structure similar to that of ordinary quantum solids and fluids. Subsequent studies with large particle accelerators have now led us to understand that space is more like a piece of window glass than ideal Newtonian emptiness. It is filled with 'stuff' that is normally transparent but can be made visible by hitting it sufficiently hard to knock out a part. The modern concept of the vacuum of space, confirmed every day by experiment, is a relativistic ether. But we do not call it this because it is taboo.
Einstein wrote:We may say that according to the general theory of relativity space is endowed with physical qualities; in this sense, therefore, there exists an Aether. According to the general theory of relativity space without Aether is unthinkable; for in such space there not only would be no propagation of light, but also no possibility of existence for standards of space and time (measuringrods and clocks), nor therefore any spacetime intervals in the physical sense. But this Aether may not be thought of as endowed with the quality characteristic of ponderable media, as consisting of parts which may be tracked through time. The idea of motion may not be applied to it.
Dave_Oblad » 29 Apr 2017, 02:04 wrote:As to the subject of my SpaceWind, we can call it SpaceTime, Aether or even a Field.
Faradave » April 28th, 2017, 8:44 am wrote:Hi Dave,
As you describe it, the two ships on parallel paths are at rest with respect to each other. End of discussion!
You can say they're moving or not* wtr to some other reference frame but they each share the same one. They're like two opposite walls of Jorrie's mobile lab. I don't see the need for "space wind".
*because you're free to declare that "other frame" to be the one that's "moving".
jocular » April 28th, 2017, 11:09 pm wrote:hyksos » April 27th, 2017, 3:51 pm wrote:
The early development of SR was actually extrapolating on electromagnetism as given by Maxwell's Equations. Maxwells equations are sinequanon for electromagnetism in physics. Well ... they are if all the magnets and wires involved are bolted to the laboratory desk. If you start moving around with magnets on moving platforms, and maybe even someone with a battery is moving along with said platform, Maxwell's equations break down.. and break down hard. This dirty secret is what Lorentz knew about, and where he enters stage left into this drama.
I have heard this but am finding it hard to find it discussed anywhere. You wouldn't have a link ,would you where this particular point is fleshed out?
Okay now you come to Maxwell's Equations for electromagnetic theory. Let me write down what we have. The first thing we have is F = q(E+... I'm sorry q times E plus V cross B is the force. And let me write down one other consequence.
Now comes the important question: This is the velocity of the particle according to whom?
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