One could consider the rest frame of the CMBR as an "absolute landscape" I suppose. One over which the Earth is hurtling at some rate, iirc.
On 8 February 2014 16:28, meekerdb <[email protected]> wrote: > On 2/7/2014 6:43 PM, [email protected] wrote: > > > On Saturday, February 8, 2014 12:44:30 AM UTC, Brent wrote: >> >> On 2/7/2014 2:45 PM, [email protected] wrote: >> >> >> On Friday, February 7, 2014 10:30:06 PM UTC, Brent wrote: >>> >>> On 2/7/2014 1:37 PM, [email protected] wrote: >>> >>> >>> On Monday, February 3, 2014 6:27:14 AM UTC, Brent wrote: >>>> >>>> On 2/2/2014 10:12 PM, [email protected] wrote: >>>> >>>> Namely that however you jig it, there's still going to >>>> be huge spacetime distortion representing the sun and a tiny one >>>> representing the earth, which - I thought - had to bias the objectively >>>> true relation between the sun and the earth for the earth being >>>> gravitationally dominated by the sun not the other way around. >>>> >>>> >>>> So the question was whether one could just consider the Sun, calculate >>>> the spacetime metric due to its mass, and then calculate the orbit of the >>>> Earth as an inertial path in that metric? In that case of course the >>>> answer is no. The metric has to take into account the mass of the Earth as >>>> well as the Sun. Just as in Newtonian theory, the Sun and the Earth, and >>>> Jupiter and the other planets all move around their mutual center-of-mass. >>>> The center-of-mass is roughly near the surface of the Sun on the side >>>> nearest Jupiter. >>>> >>>> Brent >>>> >>> >>> Hi Brent - Sure, but is it ok to look at the sun and the earth together, >>> purely as their geometry's in spacetime, and say "that one goes around that >>> one" to the same sort of accuracy we can say the earth goes around the sun >>> without invoking relativity. Or is doing that running foul of the basic >>> principles in play of relativity ? >>> >>> >>> I'm not sure what you're asking. The corrections to a simple >>> "stationary Sun, orbiting Earth" due to Jupiter are much bigger than any GR >>> effect. >>> >>> Brent >>> >> >> if you're willing to keep trying I would also like to...but please be >> assured I will understand anytime you no longer want to. So trying again >> here, I would first recap one sense of what this has been about.... >> >> - I related an experience I had a few years back, when some people much >> more knowledgeable than I in relativity...at least factually >> speaking...argued that relativity was a fundamentally different way of >> explaining the universe (with no dispute from me so far)....such that, you >> literally could not sensibly talk about frame-free visualizations. I >> responded that I thought that was only true up to a point, because for >> example, the spacetime geometry of a much larger and much smaller object, >> could be visualized as a single landscape for the purpose of saying >> something very general, like "that one goes around that one". >> >> Which they explicitly then ruled out. >> >> Of course, this statement was always untrue strictly speaking because >> both go round a common centre of mass. But the question here, is: >> >> - was that more knowledgeable source correct >> >> - was I correct >> >> - was one but not the other exclusively correct, if so which one >> >> - was there a good chance neither were correct, and you'd have to see >> what was actually said to be sure >> >> - Is what I am saying to you now, which I think is a fairly good capture >> of what I said then, correct .....so far as it goes >> >> >> My friend Bill Jefferys who used to teach astronomy at Univ of Texas says >> it doesn't matter what reference frame you choose as far as the physical >> events go, it just makes the math harder or easier. So sometimes you use a >> geocentric frame and sometimes a heliocentric frame and so forth... >> >> Brent >> > > but can you throw the relative character out of the window, and speak > of an 'absolute landscape' implied by relativity theory that is made up of > all the gravity wells, that definitely suggests a 'reality' that goes > beyond the principle of equivalence. In that, the landscape shows what's > big and what's small, so the relation between them, in one big picture. > > I ask this in context that acknowledges it wouldn't be any good > for resolving much useable knowledge about the world. In fact none at all, > save that reality does imply such a reality is really there. > > > True. Although this "absolute landscape" would look different according > to one's perspective (position, motion, etc) it hopefully represents the > intersubjective agreement of all possible observers. If you express this > landscape only in terms of invariants, not coordinates and not relative to > a particular observer or frame, then you could call it "absolute", but as > you note that tends to be a messy representation to work with, so we tend > to use some particular representation; the same way we navigate with flat > map projections instead of charting courses on globes. > > Brent > > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/groups/opt_out. > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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