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geordief last won the day on August 31 2018

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  1. Sure,your description of her "house rules" does sound a little maniacal but on the one hand her private life (and that of her household ) is of no real interest to me personally or hopefully to anyone else immune to prurience. And secondly I cut her slack on account of the strange conditions she lives in - that I would like to a kind of prison environment. I think she is a class act because she copes with her harsh conditions without real complaint when the rewards are hard to discern (apparently she considers that she has a duty to the country-I think she is deluded but I respect her fortitude ) The issue of Monarchy versus other forms of self government is what concerns me most -the rest is incidental.
  2. We Brits don't like the Monarchy (well , 'lisabeth is a class act) Would you have room for any more boarders?
  3. That and gaining more power when no one from the Repubs objects.Divide and conquer
  4. Yes, a better search doesn't bring up anything at all to back that up. Had there been anything in it at all I would have found it very interesting ...but no news is no news.
  5. Does GR have anything to say about particle physics? When two particles collide is it just a case of going through the debris and looking for new objects or are there simple collisions where it is possible to predict when the initial conditions are known? I am reading through Einstein's Popular Exposition and have come across this quote "The only statements having regard to these points which can claim a physical existence are in reality the statements about their encounters. In our mathematical treatment, such an encounter is expressed in the fact that the two lines which represent the motions of the points in question have a particular system of co-ordinate values, x1, x2, x3, x4, in common" https://www.bartleby.com/173/27.html which seems to describe the "collision" of two world lines... (I am also learning that AE was a strong user of hallucinogenetic drugs and am quite astonished not to be aware of this until now https://vocal.media/futurism/11-things-you-may-not-know-about-albert-einstein I researched this when I came upon his introduction of the "reference-mollusk" description in his book and thought "hold on a second here....what?" https://www.bartleby.com/173/28.html "This non-rigid reference-body, which might appropriately be termed a “reference-mollusk,” is in the main equivalent to a Gaussian four-dimensional co-ordinate system chosen arbitrarily" and thereafter )
  6. I am going through this section of Einstein's Popular Exposition of Special Relativity https://www.bartleby.com/173/10.html#txt1 "In the first place we require to determine the points Aand B of the embankment which are just being passed by the two points A'and B' at a particular time t—judged from the embankment. These points A and B of the embankment can be determined by applying the definition of time given in Section VIII. The distance between these points A and B is then measured by repeated application of the measuring-rod along the embankment" and have two questions I seem to need help with 1) What might be a rigorous set up of an experiment to show this scenario?(I am struggling with synchronizing the passing of the 2 points wrt to the observer's FOR) 2) Suppose we have an object moving at a relativistic speed wrt an observer.... This object emits a light signal which is both transmitted directly to the observer and is also reflected immediately **off another object which is at rest wrt the observer. Which signal does the observer see first? Do they both arrive simultaneously except for the retransmission time involved in the reflection process? **ie the spatial distance between the moving object and the reflecting object in the same FOR as the observer is vanishingly small.
  7. Is it possible to indicate what other factors might contribute to uniquely determining the local geometry? (no one factor is the unique determinant if I have understood correctly)
  8. Is the distribution of mass/Energy in the universe synonymous with the gravitational field? By that I mean ,if we attempted to visualize the gravitational field would we end up just using the arrangements of the galaxies and stars and say "that is what the gravitational field looks like.You are looking at it" (because some people seem to say the gravitational field is just a model -or a set of measurements, and others seem to say "no,it is as physically real as anything else ")
  9. No,I have given up* on that idea ( that there was a point that could be identified as the origin of spacetime allowing some kind of a privileged frame of reference) But I am still wondering whether the gravitational field** can be said to increase (or decrease) in extent over time in the same way that the universe itself is said to have expanded (and inflated) Did/does the magnetic field expand with the universe even if not from an "origin" as I wrongly suggested before ? *because it has been shown to be untenable. **am unclear whether we can talk about one gravitational field(They are after all supposedly infinite in extent)
  10. Is it possible/reasonable to assume that ,as Gravity first established itself (around T + zero seconds?) it came with a Gravity Field as part of the package ?(that Gravity and the Gravity Field were the same thing) So did the newly formed Gravity Field start off small and expand along with everything else? Does the analogy of the expanding cake in the oven apply to the Gravity Field(I have taken the raisins in the dough to represent Galaxies etc but could they equally well represent the Gravitational Field? ) Also , although it seems impossible to talk about mass in isolation from the global Gravitational Field does "global" there just mean "non-local" and so we can (if that is a sequitur) talk about different Gravitational Fields even though they are all interconnected?
  11. So it is not just the "singularity" that is a roadblock? This is a period where measurements ,if possible would be finite?
  12. Apparently spacetime was established first (At T+10^-43 seconds if I have that right) and em radiation came next. I am wondering have any simulations or discussions been done as to the evolution of spacetime (ie gravity?) during this epoch ,as it it probably referred to. Apologies if this question makes little sense but I have just come on upon this topic and would not know how to go about researching it or if there would be any point in doing so.
  13. But you would from the space station,would you? So the measurable difference would extend a small distance from the body? Is there a general boundary for any body beyond which the internal redistribution of mass becomes completely unmeasurable and within which it is measurable?
  14. More or less ,but I was also wondering whether there could be a (privileged) frame of reference based at the that origin (the origin of spacetime itself) that would get around the "problem" of all the discordant "nows" https://www.scienceforums.net/topic/120718-how-does-gravitational-mass-work/?do=findComment&comment=1125449 "..... wonder whether it is possible to talk of the whole system evolving from its earlier origin until "now" ( No one "now" but all the "nows" perhaps meeting at this origin when spacetime came into existence) No ,but thanks for the pointer.(I am just starting Einstein's Popular Exposition /GR section anyway and that will probably take me a good few weeks, if I am lucky to get through)
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