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geordief last won the day on August 31 2018

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  1. Can the same statement be made about a magnetic field (and any other field)? More generally ,can we distinguish between any object and the measurement (=perception?) of it? ** (if we can't ,does Janus' distinction redundant except to perhaps say that we can only perceive one object at a time and only extrapolate subjectively to assume that the "object" has extent in space and time -and also perhaps to guard against some people's wish to re-etablish an ether?) **so that we cannot rigorously avoid conflating the external which we perceive and the internal mechanism with which we seem to interpret.
  2. It seems like it may be a nasty fly in the ointment for GR. I know little about the subject and this is probably a stupid question...Could it be regions of negative spacetime curvature? I have heard it described as perhaps something akin to an anti gravity so would that imply negative spacetime curvature? Apologies for the level of ignorance edit: on reflection isn't Dark Energy everywhere and not confined to regions (unlike Dark Matter)? If so ,it couldn't be negative spacetime curvature,could it?
  3. Yes that is what I was thinking of. A nice simple answer that puts my question to bed.
  4. What does it mean that a source of energy will curve spacetime ? How is the energy measured? Is it relative to a particular frame of reference? Does that mean that 2 different frames of reference will measure the spacetime curvature of an identical region differently? Does "region" have to be understood in spacetime terms?
  5. I am a little unclear about this. If energy is (as I have learned) a property of things rather than a thing in its own right does it follow from your statement that matter also is a property rather than a thing in its own right? I am being too literalist (and OT)?
  6. Is the state of change what qualifies any system as existing? If somehow our own universe were to cease changing might we say it had ceased to exist?
  7. What if the sphere was larger or more massive than the Earth? Would we get fusion then? And can we also increase the density of the objects meeting at the centre (protons?) I am not suggesting anything practical. Are there any testable theories as to what happens inside a BH? Is it possible/impossible that there is a region close to the "centre" and another region closer to the "perimeter"? Is this just an area where nothing is testable or worth speculating about?
  8. What if we increased the mass? "Clearly" we would get nuclear fusion but are there any denser masses that might cause anything different. (are there any denser forms of matter than the elements we know of?) Did the lead accelerate all the way to the centre? Did the acceleration lessen as it approached the centre?
  9. Suppose we convert the Earth (or a similar sphere) into a series of tunnels connecting the surface with the centre (billions of straight tunnels) and build a cavity in the central region to accommodate billions of infalling identical samples of ,say lead ... What would happen at the centre as all these sample met and filled the cavity at the same time? (having been released all at the same time) Can this be modelled as a scenario (a computer or theoretical simulation)? Would the lead rebound to the surface repeatedly until it eventually settled in the cavity? Would a black hole form? Would any mass be lost out of a "plug" in the centre (of the Earth) in a wormhole fashion?
  10. Is it possible (ie not too complicated for me) to ask where the covector space ** fits into the relationship of those 3 vectors? (if only to perhaps light my path a little into this territory I am only now learning a bit about) ** I presume it must be there somewhere...
  11. I have it on authority **that tensors enable one to model the electromagnetic interaction between a " moving "charge and an electric conductor in such a way as to dispense with frames of reference . I wonder if anyone might have anything to say on the subject and whether it can be shown in more detail how this is the case. **
  12. Would there be any consequences if there was rather than there was not?
  13. No internal structure? Yes I looked at one of his videos. My head hurt succulently!!
  14. Seeing is believing.So what is going on at the deepest part of that beast? Something forceful enough to hold in the contents.. Just nowhere to go ,simple as that -the force of logic? Just like pumping up an inner tube? Gravity is resisted there because there is nothing there for gravity to push against..Is that just Newtonian? Or is the force of gravity zero anyway at the bottom?
  15. The void itself is expanding...? Not the distance between objects in the void?