geordief

Do different black holes exhibit different degrees of spacetime curvature (depending on their radius)? Might it be a requirement for a body to be massive that it have an inner structure of some kind?

Yes,that was loose language. I was really after the smallest known instance of mass . So it would be the neutrino? (which from memory was at one time considered massless) Is a black hole considered to be a massive object? I have read that it should be viewed as an extreme curvature of spacetime., Can it be both? Are mass and spacetime curvature somehow the same thing?

(Or maybe "What are the smallest objects with mass?") I think I may have seen that mass may be defined as a body's resistance to being accelerated. How would that apply to that smallest massive object? What would apply the force ? Another massive object? Does mass require another massive object to define itself?

Sadly the content of that link a bit old now (2007) and I can't get anything there to play. Actually,in any case I was more interested in proper 3d videos or virtual reality videos** if such exist (not that I have the facility to play them either) I get the impression that this kind of a thing might not be for the general public and perhaps used in university settings. If anyone has hands on experience with that sort of thing it would be interesting to hear. **perhaps "games" might be a better descriptor as I was imagining that there could b quite a few settings to play around with.

That would be originalist.

No,but the effect is similar.Is it not better that the appointment of Supreme Court Judges should be non partisan? The refusal to appoint Obama's pick felt like reverse packing to me.

Do all administations not try to pack the Court with their own picks. Any chance the Repubs will reap the whirlwind from this most transparent and seemingly unpopular episode? Will they be vulnerable in Red states now?

Thanks.We cross posted "simultaneously ".Will give that thread a butcher's

Edit:On reflection I see where this "model" falls down as I described it. Could it be improved by paring down the Solar system to just a few objects,say the Sun ,Earth and Jupiter as well as allowing for different frames of reference with their own clocks. Introduce a test object moving at relativistic speeds and compare how the movie plays out from the different frames of reference. Could it be a nice pedagogic tool?

Are you saying that that would just be pretty pictures but that it wouldn't show anything profound -and might actually be misleading,like the trampoline analogy? If you were to populate my 3d movie with an additional moving object (or a beam of light) wouldn't that object's trajectory be very realistic? Are there relativistic effects that this movie cannot capture?

Does the overturning of Roe v Wade bring the US legal system into further disrepute at a time it is most needed as a bulwark against the Big Lie and its attack on democracy in the States?

Yes,that is the sort of thing(I was looking for the way the different gravity wells joined up) It wouldn't be a problem to add the 3rd spatial dimension (and use 3d glasses) and to run a series of those still frames too get the time dimension, would it?

I just meant to simulate the map of curvature around and extending from the objects in the Solar system. I wasn't interested in actually seeing the objects themselves. Would that be possible?

https://www.newscientist.com/article/2325638-breast-cancer-is-more-likely-to-spread-during-sleep/ "Breast cancer is more likely to spread during sleep" A very interesting finding. A link to a pdf page in Nature in that that I can't seem to copy and paste....

Yes ,I only had in mind what would be practical (and enlightening for me) Is there anywhere that these spacetime graphs have been written down? Some sort of a graphic spacetime depiction of the Solar system at some particular time (say t=01/01/2000 at midnight) If there was then we could make adjacent snapshots (eg t=24 48 ,72 hours later etc ) and run the snapshots like a movie. Accuracy not important ,just maybe as a way of looking at spacetime events in a non local way?

Apparently it was Voltaire who first said "Dans ses écrits, un sage Italien Dit que le mieux est l'ennemi du bien"

@studiot Don't want to derail the thread but we can calculate the weather on our planet over any period if we don't mind inaccurate results. As an aside I was actually kind of amazed to hear on a BBC science documentary recently ,(forgotten the title) that a particular theory could be plugged into BB and give an accurate representation of the universe we are living in That was some forecast!

Trying to flesh out/ fill in gaps in my understanding (using you guys to help me in that) So ,would you have any examples of a "local"Cauchy surface ,defined by causal boundaries and structures that would model a real life system of objects? Could it be a snapshot(time-slice of the 4d manifold) of the Solar system ? Or is that too big a system to be "local"? I am not sure I understood exactly what you were describing by "local surfaces".Did you mean local as in " simultaneous"? (it feels to me that a slice of the manifold where t=constant could be described as "local" in the same way as a unique location in space ,but moving in time would also be "local") Hope my question was coherent.

Would it be possible to make a spacetime model of the complete (ish) Solar system?(say from 2000 to 2010) Would it be visible in the round or would it be in mathematical form only?

Would I be right to say the the curvature of spacetime is an entirely local effect and it would be wrong to make a global picture of spacetime which would hold all the sources of energy-momentum at all the different "events" in the global set? Does one have to calculate the curvature at each event and somehow knit them together in an approximative fashion in order to draw a picture of the spacetime curvature of a system as a whole?

Isn't there a disclaimer signed ahead of any such medical intervention? If the child is under age would this be signed by his legal guardians (his parents)?

Does the problem lie with the expectations and unkind judgements of society moreso than with the individual who is presented with the choice of gender reassignment or not? It feels rather like the situation of "half-casts" who can find themselves not accepted into either one of the cultures they were born into. Is it a weakness to give into the need for social approbation or is it just a realism so that we say we have to give ourselves the best chance in life if we are served with a "bad" hand of cards? Can we pursue both outcomes on parallel tracks and attempt to educate the public why difference is good as also can be "non determinacy" whilst allowing for escape ramps for those who cannot wait for society to catch up with who they think they are? I wonder how we will look back at this question in 50 or 100 years from now and if we can tell ourselves rhen that we have learned anything along the way.

You could start a thread on that in philosophy.

Yes she does.She certainly gets your attention,whereas the chair drains it I feel

Are there any cultures that have no concept (or approximate concept) of god as we might loosely understand it? It might be relevant either way. If the "concept" was everywhere in every culture it would mean it was part of our shared psychological inheritance. If not then that might tell us something very different Does anyone know the answer?