On Saturday, July 11, 2020 at 10:20:54 PM UTC-6, Brent wrote: > > > > On 7/11/2020 9:00 PM, Alan Grayson wrote: > > > > On Saturday, July 11, 2020 at 9:49:31 PM UTC-6, Brent wrote: >> >> >> >> On 7/11/2020 8:07 PM, Alan Grayson wrote: >> >> >> >> On Saturday, July 11, 2020 at 8:41:21 PM UTC-6, Brent wrote: >>> >>> >>> >>> On 7/11/2020 4:29 PM, Alan Grayson wrote: >>> >>> >>> >>> On Saturday, July 11, 2020 at 5:05:02 PM UTC-6, Brent wrote: >>>> >>>> >>>> >>>> On 7/11/2020 12:54 AM, Alan Grayson wrote: >>>> >>>> >>>> >>>> On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson wrote: >>>>> >>>>> >>>>> >>>>> On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson wrote: >>>>>> >>>>>> >>>>>> >>>>>> On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote: >>>>>>> >>>>>>> On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson <[email protected]> >>>>>>> wrote: >>>>>>> >>>>>>>> How, exactly, is the Principle of Equivalence used by Einstein to >>>>>>>> develop GR? TIA, AG >>>>>>>> >>>>>>> >>>>>>> >>>>>>> This lecture by Sean Carroll should answer all your questions: >>>>>>> >>>>>>> URL: https://wp.me/p2WMeM-3vl >>>>>>> >>>>>>> Bruce >>>>>>> >>>>>> >>>>>> I'll watch it tonight, but I think I've figured it out; specifically, >>>>>> the EP implies space-time is curved by the presence of mass/energy (and >>>>>> this is independent of the need to express the laws of physics in a >>>>>> coordinate independent way via tensors). AG >>>>>> >>>>> >>>>> Here's my reasoning regarding the EP; if an observer is in a box >>>>> subject to uniform acceleration, a beam of light starting on the extreme >>>>> left side (moving transverse or perpendicular to the acceleration >>>>> vector), >>>>> will hit a lower point on the right side, showing that uniform >>>>> acceleration >>>>> results in curved paths in space-time. But if this result is identical to >>>>> gravity, locally, it means that curved paths in space-time are produced >>>>> by, >>>>> or are equivalent to gravity. >>>>> >>>> >>>> That makes no sense. You're saying that because curved paths can be >>>> produced two different ways then they must always be produced the second >>>> way. >>>> >>>> >>>> BUT gravity is only observed in the presence of mass/energy. ERGO, the >>>>> EP implies mass/energy curves space-time. AG >>>>> >>>> >>>> And that's not even true. Gravitational waves can propagate thru the >>>> vacuum. The Schwarzschild solution is for empty space. De Sitter space >>>> is >>>> an empty cosmos. >>>> >>> >>> Light can propagate through empty space, but it can't arise from >>> nothing. Same presumably for gravitational waves. AG >>> >>> >>> Are you going to say the same thing about matter? electric charge? >>> >>> Brent >>> >> >> I'm not sure what your point is. All I was saying above is that >> mass/energy causes curvature of space-time as per the EP. A gravitational >> wave moving through empty space seems no different in principle than light >> moving through empty space. In both cases there is a mathematical solution >> for the wave motion, with the source of the wave left undefined. But every >> wave motion must has a source. AG >> >> >> And every source must have an origin? There is nothing in the equations >> that says there must be a source. >> >> Brent >> > > Can EM waves exist if there are no charges and currents? If you affirm, > has this ever been observed? This result, if it is a result, is likely an > artifact of the mathematics which has no basis in physical reality. Anyway, > are you claiming that spacetime curvature can exist in the absence of > matter/energy? Is this what the EP says? AG > > > It's what the equations say. So if waves only exist due to matter sources > that's a separate fact, not part of the theory. It seems just as plausible > to me that fields existed first and "stuff" appeared as quantized waves in > the fields. > > Brent >
What do you find erroneous in my interpretation of the EP? I never heard it interpreted to mean that curvature of space-time is NOT caused by gravity. AG > > > > -- > 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] <javascript:>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/3372804f-6bf6-44d4-9506-f73bf607e6e6o%40googlegroups.com > > <https://groups.google.com/d/msgid/everything-list/3372804f-6bf6-44d4-9506-f73bf607e6e6o%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > > -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/87f90571-be68-423f-b6e9-5d361049d077o%40googlegroups.com.
