Can we detect a blueshift of -c?
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From: Brad Guth on 22 Apr 2010 15:59 On Apr 22, 12:26 pm, jbriggs444 <jbriggs...(a)gmail.com> wrote: > On Apr 22, 9:29 am, Brad Guth <bradg...(a)gmail.com> wrote: > > > > > On Apr 21, 11:25 pm, "Peter Webb" > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > > "Brad Guth" <bradg...(a)gmail.com> wrote in message > > > >news:90d95c55-3fda-4e4a-9df7-8bf39290bed1(a)m25g2000prj.googlegroups.com.... > > > On Apr 21, 10:58 pm, "Peter Webb" > > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > > > Some parts of the Universe are moving towards us at speed c. > > > > > Some of the light from other galaxies, for example. > > > > > We can know nothing about this light until it actually reaches us. No > > > > information (eg that light was emitted by a distant galaxy) can travel > > > > faster than c. > > > > Perhaps as far as we know, yet gravity and the information it > > > represents seems to be worth at least 2c. > > > > ______________________ > > > > I think its worth much more than 2 cents. If nothing else, it keeps the > > > earth in orbit around the Sun. > > > I agree, gravity could be as fast as c2 (9e16 m/s). > > I suppose you think that's pretty fast, huh? > You probably that it's even faster than light > Imagine how much faster it sould be if we used cgs. > > On the other hand, the speed of light is about 0.3 parsecs per year. > So the square of the speed of light is under 0.1 parsecs per year (per > year per parsec). > > So it would seem that not only is the square of the speed of light a > lot faster than light, it's also a lot slower. > > Could you please use dimensional analysis to resolve this conundrum > for us, oh one whose intellect is so massive as to form a a black > hole? (Information goes in, but it doesn't come out). Those Guth black holes are filled with positrons/antimatter. How's that? Gravity at c2 is just my honest swag, as provable as is the none-zero mass of the Guth photon. I've also estimated there's <1e100 photons/ atom, and our universe is worth perhaps 1e84 atoms that never stop making photons. ~ BG
From: Brad Guth on 22 Apr 2010 16:05 On Apr 22, 11:25 am, "Greg Neill" <gneil...(a)MOVEsympatico.ca> wrote: > Brad Guth wrote: > > On Apr 22, 9:47 am, "Greg Neill" <gneil...(a)MOVEsympatico.ca> wrote: > >> This is not in contradiction with Relativity, which places > >> constraints on how fast massive objects move *in* space, and > >> the speed of light *in* space as measured by a local observer. > >> Relativity does not place constraints on how quickly space > >> itself can expand. > > > Nor on how quickly it might contract as equally undetectable if that > > blueshift is worth anything near -c. For all we know the undetected > > portions of our universe are contracting/imploding, unless there's > > something beyond that's pulling matter outwards. > > Of course even if regions of space beyond our cosmic > horizon were moving towards us at any rate we would > not be able to see them since light from there would > still have to cross the horizon in our direction and > that horizon is moving away at c; light there and > beyond can never reach us. How about photons from a vibrant 10 solar mass star that's situated well within our visual detection horizon of 13.7e9 ly, but trekking directly towards us at -c? ~ BG
From: Greg Neill on 22 Apr 2010 16:33 Brad Guth wrote: > How about photons from a vibrant 10 solar mass star that's situated > well within our visual detection horizon of 13.7e9 ly, but trekking > directly towards us at -c? It can't. Nothing physical within our horizon can be observed to move at or above c. Close to c, sure, but not at or above. The best a body can do is approach c with respect to observers in its proximity (within the local region of space moving with the Hubble flow). Every non-local observer (such as us sitting a great distance away from that region in our own local region) sees that region of space moving away in bulk according to the Hubble expansion, thus decreasing any net speed of approach.
From: artful on 22 Apr 2010 19:01 On Apr 23, 6:05 am, Brad Guth <bradg...(a)gmail.com> wrote: > On Apr 22, 11:25 am, "Greg Neill" <gneil...(a)MOVEsympatico.ca> wrote: > > > > > > > Brad Guth wrote: > > > On Apr 22, 9:47 am, "Greg Neill" <gneil...(a)MOVEsympatico.ca> wrote: > > >> This is not in contradiction with Relativity, which places > > >> constraints on how fast massive objects move *in* space, and > > >> the speed of light *in* space as measured by a local observer. > > >> Relativity does not place constraints on how quickly space > > >> itself can expand. > > > > Nor on how quickly it might contract as equally undetectable if that > > > blueshift is worth anything near -c. For all we know the undetected > > > portions of our universe are contracting/imploding, unless there's > > > something beyond that's pulling matter outwards. > > > Of course even if regions of space beyond our cosmic > > horizon were moving towards us at any rate we would > > not be able to see them since light from there would > > still have to cross the horizon in our direction and > > that horizon is moving away at c; light there and > > beyond can never reach us. > > How about photons from a vibrant 10 solar mass star that's situated > well within our visual detection horizon of 13.7e9 ly, but trekking > directly towards us at -c? It can't happen .. so why ask about it? Every object with mass travels at less than c in our (and every) frame of reference
From: spudnik on 22 Apr 2010 19:10
there is no direct observation of "moving away;" it is all presupposition of a "Dopplerian" redshift (probably related to a belief in Pascal's absolute vacuum; I mean, he did do the experiment). |