DM Candidate?
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From: Tom Roberts on 17 Mar 2010 11:52 Simple Simon wrote: > Tom Roberts wrote: >> Simple Simon wrote: >>> Is it possible that some of the dark matter is simply matter that is >>> outside of our past light cone but gravitationally bound to objects >>> within it? >> No. It is not possible for such matter to REMAIN outside our past >> lightcone. > > I don't understand. You seem to be saying that it is not possible for the > path of objects (an hence their position relative to other objects to which > they are gravitationally bound (e.g. within the same galaxy) within our > current past-lightcone to have been effected by matter outside it because > any such matter would necessarily be within some future past-lightcone of > ours. I meant that if at time t1 to us an object A was visible to us and bound to an object B that is outside our past lightcone at t1, then at time t2 (> t1) to us, B is necessarily within our past lightcone at t2. So, for instance, at least some of the supposed "dark matter candidates" you imagine 10 years ago would be visible to us today, and there would be no mystery. Another argument against this is the fact that we observe dark matter throughout the visible universe, not just at the edges. An object a mere 1,000 ly away from us cannot realistically be bound to an object >13,000,000,000 ly away; if it were, essentially everything we see would also be bound to it, and that binding would presumably cancel out in what we see. Tom Roberts
From: buenno on 17 Mar 2010 17:37 On Mar 17, 4:26 am, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > Simple Simon wrote: > > Is it possible that some of the dark matter is simply matter that is outside > > of our past light cone but gravitationally bound to objects within it? > > No. It is not possible for such matter to REMAIN outside our past lightcone. > > Tom Roberts for what else might be possible to remain outside such a cone? are these cones real?
From: buenno on 17 Mar 2010 17:43 On Mar 17, 4:52 pm, Tom Roberts <tjrob...(a)sbcglobal.net> wrote: > Simple Simon wrote: > > Tom Roberts wrote: > >> Simple Simon wrote: > >>> Is it possible that some of the dark matter is simply matter that is > >>> outside of our past light cone but gravitationally bound to objects > >>> within it? > >> No. It is not possible for such matter to REMAIN outside our past > >> lightcone. > > > I don't understand. You seem to be saying that it is not possible for the > > path of objects (an hence their position relative to other objects to which > > they are gravitationally bound (e.g. within the same galaxy) within our > > current past-lightcone to have been effected by matter outside it because > > any such matter would necessarily be within some future past-lightcone of > > ours. > > I meant that if at time t1 to us an object A was visible to us and bound to an > object B that is outside our past lightcone at t1, then at time t2 (> t1) to us, > B is necessarily within our past lightcone at t2. So, for instance, at least > some of the supposed "dark matter candidates" you imagine 10 years ago would be > visible to us today, and there would be no mystery. > > Another argument against this is the fact that we observe dark matter throughout > the visible universe, not just at the edges. An object a mere 1,000 ly away from > us cannot realistically be bound to an object >13,000,000,000 ly away; if it > were, essentially everything we see would also be bound to it, and that binding > would presumably cancel out in what we see. > > Tom Roberts are you just saying that dark matter does not exists? what is then dark matter, it must be somewhere
From: BURT on 17 Mar 2010 17:48 On Mar 17, 2:43 pm, buenno <ue38...(a)techemail.com> wrote: > On Mar 17, 4:52 pm, Tom Roberts <tjrob...(a)sbcglobal.net> wrote: > > > > > > > Simple Simon wrote: > > > Tom Roberts wrote: > > >> Simple Simon wrote: > > >>> Is it possible that some of the dark matter is simply matter that is > > >>> outside of our past light cone but gravitationally bound to objects > > >>> within it? > > >> No. It is not possible for such matter to REMAIN outside our past > > >> lightcone. > > > > I don't understand. You seem to be saying that it is not possible for the > > > path of objects (an hence their position relative to other objects to which > > > they are gravitationally bound (e.g. within the same galaxy) within our > > > current past-lightcone to have been effected by matter outside it because > > > any such matter would necessarily be within some future past-lightcone of > > > ours. > > > I meant that if at time t1 to us an object A was visible to us and bound to an > > object B that is outside our past lightcone at t1, then at time t2 (> t1) to us, > > B is necessarily within our past lightcone at t2. So, for instance, at least > > some of the supposed "dark matter candidates" you imagine 10 years ago would be > > visible to us today, and there would be no mystery. > > > Another argument against this is the fact that we observe dark matter throughout > > the visible universe, not just at the edges. An object a mere 1,000 ly away from > > us cannot realistically be bound to an object >13,000,000,000 ly away; if it > > were, essentially everything we see would also be bound to it, and that binding > > would presumably cancel out in what we see. > > > Tom Roberts > > are you just saying that dark matter does not > exists? > > what is then dark matter, it must be somewhere- Hide quoted text - > > - Show quoted text - It would have a comon origin with normal matter at the Big Bang. They would allways be found together but they are not. We have never observed any dark matter anywhere. There is another explanation for the high speeds of orbiting stars at the outskirts of the galaxies. Mitch Raemsch
From: Tom Roberts on 17 Mar 2010 18:36
buenno wrote: > On Mar 17, 4:52 pm, Tom Roberts <tjrob...(a)sbcglobal.net> wrote: >> Simple Simon wrote: >>> Tom Roberts wrote: >>>> Simple Simon wrote: >>>>> Is it possible that some of the dark matter is simply matter that is >>>>> outside of our past light cone but gravitationally bound to objects >>>>> within it? >>>> No. It is not possible for such matter to REMAIN outside our past >>>> lightcone. >> [...] > > are you just saying that dark matter does not > exists? No. I'm just saying that Simple Simon's supposition is not possible within the models we have today (GR). Tom Roberts |