Are there multiple theories for the origin of dark matter and dark energy?

[marcus]

In that case Nereid, if all the ideas of Dark (energy and matter) are so speculative that one may "take one's pick". Then I shall provisionally choose to consider the one that gets rid of Dark altogether.

One supposes that there a fundamental length constant (analogous to the fundamental speed constant c and the fundamental angular momentum hbar) and that by current estimates this constant is 9E25 meters----or if you prefer 9.5 billion light years. And that this constant affects the curvature of space and the action of gravity in the weak acceration limit.
this is one of the scariest intellectual steps I have ever considered taking.

...
It seems to me that this possible explanation, which gets rid of Dark, is very high risk---but it is attracting people to work on it. So it is interesting, I find, to watch although unsettling like watching a highwire act at the circus.

In 1899 Planck just barely had the idea that his constant existed. he had not even published the 1900 paper about the radiation law! Alejandro has given a link to an 1899 paper of Planck containing the suspicion of a basic constant. this is how it is (as I see it) now.

there is a length. It might be 9.5 billion lightyears. Prodded by kurious, I have calculated that this is the same as 9E25 meters. this length is not to be confused with the Hubble length or the "radius of the observed universe" or any of that stuff, which is very different.
this length may be conjectured to be a fundamental constant in cosmology.
as if space were pre-stressed concrete and some one had measured the
inherent stress in it and this length was an indicator of the stress (I know that sounds fantastic or dumb, I want to convey the idea of a fundamental constant---one of the deep proportions intrinsic in nature)

If there is this length and it really is a fundamental constant, and it actually participates in certain laws, then (goes this highly risky speculation) there may not need to be any dark matter or dark energy...

the point is that if L is 9E25 meters
then the Lamda they found from the supernova observations is
Lambda = 1/L²

and the mond threshold acceleration found from galaxy rotation curves
is given by
c²/6L

and some rather brave people, I think, have recently said that this makes glimmers of sense to them because of a way that Special Rel can be deformed to have more than one invariant scale

and in doing the deformation, one generates predictions which may be testable by GLAST

so there is a deadline. these ideas must be worked out in time to make a prediction before GLAST goes into orbit.

Oh and the pioneer anomaly if there really was one would be covered by
that c²/6L too. Of course all this may be merely some coincidences, however eerie.

 

[Nereid]

This distance L is about 10^25 - 10^26 metres.
The Newtonian calculation I did earlier in this thread gives a decceleration due to gravity of 10^-11 m/s^2 at this distance range.
This is of a similar order of magnitude to the acceleration of supernovae due to dark energy at the same distance.
It is as though gravity has changed signs.This may be a trivial point or it may not.

How would you go about determining whether it's trivial or not? What experiments or observations would you suggest that might help (in principle ones are perfectly OK)?

In response to Nereid's questions, I would say this:
If the acceleration of supernovae due to dark energy is related to the decceleration due to Newtonian gravity, then there is a way forward if dark energy is considered to be repulsive gravity.A gravitational force carrier (if one exists) could be changing from one physical state to another and when it does this it could change from causing attraction to causing repulsion.
Low energy Higgs particles exert a negative pressure like dark energy but I don't know if this could be used to justify saying,for example,that a gravitational force carrier with a low energy could be repulsive and a high energy carrier could cause attraction.Themain problem with attributing gravitational repuslion to force carriers is that they are not supposed to have mass according to quantum mechanics and that would then raise the question of how the universe has enough mass to be geometrically flat which is what obsevation says it is.

First, a small clarification: the observed acceleration isn't "due to supernovae", we simply use distant supernovae as a means of observing the distant universe; those observations suggest that the rate of expansion of the universe - and that includes the galaxies in which the SN live(d) - is increasing, and has been for the past several billion years.

Can you convert your word picture ("gravitational force carrier (if one exists) could be changing from one physical state to another and when it does this it could change from causing attraction to causing repulsion") into numbers? e.g. at what rate would the carrier changes have to take place in order to make the observational data?

Without working out the details of some new theory of carriers (or anything else), what experiment or observation could you do - even in principle - that would tell you whether 'gravity had changed signs', or the accelerations are of the same magnitude (but opposite signs)?

 

[Nereid]

In that case Nereid, if all the ideas of Dark (energy and matter) are so speculative that one may "take one's pick". Then I shall provisionally choose to consider the one that gets rid of Dark altogether.

One supposes that there a fundamental length constant (analogous to the fundamental speed constant c and the fundamental angular momentum hbar) and that by current estimates this constant is 9E25 meters----or if you prefer 9.5 billion light years. And that this constant affects the curvature of space and the action of gravity in the weak acceration limit.
this is one of the scariest intellectual steps I have ever considered taking.



the point is that if L is 9E25 meters
then the Lamda they found from the supernova observations is
Lambda = 1/L²

and the mond threshold acceleration found from galaxy rotation curves
is given by
c²/6L

and some rather brave people, I think, have recently said that this makes glimmers of sense to them because of a way that Special Rel can be deformed to have more than one invariant scale

and in doing the deformation, one generates predictions which may be testable by GLAST

so there is a deadline. these ideas must be worked out in time to make a prediction before GLAST goes into orbit.

Oh and the pioneer anomaly if there really was one would be covered by
that c²/6L too. Of course all this may be merely some coincidences, however eerie.

It really depends on how far from the mainstream you wish to go!

And it's not just GLAST that will test many things; Gravity ProbeB will test Garth's SCC (and much else), LISA will test the Pioneer anomaly (and much else besides), SNAP will measure the acceleration of the rate of expansion to much higher accuracy (and much else), and so on.

To be sure we all understand here - the 'concordance model' is pretty good - it is consistent with lots of cosmologically relevant data (some say there is essentially no data which isn't, within experimental error); there are a number of quite independent sets of observations of dark matter - not even MOND accounts for all these (and it's the best alternative IMHO). wrt 'dark energy', I just don't see that the data are sound enough yet - from dust, to compositionally different behaviour of SNs, to systematic effects of many kinds ... so many things to tidy up first. While not out of the mainstream, the view that the SN data aren't firm enough yet is certainly a minority view!

 

[kurious]

The most frustrating thing about dark energy and dark matter is that they could be all around us here on Earth and yet we can't detect them!
Steven Weinberg has said "dark energy is the bone in the throat" for particle physicists
and cosmologists alike.But whatever it is, if we are to understand it, then it must have at least some physical propeties in common with all the other forms of matter we have an understanding of.At one time neutrinos were suspected of being dark matter but I think observation has ruled this out now.

 

[salazar18]

Dar matter and antimatter are real. Anti-atoms have been created/ dark matter. Read Hawking's book (History of Time) for possible solutions. I have a different theory which I will make abalable later.

 

[kurious]

NEREID:
Can you convert your word picture ("gravitational force carrier (if one exists) could be changing from one physical state to another and when it does this it could change from causing attraction to causing repulsion") into numbers? e.g. at what rate would the carrier changes have to take place in order to make the observational data?

Without working out the details of some new theory of carriers (or anything else), what experiment or observation could you do - even in principle - that would tell you whether 'gravity had changed signs', or the accelerations are of the same magnitude (but opposite signs)?

KURIOUS:

If the force carriers for repulsion are increasing in number at the expense of the number of carriers for attraction, then stars should start to move away from the galactic centre and the Milky way, for example, should get bigger.Perhaps the Sun would become less luminous.Paul Dirac once suggested gravity was stronger in the past but the Sun would have burnt up too much fuel by now for this to be true.However this might not be a problem in the repulsive gravity scenario outlined above.

 

[kurious]

One last thought on attractive gravitational force carriers becoming repulsive carriers:
if attractive carriers are bosons and they turn into fermions (in analogy to photons becoming positrons and electrons) then because fermions can't be in the same region of space,space must expand.However this would require bosons to collide with baryonic matter to conserve four-momentum and it would require that the particle-antiparticle pair does not become a boson again.Quantum mechanics says that the force carrier for gravity is spin 2 even if that carrier does not turn out to be a graviton.
This spin 2 could yield 4 spin 1/2 particles but I think someone on sci.physics.research said that spin doesn't necessarily have to be conserved for this kind of transformation,
so more particles may form.When the gravitational force carriers have all become fermions the universe would not need to expand anymore and fermions could come together to form bosons and the radius of the universe could decrease.The fermions would have to be moving close to the speed of light so that their energy density is similar to their pressure - dark energy is
expected to have this characteristic.Bosons moving at the speed of light and colliding with baryonic matter normally yield particle-antiparticles moving
close to light speed.
My idea of spin should not be confused with spintessence theory for dark energy which is different altogether.