There are speculations that the gravitational effects of matter in 4 or greater LARGE spatial dimensions might account for the substantial discrepancy that exists between measured gravitational effects on normal baryonic matter and the amount of that matter that exists according to measurements. Could we be measuring the gravitational effects of "normal" matter in higher dimensions? And can large higher dimensions also explain the huge amount of dark energy that seems to be around?
It's a possibility.
Calculations suggest that gravity could 'leak' from higher dimensions, but it does not constitute proof, far more work is needed.
It should also be considered that if gravitational effects were 'bleeding in' from 'other' dimensions, for example, they might also be bleeding out from our 3 spatial and/or 1 temporal dimensions...
As long as hidden spatial dimensions, dark matter and dark energy remain unidentified conceptual entities inferred by complex interpretations of observations, it seems that one cannot be considered compelling evidence for the other.
I am not an expert in this area but it is intriguing to me that like everything else in the universe I must be having a dark matter halo (a tiny fraction of that of the galaxy) or equivalently, I and you and all other matter are awash in surrounding dark matter (please correct me if I am wrong). So if it is not WIMPS or neutrinos then what is it? I sure hope that we will have a better idea soon! Maybe as we keep looking for WIMPS we should also be considering (at least as Plan B) other possibilities like large extra dimensions. Unsettling as the thought may seem at first, it may lead to interesting new answers to perennial questions about the nature of the universe.
Hassan,
Dark matter is generally inferred from discrepancies between the projected gravitational effects expected to be produced by very large scale, compound structures composed of up to hundreds of billions of discretely self-gravitating objects of mass, and the gravitational effects identified through interpretations of observations. The existence of dark matter has not been inferred for simpler, smaller scale configurations of objects like the Solar system, whose gravitational characteristics can be more directly determined.
On the other hand, there is no explanation as to why dark matter should not be found throughout the Solar system, either. That being said, my brief, informal profile essay (and its formal references) attempt to attribute the inferences of galactic dark matter to difficulties in properly evaluating the gravitational properties of, especially, spiral galaxies. I think Occam's Razor prefers this more straightforward possibility rather than conjuring unidentified elements or spatial dimensions... At this point, if galactic rotational properties could be explained without compensatory dark matter or modifications to fundamental gravitational equations it would also lead to very interesting new questions about the nature of the universe!
James, no question that if the discrepancies can be explained without new thinking then in a sense that would be most satisfying. But consider also there are already things that are hard to explain such as the big bang, strange quantum effects, even the constancy of the speed of light that make one think that perhaps we are not thinking big enough. I have read (even on this RG site) that some people would like to apply Occam's razor more readily and suggest, for instance, that the evidence for the big bang or for speed of light being nature's speed limit is not compelling enough and that there could be other explanations. Like you, they make a valid point but where do you find yourself on this spectrum? Physics theory in its current fragmented state with so much that is difficult to explain suggests, to me at least, that maybe we are not thinking big enough. So maybe the dark matter idea is compelling enough in light of the existing evidence to not rule out thinking more comprehensively - large extra dimensions may not be the best explanation in this case but might it be the right one?
Hassan,
In my experience, large structures are built in small pieces. In the 1970's and 1980's it became widely established that dark matter was necessary to explain the peripheral rotation of spiral galaxies. Today, dark matter lies at the heart of the standard L-CDM cosmological model - the development of the entire observed universe is thought to be dependent on its existence.
Galactic dark matter was used to explain the observed distribution of gravitational effects using (IMO) simplistic methods of representing exceedingly complex distributions of (baryonic) mass. Modified gravitational theories have been devised to accomplish the same result - distributing the gravitational effects produced by exceedingly complex distributions of (baryonic) mass. Even galaxy cluster collisions are considered to be evidence of dark matter because of the apparent distribution of gravitational effects that exceed those expected from the available baryonic mass.
As merely a retired information systems analyst, in my experience these conditions suggest that the unvalidated methods used to represent such vast distributions of discrete masses comprising compound gravitational structures is the source of error.
I also have extensive experience working with subject area experts attempting to solve intractable problems. As an ancient progress report is reputed to have stated:
"We have not succeeded in solving all your problems. Indeed, we sometimes feel we have not completely solved any of them. The answers we have found only serve to raise a whole set of new questions. In some ways we feel we are as confused as ever, but we believe we are confused on a higher level and about more important things…"
See http://quoteinvestigator.com/2010/07/11/confused/
Point taken, James. I can only hope, with regard to preexisting knowledge, that we do not keep looking in the wrong places for answers to profound questions (as in "not seeing the forest for the trees").
Dear Hassan, I agree on your comments. Only adding that the current Standard model for Cosmology needs of dark matter and dark energy, but does not require more than three dimensions...
True, Juan. Limited as it is, my understanding of the standard model says that it postulates particles for dark matter (WIMPs). But these have proven to be illusive. Perhaps one day some of these will be detected like the Higgs boson (possibly in the same statistical sense) but if not then we need to think about other possibilities. Maybe now is not too early for some credible theorizing by our experts, not necessarily limited to large extra dimensions, that explains dark matter and energy and in the same stroke resolve some issues with other hard to detect SM particles.
I agree with James. GR is still a work in progress, and the traditional (meaning based on metric and torsion free connection) method is not the only one to work inside the basic hypotheses of General Relativity. Even without extra dimensions one can think to the rotational energy which is stored inside the stars and planet systems, which should be accounted for any additional impact on the curvature. Computations on these issues are fiendlishly difficult. Unfortunately nowodays it is more fashionable to invent a new mystery than to go deeper in the existant theories.
Dear Hassan,
You are young, you are your own man, and your life lies ahead.
Certes, you would like to guess a riddle of Nature and to tell it to people.
Today you think about the number of dimensions for dark matter and dark energy.
Think before whether they have at least one dimension, whether they are no more than a viral emanation of a unhealthy mind; emanation against which there was no effective medicine until recently.
Are there real grounds for the notions on dark matter and energy, black holes, Big Bang, and other miracles? Aren’t these fancies unrelated to science?
I address myself not only to you personally, but to the astrophysicists and astronomers who consider themselves rather young to afford a critical review of the widely distributed view of the Universe. The fact of the matter is that, being involved into a flow, it is getting tough with age to struggle out of it. Meanwhile, the notions on the Universe changed cardinally many times, and a new change is, I think, inevitable.
Astrophysics is grounded on Eddington’s assumption about the fusion reactions as the unique source of the stellar energy (1) and the possibility of consideration of stellar state on the basis of ideal gas laws (2) and on Einstein’s assumption of the constancy of the light speed (3) and direction (4) and gravitation coefficient (5) over the Universe.
If any one of these assumptions is mistaken, the today astrophysics of the beyond-Solar-System space should crumble to dust, because all distances, masses, and speeds of the celestial objects and all fantastic dark matters and energies, holes, dwarfs, Bangs, etc. lie on this fundament.
Meanwhile, none of these assumptions has any real confirmation, and their uncertainty increases day by day.
Assumption (1) was taken with no grounds as a result of euphoria that was born by the discovery of fusion reactions and by an opinion that it is unique solution of the problem. However, the stabilization of fusion reactions for long periods of stellar lives is rather questionable and the explanations of different processes and phenomena that follow from the assumption on fusion reactions are not conclusive.
After our PFO-CFO Solar System Formation Hypothesis (it is available at my and at Elena Kadyshevich pages in the ResearchGate site), which gives simpler explanations for the celestial processes and phenomena, the assumption (1) looks, in our opinion, even more questionable.
As for assumption (2), the degree of its validity and the consequences of its application require no commentaries (the PFO-CFO Hypothesis doesn’t use this assumption).
As for assumptions (3), (4), and (5), they are, in our opinion, completely unacceptable as grounds for earnest conclusions on the Universe, as a whole; we think that the speed of light can be dependent on the distance and, there is very likelihood, on the time by the following reasons:
(i) The gravitation coefficient might be different in different stellar systems or, all the more, in different galaxies; at least, nothing testifies against this. It is known that light deviates in gravitation field; thus, the light speed depends on gravitation. If the gravitation coefficient is different over the Universe and changes in an unknown manner, the light speed out of the Solar System is unpredictable.
(ii) Even if the gravitation coefficient is the same over the Universe, it is possible that light propagates through the inter-galaxy space, in preference, along the between-galaxy channels and through the intra-galaxy space, in preference, along the between-star channels , where gravitation to the adjacent objects is compensated; thus, it can propagate in a straight line along great but limited distances and, when propagating through multi-galaxy distances, choose the directions of minimum resistance; in this case, its direction is also unpredictable.
(iii) After development of the quantum field theory (1934), an opinion existed that gravitation is a property of each atom as such and that this property is caused by the existence of gravitons, i.e., massless spin-2 boson particles that represent carriers of this property. Meanwhile, no gravitons were discovered within nuclei. Today, it is necessary to be rather obstinate optimists to wait the discovery of such particles and there are no scientific grounds to believe that the gravitation constant is the same over the Universe. It must not be ruled out (although we do not state) that gravitation is an integral feature of the space/celestial-body systems but not the feature of each atom and that this feature depends on the size and, may be, age of the stars that form the stellar systems.
Assumption (5) is, as least, questionable, because nothing counts in its favor.
We propose a principally new view of the Solar System and Universe with no dark matter and black holes and with original solutions of different Universe problems, and we would be glad to discuss them.
I wrote earlier at the ResearchGate that, in our with Elena Kadyshevich opinion, most of the celestial objects that are observable at the vault of heaven beyond the Solar System are no more than illusions and we defended this our opinion.
Anyone, from the scepticism, can easily consider that the assumptions or principles upon which science is built are not valid, but to do so in a constructive way, one has to provide alternative principles to substitute the old ones. Particularly, the asumption of constancy of the speed of light is firmly based on the Michelson-Morley experiments and numerous attempts to found any variability of G with time have been unsuccesful.
Dear Mrs Juan Casado,
Thank you for your participation in the discussion.
Unfortunately, you are mistaken just a bit.
The celebrated Michelson-Morley experiments were performed at the Earth and their results doesn't relate to the entire Universe.
Meanwhile, I wrote the following: "Astrophysics is grounded on Eddington’s assumption about the fusion reactions as the unique source of the stellar energy (1) and the possibility of consideration of stellar state on the basis of ideal gas laws (2) and on Einstein’s assumption of the constancy of the light speed (3) and direction (4) and gravitation coefficient (5) over the Universe.
If any one of these assumptions is mistaken, the today astrophysics of the beyond-Solar-System space should crumble to dust, because all distances, masses, and speeds of the celestial objects and all fantastic dark matters and energies, holes, dwarfs, Bangs, etc. lie on this fundament."
I hope, comment is superfluous.
As for alternative principles, yes, you are right; our PFO-CFO theory of Solar System Formation is based on alternative principles, and our (together with Dr. Elena Kadyshevich) works are available at the ResearchGate site.
I would be grateful to you for discussion of other aspects of my issue and of our works.
Sincerely.
Victor, I am not as young as I would like to be. Being a mathematician by training I tend to favor contextualization for problem solving. What I mean is re-interpreting a difficult problem in a new, broader context where a solution is more readily transparent. This approach has yielded profound results in math. The most recent example is the resolution of Fermat's celebrated conjecture using abstract algebraic methods that Fermat clearly did not know about. Fermat's problem was profound exactly because it led to an explosion of results fueled by capable imaginings and not hindered by centuries of distractions by cranks who insisted on trying out methods with limited range because they were unable or unwilling to think big enough. Before that, there was Galois theory which proved the impossibility of squaring a circle, trisecting an angle and so on using the then highly abstract concept of groups (again, there were legions of cranks before that for centuries trying to do the impossible). Groups of course are no longer considered abstract, even in physics.
Closer to theoretical physics, the existence of solutions for complex differential equations of modern physics could only be established in the context of Hilbert spaces of square-integrable functions - infinite dimensional vector spaces where incidentally Heisenberg's mechanics could be most naturally understood. More recently, the beauty of some of the models of particle physics is hard to not appreciate although obviously one needs clear experimental support (which alas seems to not be so readily forthcoming).
As for dark matter and energy, my understanding of what James and others on this page seem to be saying is that the interpretation of experimental findings may be in question and more time and work is needed for these findings need to be properly understood in a quantitative sense. This fact does not preclude any theory that might be used to make sense of the data.
I think that the solar system theory that you mentioned will in time be understood for what it is and perhaps be extended if it is mathematically and experimentally valid. Until then, other promising ideas should not be discouraged. Nature will determine for us what may be right and nature is an unbiased judge for all. That's my take!
Dear Hassan,
I wish you successes.
Thank you for your issue. I read it with interest. As for me, I agree with I. Kant when he writes that only negative judgments and, sometimes, logic and exact mathematics are capable of giving the absolutely true solution. Therewith, I give preference to logic and think that the more phenomena and processes respond to any logical system and the simpler is this system, the higher is the probability that it responds to the reality.
Victor,
In fact, you are mistaken, because I am not Mrs, but Dr (and male).
Right, all experiments are made on earth, that's why we need principles on how physical laws can be extended (or not) to the rest of the Universe.
I am not ready to read all your theory and works to find the alternative principles you propose. If you really want to discuss on them, please try to summarize them here as you did with the classical ones...
Dear Dr. Juan Casado,
I am sorry very much for my double mistake.
As for the PFO-CFO Hypothesis, its shortest statement is given at my RG page under the title “PFO–CFO Hypothesis of Solar System formation: the notion of the Sun-like stars and their transformations”. It is two-page abstract of our presentation that was given at the Europ. Planet. Sci. Congr. , 2013 (EPSC Abstracts 01/2013; 8). At the same page, our (together with Elena Kadyshevich) more detailed presentations given at this congress are also available.
Dear Sir,
OK
Could you please provide a link to the document you mentioned?
Dear Dr. Juan Casado,
Please, I send you the addresses of the two-page abstract and of the more comprehensive presentation.
https://www.researchgate.net/publication/245023223_PFOCFO_Hypothesis_of_Solar_System_formation_the_notion_of_the_Sun-like_stars_and_their_transformations?ev=prf_pub
and
https://www.researchgate.net/publication/257235779_PFO-CFO_Hypothesis_of_Solar_System_formation_the_notion_of_the_Sun-like_stars_and_their_transformations?ev=prf_pub
Presentation Presentation: PFO-CFO Hypothesis of Solar System formation: ...
Presentation Presentation: PFO-CFO Hypothesis of Solar System formation: ...
Hassan:
Perhaps, an answer to your question is something like … it depends on the model[s] one considers.
Permit me to give an answer within theory/modeling I have been developing.
The work correlates solutions to quantum isotropic harmonic oscillator equations with elementary particles (and the particles' fields, some particle properties, and some interactions in which the particles participate). For each known elementary particle, a solution exists. Other solutions might correlate with yet-to-be-discovered particles (that might, in turn, correlate with solving 'problems' regarding traditional theory not matching some observational/experimental results).
Within this work, 3 spatial dimensions correlates with (for a particle with spin S (in units of h-bar)) a role of the number S(S+1) = S(S + DP - 2), with DP=3. The expression S(S + DP -2) correlates with an expression (in radial coordinates) for the Laplacian in DP dimensions. (For example, for 5 spatial dimensions, one would have DP=5 and particles for which S(S+3) pertains.)
So, to the extent this theory pertains, DP≠3 correlates with the notion that particles exist for which S(S+1) does not apply. As yet, all known particles correlate with S(S+1).
Also, some the solutions correlate with candidates for dark-matter and dark-energy elementary particles. So, there may not be a need for other that DP=3.
Permit me to attach an extract from "Physics Math Correlations," which discusses my attempted research.
I hope this proves helpful and welcome dialog and/or collaboration.
Thomas, thank you for sending the second chapter of your book. The correlations idea adds another angle from which to look at this issue.
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