Dark Matter and the Standard Model of particle physics—a search in the ‘Dark’
Published: 28 September 2014 (GMT+10)
The Standard Model of particle physics (SM) has been very successful at describing the elementary particles and the forces that bind them together. However, the Standard Model presents some significant problems for big bang theorists. This is because the SM does not contain any Dark-Matter particles, and the neutrinos in it are described as exactly massless. Which means that in its present form, it is in clear contradiction with the big bang model as required by various observations.
Ethan Siegel, modified from Lawrence Berkeley Labs.
Figure 1: Formation of deuterium (1 proton and 1 neutron)
Those observations have led to the need to include Dark Matter in the standard (ΛCDM1) big bang model, particularly during the period of nucleosynthesis, just after the big bang beginning when the light elements were allegedly formed from hot hydrogen. Therefore, the Standard Model of particle physics is in stark disagreement with the requirements necessary for the formation of the first elements in the alleged big bang.
Where are the Dark-Matter particles?
All challenges to the standard ΛCDM big bang model have been met and overcome, so far, by assuming ‘unknowns’, particularly Dark Matter and Dark Energy, wherever and whenever needed. Astronomical observations have led big bang astronomers and cosmologists to look for these new unknown Dark-Matter particles to solve many of their problems resulting from such observations; for example, the formation of stars, galaxies and galaxy clusters, the testing of the big bang model with type Ia supernova measurements, the angular power spectrum of the CMB anisotropies, galaxy rotation curves, and in particular, as focused on here, Big Bang Nucleosynthesis (BBN).2
Now it is believed that by ad hoc additions of several new unknown-in-the-lab Dark-Matter particles to the Standard Model, its contradictions to the big bang model can be resolved. But that is hardly good practice in theoretical physics, because it means one doesn’t have a workable hypothesis. Such an approach is akin to the ‘deferent’ and ‘epicycles’ employed in the Ptolemaic system to maintain a geocentric cosmology before the Galilean revolt showed that the planets revolved around the sun.3
In addition, billions of dollars have been and are currently being spent on laboratory searches for these new hoped-for particles, in particle accelerator labs like CERN and Fermilab. We have read about the $10 billion search for the Higgs boson at CERN, which was apparently successful.4 However it has caused another headache for the big bang origin of the universe and the speculation called ‘inflation’.
If found though, these new Dark-Matter particles would then change the necessary conditions in the modelling of the very early big bang universe, at the time of the formation of the light elements such as deuterium (D), helium (He), and lithium (Li), according to the theorised BBN processes.
The supposed Dark-Matter particles are exotic forms of matter that are really invisible because they do not interact with normal matter or radiation, or are extremely weakly coupled. Their presence has only been inferred by their postulated effect on gravitation. For example, galaxy rotation curves—anomalously high rotation speeds of the gases and stars in the outer regions of spiral galaxies—are explained by the presence of this postulated, unseen Dark Matter in a spherical halo around the galaxy.
According to theory, soon after the beginning of time itself, from the hot big bang ‘fireball’, eventually a plasma formed that comprised essentially protons and electrons, which were subsequently smashed together to form neutrons and subsequently the protons and neutrons were fused to form the light elements.5 See Fig. 1.
The baryon asymmetry problem
Baryons are the normal matter particles, mostly protons and neutrons, which comprise most of the known matter in the universe.
But the anti-particles (anti-protons and anti-electrons) must have also formed, with the condensation of those normal matter particles.6 However they are not observed. The lack of observations of the anti-particles in the known visible universe is another serious problem for the big bang.
The anti-matter should be present in equal amounts to the normal matter in the universe. But it is not. This is sometimes called the matter/anti-matter asymmetry, or the baryon asymmetry problem. It has become a tuning parameter in the big bang model.7 That means the theorists do not have a theoretical model that can predict what the asymmetry is, or should be, nor how it allegedly came about.
Light element abundances
How do the cosmologists expect to resolve these dilemmas? According to the standard big bang model, at the time of BBN, the universe was opaque to radiation, which means radiation was in equilibrium with the surrounding plasma; it would be absorbed as fast as it was released from the very hot fast-moving particles. If the radiation is continually absorbed before it travels any distance, it follows that one cannot directly observe that epoch using conventional telescopes of any description, radio through optical.8 But, it is believed that by measuring the abundances of the light elements one can accurately reconstruct what was happening during the BBN epoch and hence resolve these problems. Of course this presupposes that BBN is essentially correct and it now is only a research problem to solve these contradictions.
Figure 2: The alleged evolution of the light elements in the early universe. Density of Ordinary Matter is a proxy for time because, according to the theory, as the universe expands that density essentially decreases. The vertical red bar indicates the limit that the WMAP CMB observations can ‘see’.
Then by making observations of the deuterium abundance in the distant, hence early, universe, it is believed that this will resolve the issues. This follows from the assumption that deuterium could have only formed in the superhot plasma of the big bang. Then by adding to the theory sufficient Dark-Matter particles, with the right properties that give you the observed concentration of deuterium, one then says that one has detected the invisible Dark-Matter particles. That is how the ‘logic’ works here.
Now the baryon asymmetry (i.e., there is far more matter than antimatter) is used as the only free parameter, which is then determined by application of the model to observational data from the cosmic microwave background (CMB), and from the supposed primordial abundances of the light elements—hydrogen (H), helium (He), deuterium (D), lithium (Li).
It is the practice to determine the ratios of these elements with hydrogen, e.g. D/H. The observationally determined D/H values are scattered over a range of about an order of magnitude—meaning their measured values are different by about a factor of 10. Until it can be better measured there is no precise figure for this ratio, nor is its value consistent in different directions in the cosmos. It is believed that by more precisely determining these parameters (light element ratios, particularly D/H) cosmologists will be able to find which theoretical Dark-Matter particles fit observations, and excluding those that don’t. See Fig. 2. for the theoretical X/H dependence on evolution of the universe. X in this case represents the light element expressed as a ratio with hydrogen.
Are you starting to comprehend yet the elephant in the living room? The Standard Model of particle physics applied to BBN does not work unless you add new unseen particles—Dark Matter.
These are needed to resolve several problems, particularly the baryon asymmetry. The reality is that the SM is the best theory ever developed by modern physics in its very successful predictive power and ability to explain the atomic and sub-atomic world. There is really no need to include any exotic Dark-Matter particles unless you look at this hypothetical big bang nucleosynthesis.9 In other words, the need for Dark Matter to be added to the SM is largely motivated by cosmology.
Also, observations of the mass of the universe from different measurements have also indicated a discrepancy between the SM and the big bang model, and so a new neutrino—called a sterile neutrino, another form of Dark Matter—is introduced to solve that problem.10
The Dark-Matter particles are given exactly the right properties (which no particles known to man have) to keep the big bang paradigm alive. Note, I am not against positing the existence of a new particle in physics and then doing experiments to look for it. The problem here is the motivation; the big bang history is assumed for the universe, contrary to what Scripture says, and hence we must make BBN fit with the Standard Model of particle physics, resulting in the need to ‘invent’ exotic Dark-Matter particles.
Homogeneity and isotropy
The standard BBN theory relies on the Standard Model of particle physics and Einstein’s General Theory of Relativity, with the absolutely necessary assumption of homogeneity and isotropy expressed in the Robertson–Walker metric, the basis of the standard formulation of the big bang model today. But that assumption also presents another problem for the big bang.
Homogeneity and isotropy means that the distribution of matter in the universe on the largest scale is essentially uniform and the same in every direction, as seen by any observer anywhere in the universe, at the same epoch of time. This is an assumption that is essential in solving Einstein’s field equations for the equations of motion for the standard big bang model that are tested against observational data.
This means homogeneity and isotropy are basic assumptions of the standard big bang model. Independent measurements of the believed expansion of the universe in different directions11 from the best high-redshift supernova data found that to fit the data properly a 43±0.06 % disparity of total matter content, based on the overall average fraction of total matter (about 26% where 22% is Dark Matter), was needed in opposite directions in the cosmos, aligned with a preferred direction for the accelerating expansion.
This means that if you use observational data in one direction you need the universe to be comprised of 15% Dark Matter (assuming 4% normal matter) to get big bang theory to fit that data. But if you do the same in the opposite direction you need the universe to be comprised of 26% Dark Matter (assuming 4% normal matter) to get theory to fit that data. That represents a 43% disparity in Dark Matter content. That is hardly consistent with uniform expansion.
Computer simulations have indicated that, by random chance, one could get at most a 30% difference in the total matter content of the universe in opposite directions. That is significantly less than the 43% disparity needed when the big bang model was applied to the actual observational data. The analysis therefore indicated a preferred axis in the universe.12 Is this significant? The authors of that study state in it,
“However, when combined with the axes directions of other cosmological observations (bulk velocity flow axis, three axes of CMB low multipole moments and quasar optical polarization alignment axis), the statistical evidence for a cosmological anisotropy increases dramatically. We estimate the probability that the above independent six axes directions would be so close in the sky to be less than 1%.”
That is, there is a 99% probability that the universe has a preferred direction—a special axis—and it is detected by independent methods.13 That makes it neither homogeneous nor isotropic. Another team found14 large bulk flows of distant astrophysical objects reveal relative velocities much larger than predicted by the standard model, and in contradiction with it when tested against measurement data from the CMB, suggesting that the universe is not homogeneous.
Add to this the fact that investigations on the cosmological value of the fine structure constant (α)15 and the proton-to-electron mass ratio, measured in gas clouds in the line-of-sight of high-redshift quasars, indicate that these so-called ‘constants’ of nature may in fact vary with distance and direction, which in turn challenges the assumption of isotropy. A preferred direction is indicated.16 Theorists have no basis on which to predict how the fundamental constants should vary with direction in the cosmos, but if they do, then that would also mean a variation in the light element abundances, particularly deuterium.17
Often the arguments presented for a variation in the fundamental constants are motivated by worldview issues. The argument might be for some higher-dimensional space from which our universe was formed when some multi-dimensional branes collided. Quite obviously, it’s an argument based on a naturalistic origin for this universe, an appeal to materialism.18
Now there exists a discrepancy between the actual measured abundance of lithium in the distant universe and that predicted by BBN. Lithium is both produced and destroyed in stars, so it is difficult for big bang theorists to derive its expected primordial abundance. Whereas it is claimed that deuterium has no known post-BBN production mechanisms, and hence it is easier to ‘predict’ its expected abundance. Note: this is not really a prediction because the abundances of the light elements, e.g. D/H, are measured and the models are tuned accordingly. It has been called a ‘post-diction’ by some.
In particular there is a significant discrepancy for the abundance of lithium-7 derived from BBN theory with that determined from the CMB data measured with the Wilkinson Microwave Anisotropy Probe (WMAP),19 and the abundance derived from Population II stars.20 The discrepancy ranges by a factor of 2.4–4.3 below the theoretically ‘predicted’ value, and hence is a problem for the big bang models. See Fig 2. A range of theoretical models are offered to explain the apparent lithium-7 deficiency, and one of the latest offers an ‘axion’ to facilitate cooling of photons in BBN. An axion is the name for one of the putative Dark-Matter candidate particles, which has been sought after for more than 40 years in laboratory experiments.
Neutrinos present a big problem for the Standard Model of particle physics. The theory has only three neutrino species and they are massless, which is in very clear contradiction to their mass differences derived from measurements in neutrino oscillation experiments. It has been suggested that this could be solved by the addition of a ‘sterile neutrino’, which would solve the problem of estimates of the number of neutrinos (i.e. greater than 3 species) required from BBN and various processes in the putative early universe. It is claimed that a new species is also suggested by various laboratory experiments.21 Measurements of the mass of the universe from various classes of astrophysical observations suggest the need for a new sterile neutrino in order for big bang theory to be consistent with observations.
The hypothetical sterile neutrino does not interact via the weak nuclear force (as do the other known neutrinos) and hence is called ‘sterile’. It is a Dark particle, often called ‘Dark Radiation’. Cosmological measurements favour an additional relativistic neutrino when modelling the early big bang universe, hence a neutrino number greater than 3 is anticipated. Such a sterile neutrino could also lead to a huge lepton asymmetry (many more neutrinos than anti-neutrinos) and it would alter the conditions in BBN, resulting in differences to the expected light element abundances.22
Introduce a new particle and it changes many parameters, which then change the outcome of the big bang nucleosynthesis process determined by theoretical modelling. So naturally if it adjusts the elemental abundances one would get in the observed universe, then why not measure them and use them to tune the model? From this then you determine indirectly the existence of new Dark-Matter particles, even though you cannot observe them, nor detect them in a lab experiment.
Instead, the universe becomes your laboratory. But from this you cannot say the evidence is incontrovertible because you cannot interact with the universe. You are limited by what you receive in your telescopes. And computer simulations are not the same things as testing a model of the real thing, because of the problem of cosmic variance. This means that the same observations could be explained by alternate causes, and to be sure you were right you would have to eliminate all of those.
It seems to me that, outside of some new revealed information directly from the Creator, which will probably have to wait until Jesus returns, big bang nucleosynthesis is the unbelievers’ attempt to explain the observed universe without God. Because, if you could explain everything about this universe just with the laws of physics then you could feel more justified in saying that ‘this is all there is’. Of course, this is the definition of materialism—which is assumed a priori. But note what this worldview leads to, the invention of new particles (axions, sterile neutrinos and other forms of Dark Matter), and new forms of energy (Dark Energy that drives the supposed acceleration of the expansion of the universe). None of these are found in laboratory experiments. Yet this is not a small correction, but these new forms allegedly comprise as much as 96% of the mass-energy content of the universe. This is so bizarre, it is hard to believe that anyone believes it—such is the commitment to materialism.
As it stands now, though, the most successful theory known to physics, the Standard Model of particle physics, contains no Dark-Matter particles, but big bang cosmology demands them. Therefore, because of this prior commitment to materialism, the Standard Model ‘must’ be changed, else it will remain a stark reminder of the failure of the standard big bang model.
References and notes
- Λ represents Dark Energy and CDM represents Cold Dark Matter. Return to text.
- Nucleosynthesis refers to the generation of new atomic nuclei from particles such as neutrons and protons. BBN refers to the belief that certain nuclei formed in the early stages of the supposed big bang. Return to text.
- The ‘patches’ to the so-called perfect model of Aristotle resulted from the fact that the planets in our solar system have elliptical and not circular orbits. Return to text.
- The Nobel Prize in Physics 2013 was awarded jointly to François Englert and Peter W. Higgs “for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN’s Large Hadron Collider.” To balance that in 2011, the Noble prize was awarded for the discovery of the accelerating expansion of the universe. I don’t place cosmology into the same realm as experimental laboratory physics. I would say you can believe the Higgs boson has been discovered much more so than any claim in cosmology. Return to text.
- Smash an electron into a proton and you get a neutron. From these 3 particles you can build the rest of the light elements. Actually other light subatomic particles (mesons and leptons etc) are also involved but this is essentially the story. Return to text.
- In a putative earlier period the plasma initially comprised only electron/anti-electron pairs and neutrinos. See Hartnett, J.G., A Missing neutrino—Dark radiation, Answers Research Journal 7:357–361, 2014. Return to text.
- Scientific language meaning in this universe we only observe normal matter, very little anti-matter. Where is the missing anti-matter? So the theory is accommodated with a secondary hypothesis to avoid rejecting it. This would be fine if such stuff existed, but it is added to the theory only because of the worldview framework. The primary theory is never questioned. Return to text.
- Because neutrinos are believed to have formed first with the initial electron/anti-electron plasma about 1’s after the big bang when the neutrinos decoupled from their plasma, in theory one could use the Cosmic Neutrino Background (CNB) to probe that era of the early BB universe. But neutrinos are extremely difficult to detect and the CNB has not yet been detected. Return to text.
- Having said that it has been proposed that the solar neutrino deficit, the atmospheric neutrino anomaly and the Liquid Scintillation Neutrino Detector experiment (1993-1998) excess of events would be better explained with an additional (flavour of) neutrino—the sterile neutrino. There are currently only three flavours known but if there was at least one more, a sterile neutrino, neutrino oscillations between active and the proposed sterile neutrinos could have a significant effect on the R process in type II supernovae. See Aguilar, A., et al., Evidence for Neutrino Oscillations from the Observation of Electron Anti-neutrinos in a Muon Anti-Neutrino Beam, Phys. Rev. D 64:112007, 2001; http://arxiv.org/pdf/hep-ex/0104049v3.pdf. Return to text.
- See Ref. 6. paper on the sterile neutrino. Return to text.
- Antoniou, I. and Perivolaropoulos, L., Searching for a cosmological preferred axis: Union2 data analysis and comparison with other probes, Journal of Cosmology and Astroparticle Physics 12: 12, 2010. Return to text.
- This is the problem of cosmic variance. We have only one universe and to determine if something is statistically significance one must run computer simulations to see what a typical universe might look like. But we actually don’t know what one should look like. See The largest structure in the observable universe, or cosmic variance? Return to text.
- By combining the axes detected using various methods one gets the most probable single axis (or preferred direction). Return to text.
- Feldman, H.A., Watkins, R., and Hudson, M.J., Cosmic flows on 100 h−1 Mpc scales: standardized minimum variance bulk flow, shear and octupole moments, Monthly Notices of the Royal Astronomical Society 407(4): 2328–2338, 2010. Return to text.
- See discussion on fine structure constant in Is there any evidence for a change in c? Return to text.
- Webb, J. K., King, J. A., Murphy, M. T., Flambaum, V. V., Carswell, R. F., & Bainbridge, M. B. Indications of a Spatial Variation of the Fine Structure Constant, Physical Review Letters 107: 191101, 2011. Return to text.
- Berengut, J. C., Flambaum, V. V., King, J. A., Curran, S. J., & Webb, J. K., s there further evidence for spatial variation of fundamental constants? Physical Review D 83: 123506, 2011. Return to text.
- Nothing sinister is suggested in that. Cosmologists are simply operating within their worldview. Return to text.
- A spaceborne telescope which measured CMB anisotropy data—small variations or noise in the intensity and polarization of the radiation from the cosmos. Return to text.
- Stars found in galactic halos and globular clusters. They have low concentrations of heavier elements (heavier than Li) and are believed to be older stars. Return to text.
- Riemer-Sørensen, S., Parkinson, D., and Davis, T.M., What is half a neutrino? Reviewing cosmological constraints on neutrinosand dark radiation, Invited review for PASA, http://arxiv.org/pdf/1301.7102.pdf. Return to text.
- Simha, V. & Steigman, G., Constraining the universal lepton asymmetry, Journal of Cosmology and Astroparticle Physics 8: 11, 2008. Return to text.
"GUFF"! I love it! Thanks, Neil A. in the U.K. I'll be using that one. Couldn't have said it better.
And thanks, Dr. Hartnett, for the reference to the 'fudge factors' that kept the Ptolemaic model of the universe going long past its 'best before' date. What clearer illustration, on a level comprehensible to the non-mathematical (which is most people), could there be of the scientific bankruptcy of the Big Bang model than its ongoing accumulation of its own fudge factors (which, as you point out, contradict workable science, i.e. the Standard Model) to keep it going long past its 'best before' date?
It is becoming increasingly clear that the Big Bang proponents are ideologically motivated, as were the Ptolemaic model proponents, to keep supporting their scientifically crumbling model, in spite of the fact that they have to keep inventing 'pixie dust' solutions to its mounting problems and chew up workable science to do it. This is called denial, which is the last refuge of the determinedly mistaken.
Dark matter and Dark Energy comprise a class of particles and radiation generally known (well, to me anyway!) as Great Universal Fudge Factors. The acronym says it all: GUFF.
Galileo overturned Aristotelian physics with his falling objects experiment. He did have some discrepancy in his prediction - light objects fell a bit slower than heavy ones (he had not factored in air resistance). When this was raised in his conversational treatise on the subject, he made the point: My error is 10%, Aristotelian is 90%, so which theory is better? Why do physicists now forget that? Their belief system overrides good science.
It is accepted nowadays by most historians that Galileo's experiment of dropping two different weight masses from the Tower of Pisa was a thought experiment, which he did not actually do. His student however Vincenzo Viviani claims he did it. Either way your point is still valid, because free fall experiments since have proved him correct.