‘Dark matter’ is an essential ingredient to form stars naturally given only standard known physics. ‘Dark matter’ is a hypothetical exotic form of matter, unknown to laboratory physics, which does not interact with or emit light in any way, hence it is invisible to all forms of detection within the electromagnetic spectrum, from radio-waves to gamma radiation. ‘Dark matter’ itself, therefore, is outside of standard known physics. It is made-up stuff that has been given one special property, which is that it gravitates, that is, unlike normal matter, it is a source of gravity only.
Detection of ‘dark matter’
But has dark matter been discovered by any direct measurement? That is apart from inferring its existence due to anomalies like galaxy rotation curves where the motions of stars and gases in the arms of spiral galaxies do not follow the expected Keplarian law in line with standard Newtonian physics? No, it has not and that is after 40 years of searching in laboratory experiments. Yet it is believed to exist—a ‘god of the gaps’—and is essential, otherwise many astrophysical observations just do not agree with those expected by application of standard laws of physics. See Fig. 1 for image of dark matter.
Theoretical physicist Mordehai Milgrom has proposed an alternative to dark matter, called Modified Newtonian Dynamics (or MOND) wherein he slightly changes the law of gravitation on the very large-scale of galaxies to solve the problem of galaxy rotation curves and dynamics of galaxies on larger scales. In a 2014 NewScientist article1 Milgrom was asked by reporter Marcus Chown:
“Why is now a good time to take an alternative to dark matter seriously?”
To which he replied:
“A host of experiments searching for dark matter, including the Large Hadron Collider, many underground experiments and several space missions, have failed to see anything convincing. This comes on top of increasing realisation that the leading dark matter model has its failings. Among other things, it predicts that we should see many more dwarf galaxies orbiting our Milky Way than we actually do.”
This latter problem I pointed out in Why is Dark Matter everywhere in the cosmos? In this article I will focus more on the problem, not of galaxy formation, but of star formation, though the two are related. Without stars galaxies would not exist. But before I get to that consider the following.
Large scale computer simulations of the universe
A BBC news headline read “Universe evolution recreated in lab.”2 This story was about an international team of researchers who “… created the most complete visual simulation of how the Universe evolved.” They used a super-computer to create a model of the alleged early universe wherein they showed “… how the first galaxies formed around clumps of a mysterious, invisible substance called dark matter.” Fig. 2 shows the results of their simulation compared to the real Universe. The result looks very good, doesn’t it? Maybe they have solved the problem of the origin of the Universe?
They were working not on the scale size of stars, but of large scale structure of the Universe and formation of galaxies. The article reports (my emphasis added):
“In the beginning, it shows strands of mysterious material which cosmologists call ‘dark matter’ sprawling across the emptiness of space like branches of a cosmic tree. As millions of years pass by, the dark matter clumps and concentrates to form seeds for the first galaxies.”
They had to use dark matter as the ‘seeds’ or the galaxies would not condense in their simulations. Prof Carlos Frenk (Durham University) said (my emphasis added):
“You can make stars and galaxies that look like the real thing. But it is the dark matter that is calling the shots.”
Without this unknown ‘god of the gaps’ you simply cannot make the simulations produce anything that look like the real Universe. The laws of known physics will not allow that. Dr Vogelsberger of Massachusetts Institute of Technology (MIT) said (my emphases added):
“If you don’t include dark matter (in the simulation) it will not look like the real Universe,”
Finally cosmologist Dr Robin Catchpole (the Institute of Astronomy in Cambridge) adds what the reporter call a note of caution (my emphases added):
Although he hailed the simulation as “spectacular”, he added, “one must not be taken in by the sheer visual beauty of the thing. You get things that look like galaxies without them being much to do with the physics of how galaxies emerged.”
Star formation’s essential ingredient
As Prof Carlos Frenk pointed out in the above quoted article,2 dark matter is essential to making stars, and he means naturally, that is, with only the known laws of physics.
The visible Universe has about 1011 galaxies containing about 1011 stars on average, totalling about 1022 stars. Thus their formation is foundational to the Universe. Without stars there would be no universe. However, from the secular perspective, the theoretical understanding of star formation is quite lacking, but theorists are hopeful and they are continuing research via computer simulations trying to reconstruct the past history of the early universe and star formation.
The main difficulty comes in modelling the physical process of formation, which involves gravity, highly turbulent gas dynamics, magnetic fields, radiation, molecular and dust chemistry. Star formation also involves an enormous range of length and time scales, assuming only naturalistic processes, which make simulations difficult, even with super-computers.
Nowadays, dark matter is added as an essential ingredient to all simulations on star formation because once any hypothesized cloud of hydrogen gas condenses to a certain size it comes into hydrodynamic equilibrium. This means the outward force on the cloud, caused by the accumulated pressure due to heating of the compressed cloud, equals the inward force on the cloud due to the mutual gravitational attraction of all matter in the cloud. At this point no further contraction can occur, unless something else is introduced to overcome this limitation.
You may hear the expression ‘virialized’ system. In such a state a balance has developed between the kinetic energy and the gravitational potential energy of the cloud. Once this is reached no further change can occur unless energy is radiated away from the cloud cooling it, which may take an indefinite period of time, and if the matter density is below a certain value cooling is impossible. The way around that is to start with much more dark matter than normal matter, which immediately overcomes this balanced condition. That is justified by the assertion that spiral galaxies comprise 85% dark matter.
Any primordial gas cloud—consisting mostly of hydrogen—is assumed to be the product of the alleged hot big bang origin of the universe, wherein only hydrogen, helium and a little lithium was supposed to have formed, via nuclear fusion.3 According to that story, after 3 to 20 minutes the temperature of the big bang fireball had cooled to where no more fusion could take place.
Initially the elements (H, He) were in the form of a hot plasma but after about 380,000 years the plasma cooled sufficiently that the electrons re-combined with the protons and other nuclei forming essentially only hydrogen and helium gas. From that gas it is supposed, after about a billion years, give or take (the model is flexible), the first stars formed.4 But, and this is a big BUT, there is no known law of nature (physics) that allowed the first stars to form from the alleged primordial clouds of gas.
Figure 3 shows the believed formation process of a star. But note that in Fig. 3(a) the simulation begins with a dense core, such that gravitational collapse can occur in Fig. 3(b). ‘Something’ is added at the beginning else nothing can happen.
The Jeans limit
Without this ‘something,’ fundamental physics must necessarily be violated or the Jeans limit5 must be overcome by either compression of or cooling of the cloud. However, once this limit is overcome, gravity can take over (Fig. 3(b)) and compress the cloud further, to form the protostar (Fig. 3(c)). But without a mechanism to overcome this natural limitation the cloud would naturally heat up and that would prevent further compression, resulting in equilibrium.
In computer simulations of star formation the computer program is usually started with an over-density such that the Jeans mass is already achieved, hence the limit is not a problem because the simulation is started past that point (as shown in Fig.3(a) and (b)). The Jeans mass =Kρ–1/2 T3/2, where K is a constant, ρ is the cloud density, and T is the absolute temperature.
A universe without stars, that is, one that only has hydrogen and a little helium gas and the known laws of physics, is not the universe we live in. Naturalistically there are only 3 possible lines of investigation to overcome this problem, that is, to form stars naturally.
- Cool the cloud so it can continue to compress, increasing its density (ρ). Given sufficient time for cooling to occur eventually it is hoped the Jeans limit is overcome;
- Compress the cloud to overcome the Jeans limit, by employing, magnetic fields like in a tokamak6 to confine the hot plasma, or, some external force, e.g. a supernova, to compress the cloud beyond the Jeans limit;
- Introduce some new exotic matter that is unaffected by normal thermodynamic considerations, because it does not interact with normal matter, therefore it provides an added gravitational force on the cloud but without contributing to its heating. Thus it is used to overcome the problem of the equilibrium condition reached in the cloud preventing it from being able to collapse any further to form a star.
It has been proposed that a nearby exploding star (supernova) can compress a gas cloud, and it is hypothesized that our own sun formed after the supernova of a red giant in our galactic neighborhood. Shock waves are generated by the outward travelling blast waves. See Fig.4 showing (as ‘cosmic pearls’) the hot plasma travelling outward from the source of the central explosion. But the idea of the shock waves from a supernova needed to compress the gas cloud introduces a ‘chicken and egg’ problem and hence hardly qualifies as an explanation for the origin of the first stars, the population III stars, soon after the alleged big bang.
Magnetic fields in the gas cloud are also being investigated. They are no help, but, in fact, an impediment to collapse, unless the cloud can remove the magnetic fields by diffusing away the ions that carry them. The main hope of forming stars is with cooling channels, via infrared radiation from molecular hydrogen, but that requires long periods of time, and thus the simulations start with a mixture of dark matter and hydrogen (normal matter). There is no hope to form stars without the help of the assumed dark matter, no matter (no pun intended) how many hundreds of millions of years you give it. Physics is still the problem.
The following is how a Scientific American article entitled “The First Stars in the Universe”7 described the process (my emphases added):
This cooling plays an essential role in allowing the ordinary matter in the primordial system to separate from the dark matter. The cooling hydrogen would settle into a flattened rotating configuration that was clumpy and filamentary and possibly shaped like a disk. But because the dark-matter particles would not emit radiation or lose energy, they would remain scattered in the primordial cloud. Thus, the star-forming system would come to resemble a miniature galaxy, with a disk of ordinary matter and a halo of dark matter. Inside the disk, the densest clumps of gas would continue to contract, and eventually some of them would undergo a runaway collapse and become stars.
The following was written at the head of a sequence of graphics illustrating the alleged formation of the first stars and galaxies.
PRIMEVAL TURMOIL The process that led to the creation of the first stars was very different from present-day star formation. But the violent deaths of some of these stars paved the way for the emergence of the universe that we see today.
This was illustrated with my Fig. 5 (copied) showing a protogalaxy made up of a mixture of dark matter and ordinary matter (hydrogen gas).
The dark matter here is the ‘god of the gaps’ used to overcome the fundamental physics that naturally prohibits the collapse of the cloud to a star. In fact, it is assumed that most of the first proto-galaxies8 consisted of dark matter (of an unknown type of elementary particle9). The dark matter is given the needed properties to achieve the desired outcome. It does not emit radiation, which means it cannot be seen by normal electromagnetic detection methods; it does not lose energy because it does not interact with other normal matter particles. It is a ‘god’ that gravitates, creating strong gravitational forces, strong enough to overcome the resistance of the hot gas pressure in the cloud, causing the normal matter hydrogen to collapse into a star. This is just story telling at its finest.
It is further claimed that today we do observe stars forming where external forces, like shock waves from nearby supernovae, are not present. Most star formation allegedly takes place in the ‘density waves’ of spiral galaxy arms, which is a gravitational effect arising from the interactions of myriads of stars, gas, and dust orbiting in the galactic gravitational potential well. See Fig. 6.
Let’s unpack this. Firstly, even if it is true that the existing matter in the spiral arms of galaxies provided the needed gravitational potential well that causes the gas clouds to collapse into stars, this does not solve the problem of the first stars. Secondly, the argument used here—‘density waves’—is a theory to support the development of spiral arm structure that has the same problems as most of astrophysics—the need for dark matter. Because of the anomalous rotation curves of stars and gases in the disk regions it is supposed that dark matter exists in a halo surrounding the galaxy, and is found everywhere but in the core, where you would most expect to find it. But it is not needed there. Remember, it is not observed, only inferred to exist to solve problems with the motion of stars.
The ‘density wave’ theory is also used to support the notion of how a 10 billion year old galaxy can appear to have only one or two rotations (windings) in its spiral structure, when with a rotation period of 200 million years it should have 50 windings in the spiral structure. Astronomers sometimes call this the ‘wind-up problem’ of the spiral arms. The problem occurs because the inner parts of the disks of these galaxies are observed to rotate faster than the outer parts. Galaxies are not solid bodies and as they rotate they should wind up so much that their spiral structure should have been destroyed over 10 billion years of their alleged lifetime. This latter observational fact is something that biblical creationists have for a long time used as evidence supporting a young universe. The galaxies were, in fact, created almost just as we observe them, so there is no ‘wind-up problem.’
So this is all part of the story telling. Are gas clouds, in the act of collapsing into stars, actually observed in these galaxies? Well no! Intense emissions signal to astronomers active young new stars, so accordingly they report star-forming regions. But the very luminous emissions from hot hydrogen gas do not tell you how the stars were formed. Any biblical creationist model must also account for the first stars as well as stars forming in galaxies, but because the Genesis account says God made the stars on the 4th day of Creation we know that the first stars were formed by God supernaturally on that day. And because there is still this problem of the Jeans limit it is unlikely that many stars would have formed after the 4th day of Creation week.
One must invent unknown stuff—dark matter—with the right properties—the unknown ‘god of the gaps’—to get stars to form naturalistically. Without it, it just can’t happen!
But why invent this unknown stuff? There are various areas in astrophysics and cosmology where dark matter is invoked to solve some problem. But more fundamentally why invent a ‘god’ to overcome established laws of physics to explain star formation? Is it because if they don’t astronomers will have to admit that materialism fails and that there is more to the Universe than hydrogen, helium, some heavier elements, magnetic fields, radiation and the laws of physics?
References and Notes
- Marcus Chown, Forget dark matter – embrace my MOND theory instead, NewScientist, Magazine issue 2967, 6 May 2014.
- Pallab Ghosh, Universe evolution recreated in lab, BBC News, Science & Environment, 07 May 2014.
- Timeline of the big bang, The physics of the universe, accessed 2 July 2015.
- These are called population III stars, called metal poor (where metal means any element of an atomic number greater than helium). Their lack of detection has been a big big bang problem for a long time. The first population III stars are predicted to have formed at redshifts of about z = 10-30. The James Webb Space Telescope, tentatively scheduled for launch in 2018, is hoped to be able to detect some of the first galaxies, but it is doubted that it will be able to detect the first stars, the population III stars. The reality is that all stars ever observed, even in the Hubble Ultra-Deep Field, are not population III stars.
- Jeans instability, Wikipedia, accessed 2 July 2015.
- Tokamak, Wikipedia, accessed 01 July 2015.
- R. B. Larson and V. Bromm, The First Stars in the Universe, Scientific American, Special Edition, “The Secret Life of Stars”, Vol. 14, No. 4, pp. 7,9, 2004.
- Ref. 7, p. 8.
- J.G. Hartnett, Dark Matter and the Standard Model of particle physics—a search in the ‘Dark’, 28 September 2014.