Planetary system formation: exposing naturalistic storytelling
Published: 14 April 2016 (GMT+10)
Attempts to explain how stars form naturalistically have encountered significant challenges because the known laws of physics indicate it is virtually impossible.1 There is a remote possibility for star formation via the mechanism of a nearby supernova, but dark matter is generally invoked as the ‘unknown god’, a ‘god of the gaps’ to make it work, because such events are extremely unlikely.2 Without this ‘unknown god’ in their uncreated universe, the formation of the star at the centre of a planetary nebula is essentially impossible. It also follows that planet formation has a similar problem. How do planets form in a nebula of gas and dust, which according to the known laws of physics cannot condense a star at its centre?
More importantly, how do you get a solar system with planets in habitable zones? Radiation from the newly born star would drive out any excess gas and dust from the path of the planets via photo-evaporation and stellar winds, making the formation of planets very unlikely. The planets allegedly condense via the core accretion model resulting in (in some cases) a habitable planet in the habitable zone, at the right distance from the parent star where water can exist in its liquid state.3 Then water is assumed to condense on the surface of that new planet—but by what mechanism? Ultimately this is a question about life elsewhere in the universe. But I digress.
By product of star formation
Standard astrophysical dogma is that planets form around stars as a natural by-product of the star formation process.4 But there are several problems.
For the initial molecular cloud to collapse, and eventually form a star, the cloud must eliminate any magnetic fields (due to unpaired charges) that oppose the collapse. The alleged process, which removes any magnetic field induced pressure from molecular clouds, entails the ions that carry the magnetic fields slowly diffusing out of the cloud, taking the magnetic fields with them.4
But these same magnetic fields are invoked to shuttle the angular momentum from the newly forming star, at the centre of the cloud, outward into the disk region of the solar nebula, to overcome another unsolved problem. This is the angular momentum problem, where the putative central star should have 99% of the angular momentum of the collapsing cloud, but in real observed solar systems like our own, 99% of the angular momentum resides in the planets, hence in the disk of material around the central star. Their suggested naturalistic solution to this problem is just-so storytelling. See below.
Then there is the problem of the Jeans mass limitation. The Jeans mass1 is the lower limit on the mass of a cloud, of a certain temperature and density, that will lead to gravitational collapse, against thermodynamic pressure (the tendency of hot gas to expand, not contract) alone—that is, if we only consider the temperature of the cloud, which is a consequence of the cloud pressure due to its self-gravity. These two parameters, temperature and density, naturally reach an equilibrium condition in what is called a virialised cloud,5 where the gravitational energy balances the internal kinetic energy, and the cloud is gravitationally stable.
I quote here from some stellar evolution lecture notes (available online):
“These gas clouds are in a state of equilibrium so that they are not prone to spontaneously collapse on their own to form into stars. The internal gas pressure and self-gravity are balanced to maintain them as stable clouds. But of course these clouds have to become stars, so something must push them over the limit where the self-gravity will overcome the gas pressure.”6 (emphases added)
Such is the faith of the evolutionary astrophysicists! Without the Creator they must live in hope that they can find a solution to a seemingly intractable problem. I have previously discussed what is used to overcome this in star formation,1 but what about planet formation?
Astronomical observations of molecular hydrogen clouds, which it is said will eventually collapse to form stars, are considered to be dense enough to overcome the limit imposed by the Jeans mass criterion, but this does not explain how those clouds got into that state in the first place. Possibly the clouds were compressed past the Jeans limit by shock waves generated from nearby supernovae? But cloud cores with observed densities high enough that they can collapse directly to produce Jupiter masses, i.e. planet-size objects, are not observed.4
To overcome the limit imposed by the Jeans mass criterion (hence the known laws of physics), the workaround is to “assume that the Jeans criterion is satisfied and the cloud is unstable to gravitational collapse”.4
Alternatively they invoke hypothetical dark matter, which has conveniently anomalous properties, such that it is not subject to normal thermodynamics and hence provides gravitational force, tending to collapse the cloud, yet no thermal energy to support the cloud against gravitational collapse.1 Thus the thermal limit is overcome and the cloud contracts. The process continues with different regions fragmenting within the cloud, satisfying the Jeans criterion, and resulting in various regions collapsing individually, thus forming many smaller objects within the larger original cloud. This is a process called fragmentation.
As these smaller regions gravitationally collapse, according to the theory, they are alleged to radiate away, at infrared wavelengths, the excess energy from their cores, thus keeping them cool. Normally you would expect that compressing a gas causes heating, as happens in a refrigerator compressor. But it is assumed that this cooling process continues until it can no longer be sustained. By that time the gravitational force is so strong that the thermal support due to the increased pressure no longer prevents collapse. Once the temperature rises high enough, molecular hydrogen dissociates into atoms and a ‘protostar is born’. Well, that’s how the story goes.
Models of planet formation
There are two competing naturalistic models on planetary formation:3 one a ‘top-down’ approach and the other a ‘bottom-up’ approach.
The ‘top-down’ model employs a gravitational instability similar to the idea used in star formation, where, according to the theory, planets form in accretion disks. This allegedly comes about because of a higher density of material in some regions of the disks where self-collapse under gravity occurs. Once collapse occurs, the protoplanet then attracts more material onto the newly developing planet. But this idea has its problems.
“ … it appears that the solar nebula’s lifetime would not have been sufficient to allow objects like Uranus and Neptune to grow quickly enough to attain the masses we observe before the nebula was depleted. The mechanism also does not explain the large number of other, smaller objects that are present in our Solar System and are likely to exist in other planetary systems as well. … the gravitational instability mechanism doesn’t appear to readily account for the mass distribution of extrasolar planets, the correlation between planetary system formation and metallicity, or the wide range in densities and core sizes of planets, both within the Solar System and among the extrasolar planets.”7
The ‘bottom-up’ model asserts that planets grow through a process of accretion of smaller building blocks. By observing other planetary systems astronomers are led to favour this model, but no single robust model has yet been established.
The scenario is typically started with expanding nebulae from supernova explosions where the expansion causes the gases to cool. Out of the remnants of these exploding stars, elements such as aluminium, titanium, and calcium get scattered through space. When a supernova remnant meets a cooler portion of a fragmented gas cloud, which has not collapsed, the remnant may break up into ‘fingers’, or, the smaller fragmented gas cloud may be compressed by the shock wave from a nearby supernova. The result is enrichment of a solar nebula with elements synthesized in the very high temperatures of the supernovae. These elements are necessary to form the rocky inner solar system planets, like Mercury, Venus, Earth, and Mars.
The accretion model posits that grains with icy mantles collide and stick together, which allegedly leads to larger and larger particles, which also collide and stick together, until they are large enough to have a gravitational influence on other particles. Then ‘planetesimals’ are formed, which also grow by low energy collisions, and so on. It is storytelling, based on the observed fact that planets do exist around their central stars.
There is the problem of the above-mentioned radiation pressure from a newly forming central star that tends to clear out dust grains from the planetary system. But supposedly the same star aids planet formation by cooling the protoplanetary disk material so that planetesimals can condense through the accretion process from the inward spiralling small dust grains. Simulations have been performed in an attempt to understand how the dust settles out of a spherical halo with random orbits into a flattened disk in the equatorial plane of the central star.
“The rate of dust settling is proportional to the grain radius. It would take a 1 µ m grain about 107 yrs to settle to the mid-plane, which is very slow. In fact it is too slow to form planets before the disk disperses. So other processes must be at work.”4 (emphasis added)
Laboratory research, for example, on dust grains sticking to each other,8 and simulations on growth of grains in space,9 are ongoing to try to understand how small grains grow into large grains, because without a mechanism(s) there can be no planet formation. Growth via collisions has problems. For example, as the grain size increases so does the mean collision velocity, which is likely to stall the growth process or actually reverse it, as grains bounce off one another and also break one another into smaller sizes. So, some other mechanism needs to be found.
Furthermore, simulations show that once the putative grain size has reached about 1 metre at a distance of 1 a.u.10 from the protostar the grains will spiral into the protostar in only 100 years. This is known as the ‘metre-sized barrier’ to planetesimal formation. However, the latter is proposed as the mechanism that clears out the dusty lanes (orbits) for the planetesimals as seen in Fig. 1.
According to the story, these problems can be overcome by either an anomalous jump in density due to a maximum pressure increase at a certain distance from the protostar, or turbulence in the disk regions causing millimetre-sized grains to clump together. Just how either of these could come about is not known. They are introduced a priori, whereby it is assumed that such features exist in real physical systems:
“While the mechanism is not yet fully understood, the grains will eventually become kilometre-sized planetesimals.”4
More hopeful storytelling.
According to this story, from their mutual collisions the planetesimals grow as they orbit their protostar. Once they get large enough gravitation takes over and accretion occurs very quickly resulting in embryonic planets—protoplanets. The formation timescale for the protoplanets is said to be a few hundred thousand to about ten million years.
The story continues with the belief that the protoplanets continue to grow slowly via gravitational collisions, clearing out the remaining solids in the planetary disk. And in the case of our solar system, it was finished after about 10 to 100 million years.
Conservation of angular momentum
As the solar nebula cloud ‘spins up’ to conserve angular momentum, this allegedly produces a ‘protostar’ at the centre of the cloud and a flattened disk of gas and dust in orbit around it. See Fig. 2. It is assumed that the disk formed more rapidly than the star and thus most of the mass of the central star is channelled through the disk. This idea has a fine-tuning problem. It needs a process that ends up with 99.9% of the total mass of the system in the central star and only 0.1% in the disk, even though most of the matter was initially located in the disk.
“During the gravitational collapse of a molecular cloud core, the gas must contract by a factor of about 106 in size to form a star. Due to conservation of angular momentum, the initial cloud rotation is enormously magnified, which results in the small central protostar being surrounding [sic] by a large rotating disk. It is in these disks that planets form.” (Emphasis in the original)4
As the cloud collapses, due to the conservation of angular momentum, the cloud must spin faster. This creates strong centrifugal forces, which are greatest at the equator. The theory then supposes that this causes the rotating contracting cloud to spread out in the equatorial plane to form a disk as shown in Fig. 2.
Consider our sun with a mass representing 99.86% of the mass of the solar system but only 1% of its angular momentum.7 The planets on the other hand have a total combined mass of only 0.14% of the mass of the solar system yet 99% of its angular momentum (mostly in Jupiter).
Most of the angular momentum of any solar system must reside initially in the central core of the collapsing cloud, which eventually becomes the star, according to the theory. Basic physics tells us that the collapsing star must ‘spin up’ and hence contain most of the angular momentum of the system. Yet, after some time nearly all the angular momentum is allegedly transferred to the planets somehow. This is a huge problem for the evolutionary theory. Various mechanisms have been proposed to try to overcome the problem, which include viscous, gravitational, and magnetic torques. But all these suggestions are really just clutching at straws.
The proposed torques are alleged to have the effect of pushing outer matter in the disk farther out, while causing inner matter to fall towards the protostar. The desired mechanism is one that results in an effect like the one that earth’s gravitational coupling to the moon produces, causing the moon’s period to increase as it moves outwards from the earth.
While thermal motions and convection in the nebular disk is not considered an option, magneto-hydrodynamic turbulence has been proposed, which is believed to be more promising to create the needed torque. Local and global gravitational instabilities have also been suggested, which are believed to lead to the formation of spiral density waves in massive disks. These are alleged to be very efficient at redistributing angular momentum (and material) through the disk until quasi-equilibrium is reached. Lastly, magnetic breaking torques, have been considered, which are believed to form if magnetic field lines from the protostar thread the disk. As a result, angular momentum is transferred outwards from the protostar into the disk. But, as already stated, magnetic fields are a serious problem for the formation of the central star in the first place. In fact, all of the proposed mechanisms are only proposed because of a prior commitment to materialism. “We observe exoplanets around stars so there must be a mechanism.” But it is just more storytelling. See also “Giant molecular clouds”.11
Simulations and confirmation bias
How can these ideas be tested? One way is with computer simulations and another is to look for protostar systems at various stages of their evolution. But how robust is that?
No simulation actually starts with just a gas cloud, but rather with either dark matter or a very dense already-collapsing gas cloud.9 In other words, the simulations assume the necessary initial conditions that will allow the simulation to produce a collapsing cloud. If they didn’t do that the simulations would not result in any stars or planets.
Looking for stars or protostars at various stages of their supposed evolution is subject to confirmation bias—where the astronomer looks for that which he already believes to be true. Instead, God may have created a great variety of stars. Their solar systems may appear to be at what a cosmic evolutionist might label as different stages of evolution, but in fact none has actually evolved to get to that stage.
I have suggested that looking at other star systems may give us a clue to the nature of the formation of our own solar system,12 when created by God. But this also has a similar type of bias, but a bias towards the Creator, who created other forms of planetary systems throughout the Galaxy, a few observed with dust clouds around them.13
Are we seeing any planetary systems in formation today? Refer to “A protoplanetary system in formation?”3 I think it is yet too early to say. But does the naturalistic model have any substantive basis to claim an understanding of planet formation using only known physics? Definitely not, especially when dark matter and unlikely supernovae events have to be invoked. Though astronomers seemed to have settled on one model—the accretion model—it has many unsolved—even insurmountable—problems.
The whole commentary on naturalistic planetary formation is just storytelling. There are many stages where there are big gaps involving unknown processes. The gaps are glossed over with expressions of hope for a future breakthrough, yet significant problems remain. Really, the storytelling is an attempt to bypass the Creator in His role and insert evolution’s ‘unknown god’.
According to the biblical model there is no reason to expect that the Creator did not create many different forms of planetary systems, which might be incorrectly labelled by evolutionists as being at various ‘evolutionary stages’ of formation.14 I accept that God made extrasolar planetary systems on Day 4 of Creation Week about 6,000 years ago.
References and notes
- Hartnett, J.G., Stars just don’t form naturally—‘dark matter’ the ‘god of the gaps’ is needed, September 2015; creation.com/god-of-the-gaps. Return to text
- Hartnett, J.G., Is ‘Dark Matter’ the ‘unknown god’?, Creation 37(2):22–24, 2015; biblescienceforum.com. Return to text
- Hartnett, J.G., A protoplanetary system in formation?, September 2015; biblescienceforum.com. Return to text
- HET620-M09A01: Planet Formation: Disk Formation and Evolution, Swinburne University of Technology, 2011; astronomy.swin.edu.au. Return to text
- The eventual formation of a dynamic equilibrium in the cloud with the loss of any substructure. Return to text
- Stellar Evolution–Details, page Notes 5–1, uni.edu/morgans/stars/notes5.pdf. Return to text
- Carroll, B.W. and Ostlie, D.A., An Introduction to Modern Astrophysics, 2nd Ed., Pearson, Addison Wesley, pp. 862–863, 2007. Return to text
- Superglue of planet formation: Sticky ice, Spaceflight Now, Pacific Northwest National Laboratory News Release, March 2005; spaceflightnow.com. Return to text
- See movies listed here: www.astro.lu.se/~anders/research.php. Return to text
- 1 a.u. = 1 astronomical unit = the earth-sun distance of 150 million km. Return to text
- Hartnett, J.G., Giant molecular clouds, 2016; creation.com. Return to text
- Hartnett, J.G., The ‘waters above’, J. Creation 20(1):93–98, April 2006; creation.com/waters-above. Return to text
- Very few extrasolar planetary systems have been observed with the needed detail necessary to see a disk of planets and/or dust and debris. See Ref. 3. Return to text
- This is the same way evolutionary palaeontologists sort the fossil record into representing successive long ages of deep time where evolution of one kind of organism to another allegedly occurred. Return to text
I guess that to begin with, I have a question. Is not the stability of a planet's orbit a balancing of velocity, mass, and distance from the sun, and that changing any of these factors would alter or completely compromise its orbit? Now if that is correct (I assume it to be, but maybe incorrectly), does the evolutionist's accretion model as you have described it take into account this balancing act as the planet accumulates mass? It seems to me that as its mass increases, than its speed or distance (or both) needs to increase as well. If you did cover that I missed it, or maybe I am holding to wrong assumptions.
What you ask goes to the details of the model used to form planets from the protoplanetary disk. The most favoured model describes an inflow of matter from a spherical halo to the disk in the plane of the equator of the newly formed protostar. See Fig. 3 under the section "Conservation of angular momentum". The problem of angular momentum is discussed there, and it runs counter to what is needed if the newly formed solar systems are like our own.