Saturday, 7 June 2014

Creation wiki doesn’t understand star formation

Hoo boy. Creation Wiki is at its finest. Just google "star formation creation wiki"  Nobody understands how stars. great and many, numbering in the trillions form, therefore it has to be supernaturally created!

 Of course, the whole thing is  bollocks factually incorrect, but before I begin a critical analysis ......

The magnificent Pillars of Creation,  within the Eagle Nebula,  about 7000 light years from Earth. So called because they are the site of stellar nurseries, which will eventually result in the complete destruction of the Pillars. Image credit goes to
YECs love to take jabs at every model of star formation. They claim "star formation has never been observed". Then they assert that gases can only expand, stars could never form etc etc etc and in Creation Wiki's case, they bring up Psalm 19:1 as  evidence. The most obvious thing to spot is the freaking double standards. They never saw their God before, nor did they see their God instruct Moses to write the Pentateuch, nor do they even know the exact date the Pentateuch was written. Yet they believe in Him, heart, mind and soul.

If we accept the YEC model, only taking into account PV = nRT, theoretically nebulae should continue expanding forever, since there's absolutely nothing to stop them from doing so. Then why are there dense clumps in nebulae? What are these Bok globules, which seem to be producing their own light, doing in the heart of nebulae then?  Why do these formations dont appear to be obeying the ideal gas law?  Did God accidentally leave clumps of dense material in the primordium or something? 

The fact is, stars do form. We have even observed them! Furthermore, although impenetrable to light, astronomers use IR telescopes to discover that, although the gas of nebulae are generally a few degrees above absolute zero, dense regions are very hot and produce their own IR. Why is that so? 

You see, nebulae are so mind-bogglingly enormous that additional factors, one in particular, have to be taken in account. Gravity! When nebulae are of entire light years across, its inward gravitational pull is such that areas become compressed by gravitational force, overcoming gas expansion as well as possible electrostatic interactions. Notice this is somewhat similar to how stars remain stable; the outward force generated by nuclear fusion within its core is balanced by the stars inward pull of gravity.

Using the foundations of modern physics, we can of course, derive a well supported method of star formation. The key is understanding gravitational binding energy, which I ll try to explain here in simpler terms. this is defined as the energy required to pull apart a sphere to infinity. So we take a particular nebula and build a model assuming the nebula is a sphere. We slice it into "shells" to help better imagine the potential changes, where R is the radius where the binding energy is zero:

(Credit goes to Professor Chris Mihos for providing excellent online resources-his is the easiest to understand).

Where dr is the  radius of each shell.
 We know that volume of the initial gas sphere the core is v = 4/3 π r3
Since mass = density * volume, we can measure initial mass m =    4/3 π r3   ρ
(ρ is density)
So the mass of each "shell", expressed with respect to radius? dm = 4 π   r2  ρ   dr   equation 1
A simple derivative is, well, volume = mass/density, so  dV =  4π r2   dr. Label  this as the volume of each "shell" 
Now, the objective here is to derive a function that describes the change in gravitational potential  energy. We know the formula for gravitational potential energy,
 Its U = -GMm/r.

 To express the gravitational potential energy in terms of dm (mass of each "shell")Differentiate this to obtain

dU = -GM  dm  / r . equation 2

So what is M, the mass of the gas? Same as before, m of course! in this case, we perform a dirty little trick and re-use the equation for m, which is  4/3 π r3   ρ.

 M =m, so substitute  M =    4/3 π r3   ρ     and equation 1 into equation 2

As we can see here, what we have done is basically express dm in terms of dr.
To express U, dU/dr has to be integrated. So lets do that:

Since  ρ = M / (4/3  π r3   )

U =  - 3 G M2  / 5R
This is defined as the gravitational binding energy.

Now for the next step. Gravitational collapse occurs when gravitational binding energy exceeds the internal gas pressure. The critical mass is called the Jean's Mass.

Before we proceed, the Virial theorem needs to be understood first. 

(To prove total energy of a system = half of gravitational potential energy)
Remember  elementary physics, force of an object rotating around the Earth? Since centripetal force = gravitational force
mv2  /r  = GMm/r2

v= (2GM/R)^0.5 sub this into equation for K.E. 
K.E. = GMm/2R  

total energy = gravitational potential energy(always a negative) + kinetic energy = -GMm/R +GMm/2R = -GMm/2R 
The virial theorem works by the same principle-total energy E(total energy) = K(kinetic) + U(potential), 

total energy = half of gravitational energy

For its proof go here.

Now thats settled, since E = 0.5 U,

K + 0.5U = 0

2K + U =0

by ideal gas law, K.E of gas =3/2 NkT, N = number of molecules, k = Boltzmann constant
U =  - 3 G M2  / 5R, sub this into 2K + U = 0

3 NkT =  3 G M2  / 5R equation 1 

This is when the system is at virial equilibrum, i.e. the Jeans mass, when gravitational force = pressure of gas

let N = M/m where m is mass of 1 molecule,
so whats R? Remember M = 4/3 π R3    ρ
rearrange to get: equation 2:  R = (3M/4π ρ)1/3 
sub this into equation 1
we get M = (5kT/Gm)2 *(3/4π ρ)1/2

Hence gravitational collapse occurs if: 

Hence stars can form! 

Creation wiki can no longer rationalize this. The only thing they got right was that condensing material tend to form protostars before joining to birth new stars. 

the largest galactic superstructure in the Universe-the Hercules-Corona Borealis
Great Wall. Measures 10 billion light years across! Image credit goes to Wikipedia:


Again, I would like to thank Professor Chris Mihos, whose material I borrowed heavily from. Please visit his site here. 

P.S. Coming up next: the theological consequences of a literal six day creation of the Solar system. 

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