Boyle's Gas Law, What is it?

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#21 A.Sphere

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Posted 05 July 2009 - 10:43 PM

Now I have been introduced to something called the Ideal Gas Law by our member A.Sphere. This concept is a fudge factor intended to override Boyle's Gas Law. The problem...

Boyle's Gas Law is testable, demonstrable, repeatable science. The ideal gas law is hypothetical and based on the assumption of naturalism not the demonstration thereof.

Boyle's law is what drops out of the Ideal Gas Law when temperature is held constant - I assure it is not a fudge factor. It is derivable from the kinetic theory of gasses and is one of the most important principles in the extrememly succesful theory of statistical mechanics. The ideal gas law approximates the behavior of many gasses to a very high precision - no system is truly closed and no gas only interacts elastically so of course it is off a bit as is Boyle's law. By the way Boyle's law has the same limitations as the ideal gas law - the system must be closed and only be composed of elastically interacting particles. This is not true for the ISM at all.

#22 Ibex Pop

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Posted 06 July 2009 - 12:13 AM

Apparently, it is assumed that Boyle's Law overcomes gravity under all circumstances. If this is not the case, then it is a given there must be a point at which the gas density and temperature (which give us the thermal pressure) can be overcome by gravity. The latter is obviously the case, as stars exist presently. Any gas cloud with mass will collapse if the gas is below a certain temperature, and cooling in this universe is inevitable. Radiative heating will continuously drop the pressure of any gas cloud until it becomes gravitationally bound and collapses.

Say we're playing with a large nebulae. Let's say it starts at 30K, a pretty standard temperature for a dust cloud in space. It will fall together until it reaches equilibrium in its pressure against its gravity, (1/2 its gravitational potential, according to the virial theorem), and fragments (it will have some freedom of movement as a dynamic mass near equilibrium with no container), and cools some more, and does this again, and again, fragmenting into lots of protostars. Why does the fragmentation stop and the frictional energy heat up to the point of fusion once we reach the stellar scale? Because the gas becomes increasingly opaque, resisting the emission of heat energy.

This is what the present model is for stellar formation. It is mathematically backed throughout, and explaining the whole of stellar formation is beyond the means of this forum and my ability to teach and understand myself. For example, Jean's Mass is the mass above which a given volume of a given gas will inexorably collapse. Clouds of such mass are observed to be collapsing today, so unless you can tell us what we're actually observing while simultaneously showing why the math astrophysicists use (which accurately predicts what we see) is wrong, you're really in no position to say that stars can't form, particularly under the conditions the scientists predict and we observe.

The law you originally presented as defying stellar formation has the explicit caveat of temperature, and you should know that temperature always falls (net) in a closed (exempt from outside influence), boundless (heat energy may pass beyond its ability to be reflected or absorbed) system. Gravitational collapse is inevitable so long as the expansion of space doesn't exceed the gravitational collapse. I don't know how this thread happened . . .

#23 Percy

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Posted 06 July 2009 - 05:03 AM

It is waffle like this which undermines any claim you make to competence in science and would convince most scientists to ignore any other opinions you might have.

Hey, Keith, I resent it when anyone pulls this stuff with me, and I'm sure Adam resents it when you pull it with him. There are clear explanations that we can offer in response to Adam's post, and we should simply offer them and see how he responds.

I've observed that sometimes Adam can be similarly dismissive, but that's no excuse for us to do the same thing. The ad hominem has to stop someplace otherwise it justs keeps escalating until the topic is totally obscured and a moderator finally decides to close the thread.

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#24 Percy

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Posted 06 July 2009 - 05:09 AM

Thanks for the thoughtful reply. I was going to respond, but I read ahead first and discovered that Ibex Pop has already posted an excellent response in Message 22.

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Posted 06 July 2009 - 06:07 AM

Boyle's law is a special case of the ideal gas law and only holds true in a CLOSED system.

The Universe, by definition, IS a closed system. Any outside influence would be chalked up as supernatural in both of our books. The only difference is that we acknowledge supernatural markers and naturalists ignore them and/or equivocate about them.

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Posted 06 July 2009 - 10:12 AM

Hey, Keith, I resent it when anyone pulls this stuff with me, and I'm sure Adam resents it when you pull it with him.  There are clear explanations that we can offer in response to Adam's post, and we should simply offer them and see how he responds.

I've observed that sometimes Adam can be similarly dismissive, but that's no excuse for us to do the same thing.  The ad hominem has to stop someplace otherwise it justs keeps escalating until the topic is totally obscured and a moderator finally decides to close the thread.

Thanks, Percy for not only being polite but pointing out the responsibility that we all have to conduct ourselves respectfully and that includes not being dismissive. Whether Keith takes your exhortation to heart or not is unimportant, I will. I'm not perfect and when I do act dismissively I'll say right here that I won't mind having it pointed out to me. When you start getting a little war hardened, like I have, it's good to get an outside perspective to get yourself back in line.

Thanks for the thoughtful reply.  I was going to respond, but I read ahead first and discovered that Ibex Pop has already posted an excellent response in Message 22.

Okay, let me interpret Ibex's message so that there is no mistake for how he consciously or subconsciously sets the stage to limit answers to his philosophical framework, so he can reject the empirical evidence in favor of his naturalism that can not be questioned by fiat decree.

Not nearly as painful as it is to respond to.

Apparently, it is assumed that Boyle's Law overcomes gravity under all circumstances.

This is what the scientific evidence demonstrates, to believe otherwise is speculation. This may not be totally unreasonable but speculation sold as fact is deceptive. Let's continue...

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Posted 06 July 2009 - 10:12 AM

If this is not the case, then it is a given there must be a point at which the gas density and temperature (which give us the thermal pressure) can be overcome by gravity.Ã‚Â  The latter is obviously the case, as stars exist presently.

This is a fiat decree not based on observable, testable, and demonstrable science but a philosophy that demands a certain conclusion not based on evidence but a set of beliefs that limit the conclusions.

Again, this is not science but a philosophy that limits our scientific conclusions.

Saying we have stars therefore it must be according to what we believe is the same as saying; "Look at all the animals, evolution must be true." The fact that this is believed to be intellectually satisfying is a sad sign of the state of critical thought in our culture.

Any gas cloud with mass will collapse if the gas is below a certain temperature, and cooling in this universe is inevitable.Ã‚Â  Radiative heating will continuously drop the pressure of any gas cloud until it becomes gravitationally bound and collapses.

The amount of empirical data that supports this? zero.

Say we're playing with a large nebulae.Ã‚Â  Let's say it starts at 30K, a pretty standard temperature for a dust cloud in space.Ã‚Â  It will fall together until it reaches equilibrium in its pressure against its gravity, (1/2 its gravitational potential, according to the virial theorem), and fragments (it will have some freedom of movement as a dynamic mass near equilibrium with no container), and cools some more, and does this again, and again, fragmenting into lots of protostars.Ã‚Â  Why does the fragmentation stop and the frictional energy heat up to the point of fusion once we reach the stellar scale?Ã‚Â  Because the gas becomes increasingly opaque, resisting the emission of heat energy.

Again, this is all speculation based on naturalistic assumptions. You can't demonstrate this. You believe it because something like this must be true according to your worldview. Again, you can believe this if you want but it's not science.

This is what the present model is for stellar formation.Ã‚Â  It is mathematically backed throughout, and explaining the whole of stellar formation is beyond the means of this forum and my ability to teach and understand myself.Ã‚Â  For example, Jean's Mass is the mass above which a given volume of a given gas will inexorably collapse.Ã‚Â  Clouds of such mass are observed to be collapsing today, so unless you can tell us what we're actually observing while simultaneously showing why the math astrophysicists use (which accurately predicts what we see) is wrong, you're really in no position to say that stars can't form, particularly under the conditions the scientists predict and we observe.

The amount of speculation you are trying to pass off without close examination is something else. Jean's Mass is predicated on the presence of matter to draw a gravitational well. According to the big bang the beginning produced hydrogen and a little bit of helium then you jump forward to all this other matter present to make a gravitational collapse.

BTW, how does someone differentiate between a nebulae that is 'forming new stars' and one that is a nova remnant?

The law you originally presented as defying stellar formation has the explicit caveat of temperature, and you should know that temperature always falls (net) in a closed (exempt from outside influence), boundless (heat energy may pass beyond its ability to be reflected or absorbed) system.Ã‚Â  Gravitational collapse is inevitable so long as the expansion of space doesn't exceed the gravitational collapse.

Comparing gravity and Boyle's Gas Law the way you just have is like saying that spending more than what you earn will eventually lead to great savings, afterall you are earning some...

I don't know how this thread happened . . .

It did. And you haven't offered anything but speculation which is not scientific but predicated on your naturalistic assumptions. Sorry to burst your bubble.

Although virtually all secular astronomers believe that stars form spontaneously, the physics behind this alleged process is riddled with difficulties. According to the standard model of star formation, stars form from a collapsing nebula. However, when gas is compressed, it heats up.4 This higher temperature creates extra pressure which resists further compression. The collapse would have a tendency to stop before the star ever formed. Furthermore, a collapsing cloud would spin faster as it collapsed.5 This is much the same way a skater spins up as she pulls her arms in. As the cloud spins faster, it becomes increasingly difficult to pull material in further: much as weights held at armÃ¢â‚¬â„¢s length are difficult to pull closer when one is spinning. Even if the star were able to form by pulling in the material, it would be spinning extremely rapidly. A small percentage of stars do spin rapidly,6 but most do not. The sun takes about 25 days to rotate once at its equator.7

There is also a problem with magnetic fields. The intrinsic (weak) magnetic field of the collapsing nebula would become intensified as the cloud collapsed; the process Ã¢â‚¬Å“concentratesÃ¢â‚¬Â the magnetic field. The magnetic field would then resist being compressed furtherÃ¢â‚¬â€much like trying to push two magnets together when their like poles are facing each other. Gas pressure, angular momentum, and magnetic fields all work against the possibility of a condensing star. Clearly, the secular view that stars can form naturalistically has some serious problems. From a creationist point of view, stars need not form at all. God made the stars (Genesis 1:14Ã¢â‚¬â€œ16) during the creation week; they were supernaturally created.

Secular astronomers hope that future evidence will resolve these serious scientific problems, but not having enough evidence is not the real issue; itÃ¢â‚¬â„¢s the interpretation of existing evidence that is the problem. With these severe scientific problems (only a few of which have been discussed), should we not at least consider the possibility that the naturalistic worldview is wrong? This incorrect worldview has led to incorrect interpretations of the evidence, which then require further conjectures to allow the evidence to fit within the defective worldview. When we start from a biblical worldview, we find that none of the above issues are problems. On the contrary, they are assets. The seamless blend of uniformity and diversity that we observe in the created universe is a mark of the God of the Bible.

#28 Percy

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Posted 06 July 2009 - 11:11 AM

When you start getting a little war hardened, like I have...

Oh, I'm so far beyond war hardened I'm philosophical!

Apparently, it is assumed that Boyle's Law overcomes gravity under all circumstances.

This is what the scientific evidence demonstrates, to believe otherwise is speculation.Ã‚Â  This may not be totally unreasonable but speculation sold as fact is deceptive.

What leads you to believe that there is scientific evidence that "Boyle's law overcomes gravity under all circumstances?" Look at it this way. Gravity is what holds earth's atmosphere in place. The Sun is 99% gaseous, and gravity holds all this gas in place so firmly that a fusion furnace has ignited in the Sun's core. These simple observations tell us that gravity is as effective in constraining gas's tendency to disperse (an obvious inference from Boyle's law) as a sealed glass container.

In other words, not only does the scientific evidence and theory tell us that Boyle's law is subject to gravity, the mere fact that we're not breathing a vacuum says that Boyle's law had darn well better be subject to gravity, else we wouldn't be here. Boyle's law relates pressure to volume, and it doesn't matter whether the source of the pressure is a moving piston, a region of higher pressure (think weather), or gravity.

In your next message you say at one point in reply to a description of the behavior of large nebulae:

Again, this is all speculation based on naturalistic assumptions. You can't demonstrate this. You believe it because something like this must be true according to your worldview. Again, you can believe this if you want but it's not science.

While it may not be information of which you are personally aware, it is not speculation. Just as calculating the course of spacecraft to arrive at Mars is not speculation, calculating the behavior of gas clouds (using formula more sophisticated and complete than Boyle's law, which only took into account the behavior of gases at temperatures and pressures that could be produced in the 17th century) is also not speculation. You accept Boyle's law, and the more modern and sophisticated gas laws are not only completely consistent with Boyle's law for the limited range of temperatures and pressures and other conditions that it covers, but they also cover a wide range of conditions for which Boyle's law is unsuitable.

This has nothing to do with world view. Gas laws do not behave one way for creationists and another way for physicists, chemists and cosmologists.

One misconception I think you might have that may be leading you to conclude that gas clouds can't compress due to their own gravity is that you don't think that a gas cloud can have gravity, but it most certainly can, even very tenuous gas clouds. As both Ibex Pop and I have related to you, the gas cloud will be non-uniform, and areas of slightly greater density will have slightly greater gravity than other parts of the cloud, and they will attract more gas toward them, increasing their density and gravity even more and thereby attracting even more gas, and so forth.

Now I know you don't believe this, so let me direct your attention to the AIG excerpt you provided. Notice that this excerpt agrees that gas clouds collapse. They go on to cite effects that prevent this from happening to the point where stars can form, but AIG understands that gas clouds collapse due to the effects of gravity. Boyle's law does not provide gas clouds a "get out of gravity free" card.

Your AIG excerpt cites reasons that new stars can't form having nothing to do with Boyle's law. One is increasing pressure from within generated by increasing temperature (remember the increasing temperature I mentioned some messages ago?), another is angular momentum, another is magnetic fields. AIG characterizes these as "serious scientifc problems," and maybe we can get into a more detailed discussion of them, but first we have to get past this Boyle's law thing. AIG disagrees with you about Boyle's law preventing the gravitational compression of gas clouds.

--Percy

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Posted 06 July 2009 - 12:43 PM

Percy,

Don't you see what you're doing? You are explaining how Boyle's Gas Law operates in a gravitational field. You are assuming the existence of a strong gravitational presence which requires a substantially massive object to sustain an atmosphere. You're assuming the presence of the entity prior to the creation of the entity. This is a total reversal of cause and effect. This would be like saying that boiling water is what makes the burner underneath it hot.

If the gas law is so easily overcome by gravity then why doesn't the Moon have a growing atmosphere or Mercury? If clouds of gas can pull together without a massive body at any central location then the moon should have a magnificent atmosphere.

BTW, can you tell me? How does an astronomer tell the difference between a nebulae that is 'fresh' and forming stars versus a nebulae that is a nova remnant?

#30 Guest_Keith C_*

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Posted 06 July 2009 - 01:14 PM

Hey, Keith, I resent it when anyone pulls this stuff with me, and I'm sure Adam resents it when you pull it with him.  There are clear explanations that we can offer in response to Adam's post, and we should simply offer them and see how he responds.

I've observed that sometimes Adam can be similarly dismissive, but that's no excuse for us to do the same thing.  The ad hominem has to stop someplace otherwise it justs keeps escalating until the topic is totally obscured and a moderator finally decides to close the thread.

--Percy

I will be patient and wait for the clear explanations to take effect.

#31 Percy

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Posted 06 July 2009 - 01:34 PM

Hang in there, we'll get this. Before responding to specifics I'd like to again call your attention to the fact that your AIG excerpt has no problem with Boyle's law or gas clouds collapsing. Keep this fact in the back of your mind just to keep a slight spark alive for the possibility that maybe there's a misconception you haven't factored out of your thinking yet.

Don't you see what you're doing? You are explaining how Boyle's Gas Law operates in a gravitational field. You are assuming the existence of a strong gravitational presence which requires a substantially massive object to sustain an atmosphere.

Even a single electron has a gravitational field. And single atoms have gravitational fields, too. And gaseous clouds or nebulae composed of billions and trillions and gazillions of atoms have gravitational fields that are the sum of the gravitational fields of all their atoms. In the same way, the Earth's gravity is the sum of the gravitational fields of all its atoms.

Obviously a gas cloud with enough atoms to create hundreds of stars must have a heck of a lot of atoms, many, many more than our Sun. And so the gas cloud's gravity is much greater than the gravity of the Sun. The gas cloud has extremely low density. The atoms are all spread out, and so the gravity is corresponding diffuse, but because it's a gas all its atoms are free to move in the direction of the greatest gravitational pull, however slight the difference.

So no, I am not assuming "the existence of a strong gravitational presence which requires a substantially massive object." I'm assuming a tenuous gas cloud with non-uniform density. All the atoms in the gas cloud have gravitational fields and attract all other atoms in the cloud with a force inversely proportional to the square of the distance. Those regions of the gas cloud with slightly greater density, which means they have more atoms, have greater attractive force, extremely slight though it may be, than less dense regions. These slightly denser regions will attract more atoms to the region than less dense regions, and in this way they gradually become even denser and with their even greater number of atoms exert even greater attractive force on the rest of the cloud. The process of very gradual consolidation into something that might become a star takes millions of years.

If the gas law is so easily overcome by gravity then why doesn't the Moon have a growing atmosphere or Mercury? If clouds of gas can pull together without a massive body at any central location then the moon should have a magnificent atmosphere.

The Moon and Mercury both possess a most minute atmosphere, but I understand your question. Neither has sufficient gravity to retain any significant atmosphere because of the proximity of the Sun, which has no problem heating gas molecules beyond escape velocity. Mars is only about 1/10th the mass of the Earth, and even with its greater distance from the Sun it does not have sufficient gravity to retain much of an atmosphere. This is in contrast to some of the larger moons of the Jovian planets. For example, Titan, a moon of Saturn, has only about 1/50th the mass of Earth, yet due to its greater distance from the Sun is able to maintain a significant atmosphere.

BTW, can you tell me? How does an astronomer tell the difference between a nebulae that is 'fresh' and forming stars versus a nebulae that is a nova remnant?

Gee, I don't know. Anyone?

--Percy

#32 Percy

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Posted 06 July 2009 - 01:51 PM

I will be patient and wait for the clear explanations to take effect.

I guess I sound like a Pollyanna to you.

I look at it this way. People aren't convinced by other people. They aren't convinced by discussion boards like this. People can only be convinced by themselves. All others can do is plant a seed.

So you can plant the seed that evolutionists are obnoxious know-it-alls or something else similarly distasteful, or you can plant a seed that evolutionists are just as nice and sincere and reasonable as creationists (because it's true) and leave them thinking, "Gee, while you can't convince 'em, how is it that good ol' Tom (or Dick or Harry) could be so mistaken? Maybe I should look into this a bit more and figure out how they're looking at this."

Yeah, I know, what are the odds of success. My answer: much better than turning everyone off by behaving like a jerk. And in the process someone might actually learn something. Maybe even us! Hey, it could happen!

I've been involved in the creation/evolution debate for over 25 years, and in that time I've seen at least several people cross over from civility and patience to contempt, antagonism and ridicule, and it saddens me each time. But the only people who appreciate a good put down are those who already share your point of view. I enjoy reading a good put down as much as the next person, but as much fun as they are you have to realize that in the end everyone's a loser in a battle of ad hominems.

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Posted 06 July 2009 - 02:09 PM

Even a single electron has a gravitational field.Ã‚Â  And single atoms have gravitational fields, too.

Sure. and that is specifically why I used the phrase "strong gravitational presence" You see how I was planning ahead.

Obviously a gas cloud with enough atoms to create hundreds of stars must have a heck of a lot of atoms, many, many more than our Sun.Ã‚Â  And so the gas cloud's gravity is much greater than the gravity of the Sun.Ã‚Â  The gas cloud has extremely low density.Ã‚Â  The atoms are all spread out, and so the gravity is corresponding diffuse, but because it's a gas all its atoms are free to move in the direction of the greatest gravitational pull, however slight the difference.

This is exactly where you run into a brick wall scientifically. You have no point of focus to attract those atoms in the first place. Let's say you had an infinitely large gas cloud just for the sake of argument there are no thinning boundaries. There you are in the midst of this giant gas cloud. What will seed the initial draw towards one location? Every individual atom has it's own gravitational field. Who decides which atom is going to be the core of this yet to be formed solid object?

The idea that gas will stick together is further controverted by how small objects interact with much greater gravitational fields then their gaseous cousins. When two small objects collide, sticking together is the least likely occurrence. They will more then likely break each other into even smaller fragments and never combine into a larger object.

You see AiG's article doesn't focus on Boyle's Gas Law because it doesn't function in a vacuum (no pun intended). It is a component of a host of problems that any honest astronomer must acknowledge as at least a mystery, to solve the problem of how heavenly bodies could even form through only naturalistic mechanisms not to mention the claim that known naturalistic mechanisms could form heavenly bodies.

So no, I am not assuming "the existence of a strong gravitational presence which requires a substantially massive object."Ã‚Â  I'm assuming a tenuous gas cloud with non-uniform density.

What is promoting this pretend nonuniform density before any heavenly bodies are present?

#34 jason78

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Posted 06 July 2009 - 03:05 PM

BTW, can you tell me? How does an astronomer tell the difference between a nebulae that is 'fresh' and forming stars versus a nebulae that is a nova remnant?

Gee, I don't know. Anyone?

The spectrum of light from the gas of a nova remnant would have absorption lines (or emission lines) showing the presence of metals.

#35 A.Sphere

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Posted 06 July 2009 - 03:27 PM

The Universe, by definition, IS a closed system. Any outside influence would be chalked up as supernatural in both of our books. The only difference is that we acknowledge supernatural markers and naturalists ignore them and/or equivocate about them.

Last time I checked Astronomers aren't claiming that the Universe collapsed into a single star .

Within a closed system there can be energy exchange between subsystems. We are obviously talking about subsystems of the Universe which are not closed.

#36 Percy

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Posted 06 July 2009 - 04:02 PM

Sure. and that is specifically why I used the phrase "strong gravitational presence" You see how I was planning ahead.

Oh. Hmmm. Checking back, what you actually said was, "You are assuming the existence of a strong gravitational presence which requires a substantially massive object to sustain an atmosphere." What were you thinking of when you referred to "a substantially massive object to sustain an atmosphere?" I assumed you meant a planet or star. Not so?

This is exactly where you run into a brick wall scientifically.

Well, first we have to question your claim to being scientific. What you're doing is trying to apply logical and rational thinking to what you happen to know about this subject, but the position you're advocating is not a prevailing view within science, and your awareness of the current state of scientific understanding is lacking a few details.

You have no point of focus to attract those atoms in the first place. Let's say you had an infinitely large gas cloud just for the sake of argument there are no thinning boundaries. There you are in the midst of this giant gas cloud. What will seed the initial draw towards one location? Every individual atom has it's own gravitational field. Who decides which atom is going to be the core of this yet to be formed solid object?

...

What is promoting this pretend nonuniform density before any heavenly bodies are present?

You must be referring to conditions just after the big bang, and you're apparently assuming that they were completely uniform. Measurements of the Cosmological Microwave Background Radiation (usually referred to as just the CMBR) reveal that the very early universe was already non-uniform. One source of the variations is acoustic oscillations, and I know there are several other theorized contributors. It is these variations in density that formed the seeds from which galaxies and stars eventually formed.

The idea that gas will stick together is further controverted by how small objects interact with much greater gravitational fields then their gaseous cousins. When two small objects collide, sticking together is the least likely occurrence. They will more then likely break each other into even smaller fragments and never combine into a larger object.

For the most part the gases we're talking about are hydrogen and helium. Gases don't "stick together". All the atoms or molecules of a gas move about independently. This may even be the definition of a gas.

Helium atoms don't form molecules at all, and hydrogen molecules do not stick together beyond forming molecules of H2 (darn, no subscripts here), though I don't know whether hydrogen forms molecules in nebular clouds since so much of this gas is ionized (lost its lone electron). What keeps the atoms of a slighter denser region of a nebular cloud together is gravity, and other contributor to keeping it together might be the increased possibility of collisions that result in a more even distribution of kinetic energy among the atoms in this region, and the loss of energy through the radiation of heat.

You see AiG's article doesn't focus on Boyle's Gas Law because it doesn't function in a vacuum (no pun intended).

The problems that AiG's article raises could never occur if Boyle's law disallowed the collapse of gas clouds under the influence of gravity. That they feel the need to mention such problems directly contradicts your claim that Boyle's law disallows such an influence. And if you need another reason, they don't mention Boyle's law. If Boyle's law were really the overarching consideration you believe then it seems unlikely that they would failed to mention it.

It is a component of a host of problems that any honest astronomer must acknowledge as at least a mystery, to solve the problem of how heavenly bodies could even form through only naturalistic mechanisms not to mention the claim that known naturalistic mechanisms could form heavenly bodies.

Astronomers have many observations of star nurseries. It's a well observed natural phenomenon.

Stars can die from "naturalistic mechanisms" through nova and supernova, so it is difficult to understand any skepticism about their birth through the same natural laws of the universe. We even have a fairly good understanding of what happens to a star as it ages, which differs greatly depending upon the size and type of star.

--Percy

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Posted 06 July 2009 - 06:50 PM

Hi Percy,

I don't think we're going to come to any agreement on this. However, how good do you suppose our observations of space are to conclude certain non-verifiable natural mechanisms so boldly?

I started this thread a long time ago but it never went anywhere...

http://www.evolution...?showtopic=1934

I really wanted to learn and I'm still willing to learn just how conclusive our observations out to space are and how much is hypothetical assertions based on a certain body of assumptions.

Now here is the only question that I want you personally to answer, if nothing else. You claim to be a theistic evolutionist. What does a verse like this mean to you?

The heavens declare the glory of God; and the firmament sheweth his handywork.

Please explain to us how we see God's handiwork.

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Posted 06 July 2009 - 07:24 PM

And if you need another reason, they don't mention Boyle's law.

This isn't true. They do mention it, just not by name. They mention the principle thereof:

However, when gas is compressed, it heats up. This higher temperature creates extra pressure which resists further compression. The collapse would have a tendency to stop before the star ever formed.

Boyle's law describes the relationship between gas pressure and volume in a closed system but this demonstration shows an unusual characteristic of gas. It resists being compressed.

Boyle's gas law is a factor in all of this and anyone who says it isn't is trying to exclude it for mere convenience and to support untestable assumptions.

#39 A.Sphere

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Posted 06 July 2009 - 08:37 PM

This isn't true. They do mention it, just not by name. They mention the principle thereof:

However, when gas is compressed, it heats up. This higher temperature creates extra pressure which resists further compression. The collapse would have a tendency to stop before the star ever formed.

Boyle's law describes the relationship between gas pressure and volume in a closed system but this demonstration shows an unusual characteristic of gas. It resists being compressed.

Boyle's gas law is a factor in all of this and anyone who says it isn't is trying to exclude it for mere convenience and to support untestable assumptions.

Okay Adam Ã¢â‚¬â€œ I will give this a go. The Ideal Gas Law (or Boyle's Law Ã¢â‚¬â€œ it doesn't really matter here) tells us p = nkT, where n is the number density (# particles per volume), k a constant and T is temperature. This relationship tells us that if the temperature of our system is held constant we need pressure to compress a gas. Using the ideal gas law (or Boyle's Law) for star formation is not really kosher because our cloud of gas is not under constant density which affects the term Ã¢â‚¬Å“nÃ¢â‚¬Â , and it is not constant in temperature because if our cloud of gas is cooling (this affects T), and because energy is exchanged from neighboring systems so it is not closed. But I will humor you so that I may explain why you are still wrong. Lets hand wave and use the gas law anyway (despite my warnings).

Gravitational energy of our blob of gas can be given to be E = -GMm/r + mv^2/2. The first term is the potential energy term and the second term is the kinetic energy term. Notice that the potential energy term is negative Ã¢â‚¬â€œ that is important here. Now, if the cloud becomes smaller the potential energy term becomes bigger and thus more negative (the negative sign in front) and in order for our energy to remain constant the kinetic energy must get larger (more positive). Kinetic energy makes heat which in a cloud of gas gets radiated away if our system is not closed (which it isn't). So as the gas cloud gets smaller potential energy is converted into heat, some heat is radiated away, the rest heats the core and the pressure increases. A gravitationally stable cloud is one where the density of the gas cloud does not match the temperature of the gas cloud. If this is the case then the outward gas pressure with win against pressure caused by gravitational contraction (this seems to be the case that you are claiming all clouds of gas must follow). So one asks Ã¢â‚¬â€œ how can our ball of gas ever compress further? It has to cool (which it would and it does because again our system is not closed). It cools via conduction, radiation, and convection. Notice in your sacred gas law as T decreases so does p which means that the gravitational pressure is going up against a gas pressure that gets weaker and weaker as the ball of gas cools. So its like this: contracts -> heats up -> pressure increases -> cools down -> contracts -> rinse and repeat. This is just a simple sorta stupid ideal situation. In reality the cards are stacked to help gravitational pressure win because the ISM is very dynamical.

Edit: Just to be clear - the physics used in this qualitative explanation involve nothing fancy. This is all good ole fashioned testable classical mechanics and thermodynamics.

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Posted 06 July 2009 - 08:53 PM

A.Sphere thank you for your thoughtful explanation and I fully appreciate and I believe even understand what it is that you are trying to convey. However, you are overlooking the effect of something that even you are acknowledging:

It cools via conduction, radiation, and convection.

In your rinse and repeat cycle what is causing the outcome of these convection currents, generated by a heating mass of gas, that is being gravitationally collapsed, to cycle into tighter configurations? The last time I checked the whole reason convection currents occur is because a heat imbalance is seeking neutral by rising away from the gravitational center since the heated gas is less dense than the cooler gas, it rises away from the heat source, in our case the center of activity, the gravitational well. In your example this necessarily indicates that what is at the center of your heated gas cloud will follow a convection path away from the center before it can collapse. What is going to get those molecules to collapse into an even tighter configuration when any increased heat will excite the molecules in a way that promotes faster convection and greater convection cycles away from this proposed gravitational well that still has no solid core because of what our gas is doing thermally as it is compressed.

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