Big Bang Cooling

[NotReady]

I've been trying to find some cracks in the science of Hugh Ross, just to know if I'm on the right track or not. The only critique I've found of his science comes from Perakh, as follows:

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On page 135 of that book we read: "As the universe expands from the creation event, it cools, like any other system obeying the laws of thermodynamics. When the heat energy of a system fills a greater volume, there is less energy per unit volume to go around."

The quoted statement by Ross confirms the suspicion that he has an insufficient understanding of some fundamentals of physics.[4]

The temperature drop occurs because the initial thermal energy of the universe gradually converts into, first, the rest mass of the emerging stars, and, second, into the kinetic energy of the motion of those clumps of emerging matter moving away from the initial seed of the university. Judging from Ross’s preposterous statement about the temperature drop being the result of energy diluted in ever increasing volume, he has a rather nebulous understanding of elementary concepts of physics and cosmology.


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But I found several sites that also said the cooling was due to expansion, as in these:

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After the decoupling era, matter cools rapidly compared with the radiation. Cooling of the hydrogen atoms occurs because the random motions of the atoms fail to keep pace with the rate of general expansion of the atoms away from one another. Imagine an automobile race. The cars start out together and are moving at almost the same speed, but gradually they drift farther and farther apart. It takes longer and longer for any car to overtake another as time goes on: we can equally well say that the relative velocity between an adjacent pair of cars declines with time. A similar argument applies to the random motions of atoms in the expanding universe: they also decline with time as the separation of the atoms grows.


The explanation is straightforward: As space expands, light waves get stretched. If the universe doubles in size during the waves' journey, their wavelengths double and their energy is halved.


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And from Scientific American:

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This process can be described in terms of temperature. The photons emitted by a body collectively have a temperature--a certain distribution of energy that reflects how hot the body is. As the photons travel through expanding space, they lose energy and their temperature decreases. In this way, the universe cools as it expands, much as compressed air in a scuba tank cools when it is released and allowed to expand. For example, the microwave background radiation currently has a temperature of about three kelvins, whereas the process that released the radiation occurred at a temperature of about 3,000 kelvins. Since the time of the emission of this radiation, the universe has increased in size by a factor of 1,000, so the temperature of the photons has decreased by the same factor.


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These seem to be saying the universe cooled because it was expanding.

Anybody know who's right?

[m_the0ry]

In the last post you made you said,

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I don't think so - I don't believe in God because I need Him to fill in the gaps in the our understanding of the natural world - something most atheists don't understand about Christianity.

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Have things changed?

[NotReady]

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Have things changed?


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I don't think I phrased it very well. Try this:

The reason I believe in God isn't because I need Him to fill in the gaps in our understanding of the natural world.

[Leaky Eye]

I believe perakh is taking umbrage with this statement

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When the heat energy of a system fills a greater volume, there is less energy per unit volume to go around

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Which wrongly describes the mechanism by heat loss occurs. I don't see how the two other quotes contradict that, but I am not an expert here.

[NotReady]

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Which wrongly describes the mechanism by heat loss occurs. I don't see how the two other quotes contradict that, but I am not an expert here.


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Could be. The Ross statement says the same thing to me as the two others I quoted, but I know nothing of the physics. Maybe Ross was just trying to make it understandable - and I don't see how Perakh's explanation squares with the other two.

[Kaj]

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On page 135 of that book we read: "As the universe expands from the creation event, it cools, like any other system obeying the laws of thermodynamics. When the heat energy of a system fills a greater volume, there is less energy per unit volume to go around."

The quoted statement by Ross confirms the suspicion that he has an insufficient understanding of some fundamentals of physics.[4]

The temperature drop occurs because the initial thermal energy of the universe gradually converts into, first, the rest mass of the emerging stars, and, second, into the kinetic energy of the motion of those clumps of emerging matter moving away from the initial seed of the university. Judging from Ross’s preposterous statement about the temperature drop being the result of energy diluted in ever increasing volume, he has a rather nebulous understanding of elementary concepts of physics and cosmology.


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The critic here seems biased. It isn't either/or. Okay, initial thermal energy was converted into mass and kinetic energy. This doesn't preclude the universe from cooling as it expands. The critique above looks like a "gotcha" message board response.

[Leaky Eye]

Since Hugh Ross is controversial for his views on evolution I don't really see why you would be concerned with a random erroneous sentence on another subject.

[NotReady]

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The critique above looks like a "gotcha" message board response.


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There's no doubt about that. Perakh is very anti-ID and has written some books against it I think. But he also has some qualifications.

Thanks for the response. Ross goes so far out on some limbs I need to know if he's solid with the science.

[NotReady]

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Since Hugh Ross is controversial for his views on evolution I don't really see why you would be concerned with a random erroneous sentence on another subject.


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He's got a Ph.D. in astronomy. If he makes mistakes there it would be a serious issue, even it if was minor. Like DS being wrong about 1+1.

Perakh also claims Ross is wrong about some Hebrew, but that doesn't concern me at all. That I can check if I need to.

[m_the0ry]

Ok.

For clarity's sake, all of these seem to be referring to the epoch after the appearance of baryonic matter, which is by most considerations a relatively long time after the actual big bang itself. The short answer is that Dr. Perakh is nitpicking because his book shares the market that Mr. Ross' does.

The long answer is that there is an ongoing debate about the form energy takes in the nascent universe and, more importantly, how the classical laws of thermodynamics can be applied to the universe at that time. Without a doubt, Ross' statement that the 'heat energy over a greater volume = cooling' is very hard to substantiate, considering that by strict definition heat is only the transfer of thermodynamic energy and does not actually describe the system. This is the main point that Dr. Perakh rests his defense on: Ross' misuse of a word. Certainly many physicists could shake with laughter at the misuse, but to openly denounce his concepts as absurd is a little overdoing it. Likening the cosmic expansion period to the decompression of air is oversimplification, but is perfect for the readership of Scientific American, and the readership of Ross' book. No one who reads that book or that publication will be running Big Bang simulations on supercomputer clusters incorporating the newest theories of quantum loop gravity. That I can say with confidence.

Causality nitpicking aside, the expansion of the universe definitely is *correlated* to the cooling of the universe. The mechanism for this is a subject of active debate in think tanks around the world. Which returns me to my first reply; this is a question science cannot answer definitively yet.


EDIT: looks like I was wrong about his background on physics. He had a BS in physics, which speaks more than his PHD in observational astronomy on this subject. It is pretty embarrassing for someone with his education to use 'heat' like this, but I think calling it a 'crack' in his science, when his concepts are fairly clear and are meaningful, is an overstatement. I'd be surprised if it didn't get edited out in future reprints.