Atheism

If you imagine a sphere with a radius of 93 million miles with the sun at the centre what % of the radiation strikes a disc on the sphere the size of the earth ignoring any bending due to gravitational influences or any reflections or eclipses.

As life can only be supported in an extremely narrow range of circumstances what are the odds of it ever appearing?

I suppose that in an infinite universe it is a certainty. And an infinite number of times.

Not at all. I have referred many times to the negative aspects of the process. And I have criticised nothing about it. Nor would I.

All I have done is point out that there are "nice things" to those who only ever point out the "decidedly not nice things" which are mostly stories they can't verify and might well be propaganda.

Do you accept that the "delusions" have been to our advantage? If not what alternatives do you suggest? How else could we have got to where we are?

Critics of the "delusions" must be critics of what we have got unless they can supply an alternative. Which, of course, they can't and their arrogance leads them to not even think they need to do which is intellectual wuss.

I see the fig tree parable as a poetic version of evolution theory.

Nice way to put it.

First of all, my original point was that this is difficult. So if I couldn't do it at all, in spite of being a physicist making an honest effort, that would support my original point rather than contradict it.

Second, I needn't know how to cook soup in order to tell that the soup in my cup tastes rotten, or that my cup doesn't even contain any soup for me to taste. Correspondingly, even if I had absolutely no idea how to run this calculation, it wouldn't change the fact that you have not put forward a coherent argument.

All that being said, here is an outline of how I would do it:

1) Calculate the marginal increase in enthropy (dS) that a given marginal amount of energy created by nuclear fusion (dQ) generates in the sun, given the sun's temperature Ts. To do that, use the (differential) version of the macroscopic definition of enthropy.

dS = 1/Ts dQ,

2) For purposes of testing if life on Earth violates the Second Law, the relevant closed system consists of Earth and the part of the sun that generates all light reaching Earth, but no more. As you pointed out in an earlier post, this fraction is very small. So, calculate the amount of energy the sun sends in the Earth's direction, divide it by the amount of energy the sun sends in every direction, and multiply this tiny quotient by the amount of energy you found in step #1.

3) It is hard to measure the amount of entropy that life subtracts from the closed system I described in step #2. (The term "life" is sort of vague for purposes of physics.) But we could estimate an upper limit from the amount of chemical energy created Earth-wide by photosynthesis. (It's an upper limit because everything life does after photosynthesis consists of exothermic chemical reactions that increase entropy.) Again, we would use the macroscopic definition of entropy to do it:

dS = Te * dQ,

where Te is the temperature on Earth and dQ is the amount of chemical energy generated on Earth by photosynthesis.

It would take some more research, and perhaps some more back-of-the-envelope calculations, to get all the numbers that go into these formulas. But in the end, you would have two numbers with matching units that you can compare. On the left side, you'd have the product of steps #1 and #2; on the right side, you'd have the result of step #3. If the left side is greater, the creationists' Second-Law challenge is rebutted.

Is that a safe assumption to make? Can you slice a tiny fraction of the sun and call it a closed thermodynamic system???

Your previous proposal, which I worked upon, was to consider the entire solar system as the nearest thing to a closed system, which I sort of agreed with (even though of course it is not closed at all: there are no walls around it, and the sun loses to inter-stellar space almost 100% of its energy output). This is why I proposed a comparison between the respective orders of magnitudes of the total solar system and the sub-system earth.

Because the Second Law deals in rates of change rather than levels. Hence, you have to compare marginal values such as dS and dQ.

Independently, though, the formula you are now using reveals a major problem with your earlier posts, where you argued exclusively from the relative sizes of the sun and the Earth. True, the sun is orders of magnitude larger than Earth. But the inside of the sun (where nuclear fusion happens) is also many orders of magnitude hotter than the surface of the Earth (where life happens). That's important, because the temperature of each system goes into the denominator of both your formula and my formulas #1 and #3. The sun's higher temperature, then, makes dS smaller. In your earlier posts, how were you going to find out which effect dominates without even considering the relative temperatures?

Good question. Yes you can, because that tiny slice is in thermal equilibrium with the rest of the sun. Second by second, the amount of energy going from the slice to the rest equals the amount of energy going from the rest to the slice, adding up to a zero net flow of energy. And of course, the assumption is safe on the Earth's side of things because, by definition, the light generated in the rest of the Sun does not reach it.


In thermodynamics, it is the flow of energy, not walls or other boundaries, that define a system as "closed" or "open". For example, an arbitrary volume of interstellar vacuum would have no material boundaries at all. It might even have light shining through it. But in the thermodynamic sense, it would still be closed because the net flow of energy across its geometrical boundaries is zero.

I am no astrophysicist, but am aware that in thermodynamic it is always a discussion about changes, ie delta entropy, delta energy, etc. My original argument still works with changes in state rather than absolute values of "total entropy" or "total energy" (which doesn't mean much).

If a calculation of the d.entropy of the whole solar system over a certain period of time / a particular transformation cannot for some reason be done as I propose by simply dividing total energy change by average temperature change, then you can do the calculation at the level of each cosmic object of the solar system, i.e. compute entropy change for the sun, Mercury, Venus, etc, including earth and also the vast expanses of "void" (which is not technically void, has a mass and a mean temperature, etc. so one can estimate its total entropy change over a period). Then you had all those changes up to arrive at the total entropy change of the solar system over the period.

Chances are that in this computation, the numbers concerning earth will be... very very very very small as compared to the sun and to the inter-planetary space all the way to the Kuiper belt. These items will completely dominate the calculation, and whatever happens at the earth level will be negligible.

In estimating these chances, how do you account for the astronomical temperatures inside the sun, which greatly reduce the amount of entropy you generate with each unit of energy?

Then the calculus becomes much more complicated. My approach (based on your original ideas) was to deal with the entire solar system, in which as you would now I suppose agree, earth is such a small fraction that it just doesn't count.


No it's not, since closed to 100% of the sun's energetic output is lost to inter-stellar space...

Yes it is, because every photon from the sun flying into this volume at one point flies right back out of it at another. Remember, the point of mine that you just addressed was about an arbitrary volume of interstellar vacuum. The sun is a star, not a volume of interstellar vacuum. I never said the sun is a closed system, which it emphatically is not.

From memory, I don't remember that the temperatures at the surface or inside the sun are so mind-mindbogglingly high. Any ratio in temperature is going to be in a factor a few milions (10*6) or so, while the ratio in energy between the sun and earth is going to be in an (beware, guestimate) order of magnitude of trillions (10^12) times large in the former than in the latter case. So any sun d.entropy estimates is still going to be in an order of magnitude of millions of times larger than d.entropy changes on earth. Negligible.

You might have a point about the surface of the sun. The spectrum of sunlight corresponds to an effective temperature of 5000 Kelvin or so. But inside the sun, how would you achieve nuclear fusion without mindbogglingly-high temperatures? These 5000 Kelvins wouldn't even create a plasma.

Aside of this, I owe you two corrections:

(1) Being a native German, I use physical terms in slightly different ways than English-speaking textbooks do. In English, the kinds of system to which the Second Law applies are called "isolated", not "closed" as they're called in German.

(2) In either language, the point that we can treat a thermodynamical system as isolated if there's no net flow of energy and particles out or in is generally true. But it doesn't follow immediately from the definition of an isolated system, which says "no particles or energy in, no particles or energy out". I used a short cut here, the existence of which I took for granted, but shouldn't have.

If we are to reason at the level of the entire solar system (the level thought you were discussing...) then that system contains the sun, and is not a closed system; in fact it's wide open.

Worse yet, it's a system that energy flows out of, not into, which needlessly biases the problem statement against showing that evolution can happen in it. It's a good thing, then, that we are justified in concentrating exclusively on the part of the sun that produces "our" light. It lets us ignore everything outside the solar system, all the energy flowing out of the solar system, everything in the solar system except Earth and the sun, and most of the sun, too. It's an easier and far more accurate calculation.

Humongous PRESSURE is how

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Whatever the terminology, I think we can agree that the solar system is not closed / isolated. This is just a crude approximation, without which the computations we are talking about would be even ore difficult to make.

One difference might be how fitness is determined.

No it's not. The temperature required to produce a plasma rises with pressure. It's possible to produce a low-temperature plasma, but only at extremely low pressures. At atmospheric pressures on Earth, you need about 10,000 Kelvin, which is already higher than the Sun's surface temperature. I haven't explicitly calculated how many Kelvins a plasma requires at the, as you aptly put it, humongous pressures inside the Sun, but their number would have to be correspondingly humongous. For what it's worth, I googled "temperature inside sun", and Wikipedia gave me a temperature of 15,000,000 Kelvin.

Fitness is determined by utility to the organism with dominion and which writes all the books.

I hope you're not in favour of delivering us up to a blind, random, meaningless and cruel process.