So, as promised, it’s time for part two of “The Creationists and the Shrinking Sun”.
The second main tack of the creationists and the shrinking sun is to *not* use the bare
measurements of an allegedly shrinking sun as their evidence. Instead, they use it as
evidence for a very peculiar theory. It’s an interesting approach for a couple of reasons: it
actually *proposes a theory* (a bad theory, but hey, at least it’s a theory!); it uses some recent theories and observations as evidence; and it casts the whole concept of how the sun works as part of an elaborate conspiracy to prop up evolution.
So let’s take a look at the argument. Here’s a typical version of it from from [creationism.org](http://www.creationism.org/ackerman/AckermanYoungWorldChap06.htm).
>What causes the sun to shine? Prior to the rise of Darwin’s evolution theory, the great
>nineteenth-century scientist Hermann von Helmholtz proposed a simple and effective model–
>gravitational collapse. The only problem with the concept was that it would not allow anything
>approaching the vast amounts of time demanded by the theory of evolution. If the sun produced its
>energy by gravitational collapse, the sun could last no longer than a few million years, and for
>evolution to have even a ghost of a chance much more time is required.
>Around the turn of the century, the famous scientist Lord Kelvin created difficulties for
>evolutionists by presenting a number of powerful arguments against the long ages needed by their
>theory. In a widely heralded debate with the famous evolutionist Thomas Huxley, Lord Kelvin tore the
>evolutionists’ position to shreds with simple and straightforward physical arguments that the earth
>and solar system were not old enough for life to have arisen by Darwin’s proposed evolutionary
>process. Among Lord Kelvin’s arguments on the age issue was the time factor for the sun’s survival
>based upon Helmholtz’s accepted model of gravitational collapse. Lord Kelvin had the theory of
>evolution on the ropes and had seemingly dealt the knockout blow.
>What happened? The discovery of atomic radiation changed the whole picture. Evolutionists suddenly
>took new courage as the phenomenon of atomic radiation seemed to provide the necessary answer to
>Kelvin’s challenge. With regard to the question of why the sun shines, the gravitational-collapse
>model became unfashionable, and in the 1930s Hans Bethe introduced the currently accepted view that
>thermonuclear fusion in the sun’s core is the source of its energy.
> Flies in the Ointment
>Although the nuclear-fusion theory of solar burning is widely accepted in scientific circles, it has
>one serious drawback. Unfortunately, a large-scale nuclear-fusion reaction in the sun’s interior
>would give almost no indication of its existence, and so the concept is difficult to verify
>scientifically. As it turns out, however, there is one very expensive method of verification.
>Princeton astronomer John Bahcall, along with Raymond Davis of the Brookhaven National Laboratory,
>wrote a research report on this work in 1976.1
>To “catch” neutrinos (particles released during certain nuclear reactions) and verify the
>thermonuclear-fusion theory, a large cavity was dug deep underground in a South Dakota gold mine.
>The necessary apparatus for detecting neutrinos was then constructed. The importance of this
>research in terms of providing necessary testing of the widely accepted general theory of evolution
>cannot be overemphasized. As Bahcall and Davis explain:
>>One may well ask, why devote so much effort in trying to understand a backyard problem like the
>>sun’s thermonuclear furnace? . . . The theory of solar energy generation is … important to the
>>general understanding of stellar evolution. . . .
>>There is a way to directly and quantitatively test the theory of nuclear energy generation in stars
>>like the sun. Of the particles released by the assumed thermonuclear reactions in the solar
>>interior, only one has the ability to penetrate from the center of the sun to the surface and
>>escape into space: the neutrino. Thus neutrinos offer us a unique possibility of “looking” into the
>>solar interior. . . . the theory of stellar aging by thermonuclear burning is widely used in
>>interpreting many kinds of astronomical information and is a necessary link in establishing such
>>basic data as the ages of the stars. . . . Thus an experiment designed to capture neutrinos
>>produced by solar thermonuclear reactions is a crucial one for the theory of stellar evolution. …
>>It is for . . . these reasons . . . that so much effort has been devoted to the solar neutrino
>>problem [emphasis added].2
>From a creationist point of view, the results of the neutrino-capture experiments are very exciting,
>for they indicate that the thermonuclear-fusion theory of solar radiation may be entirely wrong. The
>sun is not emitting the necessary neutrinos. In an Associated Press story of March 1980, Kevin
>McKean discusses the impact of the “case of the missing neutrinos”:
>>The neutrino is a particle emitted during certain nuclear reactions, including several of those
>>believed to power the sun. It travels at or near the speed of light, like an invisible ray, and can
>>penetrate miles of very dense matter without striking anything. Trillions of neutrinos from the sun
>>stream through our bodies every second. Because neutrinos can escape from deep within the sun,
>>scientists realized they might be a good way of checking whether the reactions believed to power
>>the sun are really happening. Chemist Ray Davis Jr., of Brookhaven National Laboratory in
>>Brookhaven, N.Y., led a team that set up a neutrino detector nearly a mile underground at the
>>Homestake Gold Mine in Lead, S.D. In nearly a decade of operation the detector has found only
>>one-third the expected number of neutrinos. . . . “It seems to me that we’re not even at first
>>base,” Bahcall says. “We have just realized we have a ball game and all we know is somebody is out
>>there throwing fastballs at us and we can’t even see them.”3
>Again quoting from Bahcall and Davis:
>>For the past 15 years we have tried, in collaboration with many colleagues in astronomy, chemistry,
>>and physics, to understand and test the theory of how the sun produces its radiant energy (observed
>>on the earth as sunlight). All of us have been surprised by the results: there is a large,
>>unexplained disagreement between observation and the supposedly well established theory. This
>>discrepancy has led to a crisis in the theory of stellar evolution; many authors are openly
>>questioning some of the basic principles and approximations in this supposedly dry (and solved)
>Evidence from the Stars
>Failure to find the predicted neutrinos was the most direct and telling of a number of serious flies
>in the ointment of the thermonuclear-fusion theory of solar burning. In a 1975 article, geo- and
>astrophysicist Harold Slusher explained two other difficulties.5
>First, the chemical composition of stars should change as they proceed through their supposed
>thermonuclear life cycle. However, observational studies of what should be stars of vastly different
>ages show them all to have roughly the same chemical composition. This presents a real enigma for
>the evolutionary nuclear-process theory.
>Second, and equally damaging, is the frequent occurrence of star clusters that are gravitationally
>bound and thus presumably originating at the same time, yet containing stars of vastly different
>ages on the thermonuclear-burn sequence. Some cluster observations are so mind boggling from an
>evolutionist point of view that even if there were not an abundance of other empirical evidences,
>these alone ought to rule out the vast-age concept. The most dramatic is a cluster of four stars in
>the Trapezium of the Orion nebula. These four stars are moving away from a common point at a high
>rate of speed. If the motion of these four stars is projected backward at their present speed, their
>paths lead to a common point of origin only about 10,000 years ago. Yet, according to the accepted
>scheme, the stars in the cluster are vastly older than 10,000 years. Slusher asks, “If the cluster
>cannot be old, how can the stars be old?” Indeed, this amazing cluster raises the question of
>whether the creation itself should be considered as older than 10,000 years.
Collapsed down, this version of the argument is: “The sun doesn’t really work by fusion, but by gravitational collapse. Evidence for this includes the measured shrinking of the sun (the power comes from gravitational collapse, so it *must* be contracting); the lack of solar neutrinos (the reason the sun isn’t generating as many neutrinos as standard fusion theory predicts is because there’s no fusion going on!); and the gravitational structure of certain star clusters.
Do I *really* need to explain what’s wrong with this? Probably not, but I’ll do it anyway.
As I’ve said before on this blog, good science requires good math; and the worst math is *no* math. The theory that fusion powers the sun is a very careful, well developed theory including very solid math. The math allows the theory to make very precise predictions about what kinds of radiation we should expect from a large scale fusion reaction, including quantities of neutrons and neutrinos. The creationist criticism of the measured neutrino numbers is a demonstration of the *good* quality of the theory.
The creationist “gravitational collapse” model completely lacks any supporting math. It’s all just words. It’s easy to say that sun isn’t powered by fusion, but by something else like “gravitational collapse”, or “electromagnetic z-pinch” (to mention another awful no-math “theory” about the sun). But if you don’t include any math, you can’t make any predictions that can *really* be tested. The
creatonists can *say* “the number of neutrinos are wrong”; but they can’t say *what* number of neutrinos there *should* be according to their theory. They can *say* that “measurements show that the sun is shrinking, which agrees with the gravitational collapse theory”, but they can’t say *what rate* of shrinkage corresponds with the amount of heat coming from the sun.
In fact, what it really comes down to is that it’s *not* a theory. Because a theory makes *precise* predictions, and explains the evidence. But the “gravitational collapse” thing isn’t a serious theory. It’s a masquerade. What they’re really doing is trying to put together a list of arguments *against* an old earth; but they think that there’s more credibility to their argument if it’s
presented as a *positive* argument in favor of a theory with some kind of explanation, rather than a *negative* argument against a theory that most people have never even questioned.
All of the real “evidence” for the gravitational collapse theory are *negative* arguments: the fusion theory predicts X number of neutrinos, but we actually observe only roughly x/3. The fusion theory supposedly requires gravitationally bound clusters of stars to have nearly equal ages, but that’s not what we see. And so on. They never show how any of it *supports* their model; just how it supposedly *doesn’t* fit the real scientific model.
To make matters even worse, their criticisms aren’t even any good. The “missing solar neutrinos” thing is typical: it’s not really a problem, it was *never* a show-stopper for the fusion model of the sun, and it doesn’t do anything to support their alternative.
First, and most important: It doesn’t support their argument. Just like the “intelligent design” gang
spend their time arguing about how evolution can’t happen, these guys spend their time arguing that
the old-sun fusion model is wrong, *not* that their model is right. The missing neutrinos *do not*
support a gravitational-collapse young-sun explanation. Gravitational collapse absolutely *cannot* explain the observed neutrino flux. *At best*, the missing neutrinos were a problem for the solar fusion model, not a support for the gravitational collapse.
Second, the problem was never that great to begin with. It was a fascinating problem, certainly. And it took a lot of time and work to figure out what was going on. But it was never a big enough problem to throw away all of the other evidence that supports solar fusion. Only in the bizarre dreams of crazy creationists was this a problem that could kill the idea of an old fusion-driven sun.
Finally, the missing neutrinos problem has been solved. We know, and have known for a long time
that there are multiple kinds of neutrinos, called *flavors*; the current theory says that
there are three flavors: electronic, muon, and tau. [More recent work than what’s cited
by the creationists shows that neutrinos can oscillate between different flavors.](http://nobelprize.org/nobel_prizes/physics/articles/bahcall/) The fusion model predicts
that electron neutrinos will be produced; so the detector that was used for the original
experiments only looked for electron neutrinos. With later work to test for other flavors
of neutrinos, the “missing” neutrinos have turned out not to be missing. The creationist article that I quoted was originally written in 1986, which *was* before the solution to the missing neutrino
problem was discovered, but numerous creationists continue to quote the article I’m dissecting, and to claim that the “missing neutrinos” are a problem that proves a young earth. (Not to mention that even by 1986, there were numerous discussions of *possible* solutions to the missing neutrino problem, along with ways of testing them. The real scientists didn’t just throw up their hands and say “A problem we don’t know the answer to – we give up, goddidit.”)
As a concluding note, the article does have an addendum concerning the discovery of the solution. The addendum was placed on the web in 2002, and makes for a good laugh:
>As forecast in 1986, the issues raised in this chapter have continued to be the focus of much
>scientific research. Relevant developments from a creationist perspective are reported in a 1996
>article, Evidences for a Young Sun, by Keith Davies. Davies summarizes three lines of scientific
>evidence pointing to a young sun. Access this article at:
>More recently, scientists associated with the Sudbury Neutrino Observatory in Canada report that the
>long-sought missing neutrinos, discussed at the beginning of this chapter, have now been found. An
>article on the Sudbury findings was published in the June 19, 2001 New York Times and may be
>accessed at: http://dept.physics.upenn.edu/~geneb/phys362/press/19NEUT.html
>The implications of this development for estimates of the sun’s age and operating mechanism will
>have to await further analysis by scientists who are open to the possibility that the data points to
>a young sun.
This is BS. We observe stars with metallicites several magnitudes lower than the sun’s, and stars with 1.5 times or more the metallicity of the sun. The low metallicity stars are common in globular clusters, which are as old as the galaxy. High metallicities are seen in young stars in the disk. We do not see old, high metallicity stars.
Oh, and another thing. Maybe these creationist guys should try to find such a nice fit of models with observations using their gavitational collapse model like this:
“With later work to test for other flavors of neutrinos, the “missing” neutrinos have turned out not to be missing.”
This reminds me of the Rosenhouse article on “how real science works.” Creationism thrives in the dark corners at the periphery of science. This topic is an example of that. They pick some really arcane issue that very few people are likely to know much about. The vast majority of people who read their posts are 1) not going to know enough to question them, 2) not going to know where to go to get answers even if they did doubt it. Their typical reader will probably just put another bullet on their list. “Size of sun refutes evolution! (Take THAT Darwin!)”
That’s the list that starts with:
0) 2LOT disproves evolution,
1) woodpecker necks disprove evolution,
and eventually gets to
n-2) info theory disproves evolution,
n-1) string theory disproves evolution,
n) Size of sun disproves evolution.
All of these are easy claims to make when your audience is mathematically and scientifically illiterate.
I doubt there is any idea on this Earth that is so stupid that you can’t find a crapload of people who would swear it’s true.
Here is the talk.origin FAQ:
A while back, I was arguing with a creationist about his creationist beliefs. He claimed that scientists have no idea how all the elements in the universe were created from hydrogen. I just shook my head and pointed out the fact that nuclear fusion occurs in stars and creates the heavier elements from hydrogen. He countered that the stars don’t undergo nuclear fusion and told me to prove that fusion occurs in stars. I’d never heard that line of arguing before (that stars don’t undergo fusion), and I simply decided that he was too dumb to argue with anymore.
What makes the creationist argument so completely ridiculous is that there is no mechanism for gravitional collapse to produce any neutrinos. Thus the presence of even one neutrino falsifies the gravitional collapse theory.
>He countered that the stars don’t undergo nuclear fusion
>and told me to prove that fusion occurs in stars
Is it bad that this has me imaginging responding by launching said creationist into the sun?
Claiming that the Sun is actually a myth of the evolutionist conspiracy is actually a fantastic strategy for many reasons. For example, there’s the old evolutionist “the second law of thermodynamics doesn’t keep entropy from locally decreasing because the earth is not a closed system” carnard– this is patently ridiculous since it is based on the false premise that the earth is an open system because the sun supplies it with energy from outside. In fact the earth is a closed system– because there is no Sun!
I am most decidedly NOT a Creationist. But if I were, I’d at least advance a wrong theory that fits the facts better. To make up an example, I’d say that the sun is powered by gravitational collapse, which heats the core high enough so that large amounts of boron not observed near the surface react by fission, Fission meaning protium plus Boron-11 for the so-called Boron-fission reaction:
p + B11 -> He4 + He4 + He4
8.80 Mev (7.0 x 1013 J/kg)
That would, as I say, still be wrong, but would be harder to disprove.
I’d say that neurinos come from some other process, as an epiphenomenon. I’d throw in a pinch of spice by suggesting that the neutrinos come from, let’s say, fission of dark matter particles.
My nonsense, whipped together right here, right now. But at least it’s a scientific theory.
Creationists tend to be less interesting in their nonsense.
By the way, what is the Bad Math behind the electric zeta-pinch sun theory?
Lost some style, regarding superscript for exponentiation. Should correct above to:
p + B11 -> He4 + He4 + He4
8.80 Mev (7.0 x 10^13 J/kg)
Strictly speaking, I don’t think there is such a thing as a ‘bad theory’–only bad hypotheses. Once a hypothesis can be regarded as a theory it’s by definition ‘good’.
The word ‘theory’ is used 38 times in this post–I found it quite distracting. 🙂
That’s terrifyingly daft.
Two things stand out, quite aside from the silliness of their supposed theories. The first is their equating of “stellar evolution” with the theory of evolution as if they are saying, “My daddy wun’t no monkey, therefore nothing has ever changed, anywhere.”
The second is the (earlier) madness that physicists were changing their theory on the mechanisms of the sun based on a desire to accommodate biological evolution (not, you know, because of the data or anything), and that the gravitational collapse model was rejected when it became ‘unfashionable’ – not when it was unable to explain observations, oh no, not at all.
It should also be pointed out that the frequencies of acoustic waves passing through the core of the Sun are in extremely close agreement with those predicted from standard stellar evolution theory. What frequencies do young-sun creationists predict for solar p-modes I wonder?
Thank you, csrster, for raising the point about acoustic waves. As I recall (though I don’t have appropriate citations at my fingertips just now), one reason that neutrino people were pretty confident that they would find oscillations is that the findings of helioseismology agreed so well with our understanding of the Sun’s power source. We knew our schematic of the Sun was pretty good, so we knew that it had to be producing neutrinos inside, and so we deduced that something like oscillation had to be making them hard to spot!
These guys are really funny…
You mean, no indication like a big, glowing ball of fire giving us sunburns 150 million kilometers away?
In other words: We won´t think about this until somebody tells us what we “know” anyway. Hilarious.
Darn it, bcpmoon, I was going to comment on that one. 😉 It’s so typical of creationist thinking, though. Yeesh.
I’m actually curious about the answer to the “problem” with stars in clusters having different ages, though. I have an idea what the answer might be, but I’d like to hear from someone with a better grasp on the science.
But the “gravitational collapse” thing isn’t a serious theory. It’s a masquerade.
Playing devil’s advocate, that theory was developed by Helmholtz and Newcomb (independently), and, of course, it included quite a bit of math.
Indeed. The real problem is with maintaining the gravitational collapse theory in the face of all the evidence for stellar fusion. At the time it was proposed, the gravitational collapse theory wouldn’t have been quite so insultingly stupid as it seems now. 😉
Well, there was nothing wrong with the gravitational collapse theory. It indeed powers proto-stars (young stars that have not yet contracted to the point where fusion becomes important), and brown dwarfs. The difficulties arose when numerous lines of enquiry began to show that the earth, and by extension the sun had to be much older than a couple of million years.
nikita et al:
Sorry, I wasn’t as precise as I should have been. The gravitational collapse theory as proposed by creationists as an alternative to stellar fusion is a masquerade. You are quite right that at the time it was proposed by real scientists, it was a respectable theory with the kind of mathematical support that you would expect. But since then, new observations and new data has shown that the gravitational collapse theory doesn’t fit what we can see. The people who are now trying to bring it back are the ones guilty of creating a masquerade. They’re pretending that none of the observations of the last hundred years happened, and that the GCT as originally proposed is valid in light of todays knowledge.
The Sun? You mean that glowing ball that moves around the Earth?
After all, if you’re going to take the Bible as literally true regarding creation in 6 days instead of evolution, why stop there? You’ve got to believe in the whole ball of wax, including the following:
“On the day the LORD gave the Amorites over to Israel, Joshua said to the LORD in the presence of Israel:
‘Sun, stand still over Gibeon,
and you, moon, over the Valley of Aijalon.’
“So the sun stood still,
and the moon stopped,
till the nation avenged itself on its enemies,
as it is written in the Book of Jashar.
The sun stopped in the middle of the sky and delayed going down about a full day.”
So, as was pointed out to Galileo, the Bible says God commanded the Sun, not the Earth, to stand still – obviously ineffective, if literally true, to make the Sun stay in the same position in the sky, unless the Sun orbits the Earth.
I don’t see much on creationist or other web sites about how the publicity and photos associated with the Pioneers and other *solar*-system-traversing spacecraft have all got to be bunk, since the Bible tells us it ain’t so. Anybody else found anyone out there nutty enough to maintain this?
By the way, I often wonder if we could design a system of coordinates[or a model] where the earth is fixed and the sun moves, that satisfy our data on the solar system. I mean, it would be probably more complex and it would be harder to resolve its equations to make predictions, but is there an observation that would disprove it?
PS: it’s not a provocation, and sorry if it’s a silly question.
Saizan: “I often wonder if we could design a system of coordinates [or a model] where the earth is fixed and the sun moves, that satisfy our data on the solar system. I mean, it would be probably more complex and it would be harder to resolve its equations to make predictions….”
Heh, ever heard the comment “there is nothing new under the sun”? What you ask about was tried, and proved impossible to make work. See http://obs.nineplanets.org/psc/theman.html. A quote from that page: “Ptolemy’s system involved at least 80 epicycles to explain the motions of the Sun, the Moon, and the five planets known in his time.”
The creo article is (of course) sneaky.
First with the circumstances around the early calculations of Earth’s age. The main problem was the assumed cooling rate and stability of Earth, which set up a lot of dating clocks to arrive to the same time frame. The discovery of radioactivity fixed the first main problem, and set the scene for plate tectonics that explained sea salinity and age of rocks. ( http://en.wikipedia.org/wiki/How_old_is_the_earth )
Second with the interest for neutrino observations. The neutrino masses the oscillations point to are one of few observations outside the all too robust Standard Model, for freaks sake!
BTW, on the first post there are noted at least two more observations that a collapse model must explain: development of material from primordial nucleosynthesis and cosmic radiation signatures.
“is there an observation that would disprove it?”
Assuming a fixed earth AFAIK you would have to have most of the rest of the universe revolve around the earth with speeds above light. That is impossible. Speeds approaching light for closer objects would be directly observable as Penrose-Terell rotations ( http://math.ucr.edu/home/baez/physics/Relativity/SR/penrose.html ).
It’s true, I was there. 😉
I’m still interested in the question of differently-aged stars in clusters, by the way. I know there’s a good explanation, I just don’t know what it is. (The Talk Origins page only discusses neutrinos.)
The Age and Distance of a Stellar Cluster
I managed to teach this successfully to over a dozen college students in my Astronomy Lab, when I was an adjunct professor of Astronomy.
At this level, the theory uses Good Math, yet as elementary as intermediate algebra, and logarithms. I did not distract my class with the Virial Theorem and other more complicated matters of stellar dynamics. Let alone the equations of state of stellar interiors.
Outside of this very well established theory, there can be an occasional star of a different age in a cluster. It could have been there before the cluster was formed, or gotten captured by the cluster later. There can be a star of different age in the line of sight of the clsuter, but not in the cluster.
Beyond that, I’m no more aware that there is a “controversy” about the age of stars in clusters than I am about a so-called “controversy” witrhin science about evolution.
The clusters problem probably deserves its own post. But the
short version is that it’s more of the same kinds of errors.
The “problem” is supposedly that we can see groups of stars in clusters moving outward, and if you backtrack their paths using their current velocities, you find that they were in the center of the cluster X thousand years ago.
The problem with that “problem” is that it isn’t a problem. It *would* be a problem if stars moved at a uniform and unchanging velocity. But they don’t, they move in and out in an elaborate dance. That is, motion in clusters is cyclic. The stars move outward, are slowed by the clusters gravity until they stop and start back in; pass through the center, and start out the other side.
The “gravitationally bound” groups that the creationists complain about were formed during one of the passes through. The stars don’t need to be the same age, because *they weren’t always together*.
This creationist doesn’t appear to be talking about globular clusters at all. He/she seem to be even more confused than you give him/her credit for. He/she’s talking about a cluster of 4 (4!) stars, (as opposed to the thousands in a typical globular cluster), that are somehow both “moving away from a common point at a high rate of speed” and “gravitationally bound”.
I think this is not only a case of creationists not understanding science, but of not understanding each other’s arguments either.
In a sense the young-sun-creationists are really trying to solve a problem they don’t even have. The cooling time (Kelvin-Helmholtz time) for the outer part of the Sun is millions of years. So if God had just created a hot sun with no energy source a few thousand years ago it would have shone until today with no visible change in output. voila. The whole “gravitational collapse” thing is irrelevant – you don’t need new sources of energy over such short timescales.
(Blake: exactly right. The acoustic oscillation frequencies constrained the solar structure so tightly that there had to be a particle-physics solution to the neutrino problem – once the problem had been confirmed by several other experiments.)
There’s a fellow who earned a Ph.D. in astronomy but then experienced a religious conversion. Now he spends his time bringing astronomy into compliance with the Bible. Some of the papers at this site may be what you’re looking for.
Next step after “bringing astronomy into compliance with the Bible” might be “bringing the entire physical universe into compliance with Alice in Wonderland.”
I mean, what the hey, Rev. Charles Dodgson was a mathematician as well as Reverend in his day job, and Lewis Carroll on his own time. You know the story of his audience with Queen Victoria, right?
And didn’t I mention “down the rabbit hole” on the thread about Deepak Chopra? Rabbit Hole is to Black Hole as “darkness upon the face of the deep” is to Dark Energy.
Nova did a nice show on the solar neutrino problem titled “The Ghost Particle” a few years ago:
The question that puzzles me – has the sun really observed to be shrinking at ~2 feet/hour on average for the last 100 years – 400 years?