Traduction par Véronique Pagé
Les lettres que je reçois vont de l’affirmation amusante que nous ignorons des changements du champ magnétique aux histoires abracadabrantes à propos du “poids“ du dioxide de carbone qui le retiendrait “près du sol”. Si l’auteur semble sérieux, alors je le traite sérieusement et tente de lui offrir une réponse utile. Bien souvent, par contre, je me retrouve au coeur d’un débat futile à propos de principes physiques élémentaires et bien établis. En général c’est là que je me retire de la conversation, parce que je n’ai pas de temps à passer là-dessus. Ceci génère souvent une réponse hostile de mon interlocuteur, qui m’accuse d’avoir des intentions cachées. Plusieurs me trouveraient naïf de continuer de me donner la peine de répondre.
Mais après tout, il est possible que parmi toutes ces lettres il s’en trouve une qui contienne une idée fantastique qui n’attend que d’être entendue pour changer le cours de l’histoire scientifique. Comment identifier cette lettre parmi les autres? Il y a une histoire qui court dans ma famille qui peut peut-être jeter une lumière intéressante sur la question.
L’histoire concerne Wilhelm Reich, le psychanalyste Freudien controversé (1897-1957). Reich était un ami de mon grand-oncle William Steig, créateur de Shrek et illustrateur d’un des livres de Reich. Reich croyait avoir réussi à démontrer l’existence d’une forme d’énergie jusque-là insoupçonnée qu’il baptisa énergie “orgone”. Il avait construit un “accumulateur d’énergie orgone” qui était en gros une boîte dont les murs étaient couverts en alternance d’un matériau organique et de métal. Ses expériences minutieuses avaient démontré que la température à l’intérieur de la boîte s’élevait au-dessus de la température ambiante. Il fit des calculs qui démontrèrent (croyait-il) que l’augmentation de température était plus grande que celle prévue par la thermodynamique, prouvant de ce fait l’existence d’une source additionnelle de chaleur; il attribua celle-ci à la présence d’énergie orgone. Il envoya ses calculs à Albert Einstein, qui lui répondit aimablement, lui expliquant pourquoi ses calculs étaient erronés. Reich lui réécrit, démontrant à son avis qu’Einstein faisait erreur. Einstein ne lui répondit jamais.
Certains membres de ma famille choisirent de croire qu’Einstein était déconcerté par les calculs de Reich. La plupart des gens conclueront qu’Einstein avait décidé qu’il avait mieux à faire que de s’empêtrer dans une discussion qui ne mènerait nulle part. Cette histoire est particulièrement émouvante pour ma famille parce que mon grand-père Henry, le frère de William, a tenté de traiter le cancer qui l’a emporté en s’asseyant dans un accumulateur d’orgone. Évidemment, je ne tiens pas Wilhem Reich responsable de la mort de mon grand-père. Mais de toute évidence Reich avait tort et Einstein avait raison.
“Mais un instant”, pensez-vous peut-être, “vous n’êtes quand même pas tous des Einstein à RealClimate”. C’est vrai. Mais tout comme Einstein, nous sommes constamment soumis à la critique de nos collègues; le processus de revue par les pairs n’est rien d’autre que ça.
C’est un processus imparfait, soit, mais qui sépare efficacement les idées solides de celles qui ne mènent nulle part. Les énoncés de Greenspan sur l’économie, par contre, n’ont jamais été soumises à un tel processus. Il y a peut-être une conclusion à tirer de tout ça…
Richard C, one less vegetable in the stew, good just the same if it’s too hot, stay out.
# 198, not a bad point, but we have known about introns since the nineties and introns, or “junk DNA,” is pretty well established nowadays. Evoultionary biological trends cannot be predicted, only understood in hidnsight and and some aspects of genetics utilize quite well, probability, but evolutionary biology is far more qualitative than quantum mechanics and broad as well.
One correction, my microbiology txtbook from the seventies discussed introns in quite elegant detail, just like centrioles are not necessary in mitosis:)This economy based upon green span economics and quasi reganomics has given me alot of free time as you can see:)
Diversity #183, could be useful but the problem with “the generally accepted body of theory relating to global warming” is not that it is either wrong or incomplete, but that operational results based on it will suffer from uncertainty, i.e., imprecision, due to the way that in the theoretical framework, precision is propagated from data to results. I.e., it explains all of the available data, but some of it poorly. You could call this incompleteness, but it is of a different kind (to illustrate, replacing Newtonian by Einsteinian gravitation in the global circulation models wouldn’t be helpful; that’s not where the problem lies.)
Otherwise your logic of how to properly use scientific knowledge under uncertainty for policy making is impeccable.
Hank, 200, “N2”. However, the quick google turned up different units, so I may have divvied the wrong way.
Supply the answers. It would be far more useful than beeing sarky.
#194. No. Gravty is a fact. Not Law. g=GMm/r^2 is a law. It’s also a wrong description of the fact of gravity. It’s close enough a model of gravity to work at slow speeds, “small” masses (planetary) and macro scales.
191. The real universe doesn’t follow thermodynamic laws. It’s called “Ideal Gas Law” for a reason.
Both describe the universe sufficiently to be useful. But only within the realms that the law is appliccable and for which the errors from realities version are ignorable. E.g. a gas that is not too dense to break the ideal gas assumption that the molecules are point particles and cold enough to avoid light speed travel.
Heck, it breaks down when you shoot a supersonic bullet through the gas.
#181
Lost in the volume of responces that were highly intelligent yet off topic.
go figure
dennis baker
For what it’s worth, I found that David Archer’s book, _Global Warming: Understanding the Forecast_ was quite readable and enlightening. If you find yourself having difficulty explaining some of this stuff to engineers, perhaps you could recommend this book. Because it proceeds step by step and includes the math and increasingly complex modeling, I think it does a good job of explaining both the fundamental physical aspects of climate change and the inherent complexity. Perhaps you’ve been shy about recommending it since it’s featured on these pages, but I don’t have such restrictions — I’m just an engineer who bought a copy of the book and found it interesting and useful.
jcbmack writes:
Super. My degree is in physics. The Einstein mass-energy relation has nothing to do with thermodynamics. I’ll derive it for you.
The general equation is:
E^2 = m^2 c^4 + p^2 c^2
where E is energy, m mass, c the velocity of light in a vacuum, and p relativistic momentum. For an object stationary in the inertial frame of reference under discussion, p = 0 and the equation becomes
E^2 = m^2 c^4
Taking the square root of both sides:
E = m c^2.
jcbmack writes:
What makes you think I haven’t?
jcbmack writes:
We don’t. We disagree with your idiosyncratic ideas about what they said.
jcbmack writes:
Don’t know who you’re quoting, but it doesn’t sound like a contemporary physicist. Physicists nowadays do not say that mass increases with velocity, only momentum; mass is taken as an invariant. This is because momentum, like velocity, is a vector quantity and mass is a scalar. If you use the old “mass increases with velocity” scheme you have to specify at what angle you’re measuring the mass, and deal with “radial mass” and “transverse mass.” Thus the change in scheme.
I just want to commend Hank for the footwork he’s been doing in this and other forums. Most of us (i.e. me) are usually too lazy to go search the ‘net for relevant references unless we’re involved in some kind of argument.
Mark, thanks for posting. I don’t deny that there’s a “Law of Gravity,” but I deny jcbmack’s contention that “the Law of Gravity” is somehow higher than “the Theory of Gravitation.” He may be a scientist, as he claims, but I feel fairly confident in saying he’s never studied philosophy of science. “Theory” is as good as it gets in a science, a theory is the working model for an entire field or subfield.
In response to foodtube # 182 Gavin says: “It’s not controversial. It only ever becomes an issue if someone insists that this trumps all greenhouse gas effects – which it does not”.
Maybe it does, Gavin. How can you be so sure? With all due respect you are a well known (be it controversial) climate scientist but you are not the most qualified person to make that claim. Stick to you own expertise (or give some peer reviewed papers to back your claim) but don’t pretend to have in depth biological and geological knowledge to outright dismiss the possibility that by emitting CO2 in the atmosphere mankind may (for a change) do something good for life on earth. With an ever increasing world population maybe the benefits of increased food production thanks to higher CO2 levels (as well as the increase of the surface area fit for agriculture) outweigh the risks?
Why do we hear so little of the benefits of a warmer climate? Climate change cannot be all bad, surely there are benefits to be had. Isn’t it true that the pre-industrial CO2 levels of 280 ppm were the lowest in geological history and that life on earth (including coral reefs, for those who claim that the Great Barrier Reef will be doomed) thrived with CO2 levels between 1000 and 2000 ppm in the Cretaceous period? Only in the Late Carboneferous/Early Permian CO2 levels were as low as they are now.
[Response: I am neither well known nor controversial. But as to your main point – take sea level rise – who benefits from that? Sure there are some areas that will gain from small climate changes – vineyards in the UK for instance, perhaps wheat in Canada. But everyone who has looked at the costs vs benefits comes up with a net negative, and increasingly so as climate change gets worse. Tropical agriculture in particular is very sensitive to the projected temperature changes and associated changes in rainfall patterns. The issue has never been that the climate is today ideal – only that it is the climate we are adapted to (however imperfectly). Note that Cretaceous sea levels where ~100m higher than today. – gavin]
Mark, nitrogen and oxygen are both diatomic molecules in the atmosphere. Was “N1” just a typo?
Still haven’t got an answser for Eric.
[Response: I’ll get back to this when I can. Busy.
Meanwhile, I’m closing comments, because with election day tomorrow there will be too much temptation for people to inject their political views into the comments section of the blog!–eric]
From the (‘lay-scientist’, real scientist wanna-be) guy who you Honored by re-enforcing my – much decried by the other bloggers – observation that, by using SO2 to ‘Geoengineer’ our way out of having to use Good Sense to solve our Most Pressing of Planetary Issues, would only lead to more Acid Rain, Ocean Acidification, and – ultimately, or so I conjectured – the loss of our Primary source of the Oxygen that we all need to Breathe – Phytoplankton; I must say that I TRULY APPRECIATE what you do!
Somewhere out there are an Army of Einsteins and – perhaps more pertinently, as he had only a 10th Grade education – Farradays, who – like me – got screwed over by Bad Teachers, Bad Schools, and/or our own Bad Teenaged Selves; all of who can – and should bve allowed to – take part in the Scientific Process, even if we do not (yet) have ‘some letters after our names’.
The sad fact is that I’ve met more Very Intelligent People – who’ve been sidelined in Life, by our TOO Fascististic System – in Homeless Feed-Stations, than I’ve seen on T.V.!!!
Thank You for giving ME a Voice! I promise to Keep Fighting the Good Fight (in my case, with Christians in the S.S.A. who’ve wronged me Badly), and – when I win – to get my Ambitions to get those ‘Letters’ (like: PhD, for example) after my name!
I’m only 43 years young; and I know a Woman who did just that – at 69!!!
Martin 204
Thanks. I take inference under uncertainty for granted. I forget that many others do not. Amended text below.
The following is offered as a general and basic answer to those who deny the need to act on climate change as the scientific evidence suggests. If you feel it useful, please use it. If it needs amendment, please amend it.
The Basis of Science.
Each and every scientific theory is formed on the basis of incomplete information. It is therefore presumptively true that all scientific theories can be expected to be found to be wrong and/or incomplete. Sometimes we have already detected some of the wrongness/incompleteness. Gravity is a current example: we have imcompatible theories of macro and quantum gravity. In other cases we have not yet detected it.
To detect wrongness or incompleteness in a theory, it is sufficient to find data it fails to explain. To challenge a theory with a new theory, you require a new theory which explains the available data more fully.
Action on a Basis of Scientific Theory
If policy makers have to decide to act or not act in a field to which scientific theory may be relevant, they must take a judgemental bet on whether their decision will be improved by taking account of the scientific theory. That bet should be informed by the explanatory power of the theory in the area affected by the decision. If they decide to not take account of a relevant theory with high explanatory power, they will be betting very much against the odds.
Policy makers should not expect the scientific theory to explain all the data. It is to be expected for any scientific theory that some data will be found that it can not or can not yet explain.
Global Warming
The generally accepted body of theory relating to global warming explains a very large part of the available data, but not all of it. The theory is therefore patently incomplete – like our theories of gravity. However, unlike the case of gravity, we have no competing theories of the evolution of our climate with anything approaching the explanatory power of the generally accepted theory. It is therefore the best currently available basis for decision on whether and how to act or not to act on climate change. To decide on any other basis yet offered is to bet against high odds.
The fact that many quantative estimates for variables in the generally accepted theory are and will be subject to substantial margins of uncertainty qualifies conclusions to be drawn from the theory. However, these margins are not and cannot be a basis for refusing to accept the theory as the best available basis for policy.
In challenging the generally accepted theory as a basis for policy action, it is also beside the point to show isolated data that the theory does not explain. It is to be expected that there will be some such data. To challenge a theory as a basis for action, you need to demonstrate that it is inconsistent in itself, or with other accepted theory, or that the theory produces predictions incompatible with observed reality, or that another theory explains the existing data at least as fully. None of these requirements for a challenge have yet been met.
It follows that policy decisions on climate change are best based on the generally accepted scientific theory.
Hank, #215, yes.
BPL, #214, I would say that “the Law Of Gravity” is there, but it isn’t gravity. It’s an explanation of what you can predict gravity to do. jcb hasn’t taken philosophy of science, I agree. Neither have I but I like to read and I’ve read lots. I say
a) there is Gravity. It isn’t a law or a theory. It is itself.
b) newton created a gravitational law. It exists but isn’t gravity. As an explanation of what gravity does, it has some use. Quite a lot for us humans, really, but not for knowing what is REALLY going on
c) GR or QG are like newton’s gravitational laws a mathematical model that tries to explain what gravity will do. They work where newton’s laws are too inaccurate but they don’t work in each others playground and so we know they are wrong as an explanation of how gravity itself works.
Martin, #204. Congratulations. You took all you’ve learned and then applied them where they don’t apply.
There is no “model” of CO2 being a greenhouse gas. There is the FACT of it. It does it. How is answered by models but the fact of it is that CO2 traps IR and lets VR pass.
Fact.
In exactly the same way as we KNOW that if you drop a ball, it will fall down. Fact. It does it. How it does it and why is a model, but even if your model is “intelligent falling” the ball still falls, no matter how wrong your model.
So how does a model being wrong in some way stop CO2 being a GG? Why is it that a model that says it will do X is wrong in *just such a way* as to make it actually less than X or even nonexistent? The universe doesn’t know what you want, it does what it does, irrespective of your needs or desires.
It doesn’t.
CO2 being a GG is a fact of the sun being much hotter than the earth.
And no error in any model used to explain how it does it changes that fact.
Re #215
Hank, you still have not given a proper reply. :-(
Mark wrote
1) Molar masses and density give the same results because one mole of all ideal gasses have the same volume.
2) The air is 78% N2 not N1.
3) N2 has a molecular weight of 28 and O2 has a molecular weight of 32, so air has a molecular weight of 29 as already mentioned by Martin.
4) CO2 has a molecular weight of 12 + O2 = 44 so it 50% heavier than air but that is not enough to cause it separate out, particularly in the turbulent conditions of the troposphere.
Surely you knew all this. Why so coy?
Cheers, Alastair.
Physical chemistry is a combination of chemistry and physics,it is fine that you derived the equation, but it relates to thermodynamics just the same; chemists make those lasers work, those DVD’s play, and I have taken calculus physics, modern physics,(multi variable calculus physics)which means technically I too have a degree in physics, but my focus has been chemistry, biology, and I took a few graduate courses dealing with meteorology, ocean dynamics,geology, atmospheric science and my undergraduate courses were filled with earth science related material and after all the math needed for Pchem engineering mathematics is not difficult nor is graduate physics:)so the derivation you just made is discussed in math classes before, even calculus one, so I am not sure what you are trying to prove.
Barton, the quote is from NASA’s site, sorry, I should have left the reference, I will leave next time I post. I acknowledge your comment on vector versus scalar quantities.
And no my ideas are not idiosyncratic, they are consistent with the raw data, the math which supports it and reasonable implications they hold.
Oh and Mark, be careful, thermodynamics laws are never broken, no matter what the situation. Mark study the real gas laws. Thermodynamics always holds. Some considerations are kinetic as opposed to thermodynamic, but these laws have never been broken by any observed phenomena or plausible calculation. In p chem we really got into real gases, no more ideal, though yes,under many situations an ideal gas model will suffice.
Also I left plenty of references to show my points, if you have time, read them. Engineers utilize the ideal gas laws as it is easier to work with and provides as a tool to get good approximations of real gas behavior. Any real gas condenses to a liquid or a solid at some temperature higher than absolute zero, and this is why ideal gas laws are only approximations, albeit useful ones.
At sufficiently low pressures: Pv = nrt (absolute pressure times volume equals number of moles times ideal gas constant times absolute temperature)
Now a real gas equation, Van der waals: (p+a /VM2) (Vm-b)= RT. Vm is molar volume. Or represented as: P+a divided by V2 (v-b)= nRT. This is just a small example, however, keep in mind that aerodynamics, Mark is a very nasty science, a bullet propelled through the air does nothing to dispute thermodynamics, and the way in which thrust, drag, lift and weight effect the moving body, all obeys the laws of physics and is described nicely by aerodynamics. For example, for airplanes it is all newtonian mechanics anyways, not relativity, and 1/2 rho v squared gives the air density at a particular altitude. We have the balancing and unbalancing forces, the friction, heat production, local conditions; temperature itself just being the average kinetic energy.
Physics can all be explained by physical chemistry, in a very practical way.
When I say law for gravity, well, it has been around (theory of gravity) long enough validated, and observed long enough that under the appropriate conditions it is always true and complete and it is quantifed neatly in the math itself. I do not dispute that quantum gravity and string theory are going to as they are amended and data provided, provide further insight. Even then gravity is pretty well in tact, that apple will not stop falling on your head:) Even laws sometimes are refuted, theories are not laws in the making per se, laws are neatly quantified usually by one equation and have been upheld for a very long time. Evolution on the other hand, has been upheld for a long time, but lacks a neat equation to sum it up AND though it is accepted as a scientific explanation with over a hundred years of evidence to support it, we do have key missing points and we cannot predict future niche trends like we can calculate the position of a moving body at a particular time.
In physics we most certainly played around with E= MC2, anyone care to tell me what the original equation looked like before it became E=MC2? (M=e/c squared) It still represents mass and energy conservation. Of course the laws of physics are the same in all inertial frames and the speed of light is constant in all inertial frames.
B meson deacy: E= (pc)2 + mc (mc22 Where p equals momentum the product of mass and velocity. Energy and momentum conservation tell us that the motion of things before decay and the motion of things after decay have to add up to equal.
So E= MC2 only works for masses that are rest all by itself, but in a branch of physics, particle physics, nothing is ever at rest, however, E=MC2 forms a basis for other calculations do be made and without it, many of them would be impossible. When forming anti-electrons for example, for use in collisions, the equivalence of mass and energy is the explanation of how they are produced.
Also the C2 aspect of the equation acts as a symbol of an enormous amount of energy that can be produced from a small amount of matter which is traveling at the speed of light; we then get into interesting paradoxes like: an object approaching the speed of light would have infinite mass, but an object traveling at the speed of light has no mass. (photons, and light duality)
E= MC2 also tells us that the mass of the reactants is the same as the mass of the products in a chemical reaction (Lavoisier 1770’s)and law of conservation of energy in that particular reaction are not right. When water is formed from hydrogen and oxygen, the weight is a little bit less than would be expected. Now the change is so small, that it is not really noticeable until you see the data from nuclear reactors and particle accelerators.
Think of it this way a few grams of any substance if completely converted to energy would be equal to the power of an atomic bomb.Of course these converesions do not occur readily or under normal circumstances. and this is a good thing, as we would not be able to sustain life if it did.
All the laws do connect and as we know matter cannot be created or destroyed, their is no violation by any other law in this regard.
On that note, I am going to look at this new blog with great interest on the Global Climate Models, and refrain from rhetoric:)
The total energy content of the world is constant and the total entropy is continually increasing.
First and second laws of thermodynamics.
[Response: … which apply for a closed system only. The climate is however open. Ice ages anyone? – gavin]
>coy?
It’s a typo or from some source; don’t see how it helps with the CO2 question. There’s so much physics being asserted without sources now I’m just admiringly confused.
Absolutely right Gavin:) if it were closed we would be in big trouble:)
On another note on the speed of light, quantum mechanical tunneling assists in explaining why the emission slows down from the initial velocity from the sun:) So when we say the speed of light in a vaccum it is not that light slows in velocity, literally, but emissions do slow, final versus initial.
The isotopic data(e.g. carbon and strontium)along with the various other proxy data and even the little ice age in the 1800’s make it quite clear, that heat levels (absorbance, transfer, etc…) do change. Entropy does increase, but into the universe, also active processes protect objects from immediate effects of entropy. (cloud formations, or in the body, anabolic processes, and energy coupling)The sun supplies energy and not all of the energy remains, only a portion does, without it, it would pretty cold.
The earth is a system that does have natural responses to artificial insults, just the limits are becoming teased.
So the laws of thermodynamics are not violated, they just need to be understood. The earth is still warming and some heat and some escapes. Entropy is certainly not theoretical, people need to read and learn what it is all about. For the non scientist there comes a point where they can no further without schooling or reading from the basics of theory, law, math and connecting the dots and working through the problems and finding the real answers.
Mark, the Scientia Media and Monlinism: scientia media was a ky term used in the theology of Luis de Molina (1535-1600)Jesuits, later on instructed using variants of his teaching, by such persons as: Robert Bellarmine, Leonard Lessius, Francisco Suarez, and Gabriel Vasquez, which attempted to resolve the apparent conflict between the doctrines of grace and free will.
Scientific method: “method,” means “following a way,” from Greek, which meant along way. Descartes wrote an important work titled: Discourse on the Method of Rightly Conducting the Reason and Seeking Truths in the Sciences. By the time of Newton the concerns narrowed to natural philosophy. Rules of Reasoning in philosophy, Newton’s own work sums this up nicely. Newtom himself claimed to not make hypotheses, but he in fact had notions that seemed very hypothetical:) We should find greater reward in seeing what the scientist does as opposed to what he says about it, an objectied stance on a subjective person in a “paradigm,” or school of thought that attempts to be objective.
Of course the Greeks long before attempted to explain the laws and natue of the univers long before anything like the modern ideology of science developed, which by the way was not a continuous process (medival times, Salem witch trials, etc…) Then again the Egyptians had mathematical and scientific methods that we still do not understand to this day. (pyramid building the exacting measurements of the stones cut) The Hebrews also forged weapons of such high tensile strength that we still have difficulties in archaeological metalurgy to this day replicating such swords. The development of the sickle sword has some interesting history.
the understanding of what constitutes reality, cause and effect and this epic debate are also captured well by David Hume and Immanuel Kant. And again to reitterate I mentioned Kuhn and Popper.
I own the Encyclopedia of Philosphy, Complete and unabridged, entire set from Macmillan Publishing Co., & The Free Press. Great tool, the books are a little dusty, but they do an excellent job in elucidating minutia in esotetic matters, as well as telling the background story in a really detailed manner.
Tried understanding it jcb?
Ask me a question Mark and you will see… Took formal classes and I have had students in the subject matter.
Ethics courses served me well also. Within science, however, we do not think of things in exactly the same wey, we are busy answering difficult questions that only science can answer, where philosophy is only the bearing: how is the discovery going to be appllied, ethically.
Mark,you are like a cookie for the cookie monster… and I have not had a cookie in quite some time:)
Careful how the cookie crumbles… ;-)
I must apologize for trusting the New Yorker’s index system. I found that William Steig was drawing covers for them even as far back as 1932, if not farther.
Cookies can get messy:)
jcb you’ll notice that the cookie monster never actually EATS the cookies. He just makes a mess.
An Analogy Time production.
Thank you.
Now, two people here really don’t feel you’re thinking of the philosophy of science. One could be just a difference of opinion. Two is an indicator that either
a) you don’t understand it
b) you aren’t able to indicate your understanding
Bohr had a problem with (b) so don’t feel bad.