Quick post, I’m in between sessions here in Washington DC.
Dr. Richard Lindzen just gave a keynote talk on climate sensitivity and the state of climate science. Here is the powerpoint below:
Powerpoint link, “hot off the press” so to speak, minutes old.
More later
George E. Smith (15:29:07) :
Hi George. I have to speak up for strings :). It is the only theory at the moment that we have that can unite all known forces , including gravity , in a simple system of equations. Elegance has a lot to do with theoretical preferences.
The reason that they are attractive, which keeps you warm at night
The nonsense that Maxwell’s four equations of electromagnetism, are actually just a subset of ten or eleven equations, and that suddenly each equation becomes synonymous with a physical “dimension”, six or seven of which are rolled up so tightly in the concept of string theory or some other neo-religious baloney; keeps me warm at night when I would otherwise freeze.
is that this unification of known forces except gravity had already happened with the three forces : gauge theories, molded after Maxwell’s equations, are very successful in describing elementary particles. String theories are a step further, trying to incorporate gravity too.
I do not know if they will be the theories of the future, but they have a simple origin: the multidimensional harmonic oscillator, an ubiquitous approximation for any solution of problems in many quantum mechanical cases. They have elegance in concept, but I agree that all that curling up reminds of hair :).
Now zero point energy, if we take the ubiquitous harmonic oscillator solutions, is the ground state energy. This does not mean that the ground state has 0 absolute energy ( even +/- heisenberg’s principle). It could very well be that our earth is in a position of the galaxy where we are sitting at very high potential energy, and that is our zero point energy. If there are other physical forces than the four we know, it is possible that , in a similar way we get energy from waves in the sea by using one way valves under platforms, a smart inventor in the future could tap the vacuum sea :).
For people who are interested to read a bit about strings, here is a lecture by a prominent theoretician for the CERN summer student program
http://indico.cern.ch/conferenceDisplay.py?confId=a054096
Description: After having outlined the difficulties that Einstein and others have encountered in trying to unify our understanding of macroscopic/classical and microscopic /quantum physics, I will explain in simple terms how the latest particle theory revolution, string theory, may finally offer a surprisingly simple realization of these long-standing dreams. Einstein thought that his difficulties stemmed from a clash between the classical and the quantum. Yet, paradoxically, superstrings appear to realize his dream thanks to -and not against- quantum mechanics.
Note: Some knowledge of quantum mechanics and special relativity is needed. Having followed previous courses of the school should provide a sufficient background.
George E. Smith (09:58:50) :
How the hell can a “string” be fundamental; or anything else that has shape or vibrations or any other properties that dictate that it must also be structured of something even more fundamental.
Ah, the problem with Maxwell’s theory in a nutshell. At a time when people needed an ether for electromagnetic waves to propagate that was the something structured, but when special relativity came in, bang goes the ether. So the electromagnetic waves structure themselves in space, that is what the equations tell us. Grand Unified Theories extended this concept to include the weak and strong force. Strings include gravity, all by the same mechanism as with Maxwell’s equations.
And people actually get paid to come up with this rubbish.
Yes, isn’t that great 🙂 . It might be that your great grandchildren will be using the technology that will have come out of this rubbish, the way now we are using Maxwell’s “rubbish” to communicate over thousands of miles. Or if not exactly strings, something somebody will come up with trying to fit or refute strings. That is the story of scientific advancement, not engineering.
Now I could confuse the issue further by bringing in ether by the side door, but I will not do it.
Oh TEKs do sometimes blow up you know.
Many, many years ago when I was doing something or another I could not get the display to stabilise, twiddle as I might. And I twiddled mightily to no avail.
Everyone else in the lab with their tea and bickies, it was elevenses, was standing around watching with interest to see when I would notice the smoke and flames pouring out of the back.
Kindest Regards
>> Ric Werme (18:41:24) :
Hmm, orbital angular momentum would stay the same (twice the distance times half the speed), and that’s a problem because the Earth’s spin has to slow down. I guess the answer is that the Earth actually orbits the center of gravity (the barycenter) of the Earth/Moon system and that distance will increase for both Earth and Moon. The Earth is so close to the barycenter we might not be able to treat it as a point so I hope the Earth manages to gain some angular momentum due to the orbital motion. Please straighten me out if I’m confused. <<
Now I’m awake enough to do this calculation. We need several formulas. Angular momentum is the vector cross product of distance with the linear momentum. We can ignore the vector arithmetic and just do the scalar math. LM = REM*PM = REM*MM*VM. (Where LM is the Moon’s angular momentum, REM is the distance from the Earth to the Moon, PM is the Moon’s linear momentum, MM is the Moon’s mass, and VM is the Moon’s velocity.) I’ll just assume that the Moon’s orbit is circular so we can use the formula for centripetal acceleration: a = v2/r. If we multiply through by the Moon’s mass we get the formula F = MM*VM2/REM. We need Newton’s gravity formula F = G*m1*m2/r2. Substituting for our case, we have F = G*ME*MM/REM2. (Where G is Big G, ME is the mass of the Earth, and so on.) If we solve for the Moon’s angular momentum we get LM = MM*((G*ME*REM)(1/2)). So if we increase the distance of the Moon four-fold, then the angular momentum doubles.
Jim
[I see it’s a waste of time to use sup and sub HTML tags on this blog. I’ll re-post it without trying to be fancy.]
>> Ric Werme (18:41:24) :
Hmm, orbital angular momentum would stay the same (twice the distance times half the speed), and that’s a problem because the Earth’s spin has to slow down. I guess the answer is that the Earth actually orbits the center of gravity (the barycenter) of the Earth/Moon system and that distance will increase for both Earth and Moon. The Earth is so close to the barycenter we might not be able to treat it as a point so I hope the Earth manages to gain some angular momentum due to the orbital motion. Please straighten me out if I’m confused. <<
Now I’m awake enough to do this calculation. We need several formulas. Angular momentum is the vector cross product of distance with the linear momentum. We can ignore the vector arithmetic and just do the scalar math. Lm = Rem*Pm = Rem*Mm*Vm. (Where Lm is the Moon’s angular momentum, Rem is the distance from the Earth to the Moon, Pm is the Moon’s linear momentum, Mm is the Moon’s mass, and Vm is the Moon’s velocity.) I’ll just assume that the Moon’s orbit is circular so we can use the formula for centripetal acceleration: a = v^2/r. If we multiply through by the Moon’s mass we get the formula F = Mm*Vm^2/Rem. We need Newton’s gravity formula F = G*m1*m2/r^2. Substituting for our case, we have F = G*Me*Mm/Rem^2. (Where G is Big G, Me is the mass of the Earth, and so on.) If we solve for the Moon’s angular momentum we get Lm = Mm*((G*Me*Rem)^(1/2)). So if we increase the distance of the Moon four-fold, then the angular momentum doubles.
Jim
There is a problem with Dr. Lindzen’s equations. It does not change his conclusions, but actually supports them more emphatically. The feedback gain formula on slide 14 does not work if the system is unstable, i.e., if the feedback is positive. In this case the instability is self-sustaining, and the system quickly diverges until it reaches a boundary or oscillates between boundaries in a wildly fluctuating limit cycle.
This, fundamentally, is why the climate system cannot be dominated by positive feedback. Positive feedback is pernicious and assertive. It does not lie in wait for a trigger. It feeds off itself like a cancer and marches forward relentlessly until the patient is dead.
If our climate system were dominated by positive feedback, it would long ago have spiraled out into a runaway greenhouse, and the Earth would be like Venus already, indeed, eons ago.
>> Bart (17:43:14) :
. . .
If our climate system were dominated by positive feedback, it would long ago have spiraled out into a runaway greenhouse, and the Earth would be like Venus already, indeed, eons ago. <<
This is one of the strongest arguments against AGW. Long-lived systems aren’t inherently unstable. I’ve made this statement many times, and it seems to fall on deaf ears. Apparently the believers in AGW that I’ve dealt with can’t process the statement and have little understanding of the realities of feedback in systems. Of course, I’m not a climatologist, so my opinion has little value.
Jim
I have been in contact with Dr. Lindzen on this matter. He has clarified that the model is in discrete time, so the usual connotation of “positive” and “negative” feedback that everyone in the world but climate modelers, apparently, understand 🙂 as the delineating line between stability and instability in a continuous time system does not apply.
The model essentially assumes that the change in flux due to temperature is instantaneous, so if the factor “F” in Dr. Lindzen’s presentation is positive, the effect of the delta heat added is amplified.
I will have to contemplate if I can find any other weaknesses in this argument, but for now, I would have to withdraw my previous comment. In any case, it is Dr. Lindzen’s position that the “F” factor is, in fact, negative, hence there is attenuation rather than amplification.
Did Lindzen use up-to-date data this time? Or did he use old data like he did for http://wattsupwiththat.com/2009/03/30/lindzen-on-negative-climate-feedback/ ?