Guest essay by Eric Worrall
Consider the following descriptions of three scientific theories. Which is the odd one out?
1. The buildup of anthropogenic carbon dioxide may lead to dangerous climate change, not because CO2 is a particularly powerful greenhouse gas, but because the slight warming caused by excess CO2 will cause sea water to evaporate, filling the atmosphere with water vapour. Water vapour is a far more powerful greenhouse gas than CO2. The evaporation of water vapour will trigger a chain reaction, a runaway greenhouse effect, in which global warming caused by the evaporation of ever increasing amounts of sea water forces yet more sea water to evaporate. In Dr. James Hansen’s words, “The oceans will begin to boil”.
2. We have already been visited by aliens, who most likely continue to monitor us. The alternative is to believe the preposterous proposition that we are the only intelligent life inhabiting any of the planets circling our galaxy’s 100 billion stars. The reason this must be true – all we have to do is look in the mirror. In a few decades, or at most a few centuries, humans will have the technology to build nanotech space probes the size of a grain of sand or smaller. Probes which can visit other stars, and transmit information back to us. Such probes are already on the drawing board.
See: http://www.space.com/612-nanotechnology-scientists-pin-big-hopes-small-scale.html
Since the probes we shall build will be incredibly small, it will be possible to launch them at near light speed, for trivial economic cost. Scientists have even discovered ways such probes could be steered and decelerated as they approach their destination, using the Galactic magnetic field. If just one group of intelligent aliens in our galaxy of 100 billion stars reached our level of technology, at least half a million years ago, and made the decision to send out such space probes, then there has already been enough time for their high speed probes to reach our star system, and report back what they found.
3. Human lives are in danger right now, from asteroids and comets flying through space. As the shock advent of the Chelyabinsk meteor demonstrated, Earth can be struck unexpectedly at any time by meteors and other space bodies, many of which have the potential to cause widespread devastation. The Chelyabinsk meteor detonated with a force of 500 kilotons of TNT – it is only due to good fortune that the explosion, which caused some buildings to collapse and widespread damage and injuries from breaking glass, did not cause serious loss of life.
See: http://en.wikipedia.org/wiki/Chelyabinsk_meteor
So which theory is the odd one out?
The answer is theory three of course. Unlike the other two theories, theory three is supported by observational evidence. The other two theories, however compelling they seem, are just speculation.
| Story Title | Separating fact from fantasy |
| One line summary of story |
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“dccowboy says:
April 10, 2014 at 4:24 am
“He strongly believes a run away green house effect has made Venus inhospitable. ”
I don’t know if Dr Hansen does believe this, but many of my acquaintances on the AGW do. They constantly cite this as an example of what we face. I find the idea ludicrous. The only thing Venus and earth have in common is relatively close size. Venus has no magnetic field to shield it, it has never had oceans, it has no large satellite, the composition of its atmosphere is not only far denser, but also very dissimilar to earth’s, and finally Venus receives a good deal more solar radiation than earth. ”
When the solar system formed, the sun was only about 70% as luminous as it is now.
Since Venus is about 70% as distant from the sun as earth is, 4.5 billion years ago Venus was getting about the same amount of radiation from the sun as the earth gets now.
Unfortunately for Venus, the sun has been heating up. When the luminosity of the sun increased by 5%, there was a runaway greenhouse effect.
Google “Goldilocks and the Three Planets”
http://www.phys.lsu.edu/faculty/cjohnson/climate.html
“This is the complete carbon cycle: rainwater removes CO2 from the atmosphere and puts it in the crust, and volcanic action releases CO2 from the crust and puts it back in the atmosphere.
What happens on Venus? Venus has no water! Early in its history Venus may have had water, but it is too close to the Sun to retain it. When water molecules rise high in an atmosphere, ultraviolet radiation split the water molecules into its component gases, oxygen and hydrogen, and the lighter hydrogen molecules escape into space. While Earth’s lower atmosphere is about one percent water vapor (although it seems much higher in the humid Louisiana summers), the upper atmosphere, where ultraviolet radiation can penetrate, is very dry: a cold trap, a combination of pressure and temperature, prevents water vapor from rising high in the earth’s atmosphere. Venus has a cold trap, too, but because Venus is closer to the Sun its cold trap is much higher in the atmosphere and any Venusian water molecules rise high enough to be broken apart by ultraviolet radiation. ”
The Sun has increased in luminosity not quite 1% every hundred million years. When the luminosity increases to 1.05 current luminosity, in about 500 million years, Earth will suffer a runaway greenhouse effect and wind up as Venus’ identical twin.
If our planetary system orbited a star only about half as luminous as the sun, say Tau Ceti, Venus’ evolution could have been similar to Earth’s. After about 7 billion years, Venus would be getting about the same radiance from the sun as the Earth gets now, and the Earth would be getting the same amount of radiation from Tau Ceti as OUR earth received 4.5 billion years ago- a system with the potential for TWO lifebearing planets!
izen
None of the three scenarios listed reaches the level of a scientific theory. … The danger from asteroid impacts is in fact quite closely constrained by observation. Major events are much less frequent than the timescale of the development of human civilisation. … The whole article of this post is undermined by the apparent indifference to the definitions of scientific theory, hypothesis and speculation.
If by major events you mean dinosaur killers, sure, they are very rare. But if by major events you mean strikes which have the potential to cause significant loss of life, they happen once per century or so. For example, the Tunguska event in 1908 had an explosive force equivalent to 10 – 15 megatons of TNT, rather than the 500 kilotons of the Chelyabinsk meteor. If the Chelyabinsk meteor had been the size of the Tunguska meteor, the explosion would have utterly flattened the city, and killed most of the inhabitants – no different to being struck by a large nuclear bomb.
http://en.wikipedia.org/wiki/Tunguska_event
In the wake of the Chelyabinsk meteor, there has been some concern that estimates of the probability of meteors causing loss of life are too low. This is certainly something I would like to see researched.
http://www.theregister.co.uk/2013/11/06/chelyabinsksized_meteors_impacts_seven_times_more_common_than_first_thought/
MikeB says:
April 10, 2014 at 4:15 am
“For example, let’s say that an increase in CO2 leads to a warming of 1 degree C. That warming produces a rise in water vapour and more CO2 (released from the warming oceans) such that the temperature rises a further half degree in response. That half degree rise in turn causes a further rise of one quarter of a degree, which causes another rise of one eighth of a degree and so on. This is a positive feedback series but it is also ‘convergent’.”
No, that is not a positive feedback.
The division of feedbacks into “positive” and “negative” categories is a legacy of continuous time systems theory. E.g.,
dx/dt = a*x + u
where a is a constant and u is an input. This differential equation has positive feedback if a is positive, and negative feedback if a is negative. If a is positive, the system is unstable, and vice versa.
A zero-order-hold discrete time difference equation approximation to that system is
x(k+1) = e*x(k) + ((1-e)/a)*u(k)
where e = exp(a*T), and T is the sample period. This system is stable if e is less than unity. That is the case if a is negative. The dividing line is no longer whether e is positive or negative (as an exponential function, it is always positive), but whether it has magnitude less than unity.
Your example is a discrete time system. It is stable because your increase is always a fraction of what it was before, i.e., your gain is less than unity. This is a negative feedback system.
Positive feedback is inherently unstable. It can only be stable if it is enclosed within a larger negative feedback loop which overwhelms it. E.g., in the system above, we could have two effects proportional to x
dx/dt = (a+b)*x + u
We can have b positive iff a+b is negative.
That, however, is not the system we have. What we do have is a hypothesized model of the form
1) dT/dt = -a*T + b*C
where a and b are positive constants, T is temperature anomaly, and C is CO2 concentration. Now, if C were an independent input, the system would be stable. If we had a system of the form
C = c*T + H
where H is human inputs, the system would become
dT/dt = -(a-b*c)*T + b*H
That system would be stable so long as a-b*c were greater than zero.
However, that is NOT what we have. Empirically, we have a relationship of the form
2) dC/dt = k*(T – To)
where k is a positive coupling factor, and To is the equilibrium temperature. This system, composed of equations (1) and (2), is always unstable for any b greater than zero. And, that ineluctably leads us to conclude that temperature sensitivity to CO2 concentration, in the present climate state, is at best negligible.
I went into some detail discussing this phenomenon here, if you are interested in further reading.
Bart says:
April 10, 2014 at 2:18 pm
erratum:
x(k+1) = e*x(k) + ((e-1)/a)*u(k)
skience says:
April 10, 2014 at 2:25 am
skeptic science
“That the assertions must be such that even if the assertion itself is found to be untrue, that the skeptic can show that the assertion itself was valid given the evidence then available”.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Nice essay skience. I would hate to say how many times I have used the above in my career from the 60’s to the 2000’s when I “retired” to farming. The courts have (had) an expectation of use of the “standards” of the day in engineering, though that is being replaced by “Best Available Technology” which has variants relative to location, affordability and cost/benefit. Good documentation is the key. As it should be with science.
====================
Enjoyed you comments.
son of mulder says:
April 10, 2014 at 2:13 am
“The aliens are already here. They arrived in their ships the size of a grain of sand and the only reason we haven’t seen them is because they are hiding in the oceans.”
Sand grain, bad choice. It could have been troweled between a course of bricks or glued onto paper to make sand paper, or melted into glass, or worse still, fracked to death in Brady Texas.
@Gary Young Pearse
So that is why one of my bricks keeps trying to levitate. 😉
Theory #1 is the odd one out. Of the three it is the only one that is immediately disprovable through examination of the argument itself. As any mathematician, scientist or engineer familiar with feedback loops understands (heck, even many uneducated but reasonably intelligent people) if a system has positive feedback on the same scale as impetus received or larger it will be extremely unstable and be subject to runaway behavior the moment it shifts from equilibrium. This is not even controversial in the slightest.
Add to that simply the uncontested fact that temperatures have fluctuated significantly in the past on all time scales, and the rather obvious fact that at no time has the planet pulled a mercury, lost its atmosphere and burned to a crisp, and you have clear, unanswerable refutation of the theory.
Theory #2 may be tenuous but I doubt it can be repudiated so simply on the basis of the argument itself plus a modicum of simply factual knowledge. It is an outrageous theory, but would require either a highly sophisticated analysis or very complex factual data to refute.
Theory #3 makes apparently outrageous statements but its claims are very close to being quantifiable, and some version of the theory rises to the level of not being in dispute at all. Every credible scientist I know grants that there is some nonzero probability that its scenario could play out. The only question is “with what probability?”
WISE Math
… Theory #2 may be tenuous but I doubt it can be repudiated so simply on the basis of the argument itself plus a modicum of simply factual knowledge. It is an outrageous theory, but would require either a highly sophisticated analysis or very complex factual data to refute. …
There are of course hidden assumptions and problems with at least the first two theories ;-).
Interestingly though, the futurist Ray Kurzweil uses a variation of theory 2 to support his proposition that we are alone in the galaxy, possibly the universe, in his book “The Age of Spiritual Machines” – that if we weren’t alone, the solar system should be swarming with alien nanotech. Though Kurzweil gives at least one reason why we might not be able to detect such nanotech machines.
Kurzweil currently works for Google, they hired him to help head a project to improve the ability of their systems to understand and extract meaning from natural language – so he is very credible on issues related to artificial intelligence and high technology.
The SciFi author David Brin uses a version of the alien contact theory as the basis of his book “The Crystal Spheres”. David Brin’s most well known book is probably “The Postman”, a great book which was turned into a rather unfortunate Kevin Costner movie.
I said number 1. Because hot air can not boil water. Therefor it’s impossible.
The other two theories are plausible.
As presented, #3 stands out, but the whole question is whether the claims of evidence stand up. It’s just dishonest to say that overall, #3 is the theory that stands up without addressing every piece of claimed evidence.
–For example, let’s say that an increase in CO2 leads to a warming of 1 degree C.–
So some decade after 2050, Global CO2 have contined to risen and it causes global temperature to rise by 1 C before the end of 21st century.
-That warming produces a rise in water vapour and more CO2 (released from the warming oceans) such that the temperature rises a further half degree in response. —
Even assuming a rise in average global temperature increase global water vapor. A rise in global water vapor does not have any significant effect upon ocean temperature.
Nor does the average global temperature air temperatures of 15 C warm oceans in any significant way. There is no reason to assume it warms the surface of ocean and less reason to assume warmer air or water vapor would warm the vast majority of the ocean-
which currently as an average temperature of about 3 C.
This is very valuable, and I was about to criticize Bart but figured out a deeper observation that nullified my observation:
Bart says:
MikeB says:
“For example, let’s say that an increase in CO2 leads to a warming of 1 degree C. That warming produces a rise in water vapour and more CO2 (released from the warming oceans) such that the temperature rises a further half degree in response. That half degree rise in turn causes a further rise of one quarter of a degree, which causes another rise of one eighth of a degree and so on. This is a positive feedback series but it is also ‘convergent’.”
No, that is not a positive feedback.
The division of feedbacks into “positive” and “negative” categories is a legacy of continuous time systems theory. E.g.,
dx/dt = a*x + u
where a is a constant and u is an input. This differential equation has positive feedback if a is positive, and negative feedback if a is negative. If a is positive, the system is unstable, and vice versa.
A zero-order-hold discrete time difference equation approximation to that system is
x(k+1) = e*x(k) + ((1-e)/a)*u(k)
where e = exp(a*T), and T is the sample period. This system is stable if e is less than unity. That is the case if a is negative. The dividing line is no longer whether e is positive or negative (as an exponential function, it is always positive), but whether it has magnitude less than unity.
Your example is a discrete time system. It is stable because your increase is always a fraction of what it was before, i.e., your gain is less than unity. This is a negative feedback system.
Positive feedback is inherently unstable. It can only be stable if it is enclosed within a larger negative feedback loop which overwhelms it. E.g., in the system above, we could have two effects proportional to x
dx/dt = (a+b)*x + u
We can have b positive iff a+b is negative.
That, however, is not the system we have. What we do have is a hypothesized model of the form
1) dT/dt = -a*T + b*C
where a and b are positive constants, T is temperature anomaly, and C is CO2 concentration. Now, if C were an independent input, the system would be stable. If we had a system of the form
C = c*T + H
where H is human inputs, the system would become
dT/dt = -(a-b*c)*T + b*H
That system would be stable so long as a-b*c were greater than zero.
However, that is NOT what we have. Empirically, we have a relationship of the form
2) dC/dt = k*(T – To)
where k is a positive coupling factor, and To is the equilibrium temperature. This system, composed of equations (1) and (2), is always unstable for any b greater than zero. And, that ineluctably leads us to conclude that temperature sensitivity to CO2 concentration, in the present climate state, is at best negligible.
—I was going to criticize Bart for saying “That’s not what we have.” This criticism would be on the grounds of this: we don’t know what we have.
That is true.
However, we do know (if we trust the measurements) that CO2 can be much higher and if so the planet will not run away into unhindered warming.
So, Bart’s observations are very valuable. you can look at an equation/model and figure out whether, in the long run, it essentially has a negative feedback for CO2 or not.
**This MUST be specified in the model from the get-go!!!***
If you develop a climate model with CO2 radiation/heat capture as one factor. it either is in the model in a way that ensures there will be negative feedbacks as CO2 increases, or not.
THAT simply is a matter of the construction of the mathematical model.
Bart, or others, can look at these models, if only someone will let them, and can figure out the assumptions, such as “CO2-promoted atmosphere temp increases are un-checked,” that are inherent in the model.
If you model increased CO2 to lead to increased atmosph heat, and run scenarios, it is inevitable that you will get a model with catastrophic atmosph heat increases.
In other words, I am sad to say that we cannot model future climate without making some guesses or assumptions, or treading upon terra cognita. You have to take your stance with a climate model: will I allow it in the future to run away in a positive feedback loop, or not?
Once again, the term “theory” is used inappropriately. The conjecture is an hypothesis. A theory must have passed falsification tests. Worrall should know better.
Marty Cornell
Once again, the term “theory” is used inappropriately. The conjecture is an hypothesis. A theory must have passed falsification tests. Worrall should know better.
If you want to split hairs, from a technical POV I probably should have used the word “conjecture” – but in the context I presented, the meaning should have been clear. The purpose of my post was to illustrate the difference between speculative conjecture and evidence based theory.
–What happens on Venus? Venus has no water! Early in its history Venus may have had water, but it is too close to the Sun to retain it. When water molecules rise high in an atmosphere, ultraviolet radiation split the water molecules into its component gases, oxygen and hydrogen, and the lighter hydrogen molecules escape into space. —
At Earth distance sunlight has about 50 watts per square of UV light, and at Venus distance it should be about 100 watts.
I doubt 100 watts per square meter of UV will split much water.
–While Earth’s lower atmosphere is about one percent water vapor (although it seems much higher in the humid Louisiana summers), the upper atmosphere, where ultraviolet radiation can penetrate, is very dry: a cold trap, a combination of pressure and temperature, prevents water vapor from rising high in the earth’s atmosphere. Venus has a cold trap, too, but because Venus is closer to the Sun its cold trap is much higher in the atmosphere and any Venusian water molecules rise high enough to be broken apart by ultraviolet radiation. ”
The Sun has increased in luminosity not quite 1% every hundred million years. When the luminosity increases to 1.05 current luminosity, in about 500 million years, Earth will suffer a runaway greenhouse effect and wind up as Venus’ identical twin.–
I don’t know the efficiency that UV split water. But it’s easy to get the energy of combining hydrogen with oxygen and getting heat energy:
141.86 megajoules per kg.
http://en.wikipedia.org/wiki/Energy_density
So combine 8 kg of oxygen and 1 kg hydrogen gets 9 kg of water
In terms least possible energy 141.86 divide 9 equals amount energy
to split 1 kg of water. So 15.76 MJ. Or 15.76 million watt seconds.
At 100 watts Of UV per square meter it require 43.77 hours if all energy was used and 100% efficient, to split 1 kg water per one square meter.
Of course there is a large area: 127 trillion square meter. So 127 trillion kg in 43.77 hours.
Earth’s Total mass of hydrosphere: 1.4 x 10*21 kg.
So 1.27 x 10^14 kg water, so 4.8 x 10^8 hours
480 million hours is 54,794.5 years.
So at Venus distance to split Earth amount water require at best 50,000 years and
100,000 years at Earth distance.
Of course if all UV was consumed splitting water, one could not get a sun tan on Earth, and
there would be much more gnashing of teeth about this rather than ocean disappearing in 100,000 years. Or Earthlings could manage to deliver several earth ocean worth water from space in 10,000 year period, people might upset that they have us tanning booths to get a tan on the surface of planet Earth.
Richards in Vancouver 12:53 pm
Sounds reasonable to me.
Eugene WR Gallun
About the flying cars —
Everyone is forgetting that they were also supposed to be atomic powered.
Eugene WR Gallun
OLD DEATH TRAIN HANSON —
ALWAYS GOOD FOR A LAUGH
More holy than thou
He warns you of Venus
The only thing now
That hardens his penis
He rants at the crowds
A coot with the hypers
His mind in the clouds
A load in his diapers
He quotes from the Greens —
We work for the many!
(Diversity means
The colors of money)
He quotes from the Reds —
Consensus is dictum!
(Good Socialist heads
Are all up one rectum)
A Fascist he cries
This Goebbels of weather
The truth is in lies
The bigger the better!
So just like a skunk
His sight is alarming
His science is junk
There’s no global warming
Eugene WR Gallun
Eric Worrall
Theory 3 is likely as earth has been hit by big meteors (5 km diameter) every 20 million years. The last big one was 65 million years ago. The dinosaur-killing meteor.
Theory 2 has no observational evidence but theoretically possible. SETI astronomers believe the aliens are not here but far away.
Theory 1 is almost impossible especially the boiling of the oceans. It has not happened in the last 3.5 billion years. The last time the oceans boiled was when earth was hit by a planet. This is the Big Whack theory that many astronomers believe how the moon was formed.
@-PeterinMD -re:- Venus had ‘oceans’
How do you know it did? Good science says it didn’t until proven it had. Otherwise fairy’s hobbits, etc exist, since you can’t prove they don’t!
The deuterium isotope ratio is the evidence, proof if for liquor and maths not science.
‘The alternative is to believe the preposterous proposition that we are the only intelligent life inhabiting any of the planets circling our galaxy’s 100 billion stars. The reason this must be true – all we have to do is look in the mirror. ‘
And as I peer into my mirror, I wonder where and how much is this vaunted “intelligent life on earth”? 😉
“Dr. Strangelove says:
April 11, 2014 at 12:51 am
Eric Worrall
Theory 3 is likely as earth has been hit by big meteors (5 km diameter) every 20 million years. The last big one was 65 million years ago. The dinosaur-killing meteor.”
The meteor that formed Chesapeake Bay hit only about 35 million years ago. That one wasn’t drastic enough to wipe out 70% of all living species, but such an event WOULD be drastic enough to radically reduce the human population.
Skience – Good post indeed and we certainly have trouble in all our sciences. The trouble with physics for instance is that people don’t know what the trouble really is, like Peter Woit, who wrote a book with that title. Like Global warming a blind approach to Einstein’s special relativity, has incorporated errors into thephysics which is taught in standard texts like MTW. Einstein has admitted it, but typically in a way that almost everyone missed. It is thoughly discussed in EEinstein’s Resolution of the twin clock paradox by C.C. Unnikrisnan at iisc.ernet.in .
Einstein wrote the dialogue in 1918, and was already in the midst of a complete change in his approach. he would even admit there was an ether and a preferred frame.
The movement to make Einstein a god has blinded generations to the problems left behind his theory like the two clock problem and the twin paradox, which blows it out of the water.
Unfortunately the villainous term Jewish Physics was twisted from being the creatures of its inventors, Poincare and Planck, Einstein and the Jews were tagged with it.Sound familiar?
This was before Hitler so this was just the nasty state of Germany at that time. Philip Lenard a Nobel Laureate also from1905, was chief Einstein basher but there were others and they had valid reasons but now the climate of dogmatism and worship of Einstein has created problems that are seriously infecting the field with rot. Even now, like global warmers must, I say that i love Einsteinand am no basher, just a realist!:]
Sorry for the typos. Philip Lenard later became a Nazi and Einstein was forced to emmigrate because of the poisonous atmosphere and danger to his life. If Einstein had given Poincare proper credit for his great contributions, he would not have been so easy to tar with the ‘Jewish physics’ misnomer and epithet.
Since I am in moderation i suppose even more explication is warranted. The reasons Einstein was bashed at a famus physics conference were scientific and not anything else. Einstein was abashed by the united stand of everyone against him and he relented at Leiden. This story should be famous but it isn’t. Physics is so connected with human progress and even continued existence that it is more important than climate sciece which is a mish mash of conflicting ideas and now the battle of grant money being corrupted by the government is also twisting the science. A bad and hopefully a salutary example for everyone in the sciences.