UPDATE May 2021. I've boiled this all down to a simple explanation based on common sense, basic maths and a rudimentary knowledge of the Gas Laws.
Please read my post Acceleration ≈ Gravity
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It appears that I have wasted all week trying to explain this effect, which seems blindingly obvious to me as it fits in with everything else we know about anything and I'm pretty sure that our physics teacher mentioned it once in passing:
Earth surface temperature (as well as the surface temperatures of 5 other rocky planets in our solar system) can be very accurately determined solely on the basis of two variables:
1. atmospheric pressure at the surface, and
2. solar irradiance at the top of the atmosphere.
For sure, it is only a starting point and you will probably have to make lots of other little up and- downward adjustments, but having Googled around, as per usual anything which offers an alternative/complementary/non-GHG induced explanation for why surface temperatures are what they are gets mired in purely political controversy and nit picking.
As PaulC points out, the paper linked to was withdrawn (yes I knew that), but an idea is not responsible for the people who hold it (pace Bayard). It is even hotly debated whether luminaries such as Maxwell and Feynman supported or rejected the idea, that's how mad it is.
I don't see how hard it can be to do all the measurements of a few different planets with differing atmospheres (I'm not sure why we should restrict it to rocky planets) and settle the matter one way or another to everybody's satisfaction, but hey...
Put On Your Big Boy Pants, Maybe?
3 hours ago
25 comments:
That paper you've linked to has been withdrawn. Den Volokin and Lark ReLlez are 'claimed' to be the authors. Ned Nikolov and Karl Zeller are the real names of the authors. Yes that's Den Volokin and Lark ReLlez spelled backwards. You couldn't make it up really...
You don't need a paper like that to prove the the CAGW theory is simply that, a theory and that there are plenty of other explanations for the same effect.
This discussion kicked off with a paper which suggested that the nitrogen and the oxygen in the atmosphere had absolutely no effect in keeping us warm and that all the work was being done by CO2 and H20, (despite the fact that there is more than 26 times the amount of H2O in the atmosphere than there is CO2, and 24 times the amount of Argon, but hey, CO2 has to be in there for religious reasons, you can't prove man's to blame if you concentrate on H2O)
I didn't read the post carefully, so thought that it was the standard AGW argument and so I made the point that most of the work is done by H2O. However, when Mark put me right, and I read the post again it was quite obvious that an atmosphere containing only N and O2 would not result in the same surface temperature as no atmosphere at all.
Posts on the subject then started down the long road of invoking the gas laws where they didn't apply, ignoring the laws of thermodynamics altogether and confusing changing with steady states and radiation with other forms of heat transfer.
It seems perfectly possible that the Earth's surface is warmer to an it would be if there was no atmosphere because the sun warms the surface and the surface warms the air by conduction and convection and this warming effect continues out to the edge of the atmosphere, where there is no more air to warm. As you get further from the heat source, the surface, so the temperature drops. This effect is noticeable wherever you have a heat source and air. So that accounts for the cooler/higher and warmer/lower effect.
It is an undisputed fact, even by climate "scientists", that the Earth has an atmosphere due to gravitational attraction. This attractive force falls off in proportion with the square of the distance from the earth, therefore one would expect the amount of air retained and hence its concentration also to reduce as you get further from the Earth. So that accounts for the thinner/higher and denser/lower effect.
The global warmmongers are concerned with the energy balance of the Earth, which is due to radiation, so is completely separate to the phenomena described above. I am quite prepared to believe that if there was no H2O in the atmosphere, it would be a bit colder down here on the surface, but only by a few degrees. However the rest of their religious tenets I am not prepared to believe. In order to do so I would have to believe the following:
The global temperature is constantly rising (although there is plenty of evidence that it is not).
The rising temperature is solely caused by an increase in CO2 in the atmosphere (despite the acknowleged effect of the 26 times more concentrated H2O vapour and the evidence for an increase of energy input from the sun).
The rising levels of CO2 in the atmosphere are solely caused by burning fossil fuels (ignoring the possibility that it could be the other way round, that CO2 concentration follows atmospheric temperature).
That "the science is settled" and anyone who questions these beliefs is a heretic, sorry a "denier" and must be put to the extraordinary question, sorry, must be in the pay of the oil companies.
So you can see that you only have not to believe in one of those things and the chain of reasoning that leads from evil rich oil company shareholders to catastrophic global warming is broken, with the result that it cannot now be proved that you, too, can save the world and that there may be nothing we can do about it, even if there is anything to do anything about (apart from not wasting a valuable resource moving things around the planet, but that is quite a separate matter).
"You don't need a paper like that to prove the the CAGW theory is simply that, a theory and that there are plenty of other explanations for the same effect" B
1. I agree. AGW is a theory.
2. So is evolution ...and what was it...Newton's theory of gravity.
3. Other 'explanations for the same effect' don't work as well. That's always a problem for those alternatives. They have to run the gauntlet of peer review,verification etc.
I agree though that when the data arrives which supports the theory that increases in cloud cover/water vapour unrelated to increases in co2 (who knows what it is related to?) are responsible for increases in surface temps since the 20thC then it could become an accepted theory rather than one of a long line of popular ideas found on the internet.
PC, I knew it had been withdrawn but I didn't know why. Thanks - but who are Ned Nikolov and Karl Zeller? Famous or infamous for something?
B: it is hard to disagree with your oft repeated explanation on a folksy level if we are just explaining things on Earth to an interested child:
"It seems perfectly possible that the Earth's surface is warmer to an it would be if there was no atmosphere because the sun warms the surface and the surface warms the air by conduction and convection and this warming effect continues out to the edge of the atmosphere, where there is no more air to warm.
"As you get further from the heat source, the surface, so the temperature drops. This effect is noticeable wherever you have a heat source and air. So that accounts for the cooler/higher and warmer/lower effect"
However the gravito-thermal effect is quite a different concept, independent of your theory and independent of any AGW theory.
Like I keep saying,
a) look at the gas giants. Clearly there is very little warming from the sun that far out in the solar system - so why is the "bottom" of their atmosphere i.e. the centre of the planet so incredibly hot? This cannot be explained with your theory. Venus is a less extreme example of this.
b) look at the fact that the bottom of Earth's atmosphere 33C warmer than it would be from sunlight alone (-15C), your explanation would suggest that the pressure of the atmosphere itself has no effect on surface temperatures - a blanker can only keep in the heat that was there in the first place - so the bottom of the atmosphere should only be -15C.
c) look also at the fact that the 'top' of the Earth's atmosphere (as arbitrarily defined) is approx. 33C colder than it should be. Your explanation doesn't cover this either.
The gravity-thermal theory covers all these things very nicely indeed. Hence and why it seems most plausible to me, the laws of physics are the same everywhere. We don't drag politics into explaining conditions on Jupiter or Saturn. How much difference H2O and CO2 on Earth make is a separate topic - "not much" is the obvious answer, but it might still be a couple of degrees C, what do i know?
B. That comment you made regards 'increased energy input from the sun'. At what point do you give up on an argument or 'theory'? I only ask because the idea that the Sun might be responsible for warming these last few decades has been all but ruled out. Numerous studies done with highly accurate measuring instruments show a sun which is slightly cooling since the 70's. What to do when the data won't conform to expectations is not exclusively a problem for AGW proponents.
MW. Those guys worked for the US dept of agriculture apparently. One was/is a meteorologist. It made the broadsheets in America in recent days/weeks.
However the gravito-thermal effect is quite a different concept, independent of your theory and independent of any AGW theory.
Unfortunately it is simply a misunderstanding of some basic laws of physics. Of course it fits, you made it fit by disregarding all the bits where it didn't fit. You've disregarded the fact that you are treating a steady state system as if it were a changing state system, you've disregarded the laws of thermodynamics and you have brought up examples to support your theory that have completely different explanations e.g.
"look at the gas giants. Clearly there is very little warming from the sun that far out in the solar system - so why is the "bottom" of their atmosphere i.e. the centre of the planet so incredibly hot? This cannot be explained with your theory. Venus is a less extreme example of this."
From here http://education.seattlepi.com/planetary-cores-assumed-very-hot-6949.html we find:
"Planets and stars both form out of nebulas, collapsing clouds of gas and dust. The various processes that result in a planet’s formation create heat that slowly dissipates from the planetary core, which creates a molten, fluid interior that cools into an exterior crust."
and
"Smaller planets, such as Earth, cool more quickly than larger planets like Jupiter. This process creates the solid crust that allows for terrestrial growth."
and
"Most of the heat in a planet’s core is left over from the early period of the planet’s formation. Gravity in a planetary nebula draws material to the center, where it collides, accretes, and draws more material toward itself. As the density of this central mass grows, it generates heat that only begins to dissipate once the planet finishes its formative processes. Residual heat dissipates slowly over time, through both convection and conduction. "
So the gas giants do not prove your theory.
"look at the fact that the bottom of Earth's atmosphere 33C warmer than it would be from sunlight alone (-15C), your explanation would suggest that the pressure of the atmosphere itself has no effect on surface temperatures"
Well yes, because, in a static state, the pressure has no effect on the temperature. I keep saying this but I'll say it once more and give up - Gay-Lussac's Law only applies to a change in state. The only thing that changes from the top of the atmosphere to the bottom is the position of the observer.
"a blanker can only keep in the heat that was there in the first place - so the bottom of the atmosphere should only be -15C."
Complete straw man: the surface of the earth is heated by infra red radiation which can pass through the atmosphere, which is not a blanket.
"look also at the fact that the 'top' of the Earth's atmosphere (as arbitrarily defined) is approx. 33C colder than it should be. Your explanation doesn't cover this either. "
Well, it's kind of difficult to disprove that anything which is arbitrarily defined is different from how it "should" be, but your theory would postulate a straight line graph of temperature versus distance from the surface, but in fact it is anything but: https://en.wikipedia.org/wiki/Atmosphere_of_Earth#/media/File:Comparison_US_standard_atmosphere_1962.svg
"The gravity-thermal theory covers all these things very nicely indeed."
I think I've just demonstrated that it doesn't
"Hence and why it seems most plausible to me, the laws of physics are the same everywhere"
Not disputing that for one second.
"We don't drag politics into explaining conditions on Jupiter or Saturn."
No we don't. At least I haven't and you haven't.
"So is evolution ...and what was it...Newton's theory of gravity."
Not everyone is convinced by the theory of evolution (and I don't just mean those creationist idiots) and no-one is using the theory of gravity as the basis for a crusade. That's the thing about CAGW - every link in the chain has to stand up, because its the ends of the chain that matter, the link between the evil oil companies at one end and the collapse of civilisation at the other is the important bit. All the papers, all the theories, all the research is being done to support that chain, to preserve that link. That's why these people aren't scientists, they are constantly setting out to add more proof to the theory, to make the chain thicker and stronger. That's not what scientists do. Scientist set out to disprove the theory. The science is never settled, because if a scientist doesn't succeed in disproving the theory, they have another go and another go and so on until they do succeed. Then it's time for a new theory, like Einstein came up with after he's tested Newton's theory of gravitation to destruction. With climate "scientists" it's not like that, it's "here's another computer model I've put some data into and hey, it proves the theory of CAGW. Now can I have another grant, please?"
Anyhow this whole thing has become so politicised and there is so much money at stake on both sides (Big Oil and Big Green) that it is impossible to trust anything you read anywhere. So what it boils down to is what you believe, just like any other religion.
B. It's all a conspiracy then...
I noticed you ignored the question I posed above. Namely, at what point would you abandon the claim you made that H2o in the atmosphere (increased by what you don't state) and increased "energy output from the sun" (possibly the source for your claim about h2o?). Seeing as all the data gathered in recent years clearly indicates a slightly cooling trend in the sun over the last several decades. You can't berate scientists even whilst ignoring data which confines that particular line of enquiry into the metaphorical bin!
I did also notice a lack of any response yesterday on the other thread when I pointed out the error in this comment by yourself: "Gravity is more or less the same as acceleration."MW
"No it isn't. Gravity is a force, measured in Newtons. "
Einstein made plain the equivalence of acceleration and gravity in his general theory. It's widely regarded as his greatest insight. That gravity is not even a real force but a consequence of a distortion in space-time caused by mass. Gravity thus follows from a change in the geometry of space (curvature). Newton's G is just a very good approximation.
B, the facts fit the GTGE theory quite neatly and the explanation is easy to understand on an instinctive level, the same as gravity being at the same speed as light, or light bending round massive objects etc.
But i accept that far greater minds than ours have debated the matter and not come to a conclusion one way or another so I can see why a lot of people don't think the explanation is correct. It's not like I'm that bothered actually.
"It's all a conspiracy then..."
Only to the extent that any postulates that counter CAGW are a conspiracy by the evil oil companies, otherwise no. Unless you consider all religions to be conspiracies.
"I noticed you ignored the question I posed above. Namely, at what point would you abandon the claim you made that H2o in the atmosphere"
does what?
I noticed you avoided my point about whether increased CO2 causes the atmosphere to warm or whether the warming atmosphere causes an increase in CO2 and how do we tell the difference?
"(increased by what you don't state)"
Well, of course not, I never said it was increasing in the first place. However, it is an undisputed fact that warmer air holds more water than cooler air.
"and increased "energy output from the sun" (possibly the source for your claim about h2o?). Seeing as all the data gathered in recent years clearly indicates a slightly cooling trend in the sun over the last several decades."
There appears to be a lot of evidence that the Earth has not been heating up for at least two decades, so that depends on what you mean by "several".
"I did also notice a lack of any response yesterday on the other thread when I pointed out the error in this comment by yourself: "Gravity is more or less the same as acceleration."MW
"No it isn't. Gravity is a force, measured in Newtons. "
I'd given up with that thread, because the same old arguments were being trotted forth on this one.
However, are you seriously disputing either that gravity is a force or that it is measured in Newtons? How can gravity be an acceleration when objects experience the force of gravity without accelerating? How fast are you accelerating as you read this? If you are not accelerating, why then are you not floating around near the ceiling?
Sure, acceleration provides a force the same as gravity to an object, but that doesn't mean a force always provides an acceleration. Things can experience a force and not move. Regardless of what you think Einstein said about gravity, are you seriously trying to claim that the force that acts on static objects is different to that which acts on moving ones?
"the facts fit the GTGE theory quite neatly and the explanation is easy to understand on an instinctive level"
Yes , but the facts fit the theory of CAGW quite neatly, too and the explanation is easy to understand on an instinctive level, which is why so many people believe it to be "the truth". It all depends on which facts you use (and so long as you don't drag in gas giants).
B: "the facts fit the theory of CAGW quite neatly, too and the explanation is easy to understand on an instinctive level"
The second assertion is quite correct, we are always told that GHG act a bit like a blanket, the glass in a greenhouse or a one-way mirror etc, that allows UV in but traps half the IR trying to get out. All these are just folksy analogies - which we can easily 'understand' or accept as plausible.
(Although on a micro-level, the explanations seem a bit thin to me, but never mind. The next argument is does the impact of increasing CO2 lead to ever smaller increases in temperature or ever larger ones aka 'runaway climate change'? I suspect the former, but who knows?)
The first part is clearly untrue. Does mankind emit more CO2 than otherwise? Almost certainly yes. Have CO2 levels increased over the past 200 years? Also almost certainly yes.
So far so good but that is not the point.
These clever people who do the really long term charts comparing CO2 levels and average temperature going back millions of years show that there is little or no correlation between the two, and that if anything, rising temperatures seem to precede higher CO2 levels rather than the other way round.
"and that if anything, rising temperatures seem to precede higher CO2 levels rather than the other way round."
Heresy!
B, it's not heresy, that's what the charts say, also that CO2 levels have been two or three times as high in the past without 'runaway climate change'. if they showed a relationship as predicted, then I'd take it at face value.
I assume for these purposes that the charts are reasonably correct and accurate, they might well turn out to be nonsense.
B. You have posited increased energy output from the Sun. Since 1978(since when the most accurate measurements have been made)the Sun has cooled slightly and has clearly demonstrated a downward trend in temperature.
In the same period global surface temps have risen. Or do you insist the sun has warmed in the last few decades and the surface temps have gone down or remained static for the last 35 plus years?
As for gravity. It's no more than a useful accounting exercise to think of gravity as a force and utilise Newtons equations.
They are no more than a very good approximation of reality. Relativity is not the final word but supersedes Newtons theory of gravity. So no it is not a force.
When a body experiences what you insist is a force due to another nearby massive body it merely travels along a curvature in space (space-time really). No force involved. As opposed to real forces...like electro magnetic.
Einstein states that acceleration and gravity are equivalent. He even wished he had called his theory by that name. You might not like it, but relativity beats Newtons theory of gravity hands down. It has been verified to extraordinary degrees. So if you don't quite get it (and relativity is counterintuitive writ large so no reason why you should) there are dozens of good explanations online.
MW. As with most things even if "rising temperatures seem to precede higher CO2 levels rather than the other way round" and this is not always and everywhere the case, it can be interpreted entirely differently depending on your inclination!
The increased warming periods in the last million years or so are believed to be precpitated by the milankovitch cycles not increases in co2 out of nowhere. So some slight warming occurs which initially causes the release of co2 from the oceans so which itself the acts as a positive feedback on temperature facilitating further rises.Albedo micks in with other factors (less blue green algae more water vapour etc) until another change instituted by milankovitch cycles sends the whole process into reverse. Co2 lags and leads but it is not claimed to be the starting gun for global warming. So the lagging argument is a good example of a straw man argument. At least, that's what those naughty conspirators over at the IPCC have explained.
"You have posited increased energy output from the Sun. Since 1978(since when the most accurate measurements have been made)the Sun has cooled slightly and has clearly demonstrated a downward trend in temperature.
In the same period global surface temps have risen."
OK fair enough, I'm quite prepared to believe that the sun has cooled since 1978, but AGW is supposed to have been going on since the Industrial Revolution or thereabouts, not just since the late seventies. Given that the Earth has not got any warmer since 1999, tha is only twenty years where the sun has been cooling slightly and the Earth warming, which, in the sort of timescales we are talking about is a blink of the eye.
"They are no more than a very good approximation of reality. Relativity is not the final word but supersedes Newtons theory of gravity. So no it is not a force."
So it behaves exactly like a force, in that it causes an unconstrained mass to accelerate according to the equation Force = mass x acceleration, but somehow it is not the same as an electromagnetic force that has exactly the same effect. You still haven't explained how, if it is an acceleration, it applies to static bodies. Or is it some special type of acceleration that doesn't move?
Einstein's theory of relativity may explain the "why it works" of gravity, but Newton's laws explain the "how it works", and for all practical purposes, the "how it works" theory is the useful one. You don't have to understand the Carnot cycle to be able to drive a car.
"The increased warming periods in the last million years or so are believed to be precpitated by the milankovitch cycles"
How certain are you that this current warming period isn't caused by the same effects?
B. Not in any particular order.
Milankovitch. Not certain. As in most things. However it seems that the cycle has been pointing downwards so we should have been cooling for some time not warming at all.
Force and G. How is there a force? By what means? You say Newton provides the how but he didn't have clue. He said it himself. The notion was "absurd". He knew not 'how'. He said it was for others to figure out the great mystery of his instantaneous action at a distance, explicit in his 'force' equations. Einstein did it 250 years later.
In a moment he described as 'the happiest moment of his life' he understood that gravity and acceleration are equivalent and indistinguishable. The astronaut feels no force as he sits in his spaceship above planet earth. He just slides down the space-time well.
Warming and the Sun.
1. There has been warming since 1998 even if at a slower rate. And you are both offering up solar radiance as a cause of GW even whilst denying there is GW. Not really playing with a straight bat. ;)
2. No AGW friendly model posits constant warming as a result of increases in co2.
Every model I am aware of at least attempts to allow for a plethora of mitigating factors. eg. Ocean currents and yes even sunspot activity etc...
And when you speak of surface temps since 98 is it correct or forboten to refer to deep or shallow ocean temps...where 97% of the heat ends up? We have some good data on ocean temps but you might argue it's besides the point. I would disagree.
"Force and G. How is there a force?"
What's stopping you floating up to the ceiling with your computer as you read this?
"By what means?"
As you correctly point out, Newton admitted he had no idea why gravity did what it did, he was just describing how it did what it did, i.e. he pointed out that the apple fell to the ground and described how the apple fell to the ground. Einstein produced a theory of why the apple fell to the ground.
"He knew not 'how'".
You (deliberately?) misunderstand me. "How" here does not mean "by what cause" but "in what manner". That's why I contrasted it with "why". Surely that was obvious.
"In a moment he described as 'the happiest moment of his life' he understood that gravity and acceleration are equivalent and indistinguishable. The astronaut feels no force as he sits in his spaceship above planet earth."
I've already covered this point, but you are ignoring it. I think you are misunderstanding Einstein for your own ends. To anyone who knows anything of mechanics or structures it is obvious that gravity is a force. Perhaps you would like to present a talk to the Institute of Civil Engineers and tell them everything they've learnt in their careers about gravity is wrong, because Einstein is supposed to have said so.
"And you are both offering up solar radiance as a cause of GW even whilst denying there is GW."
At what point have I ever denied there is global warming? Yes, going by some data (but not by others, which can you trust?) there has been no warming since the millennium, but |I'm quite happy to beieve that before that things were hotting up quite nicely. However, what I am sceptical about is what is causing that warming. So GW, yes, but AGW, no, not convinced and CAGW, no, scaremongering.
So you accept there is global warming (lets set aside you erroneously state there has been none for 18yrs)and posited the likely cause as increased H2o in atmosphere AND increased energy output from the sun.
You seem during this thread to have accepted that there has in fact been a reduction in energy output from the sun so removing one of your pillars for an alternative to AGW leaving just H2O alone as a cause of warming. Quite a bare bones proposal when you don't have any explanation for your increased H2O even though increased CO2 offers just such an explanation seeing as it's increase allows for an increase in atmospheric water vapour.
Careful...you might unintentionally end up as an AGWarmer!
Re your difficulty accepting what every first year physics student accepts; namely that gravity is not a real force ( though it generally works well enough to consider it as such) think of another force which is not really a force. ie: centrifugal force. You feel it when accelerating in a circular path but there is no actual such force.
Ditto G. It is convenient and fine as well as useful for engineers to consider G as a force and utilise Newtons equations in doing so. However since they are unconcerned with either very high gravitational fields or high velocities they can afford to. That's why Newtons equations couldn't make sense of Mercurys orbit around the Sun nor of why your own sat nav system in your car would be utterly useless if they had to rely on Newtons equations. Einstein's relativistic version of the same cope perfectly well with both Msrcury's orbit and our satellite navigation...because the former is a very good approximation but the latter is correct and describes reality not merely an approximation of the same.
You don't feel a force sat in your armchair.
Rather you feel the pressure of the armchair pressing onto your posterior.
And for the same reason you don't feel a force from the sun. We travel in a geodisic. A straight line in curved space time. That's both 'how' AND 'why' we don't float to the ceiling or remain seated in our armchair...not any useful fiction like a force of gravity.
P.S. What "I say Einstein said". Would it make any difference if I gave you verbatim quotes from Einstein? Or are you just determined that Einstein really believed gravity was a force despite his Magnus opus, GR and numerous statements to the contrary.
This taken from a website titled. Relativity for engineer.
"Einstein later worked out how the force of gravity is NOT QUITE A FORCE, but rather an artifact of the natural movement of objects through curved four-dimensional spacetime".
"(lets set aside you erroneously state there has been none for 18yrs)"
Unless you are able to access primary sources, your source for information on climate change is the same as mine: the internet. I have seen websites that state categorically that there has been no warming since the millennium and ones that state categorically that there has been. They can't both be right. Despite what the AGW propagandists put out, not everyone who is sceptical about AGW is in the pay of the oil companies; it is very unlikely that thousands of ordinary Joes and Joannas are somehow being paid to post false info
on the 'net. However, on the other side, the global warmmongers, there are thousands of people who truly believe that we are going to hell in a handcart and that it is all down to the profligate burning of fossil fuels. Whilst there is an obvious logistical problem in the oil companies dishing out the cash to fund the deniers, no such limits apply to the warmmongers because all they have to spread about is an idea, and a very seductive on it is too.
In any case, you haven't answered my point about the cooling only being recorded since 1978.
"leaving just H2O alone as a cause of warming."
Not at all. I said that I thought that H2O was doing all the heavy lifting as far as the greenhouse effect was concerned, not that it was responsible for any global warming. That presupposes that I believe the warming is caused by the greenhouse effect, which I don't. Before you ask me what I think is causing it, the answer is I haven't a clue, although the Milankovitch cycles seem a likely candidate, given that's what's always done it in the past.
"Re your difficulty accepting what every first year physics student accepts; namely that gravity is not a real force"
First year of what? I did physics "A" level and I was never taught that. I did an engineering degree and wasn't taught that either, however I'm quite prepared to believe they didn't trust us engineers with such advanced ideas. To what level did you study physics, may I ask?
"You don't feel a force sat in your armchair.
Rather you feel the pressure of the armchair pressing onto your posterior."
Well, if you had done enough science to get as far as SI units, you would know that the unit of pressure is the Pascal, which is defined as one Newton per square metre and the Newton is the unit of, guess what? force. So you can tell the General Conference on Weights and Measures that they've got it all wrong after you've finished telling the ICE.
"Would it make any difference if I gave you verbatim quotes from Einstein? Or are you just determined that Einstein really believed gravity was a force despite his Magnus opus, GR and numerous statements to the contrary."
No, it wouldn't and no I am not challenging Einstein. I am challenging your grasp of physics. As Mark has so amply demonstrated, it is very easy to read some laws and theories and get totally the wrong end of the stick. I am not going to argue with you further about this because you appear to be convinced you are right, no matter what I say.
"Milankovitch cycles seem a likely candidate, given that's what's always done it in the past."
Where did you get that from. As far as I am aware those cycles are merely exogenous factors which by themselves can't have caused the magnitude of temperature changes recorded. The claim is only that the cycles are what tips the ice ages into interglacials and vice versa. Still you obviously haven't given it all that much attention.
1st year physics meant first year undergraduate not A level. I am currently doing a post graduate in physics at the OU.
My son has a degree (first from Leeds)in civil engineering and he tells me they simply don't touch relativistic physics so you would hardly expect to be familiar with it unless you had some interest...which until this blog you obviously didn't. I mean, only last week you were describing gravity (and it was Newtons gravity not Einsteins) as inversely proportional to the cube of the distance between masses when even an A level student would know you were trying to describe the inverse 'SQUARE' law. So please show a bit of humility before questioning other peoples physics credentials.
As I already pointed out, force equations ala Newton work extremely well but not as well as Einsteins equations with their relativistic adjustments. Engineers that build bridges don't need them but those programming satellite navigation do because an approximation doesn't come close to being acceptable where realistic results are required ie; where gravity and speed are significant factors...as in sat nav systems.
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