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Error is a constant companion to science. By error I mean any divergence from reality from being outright wrong to being deficient in generality. Classical mechanics is correct insofar as it applies. It turned out to be dead wrong for processes at the atomic and sub-atomic level. But it is perfectly good for building bridges or sending a vehicle to another planet.

For the longest time men of science believed heat was a kind of fluid. It lived between the atoms of stuff and inhabited the pores in materials. It was believe that heat fluid (called Caloric in its day) flowed from where it was to where it wasn't. And this actually corresponds to our own experience. Heat comes from the hot body and moves to the colder body. That is a fact. But a competing theory of heat won out in generality, the notion that heat is average molecular motion or kinetic energy. In a word, heat is a kind of motion. Robert Joule (after whom the unit of energy is named) show that there was a strict equivalence to heat as measured by temperature and mechanical motion. In short heat energy has a kind of equivalence to mechanical (or kinetic) energy.

Sadi Carnot the brilliant French scientist was an exponent of Caloric theory, yet he was able to come up with a correct theory of the operations of a cyclic heat engine and he even formulated a correct statement of the second law of thermodynamics, even though it was based on an erroneous theory of heat.

Maxwell and physicists of his time believed that light was carried through space by some kind of an elastic substance that filled all of space, yet did not impede the motion of bodies. This is the famous luminiferous aether, the light carrying substance. In 1887 Michelson and Morely did an experiment to measure the velocity of a light source with respect to the aether. The outcome was negative and indicated there was no aether. Yet Maxwell's theory accounted for many of the properties of electromagnetic radiation and is still used even today. But we know from the Compton Effect and Photoelectric Effect that light is particles and not waves although it has some wave like behavior.

Which gets us back to AGW. The current IPCC GCMs (global climate models) is based on a mistaken equivalence of atmospheric CO2 with the glass window of a hothouse (or greenhouse). Even so, some of the predictions showing temperature rise can be right although the estimates of how much are off by quite a bit. It turns out there are some very complicated feedbacks and heat circulations in the Earth's atmosphere that are yet to be accounted for correctly. So you see, even a broken clock tells the right time twice a day sometimes.

The basic blunder of the IPCC and its allies is making the entire question of climate dependent on CO2 loading in the atmosphere. There is more to it than that. And the greatest evil effect of their error is the politicizing of the climate question. People who raise questions about the current climate models are regarded very much like heretics in Spain.

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The only thing about the speed of light I can get my scientifically ignorant brain around is light does not exist without that and that gravity can destroy light via a "black hole" and maybe slow it down a little or bend it?. This would mean light and the speed of light are inextricable. Since gravity varies respecting mass it makes sense to call the speed of light "the cosmological constant". For almost completely ignorant speculation (from me), maybe gravity (waves?) is the "aether" through which light "propagates" and there exists a general gravity constant in the universe with relatively minor mass variations respecting local effects?

So, I turn on a light and its light is immediately subject to a gravity suck causing speed of light propagation? Light is a parasitical attribute of gravity? Since gravity is everywhere light goes everywhere--in all and any directions--unless some mass blocks it. Without gravity light could not have the power to travel for billions of years to reach our telescopes. Strike a march. Feel the heat energy. It's dissipating already. Shine a flashlight on your arm. There's no heat to feel. But it's light. How did it get from the battery to your arm? The energy heat from the battery didn't even go that far.

--Brant

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So, I turn on a light and its light is immediately subject to a gravity suck causing speed of light propagation? Light is a parasitical attribute of gravity? Since gravity is everywhere light goes everywhere--in all and any directions--unless some mass blocks it.

Think again. On the surface of Earth, its gravity is only one direction. Light radiates in all directions.

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I wonder what kind of layer humans will leave in the sediment and clay? Personally, I think it will be a deep layer because we have the means to survive as long as the dinosaurs. Perhaps our numbers will increase and eventually lessen as the current population / resources trend indicates, or we will expand to find new resources. The Science channel had an interesting documentary about potential barriers that need to be passed to achieve human expansion into the universe and that is not ego or Anthropomorphism speaking, but it is a rational, scientific analysis. Our biggest barrier is now political and philosophical in nature. We will survive the World Wars, the Nazis, the bomb,and the Islamists. We can envision a troubled but better future in science fiction and science is catching up to the fiction. That Halle Berry show Extant about to continue during the summer is a fine example of alarmist fiction but it also envisions the wonderful possibilities.

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Merlin, the earth's gravity isn't strong enough to do that. Think of a black hole or maybe a gigantic sun. There's a sun out there it would take a million years to fly around at 600 mph. It's best to think of a light source on the moon with no blocking from the mass of the earth's atmosphere. Or from our sun. The sun has tremendous gravity but the sky is filled with night-time star light, but not from any black holes.

--Brant

you cannot take my rant about the physics of light as anything other than maybe something of interest to think about

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A photon can go only the way space is bent. Fortunately the gravitational field of our sun is weak as gravitational fields go so light pretty well travels in straight line. Only light rays (streams of photons) going near our sun are diverted by any observable amount and that is very little. The light ray the Edditingon saw of diverted only by 0.175 arc seconds. It took fancy equipment to detect that.

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So, I turn on a light and its light is immediately subject to a gravity suck causing speed of light propagation? Light is a parasitical attribute of gravity? Since gravity is everywhere light goes everywhere--in all and any directions--unless some mass blocks it.

This subject is so very tricky, Brant. For my own understanding of these particulars, I steep my thoughts in the notion that light (or the entire electromagnetic spectrum of radiation) is a form of energy, not matter as we understand it. Consider a photon: what is a photon? How does it behave?

As I understand it, a photon is a 'quantum' of energy -- it is an elementary 'particle' that has no mass, and is a force carrier.

But how can a massless 'packet' of energy be effected by gravity?

The simplest explanation that I can grok is that gravity has effects on energy in the concept of space-time. A photon travels at a constant speed (in a vacuum) and in a straight direction -- but the fabric of space-time 'bends' the light wave/particles from our earthly perspective. A 'gravitational lens' is said to operate -- 'bending' light -- when hugely massive objects 'curve' space-time. By hugely massive I mean stars ...

So, in this sense, light in a vacuum propagates in a straight line ... from the perspective of the photon itself, subject to gravity.

I searched and searched for a very simple explanation of this, and here is what I found -- it might help you as it helped me to grok:

In general relativity, gravity effects anything with energy. While light doesn't have rest-mass, it still has energy---and is thus effected by gravity.

When you think about how gravity affects light you really need to think in terms of general relativity, which describes gravity as the effect of a curved space-time on moving particles. Summarized by John Wheeler, mass tells space how to curve and space-time tells mass how to move.

Now that I have had a long gander at the Wikipedia entry on the Photon, I realize I may have got everything bass-ackwards ...

Without gravity light could not have the power to travel for billions of years to reach our telescopes. Strike a march. Feel the heat energy. It's dissipating already. Shine a flashlight on your arm. There's no heat to feel. But it's light. How did it get from the battery to your arm? The energy heat from the battery didn't even go that far.

The heat energy from a match is just one part of the electromagnetic spectrum. That can be absorbed (by molecules in the air or molecules of a hand, arm) and it can be re-emitted given the right molecular conditions.

The part of the electromagnetic spectrum that is visible light is not a vector of heat. The modern flashlight emits a greater proportion of photons with a differing wavelength to the 'heat' or infrared portion of the spectrum.

Here's a table that sorts out the wavelengths, from the refuge of scoundrels, Wikipedia.

infrared.png

-- and a final bit of quotation from the same article, which explains the energetic spectrum of sunlight:

Sunlight, at an effective temperature of 5,780 kelvins, is composed of nearly thermal-spectrum radiation that is slightly more than half infrared. At zenith, sunlight provides an irradiance of just over 1 kilowatt per square meter at sea level. Of this energy, 527 watts is infrared radiation, 445 watts is visible light, and 32 watts is ultraviolet radiation.

On the surface of Earth, at far lower temperatures than the surface of the Sun, almost all thermal radiation consists of infrared in various wavelengths. Of these natural thermal radiation processes only lightning and natural fires are hot enough to produce much visible energy, and fires produce far more infrared than visible-light energy.

Back to the heatwave I go.

Edited by william.scherk
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But how can a massless 'packet' of energy be effected by gravity?

Answer: Spacetime is bent by a gravitating body. The photon takes the short route through a curved space. Predicted by Einstein in 1915, experimentally corroborated by Eddington in 1919.

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But how can a massless 'packet' of energy be effected by gravity?

Answer: Spacetime is bent by a gravitating body. The photon takes the short route through a curved space. Predicted by Einstein in 1915, experimentally corroborated by Eddington in 1919.

Spacetime is epistemological. Gravity is metaphysical. There is nothing qua spacetime for gravity to bend. Space is actually distance and time is a measure of motion. I'd guess Einstein was speaking in shorthand. It's light that's bent in your example. As for gravity, we only know it by its effects. Scientists are trying to find its "waves."

--Brant

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But how can a massless 'packet' of energy be effected by gravity?

Answer: Spacetime is bent by a gravitating body. The photon takes the short route through a curved space. Predicted by Einstein in 1915, experimentally corroborated by Eddington in 1919.

Spacetime is epistemological. Gravity is metaphysical. There is nothing qua spacetime for gravity to bend. Space is actually distance and time is a measure of motion. I'd guess Einstein was speaking in shorthand. It's light that's bent in your example. As for gravity, we only know it by its effects. Scientists are trying to find its "waves."

--Brant

Then explain the gravitational lens effect predicted by General Relativity and observed thousands of times since. Every time your GPS gives you your correct location General Relativity is corroborated yet again.

As physicist Edwin Wheeler once said: Mass tells space how to bend and space tells mass how to move.

Philosophical babble gab has no place in physics.

ba'al chatzaf

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But how can a massless 'packet' of energy be effected by gravity?

Answer: Spacetime is bent by a gravitating body. The photon takes the short route through a curved space. Predicted by Einstein in 1915, experimentally corroborated by Eddington in 1919.

Spacetime is epistemological. Gravity is metaphysical. There is nothing qua spacetime for gravity to bend. Space is actually distance and time is a measure of motion. I'd guess Einstein was speaking in shorthand. It's light that's bent in your example. As for gravity, we only know it by its effects. Scientists are trying to find its "waves."

--Brant

Then explain the gravitational lens effect predicted by General Relativity and observed thousands of times since. Every time your GPS gives you your correct location General Relativity is corroborated yet again.

As physicist Edwin Wheeler once said: Mass tells space how to bend and space tells mass how to move.

Philosophical babble gab has no place in physics.

ba'al chatzaf

You're the one doing the philosophical babble gab: spacetime has no substance--it's just an idea--gravity does. Gravity bends light. That's what was demonstrated. "Spacetime" is philosophy. Einstein was both a scientist and a philosopher. You too--I suppose about the "scientist"--there's no denying your continual use of philosophy or you wouldn't post anything on a non-scientific forum. What you are now saying is take away "spacetime" and his Relativity theory is invalidated even though gravity bends light? I would bet, and maybe I'm wrong, Einstein used "spacetime" for laymen as myself to make his ideas somewhat understandable to them--and you? Why? No math required? I'm not saying his Relativity is all philosophy, but perhaps it is. Maybe it's just a temporary explanation that works so far and there's a more classical explanation--or more esoteric one. If you want to talk about science instead of merely relating your own ideas about physics, go to forums where there are scientists doing that. You cannot convince me of anything in this area for I'm far too ignorant except to take it on faith, something I do not do.

--Brant

Petr Beckmann would plow you under the same way you try to do to me, and Petr Beckmann might be wrong and you right but he would tie you up in knots and leave you gasping--I avoid that by sticking to philosophy and avoiding philosophical scientific pretensionism and all I've really said is spacetime is only an idea (two, actually) for it has absolutely no substance and no power therefore to affect anything, but I accept that gravity can bend light (gravity is a thing and light is a thing) and will accept spacetime as a thing as soon as it's measured, weighed or what have you, and shown to act on something besides itself as proof of its existence such as gravity acting on someone who jumps up in the air (Could gravity be part of spacetime thus supporting your proposition? It would have to be more than gravity or why call it anything but gravity? Space is a measure of distance and time is a measure of motion so you'd have to expand the concept in more than one way, but gravity would be a start.)

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But how can a massless 'packet' of energy be effected by gravity?

Answer: Spacetime is bent by a gravitating body. The photon takes the short route through a curved space. Predicted by Einstein in 1915, experimentally corroborated by Eddington in 1919.

Spacetime is epistemological. Gravity is metaphysical. There is nothing qua spacetime for gravity to bend. Space is actually distance and time is a measure of motion. I'd guess Einstein was speaking in shorthand. It's light that's bent in your example. As for gravity, we only know it by its effects. Scientists are trying to find its "waves."

--Brant

Then explain the gravitational lens effect predicted by General Relativity and observed thousands of times since. Every time your GPS gives you your correct location General Relativity is corroborated yet again.

As physicist Edwin Wheeler once said: Mass tells space how to bend and space tells mass how to move.

Philosophical babble gab has no place in physics.

ba'al chatzaf

You're the one doing the philosophical babble gab: spacetime has no substance--it's just an idea--gravity does. Gravity bends light. That's what was demonstrated. "Spacetime" is philosophy. Einstein was both a scientist and a philosopher. You too--I suppose about the "scientist"--there's no denying your continual use of philosophy or you wouldn't post anything on a non-scientific forum. What you are now saying is take away "spacetime" and his Relativity theory is invalidated even though gravity bends light? I would bet, and maybe I'm wrong, Einstein used "spacetime" for laymen as myself to make his ideas somewhat understandable to them--and you? Why? No math required? I'm not saying his Relativity is all philosophy, but perhaps it is. Maybe it's just a temporary explanation that works so far and there's a more classical explanation--or more esoteric one. If you want to talk about science instead of merely relating your own ideas about physics, go to forums where there are scientists doing that. You cannot convince me of anything in this area for I'm far too ignorant except to take it on faith, something I do not do.

--Brant

Petr Beckmann would plow you under the same way you try to do to me, and Petr Beckmann might be wrong and you right but he would tie you up in knots and leave you gasping--I avoid that by sticking to philosophy and avoiding philosophical scientific pretensionism and all I've really said is spacetime is only an idea (two, actually) for it has absolutely no substance and no power therefore to affect anything, but I accept that gravity can bend light (gravity is a thing and light is a thing) and will accept spacetime as a thing as soon as it's measured, weighed or what have you, and shown to act on something besides itself as proof of its existence such as gravity acting on someone who jumps up in the air (Could gravity be part of spacetime thus supporting your proposition? It would have to be more than gravity or why call it anything but gravity? Space is a measure of distance and time is a measure of motion so you'd have to expand the concept in more than one way, but gravity would be a start.)

Gravitation Lenses Light. A demonstrated fact. Beckmann was a semi-crackpot. Realtivity theory both special and general is about as solid as scientific theories get.

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