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jschell wrote: Radio waves, TV and light all can leave earth.
Radio doesn't, whereas TV waves do. AM/FM radio does not leave earth, but TV broadcasts do. Hence, the remark that the first an alien notices from our broadcasts, is a speech from Hitler.
jschell wrote: In an absolute vacuum all travel at the speed of light.
Nope. If that was true, all mass from a supernova would reach us as the same speed. We can see the light, but we do not get the gold created in that nova.
jschell wrote: All of them can behave like a wave or particle.
Again, no; only some "idiot" subatomic particles do. No proton ever pretends to be a wave?
Bastard Programmer from Hell 
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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Eddy Vluggen wrote: Radio doesn't, whereas TV waves do
Your definition is weak.
How do you think Nasa communicated with Apollo astronauts? Would you categorize that as "TV"?
As an example although an FM radio transmission tends to bounce on the atmosphere it can escape.
Eddy Vluggen wrote: Nope. If that was true, all mass from a supernova would reach us as the same speed.
"mass" is not electromagnetic. A supernova emits all kinds of things that are not electromagnetic.
Second space is not an absolute vacuum. As I said it is not possible, not anywhere, to have a absolute vacuum. Actual outer space is full of all sorts of stuff which impacts anything moving through it.
Given a fixed, contained, uniform medium electromagnetic waves travel through that medium at a speed that reflects the medium. It will be slower than the absolute limit of the speed of light because the medium will have something in it.
Eddy Vluggen wrote: No proton ever pretends to be a wave?
A proton is not "light". A proton is matter. It has mass. It is a particle. A traveling proton (and other particles) can exhibit wave like behavior.
Ocean waves are of course matter but they too exhibit wave like behavior.
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jschell wrote: Your definition is weak.
You overestimate me; it ain't my idea. We got told that radio is subject to gravity, and TV waves would be different?
jschell wrote: Ocean waves are of course matter but they too exhibit wave like behavior.
Methinks different kind of wave 
Don't get angry over my lack of knowledge.
Bastard Programmer from Hell
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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Eddy Vluggen wrote: Just one small thing; it uses trillions of nuclear explosions to do so. So yes, if you can generate that amount of heat, you may loose lose a bit due to radiation
The source of the energy is irrelevant. Anything above a temperature of absolute zero (that is everything) will radiate energy and it's "temperature" will drop, ultimately to infinitesimally above absolute zero. It's why the universe is expected to eventually be uniformly cold and dark.
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"Expected", is the correct term. It would mean that there's energy somewhere in a vacuum, innit? Wasn't that how this all started?
Bastard Programmer from Hell
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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It sounds like a thin radiator.
My garage is a cold universe in the middle of winter.
Besides "block heaters", we used to have "car heaters" you would bolt under the dash and plug into a spare outlet. Then there were the "frost shields" you stuck on the windows for a hole to look out from. In warmer climates they would ask about your "bullet shielding" on the windows.
"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I
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Yes, they are claiming that their patented material emits infrared radiation in the 8-13 micrometer range that avoids the heat trapping molecules of the atmosphere. Basically, the night sky looks like a transparent window glass to these specific wavelengths of the electromagnetic spectrum. The net effect is to cool the emitting material down. During the day, the material needs to reflect at least 94% of all of the rest of the electromagnetic spectrum to keep the material from heating up and disturbing the cooling effect.
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Or you put a mirror over it during the day. Now, please explain how IR interacts with magnetism?
Yes, you could radiate energy away, by creating something that looks like a sun to nocturnal animals that can actually see IR. That implies loosing energy, not creating power.
Bastard Programmer from Hell
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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Eddy Vluggen wrote: Now, please explain how IR interacts with magnetism?
The clue's in the name. IR is InfraRed radiation, which means it's ElectroMagnetic radiation with a frequency lower than the color Red.
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Isn't IR light, instead of being magnetic?
I need to do some serious reading to catch back up on the topic 
Bastard Programmer from Hell
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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IR and visible light are both forms of electromagnetic radiation. The only difference between then is that IR has a lower frequency (and longer wavelength).
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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Infrared and visible light, plus radio, UV, microwave, x-ray and gamma radiation are all electromagnetic waves at different frequencies. So they are all also photons with different energies.
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That confuses me, as photons have mass. Also, the concept of light being a magnetic wave is new.
Any good tips on reading-material?
Bastard Programmer from Hell 
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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Thank you; added both to list, bought one. 
Bastard Programmer from Hell
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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Photons don't have mass. If they did, they couldn't travel at the speed of light.
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StarNamer@work wrote: Photons don't have mass. If they did, they couldn't travel at the speed of light.
Well, particles have mass. Somewhat more special than neutrinos?
"Photons are traditionally said to be massless. This is a figure of speech that physicists use"
What is the mass of a photon?[^]
Bastard Programmer from Hell
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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Years ago, I did postgraduate research in Nuclear Physics, hence I use the shorthand most physicists use.
The article you linked puts an upper limit on the rest mass of the photon at 7 x 10^(-17) eV which is about 1.2 x 10^(-49) gm.
Also, I can't recommend any books since this is all just stuff I learned 50 years ago and keep updated by reading the odd article.
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Sure, look up thermoelectric. The short explanation is there are certain materials when bonded together have an electrical barrier on the layer between the materials. The hot side is generally where the heat energy causes electrons to break away from atoms of the material and the cold side is where the electrons want to flow to. When the material absorbs enough IR energy the electrons from the hot side have enough energy to cross the barrier and enter the cooler side (they don't have enough energy to cross back over). They gather there and are available to use as an electric current. The Voyager 1 and 2 space craft have been using thermoelectric power for last 45+ years.
I honestly am quite skeptical that there would enough of a difference in the hot and cold side of the system that was represented in the article that showed them using the heat radiated at away to space. It only seemed to be a few degrees C, even given that space is very, very cold. You still need a hot side that supplies enough kinetic energy to rip the electrons from their orbits around the atoms of the material and send them across the barrier to collect on the cold side.
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Converting decaying plutonium?
So, it is using a fuel, not just relying on the cold of space to provide power?
Bastard Programmer from Hell
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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yes, that is true. However, the cold of space is the other half of the generator. The decaying plutonium provides the heat source and space is the cold side. There is no generation of power from the cold of space. It is the heat sink necessary for the thermoelectric effect. The article title was poorly chosen. The net effect of their patented emitter material was a 5 degree C drop in temperature with the narrow band IR emitter. This is simply not enough of a temperature difference to generate power. It can enhance terrestrial HVac systems though. I believe that is what that Sky... company was using it for.
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For Voyager, decaying plutonium provides the "hot" side, space provides the "cold" side; otherwise, the only source of heat would be how warm the craft was when it launched!
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jschell wrote: Is there something in that to insure that it actually 'reaches' space?
Yes.
As the article mentions, the radiation frequencies are chosen such that the atmosphere is completely transparent to the radiation. Hence it doesn't interact with the atmosphere and does actually radiate into space.
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StarNamer@work wrote: the radiation frequencies are chosen
Chosen?
https://www.skycoolsystems.com/technology/[^]
"The film reflects sunlight to prevent the panels from heating up during the day"
No choosing on that one. And the atmosphere does absorb sunlight.
"and also emits infrared heat to the cold sky"
Now that one is unclear to me and perhaps what you are referring to.
However infrared is in fact absorbed to some degree by the atmosphere.
And where exactly is the infrared coming from? Best I can suppose is it just moving it from the building (inside) to the outside. But that depends on how it moves and there will be a loss factor (not stated.)
Then that page also states the following
"When fully replacing an air conditioning system, we expect an 80% to 90% energy reduction for cooling."
If true then I don't understand why acceptance would not be instantaneous? That would cut total US energy needs by 8%.
Frequently Asked Questions (FAQs) - U.S. Energy Information Administration (EIA)[^]
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jschell wrote: Chosen?
From https://spectrum.ieee.org/energy-from-cold
Within the mid-infrared range, which is where heat radiation from typical earthbound objects is concentrated, the most applicable atmospheric transmission band is in the 8- to 13-micrometer-wavelength range.
Glass is a great material for an emitter. Its atomic vibrations couple strongly to radiation around the 10-μm wavelength, forcing the material to emit much of its heat radiation within the transmission window
So the material is chosen such that it's radiation frequency is in the transmission window, effectively choosing the frequency.
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