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A comment on Transparent ceramics made with aluminum. Parent comment

Re:Transparent ceramics made with aluminum by tim333 on Wednesday April 04, 2018 @05:58AM (#16753364)
Roughly light is electromagnetic radiation and puts force on electrons it comes in contact with. If the electrons are fixed in a non conductor they don't move much and so don't absorb the energy. If they can move as in most metals the force accelerates them and they absorb energy from the radiation, stoping of reducing it.
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Re:Transparent ceramics made with aluminum by agumonkey on Wednesday April 04, 2018 @07:21AM (#16753706)
What about partial ? or only to some wavelengths ?
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Re:Transparent ceramics made with aluminum by mannykannot on Wednesday April 04, 2018 @08:13AM (#16753963)
X-rays penetrate metal to some extent, though they also scatter off the atoms. Radiography of high value/risk metal components (such as the stressed parts of gas turbine engines) is a mainstream non-destructive testing technique.
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Re:Transparent ceramics made with aluminum by nerfhammer on Wednesday April 04, 2018 @01:10PM (#16756744)
huh, is this why sometimes metal gets unbelievably hot if left in the sun? but that should be true of any opaque material
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Re:Transparent ceramics made with aluminum by CompelTechnic on Wednesday April 04, 2018 @02:01PM (#16757252)
For a given temperature rise, metals feel hotter than many other materials because they have a high thermal conductivity and enough heat capacity to deliver a lot of heat quickly.

As another though experiment, consider that you dread walking barefoot across cold tile floors but can bear to walk across carpeted floors in the same house. These two materials are at the same temperature.

Also consider aluminum foil you just pulled out of the oven. It's thinness runs contrary to the large thermal capacity of a solid chunk of metal- you can touch it immediately because you are such a large heat sink compared to it that it can't burn you even while it has only just started (rapidly) cooling from 350°F.

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Re:Transparent ceramics made with aluminum by dbsvsv on Wednesday April 04, 2018 @06:06AM (#16753389)
My physics is only high school level so as I see, in the case of fixed - does the photon not get scattered/reflected or does it pass through the electron? And why no orbital transition?
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Re:Transparent ceramics made with aluminum by ger_in_no on Wednesday April 04, 2018 @06:51AM (#16753557)
Reflection on the surface of polished metals occurs because of the collective movement of electrons at the surface, caused by the incoming photons. Light of most wavelengths, especially low-energetic infrared doesn't have enough energy to cause orbital transitions in most elements.
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