metalresearcher
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The Action Lab video about negative Kelvin temperature violates laws of thermodynamics ?
https://youtu.be/jdjTYlReE-I
This guy has excellent videos on several science subjects. Now one where he burns with a bright blue laser in a piece of wood and he claims 'unlike a
flashlight, with a laser and magnifier one can get any temperature you want.'
If that were true, then nuclear fusion or other extreme high temperature processes could be much easier to attain.
Is this true ?
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Twospoons
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Its not really true you can achieve 'any temperature you want'. Focusing a laser beam using a lens has a fundamental limit on the resulting spot
size, which is a function of wavelength, beam quality, beam size and focal distance. Look up 'diffraction limited spot size' for the formula. So there
is a maximum power density you can achieve with any given laser. Its also worth noting that the temperature achieved is a balance between energy
absorbed and energy re-radiated.
That said, there are petawatt class lasers being used for physics research (we're talking pulsed, not continuous) so some extremely high instantaneous
temperatures are possible.
Helicopter: "helico" -> spiral, "pter" -> with wings
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Texium
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Thread Moved
25-1-2024 at 16:56 |
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