Recent content by Papatom

Hi, The article below states that they made a material that blocks the motion of molecules in only one way but passing the other way is possible. See the article. https://physicsworld.com/a/blocking-the-symmetry-of-motion/ This seems to me in contrast with the second law. You can for example...

More specific: In a closed system with all temperatures in equilibrium at 300 K is it possible to upconvert IR photons to photons that at the end can charge a battery? This is in contradiction with the second law. Where is my mistake?

Wiki states: Photon upconversion (UC) is a process in which the sequential absorption of two or more photons leads to the emission of light at shorter wavelength than the excitation wavelength. https://en.wikipedia.org/wiki/Photon_upconversion Is it possible to have the emitted light with the...

thank you

Hi, if I read the article (see link) I get confused: Is it emission or reflection? If it is emission, how is it possible that the photons are emitted to one side? (Unfortenately I do not have access to the original article.)...

I think I understand: A plane can travel 50 m/s but the temperature indide does not increase significantly or drop after slowing down.

Thank you for your reply, I still do not understand this fully. Air molecules travel about 500 m/s. Assume the wind is 5 m/s. Then they have an average velocity of 505 m/s. You put a windmill somewhere and the molcules slow down to 404 m/s. Less kinetic energy so a drop in temperature. Where is...

Hi, From the movement of air molecules electricity is generated. The kinetic energy of the air molecules is converted into usefull energy and the air is cooled down. Why do windmills not violate the second law of thermodynamics?

My question is inspired by this thread: https://www.physicsforums.com/threads/can-you-solve-this-geometry-problem-for-nine-year-olds.890794/ If you an isosceles triangle and you put in a corner (or somewhere else) a light beam (laser) the beam will reflect one or more times before it comes down...

Hello, I am Tom and interested in almost everything with science although I do not understand everything. I work in chemistry. I hope I will learn new things on this site.