tag:blogger.com,1999:blog-1500584444083499721.post6686170529001320222..comments2024-03-24T09:28:42.755+01:00Comments on CJ on Mathematics and Science: Maxwell Believed in BackradiationClaes Johnsonhttp://www.blogger.com/profile/07411413338950388898noreply@blogger.comBlogger20125tag:blogger.com,1999:blog-1500584444083499721.post-63834725511224377832012-03-29T17:19:33.076+02:002012-03-29T17:19:33.076+02:00"Claes JohnsonMar 12, 2012 01:29 AM
It is ne..."Claes JohnsonMar 12, 2012 01:29 AM<br /><br />It is necessary to make a distinction between on one hand radiation = electromagnetic wave and on the other hand radiative heating = increase of internal energy of material body. This is not done in the present discussion and the result is confusion which fosters alarm."<br /><br />exactly! and you are right about the frequency and cut offs as being the reason why a warm body may not be radiatively heated bu a cooler body, this is to do with quantum interaction of radiation with electron orbitals. If the incoming radiation is of too low a frequency, it cannot excite the electon to a higher quantum level and therefore cannot heat the body. It is the excitation of electrons that is the means by which radiation is converted into kinetic heat. Radiation into vibration. EM vibration into physical vibration.Johnnyguitarmanhttps://www.blogger.com/profile/11024844053103548217noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-25296943210059290882012-03-14T18:09:11.712+01:002012-03-14T18:09:11.712+01:00Yes, I have commented.Yes, I have commented.Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-49339783254329352212012-03-14T17:17:39.557+01:002012-03-14T17:17:39.557+01:00Hav you seen the comments at the end here Claes?
...Hav you seen the comments at the end here Claes?<br /><br />http://claesjohnsonmathscience.wordpress.com/2012/03/12/interaction-light-matter-trivial-and-nontrivial/Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-20142037162250171792012-03-13T17:27:33.851+01:002012-03-13T17:27:33.851+01:00"It is necessary to make a distinction betwee..."It is necessary to make a distinction between on one hand radiation = electromagnetic wave and on the other hand radiative heating..."<br /><br />There are not different types of EM-waves(radiation)! This has been discussed many times. Radiative heating is performed by quite ordinary EM waves. The EM energy can be transformed into different types of energies.Lasse Hhttps://www.blogger.com/profile/11510250462126238787noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-52825017036814693972012-03-13T13:45:38.581+01:002012-03-13T13:45:38.581+01:00The Sun and the Earth form an interacting system a...The Sun and the Earth form an interacting system and it is meaningless to speculate about what would happen if the Sun was not there.Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-46935185152673058042012-03-13T12:09:46.550+01:002012-03-13T12:09:46.550+01:00At equilibrium the earth radiates the same energy ...At equilibrium the earth radiates the same energy (for a short time) whether or not the sun is there, acc to what Maxwell states in 3)<br />And his statement 2) is so evident, the sun radiates the same energy whether or not the earth is there.Lasse Hhttps://www.blogger.com/profile/11510250462126238787noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-42396104101787067382012-03-13T00:08:38.217+01:002012-03-13T00:08:38.217+01:00You are missing the point and the logic: The Sun m...You are missing the point and the logic: The Sun makes the Earth radiate, so it is meaningless to say the Sun does not prevent the Earth from radiating.Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-71663983641285212752012-03-12T23:01:46.653+01:002012-03-12T23:01:46.653+01:00My claim was: Maxwell is right in his claim 3)
At...My claim was: Maxwell is right in his claim 3)<br /><br />At equlibrium the heat energy is transformed to radiative energy, otherwise the body will heat up. Example: Radiation from sun transforms into IR from earth.Lasse Hhttps://www.blogger.com/profile/11510250462126238787noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-32547953430262704252012-03-12T22:11:10.323+01:002012-03-12T22:11:10.323+01:00No, the point is that radiation above cut-off is a...No, the point is that radiation above cut-off is absorbed and stored as heat instead of being re-emitted.Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-47151433629565490502012-03-12T21:39:20.879+01:002012-03-12T21:39:20.879+01:00"I don't see the problem: For frequencies..."I don't see the problem: For frequencies below cut-off of all bodies there is no heating effect."<br />Ok,the bodies emit and absorb radiation with frequencies within their spectra. Above cutoff the radiation is just absorbed and transformed to radiation within the spectrum. <br />But this means that radiation from the atmosphere(back-radiation) exists even if it is not heating earth directly. So Maxwell is right in stating:"3...nor has a hot body any power to stop the radiation of a cold body."Lasse Hhttps://www.blogger.com/profile/11510250462126238787noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-3523912923024060312012-03-12T19:03:54.101+01:002012-03-12T19:03:54.101+01:00But it is highly absorbent in the infrared and has...But it is highly absorbent in the infrared and has another cut-off in the longer waves.<br /><br />It's also not temperature dependent.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-14803679160888337532012-03-12T18:49:47.550+01:002012-03-12T18:49:47.550+01:00The spectrum of liquid water shows a quite sharp d...The spectrum of liquid water shows a quite sharp drop to zero between 1000 nm and 100 nm including the visible spectrum and part of the ultraviolet.Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-68299272208160597072012-03-12T18:34:37.601+01:002012-03-12T18:34:37.601+01:00How does the cut-off conform to the absorption spe...How does the cut-off conform to the absorption spectra of water?<br /><br />http://www.britannica.com/EBchecked/media/1369/The-absorption-coefficient-for-liquid-water-as-a-function-ofAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-40081439367822456582012-03-12T18:28:33.476+01:002012-03-12T18:28:33.476+01:00I don't see the problem: For frequencies below...I don't see the problem: For frequencies below cut-off of all bodies there is no heating effect.Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-78677090777764371742012-03-12T17:06:52.820+01:002012-03-12T17:06:52.820+01:00But I am talking about frequencies in resp spectra...But I am talking about frequencies in resp spectra that all three bodies have in common, frequencies that all bodies emit and thus also can absorb. These frequencies exist and, I repeatt, how can the middle temp body treat them differently. There is no information in the EM-wave about the origin.Lasse Hhttps://www.blogger.com/profile/11510250462126238787noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-46862594838204296032012-03-12T16:01:22.349+01:002012-03-12T16:01:22.349+01:00Yes, there is because the cut-off is one-sided hig...Yes, there is because the cut-off is one-sided high frequency cut-off, discriminating like a semi-conductor.Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-33891104381987940992012-03-12T12:18:44.834+01:002012-03-12T12:18:44.834+01:00But how can a (black)body distinguish between ener...But how can a (black)body distinguish between energy with the same frequency coming from two bodies, one warmer but with overlapping spectrum of the colder. The receiving body has a temp in between. Absorption in one case and reflexion in the other! There is no logic in that.Lasse Hhttps://www.blogger.com/profile/11510250462126238787noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-16835530091201382622012-03-12T09:29:11.273+01:002012-03-12T09:29:11.273+01:00It is necessary to make a distinction between on ...It is necessary to make a distinction between on one hand radiation = electromagnetic wave and on the other hand radiative heating = increase of internal energy of material body. This is not done in the present discussion and the result is confusion which fosters alarm.Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-71222318049548496492012-03-11T23:48:23.419+01:002012-03-11T23:48:23.419+01:00Two bodies with different temps may have some part...Two bodies with different temps may have some part of their radiation spectrums overlapping. And if some frequencies are emitted, they are also possible to be absorbed, even if they are coming from a colder body. Something strange with that? <br />Remember that E-M-waves are force fields acting on charged particles even if these are vibrating more or less.Lasse Hhttps://www.blogger.com/profile/11510250462126238787noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-7330539292298510762012-03-11T21:59:03.446+01:002012-03-11T21:59:03.446+01:00"3...nor has a hot body any power to stop the..."3...nor has a hot body any power to stop the radiation of a cold body."<br />If it had, the result would be that two bodies with equal temps would seize to radiate towards each other. Anyone believing that?Lasse Hhttps://www.blogger.com/profile/11510250462126238787noreply@blogger.com