Siyatanush Posted January 5, 2019 Share Posted January 5, 2019 If we are able to see the world only in terms of fundamental particles it is made up of, which colour shall we see? Link to comment Share on other sites More sharing options...
Strange Posted January 5, 2019 Share Posted January 5, 2019 4 hours ago, Siyatanush said: If we are able to see the world only in terms of fundamental particles it is made up of, which colour shall we see? Colour is a property of bulk materials, caused (mainly) by the way light interacts with the electrons in the material. So, for example, most conductors (such as metals) are highly reflective of most wavelengths because they have a "sea" of free electrons. Some materials are coloured because the microscopic structure causes interferences patterns - this is the reason for the colour of some butterflies and beetles. Individual fundamental particles may interact with light but they won't have a colour (they are two small to be seen, anyway). Link to comment Share on other sites More sharing options...
studiot Posted January 5, 2019 Share Posted January 5, 2019 (edited) 1 hour ago, Strange said: Individual fundamental particles may interact with light but they won't have a colour (they are two small to be seen, anyway). Yes take note of this. But also note that some fundamental particles (quarks) have a 'color ' as well as an electric charge and other properties such as 'flavour'. This color is not the same property as the coulours we see, which are due to light. https://en.wikipedia.org/wiki/Color_charge Edited January 5, 2019 by studiot Link to comment Share on other sites More sharing options...
Siyatanush Posted January 5, 2019 Author Share Posted January 5, 2019 So which colour shall we see? Link to comment Share on other sites More sharing options...
Strange Posted January 5, 2019 Share Posted January 5, 2019 1 minute ago, Siyatanush said: So which colour shall we see? You won't. Fundamental particles are too small to see. Colour is a property of bulk materials, not fundamental particles. 1 Link to comment Share on other sites More sharing options...
studiot Posted January 5, 2019 Share Posted January 5, 2019 Strange has told you, and I emphasised that you won't see a colour. The interaction of light with fundamental particles eg Compton scattering does not change the frequency of the Xrays. Link to comment Share on other sites More sharing options...
Siyatanush Posted January 5, 2019 Author Share Posted January 5, 2019 So in terms of fundamental particles we will see nothing in the world. Link to comment Share on other sites More sharing options...
studiot Posted January 5, 2019 Share Posted January 5, 2019 I give up here. Link to comment Share on other sites More sharing options...
Sensei Posted January 5, 2019 Share Posted January 5, 2019 (edited) "color" is layman interpretation of energy/frequency/wavelength of photon, particle of light. https://en.wikipedia.org/wiki/Photon If photons have low energies, they are in radiowave, microwave, infrared spectrum. Invisible for human eye. But detectable by specially designed instruments. If photons have energies between approximately 1.8 eV (which corresponds to 700 nm wavelength) and 3.1 eV (400 nm wavelength), human eye is detecting them and brain interpreting as various colors. Red, yellow, green, aquamarine, blue, violet, and their intermediates. Colors of rainbow. Visible spectrum of light. https://en.wikipedia.org/wiki/Visible_spectrum "white color" is almost uniform mixture of photons with various energies without any significantly dominating above the others. Different materials are absorbing photons with different energies. The most often, high energy photon is absorbed, and one or couple new one with lower energies are emitted to environment (photons that were completely absorbed increase internal energy of object which absorbed them). Rarely couple lower energy photons are absorbed and one higher energy photon is emitted. https://en.wikipedia.org/wiki/Absorption_(electromagnetic_radiation) https://en.wikipedia.org/wiki/Emission_spectrum Objects with internal energy emit photons correlating to temperature of object. It's called thermal radiation. https://en.wikipedia.org/wiki/Thermal_radiation Layman says/thinks "I see red light". Quantum physicist says/thinks "I see photon with 1.9 eV energy". Your initial question should be rephrased to "are fundamental quantum particles emitting photons, and if yes, with what energies?" Edited January 5, 2019 by Sensei Link to comment Share on other sites More sharing options...
swansont Posted January 5, 2019 Share Posted January 5, 2019 7 hours ago, Strange said: Colour is a property of bulk materials, caused (mainly) by the way light interacts with the electrons in the material. Some gases as well. (bromine and chlorine come to mind) 1 Link to comment Share on other sites More sharing options...
Strange Posted January 5, 2019 Share Posted January 5, 2019 1 hour ago, swansont said: Some gases as well. (bromine and chlorine come to mind) Good point. And I suppose this implies a single atom can have a colour, even if we need some number of them for it to be detectable. (In my mind "bulk materials" included gases, but it may well have a more formal definition that doesn't.) Link to comment Share on other sites More sharing options...
Sensei Posted January 5, 2019 Share Posted January 5, 2019 (edited) 2 hours ago, swansont said: Some gases as well. (bromine and chlorine come to mind) If you shoot a bunch of UV photons toward e.g. Hydrogen gas, at least some of them will be absorbed by Hydrogen, and new one photons will be emitted with lower energies. It all depends on photons initial energy, and quantity of photons, and quantity of possible collisions photon-medium, whether human-eye will be able to see in visible spectrum reemitted by material photons. Edited January 5, 2019 by Sensei Link to comment Share on other sites More sharing options...
swansont Posted January 5, 2019 Share Posted January 5, 2019 1 hour ago, Strange said: Good point. And I suppose this implies a single atom can have a colour, even if we need some number of them for it to be detectable. (In my mind "bulk materials" included gases, but it may well have a more formal definition that doesn't.) That’s fair. I’ve understood it to differentiate from surface effects, which generally implies a solid or liquid. Link to comment Share on other sites More sharing options...
beecee Posted January 5, 2019 Share Posted January 5, 2019 11 hours ago, Strange said: Colour is a property of bulk materials, caused (mainly) by the way light interacts with the electrons in the material. So, for example, most conductors (such as metals) are highly reflective of most wavelengths because they have a "sea" of free electrons. On an old, now defunct science forum, run by the ABC [Australian Broadcasting Service] we had a tremendously long debate entitled, "What Colour is an Orange in the dark" The answer is of course it has no colour, as colour while being interpreted as you have said, must be qualified with the fact that the colour of any object in the first instance, depends on the nature of the EMR that falls on the body. eg; On New Years Eve, the normally white sails of the Sydney Opera House, were seen in many different colours depending on the light that fell upon the sails. as it really is..... 1 Link to comment Share on other sites More sharing options...
studiot Posted January 5, 2019 Share Posted January 5, 2019 (edited) Nice one Cyril. Nice one Son +1 Edited January 5, 2019 by studiot Link to comment Share on other sites More sharing options...
QuantumT Posted January 5, 2019 Share Posted January 5, 2019 Almost a year ago they managed to reflect light from a single strontium atom. I know it's much larger than a particle, but still amazing. https://epsrc.ukri.org/newsevents/news/single-trapped-atom-captures-science-photography-competitions-top-prize/ Link to comment Share on other sites More sharing options...
swansont Posted January 5, 2019 Share Posted January 5, 2019 54 minutes ago, QuantumT said: Almost a year ago they managed to reflect light from a single strontium atom. I know it's much larger than a particle, but still amazing. https://epsrc.ukri.org/newsevents/news/single-trapped-atom-captures-science-photography-competitions-top-prize/ It’s not reflection. Absorption and re-emission using an atomic transition. Link to comment Share on other sites More sharing options...
QuantumT Posted January 5, 2019 Share Posted January 5, 2019 3 minutes ago, swansont said: It’s not reflection. Absorption and re-emission using an atomic transition. Ah! Okay. Link to comment Share on other sites More sharing options...
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