37
votes
Is light only emitted by atoms? i.e are they the only source of light in the universe?
Yes, there are many sources if light besides atomic transitions.
Classical sources
Objects with a temperature above absolute zero emit thermal radiation due to the random motion of their atoms and ...
- 23.2k
14
votes
Accepted
How does quantum mechanics explain the color of macroscopic objects?
There are two important details. One is that in a solid, the atoms interact with each other, which broadens the lines into a continuum.* The second is that when an atom/material absorbs a photon and ...
- 1,503
8
votes
Is light only emitted by atoms? i.e are they the only source of light in the universe?
Most of the visible light in the universe is Thermal Radiation. At high energies, there are also effects like Synchrotron Radiation or Pair Annihilation that don't require atoms to be present.
- 6,245
6
votes
Is it correct to say that light makes things visible but light itself is invisible?
This is not really a question about physics, but a language issue. Define "visible".
An object emits light, and you (as an observer) detect the light with your eyes.
If "visible" ...
- 4,178
5
votes
How does quantum mechanics explain the color of macroscopic objects?
A macroscopic substance is composed of countless fundamental particles in continuous mutual interaction with every other fundamental particle nearby. Every interaction has associated, in-principle-...
- 11.2k
4
votes
Light in glass/water
The wavelength is the speed divided by the frequency (and the frequency is constant). Light has some wavelength in air; then it decreases when it enters class; then it leaves the glass and its back to ...
3
votes
Accepted
Can the human eye see the images of 300 nm light on a screen through a diffraction grating?
No, the human visual system cannot perceive light shorter than 400 nm.
In a common lab experiment, light from a hydrogen discharge lamp is sent through a diffraction grating and separated into its ...
- 2,731
3
votes
Is light only emitted by atoms? i.e are they the only source of light in the universe?
There seem to be confusion about the processes resulting in emitting radiation and sources of light - i.e., the objects where the light comes from.
The processes are any processes involving ...
- 51.7k
2
votes
Is light only emitted by atoms? i.e are they the only source of light in the universe?
I am almost embarrassed to add this given the existing highly upvoted answers, but at least one important source of light has been omitted - the Cosmic Microwave Background is also technically light (...
- 1,194
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