A single element has a well defined emission spectrum. Most elements emit strongly in a band of frequencies that cover portions of visible light. Since electromagnetic colors are additive, if you combine these emissions the resultant light will appear to be some shade of white. Warm white,cool white etc. In that sense single element white light emission is possible
But practically it is a massive engineering challenge to emit white light from a single element. Why? Well because each emission frequency corresponds to a specific energy input. To be able to emit different frequencies from a single element we will have to apply different input energies to the emitter. How are we going to do that?
As an example consider sodium vapor lamp. It is the most efficient artificial lighting device ever created. Even more efficient than LEDs. You might have seen it on highways and parking lots where it emits a characteristic yellow light.
Have you ever asked yourself why yellow? Its because yellow is one of the colors at which sodium emits strongly. But it is not the only color. Sodium also emits at red and green and blue. Why then have sodium vapor lamps have not been able to emit white light? It is the same challenge which we discussed before. It is practically very difficult to control the distribution of energy inside a material system so that it behaves the way we want it to. That is precisely the reason why sodium vapor lamps were replaced by LEDs despite being the most efficient light sources. Monochromatic colors are not all that appealing to consumers.
Some advancements have been made in single element white light emission. Flourescent quantum dots are nanosized particles that are designed to take advantage of broadband spectral emission. As the size of the dot decreases it emits at higher energies of its spectrum. By mixing various sizes of dots different light frequencies can be attained leading to a white light using single uniform energy as input.
As far as the sun is concerned the light from the sun is not representative of hydrogen emission spectrum. It can be easily verified with a prism comparing the seperated beams with hydrogen emission spectrum. They don't match. Not even close. Why?
Well thats because hydrogen is not the only element on sun. The sun had so much matter that it created 9 planets from itself.All the sand,all the iron,cobalt,diamond on earth. All the moons of jupiter.All the asteroids are just insignificant solar dust. The sun still has enough matter that it can create many planetary systems and provide enough energy to all of them.
The Sun is so hot that matter on the sun does not exist in its normal state. The boundaries that distinguish elements on the periodic table disappear. Matter is torn open,its electrons are thrown away, the nucleus that remains,if it remains is in constant high energy collision with other unrecognizable/unclassifiable entities. You will not be able to diffrentiate between hydrogen and iron in the hottest part of the sun. These places along with all others are responsible for emission of light from the sun. Nuclear energy,electrical energy,magnetic energy,heat, gravity are all in play here. Good luck in trying to find which portion of light came from which element.
If determination of source material is difficult in visible light its impossible in other frequency bands. Microwaves,milimeter waves,infrared, x rays and gamma rays.
Sun is a rainbow of colors. All light. But the sun is not merely another star. It is the only known star to have birthed life. That is why it is worshipped.
#energy #matter #light
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