SpeakBlackbodyRadiationEasily

   'Blackbody Radiation' is a term that Physics students encounter at many turns, in several diverse sub-topics - say Thermodynamics, Quantum Physics, The PhotoElectric effect and so on. This is somewhat analogous to a topic occurring prominently in all accounting subtopics, such as Financial Accounting, Cost Accounting, Management Accounting, Taxation etc.  

What is a Blackbody, in Physics?

The term 'Blackbody'  implies that the body absorbs and emits radiation. There are no losses in the absorbed radiation, say, by reflection.

 What is the 'Blackbody radiation' experiment?

 It was a theortical experimental setup to emulate Black bodies found in nature.

Why does this matter?

 All bodies in Space are near perfect Black Bodies. So, understanding Blackbodies helped us understand Space and Universal evolution better.

 

Is that all?

On  Earth in our mundane lives, Blackbody radiation has uplifted Physics to new levels - has opened up Quantum Physics. That has opened up several breakthroughs one or two of which are LED lights, Laser Beams, Semi conductors and on and on and on.  And now, Q computing.

More fundamentally, the physics that has evolved along with Blackbody Radiation understanding has led us to believe that matter and waves - both exhibit Particle and Wave - dual nature. 

That is still not understood how. But it is.

Then there is  this - the Blackbody radiation curve.

   Image Credit- Niall Deacon / IAU OAE, License: CC BY 4.0

 

What is so interesting about this curve?

The curve is same, no matter whether Copper or Gold or Aluminium, for a given temperature!

So?

This means, looking at this curve, we will be able to tell how hot, say a star in interstellar space is. 

How does know that help?

That tells us the age of the star, the size of the star and so on

But, what is the point when I do not know what the star is made up of  - given that the radiation curve is the same for all matter?

True, the Blackbody radiation is temperature specific only. But as the radiation travel outwards, the gases that surround the star absorb those parts of the radiation in the curve, that they like!

 More correctly, say, Sodium in that gas mixture absorbs  radiation of wavelength that is specific to it. A And when seen from earth, that wavelenght is absent in that spectrum, and appears black. That tells us that Sodium is present in the gas of that star.

So now, we not only know  how old is the star, and how big it is but we also know what elements make up its gaseous surface! 

more to come..