This piece of paper give off electromagnetic radiation.
This block of wood gives off electromagnetic radiation.
This dry erase eraser gives off electromagnetic radiation.
And it you are okay with this you should be able to get the question right on the test.
But that is kind of not the point here.
You need to embrace this with your heart and your soul.
lets move forward. 1890
The physicists of the late 19th century were surprisingly good at spectroscopy.
They knew that the electromagnetic radiation covered a wide range of frequencies.
They knew that the frequencies were related to energy
so that the electromagnetic radiation was a range of energies.
They knew that visible light was a narrow band within this much broader range
and they knew that infrared radiation was off the low energy end
and ultraviolet radiation was off the high energy end.
and furthermore, they knew that ordinary objects give off infrared radiation.
But the thing that they did not understand was
"what is electromagnetic radiation?" They knew it was a wave.
In the 1890s physics was dominated by the work of a 15th century
English scientist named Sir Isaac Newton.
Newtonian physics was all about things that can be seen and things that can be understood.
so...waves... waves are like a guitar string twanging, or .....
like wiggling a rope...like swinging a rump rope.
" so what are electromagnetic waves anyway?"
They must be things that wiggle, according to Newtonian physics.
So things wiggle and they make electromagnetic waves.
so..if you take an object...like ... a clay pot might be a good
or maybe a piece of metal or something ... and heat it up.
The infrared radiation should turn into red light.
And then if you keep heating it, The red light should turn into green light
it should go into higher energies it should turn green
and if you keep heating it, it should go to blue light.
and then if you keep heating it, it ought to go to ultraviolet light and
perhaps not give off visible light at all once it gets hotter than
The appropriate temperatures.
But the problem was that the observations did not demonstrate that
The observations are that, an object when heated, turns red...red hot
and then, as you keep heating it, the green light and the blue light,
appear simultaneously, the red light doesn't go away
and the result of this is it turns white.
so it pretty much goes from red hot to white hot.
and ultraviolet radiation never .... it never gives off ultraviolet radiation.
no matter how hot you heat it.
So how can this be explained? They had a name for it at the time.
this was well understood within the physics community in the 1890s
"the ultraviolet catastrophe" was that the observations
did not fit Newtonian physics.
Max Planck was a German scientist. He was a chemist in Germany.
He was an energy guy.
He was interested in things like enthalpy, and entropy.
and Gibbs free energy and free energy and all that
hard stuff that is in physical chemistry textbooks.
He, as far as I can tell, had no knowledge or information
or interest in molecular structure. Atomic structure wasn't his thing.
Electromagnetic radiation was not his thing either as far as I can tell
He was an energy guy.
He looked at the ultraviolet catastrophe and made a jump.
He jumped off into the unknown and said that light is a quantum
light is a ... light is kind of like a thing.
Green light is green light. Green light doesn't come from red light.
green light is a thing on its own.
I think that one of the great educators of our era is Bill Nye
Bill Nye says that "everything is either matter or energy"
So I listen to this ....... "matter or energy"
so "everything" includes energy. so energy is a thing
And I think that it goes back to Max Planck.
Max Planck says that energy is a thing. Green light is green light
red light is a thing
red light and green light are not the same thing and never will be the same thing
And then the behavior of black body radiation:
you heat something up and it gives off red light
the red light comes from something
and then you heat it up even further and it gives off green light
Green light comes from something different
Blue light...you heat it up even further and it gives off blue light.
and blue light is something yet different still.
And, not matter how hot you heat it....
whatever gives off ultraviolet radiation never happens
and Max Planck doesn't dive into the what's and how's on the molecular level.
He is an energy guy.
The quantum mechanical revolution comes from Max Planck.
and it is interesting that it did not have anything to do with atomic structure.
He comes up with a new idea of energy. He says that energy is a thing
I want to end with this image:
You have a red flashlight
you take the red flashlight into outer space for simplicity
Shine the red flashlight out into the emptiness of space.
The red light leaves the flashlight. The red light goes and goes and goes as red light
it doesn't turn into green light. it doesn't turn into blue light.
it doesn't tire out it doesn't go away.
The red light is a thing just like this piece of paper is a thing
it is a thing. and nothing happens to it unless it interacts with something.
100 million years from now the red light that left the flashlight
is still going to be going somewhere.
the relevance of this is completely over whelming
but I think one aspect that we can look at right now is that here on the planet earth
we look at a star that is 100 million light years away
we are looking at radiation that came from that star 100 million years ago.
by looking at that radiation carefully, we can tell all kinds of things about
the star.....We can find out all kinds of things about the star
as it was 100 million years ago because that is when the light left the star.
I think it is cool.
and trust me about this one. That test you are about to take.
it is not as important as you think.