Blackbody radiation and ultraviolet catastrophe?

[Stratus]

I'm sorry, this will be my last question for a while, I promise xD.

 

I'm currently reading through a book of the history of quantum physics and got to the Ultraviolet catastrophe, which as i'm sure you know was when classical physics predicted an infinite energy/wavelength light. I believe that's what it is anyway

What I do know about this subject is

1. In the classical interpretation, the intensity would keep increasing as long as the blackbody keeps receiving energy and the wavelength would keep going down forever. This would create a very high intensity higher than ultra violet ray, correct?

2.I don't understand the quantum view though. Why does a blue light keep going up in intensity and down in wavelength, then at a sudden point, the intensity starts dropping. Why is this?

An example of this is here

http://upload.wikime...lackbody-lg.png

On the correct interpretation, you can see the blue and all other color light reaches a certain intensity then drops. Why?

Also, well i'm talking, I don't really understand the idea of a blackbody either. If you could explain this all in laymen's terms, I would very very very much appreciate it

I'm sorry for all the questions.

[swansont]

The basic issue was that the physicists were trying to apply a thermodynamic concept called the equipartition of energy. If you have a ensemble of particles that can interact, the energy will be split up between all of their degrees of freedom of motion. Example: you have a frictionless pool table. Even if you start off with motion of one particle in one direction, eventually that energy will spread between all the particles, and their energy will be split between the two directions they can move. If they were a little "stickier" in how they scatter, and caused them to spin, you'd end up splitting between the x and y motion and the rotation of the balls, too. That's the equilibrium condition, and systems left to themselves tend to reach an equilibrium.

 

But radiation in a cavity doesn't do this. You have all of these modes (standing waves) present in the cavity, but the energy doesn't split up equally. It can't, because of the discovery that E = hv. If you excited all the modes equally, it would take an infinite amount of energy — that's the catastrophe. The energy has to distribute itself in a way that's different from the classical expectation.

[EdEarl]

The blue, green, and red lines on the graph must not correspond to blue, green and red light, because blue light wavelengths are around 475 nm, green around 510 nm, and red around 650 nm. The lines represent the intensity of light emitted at variouis wavelengths (colors) when the black body is 5000K (blue line), 4000K (green line), and 3000K (red line). Light intensity is related to the number of photons being emitted. And, the energy per photon is higher for shorter wavelengths of light.

[Stratus]

The blue, green, and red lines on the graph must not correspond to blue, green and red light, because blue light wavelengths are around 475 nm, green around 510 nm, and red around 650 nm. The lines represent the intensity of light emitted at variouis wavelengths (colors) when the black body is 5000K (blue line), 4000K (green line), and 3000K (red line). Light intensity is related to the number of photons being emitted. And, the energy per photon is higher for shorter wavelengths of light.

ah, i see. so the lines are just colored like that to make them stand out? They aren't really blue, green, and red?

 

The basic issue was that the physicists were trying to apply a thermodynamic concept called the equipartition of energy. If you have a ensemble of particles that can interact, the energy will be split up between all of their degrees of freedom of motion. Example: you have a frictionless pool table. Even if you start off with motion of one particle in one direction, eventually that energy will spread between all the particles, and their energy will be split between the two directions they can move. If they were a little "stickier" in how they scatter, and caused them to spin, you'd end up splitting between the x and y motion and the rotation of the balls, too. That's the equilibrium condition, and systems left to themselves tend to reach an equilibrium.

 

But radiation in a cavity doesn't do this. You have all of these modes (standing waves) present in the cavity, but the energy doesn't split up equally. It can't, because of the discovery that E = hv. If you excited all the modes equally, it would take an infinite amount of energy — that's the catastrophe. The energy has to distribute itself in a way that's different from the classical expectation.

ah, i see. The reason that it would take an infinite amount of energy to get every standing wave equal is because of the different frequencies I would imagine?

[swansont]

ah, i see. The reason that it would take an infinite amount of energy to get every standing wave equal is because of the different frequencies I would imagine?

 

Yes. The frequency has no upper limit, so E=hv means you are trying to excite higher and higher energy modes as frequency increases.

[Stratus]

Ah, okay, that makes sense.

 

related to this topic, earlier today I realized that I wasn't sure if it was the wavelength or the frequency that determined the type of wave (color wave, uv, if, etc), so in my research (which was quite conflicting, some sites said wavelength, some said frequency), I came across this graph

 

 

while I was looking at it I noticed that the wavelength and frequency are inversely proportionate (wavelength goes up, frequency goes down and vice versa). I knew this from some books I had read, but this caused me to wonder. Is it possible for these to become un-proportionate? IE: a microwave with the normal 10^-2 wavelength, but a frequency of 10^12, which corresponds to IR.

 

Is this possible, or? What would the wave look like if this could happen?

[swansont]

[math]c = \lambda\nu[/math] (c/n if you're in a medium) and c is a constant

[EdEarl]

Frequency and wavelength are inversely proportional for all kinds of waves, including ocean, sound and light.

[Enthalpy]

Not ocean waves.

 

For sound and light, yes if the medium is non-dispersive.

[SamBridge]

I have a sort of possible question swansont, I looked at black body radiation and this catastrophe and it was said that Einstein used quantinization of matter and energy to explain this pattern mentioned. It did not specify how, but my guess is that if you get atoms to a high enough energy state, infra-red light will not have an energy of the proper value that is capable of interacting with a majority of atoms in that excite to higher energy state, almost like the wavelength was too large to fit what was needed. Is that right at all?

Edited May 22, 2013 by SamBridge

[swansont]

I have a sort of possible question swansont, I looked at black body radiation and this catastrophe and it was said that Einstein used quantinization of matter and energy to explain this pattern mentioned. It did not specify how, but my guess is that if you get atoms to a high enough energy state, infra-red light will not have an energy of the proper value that is capable of interacting with a majority of atoms in that excite to higher energy state, almost like the wavelength was too large to fit what was needed. Is that right at all?

 

Quantization of energy gets around the problem of why all the different modes aren't excited. You then get a distribution of energies and "fill up" the modes. There's no demand to have all of the UV modes populated, as there was in the equipartition case. Different statistics apply to the situation.

[SamBridge]

Quantization of energy gets around the problem of why all the different modes aren't excited. You then get a distribution of energies and "fill up" the modes. There's no demand to have all of the UV modes populated, as there was in the equipartition case. Different statistics apply to the situation.

Can I plz have an answer? If it atom is at a high energy state, you most likely can't excite it with a radio-wave...right? The probability distribution of thermal energy or the uncertainty of the thermal energy occupies the whole "box" after a certain amount of time, acting almost like a standing wave, and after an atom is excited to a certain point, say the material is 4000 degrees F, electrons in atoms cannot posses higher frequencies of their oscillation modes because __________...

Edited May 23, 2013 by SamBridge

[swansont]

The UV catastrophe has nothing to do with atomic states. The concept is standing wave modes in cavities.

[SamBridge]

The UV catastrophe has nothing to do with atomic states. The concept is standing wave modes in cavities.

It has to have something to do with it if electrons do not continue increasing their energy state or making bigger quantum leaps. The thermal energy builds up and acts like a standing wave. Great. What's the problem exactly? Because of the uncertainty of the thermal radiation over distance, the heat in a way builds up to eventually build a standing wave in a similar manner that you make a standing wave on a string by trying to continuously vibrate it in the right way, but what about the mode of thermal radiation or any causes the UV catastrophe? It get's hotter, but electrons of the material still do not excite to a high enough energy state to produce large amounts of UV light upon again changing their state.

[swansont]

The UV catastrophe was the failure of classical physics to explain light in a cavity. There was no QM at the time, so there were no quantum leaps.

[SamBridge]

The UV catastrophe was the failure of classical physics to explain light in a cavity. There was no QM at the time, so there were no quantum leaps.

Well, ok, but what about the lack of leaps lead to the catastrophe? 2 years and I still can't ever get a straight answer out of you.

Edited May 23, 2013 by SamBridge

[swansont]

Well, ok, but what about the lack of leaps lead to the catastrophe? 2 years and I still can't ever get a straight answer out of you.

 

THE UV CATASTROPHE HAD NOTHING TO DO WITH QUANTUM LEAPS.

 

You can't "get a straight answer out of me" if you ask a question and then insist on a particular answer. I have said, multiple times now, that this had nothing to do with atoms and transitions. Why do you keep asking about them? Why do you keep trying to make a connection? How is somehow my fault?

[SamBridge]

THE UV CATASTROPHE HAD NOTHING TO DO WITH QUANTUM LEAPS.

 

You can't "get a straight answer out of me" if you ask a question and then insist on a particular answer. I have said, multiple times now, that this had nothing to do with atoms and transitions. Why do you keep asking about them? Why do you keep trying to make a connection? How is somehow my fault?

I keep asking because specific frequencies of light can be formed by atoms in excited states. Since thermal photons can do this, it must in some way have something to do with it. Besides, I did mention that Einstein used quantinization of energy in light to explain the UV catastrophe, but you were very vague and merely said there's different statistics in QM that aren't in CP, which can be interpreted as a whole host of things.

Edited May 23, 2013 by SamBridge

[swansont]

I keep asking because specific frequencies of light can be formed by atoms in excited states.

 

Yes, they can. This has nothing to do with the UV catastrophe.

 

Since thermal photons can do this, it must in some way have something to do with it.

 

I don't see the connection. The thermal spectrum is not discrete, it is continuous.

 

Besides, I did mention that Einstein used quantinization of energy in light to explain the UV catastrophe, but you were very vague and merely said there's different statistics in QM that aren't in CP, which can be interpreted as a whole host of things.

 

Here we go again. I was vague. It is my fault that you aren't familiar with the statistics involved.

 

Or, we could look at it from a different perspective. I told you different statistics were involved. You could then go pick up a textbook and start learning about this. Or even just Google it.

 

Look, I don't know what you understand and don't understand. I'm not telepathic. If you ask a question about the UV catastrophe, for some detail, I have to assume you have some familiarity with what the UV catastrophe was. But if you don't, you should be asking a different question. Or reading a book and learning the basics. I don't owe you anything here. For you to complain about answers, when you apparently haven't put in the effort on your part, galls a bit.

[SamBridge]

I don't see the connection. The thermal spectrum is not discrete, it is continuous.

There's one connection right there. The thermal spectrum is continuous , energy states of atoms aren't, that's bound to cause some problems.

 

 

 

Here we go again. I was vague. It is my fault that you aren't familiar with the statistics involved.

No it's your fault that you were vague and purposely chose not to give any details. If I'm studying meteorology and I ask someone or a book "how do thunderstorms form?" and it just says "there's water in the atmosphere", regardless of my studying meteorology, that's pretty vague. Any knowledge of statistics I have isn't applicable at all in any way because you were so vague that there's no possible way I could tell how to apply them or even what specific statistics you're referring to. A lot of statistics in QM can be described using waves, bell-like curves, or a cross of the two in a sine wave which a horizontal asymtote at x=0 with different modes, light in a box tends to act like a standing wave.

 

 

 

Look, I don't know what you understand and don't understand. I'm not telepathic. If you ask a question about the UV catastrophe, for some detail, I have to assume you have some familiarity with what the UV catastrophe was. But if you don't, you should be asking a different question. Or reading a book and learning the basics. I don't owe you anything here. For you to complain about answers, when you apparently haven't put in the effort on your part, galls a bit.

UV catastrophe happened when scientists projected that the radiation of a black body object would give off more UV light and higher frequencies as they increased the temperature, and were wrong, I knew that before coming into this thread.

Saying "there's new statistics, therefore because I mentioned these new statistics you must now know everything about how those statistics are applied and their meaning and where they came from" is hardly a scientific description at all.

Edited May 24, 2013 by SamBridge

[swansont]

There's one connection right there. The thermal spectrum is continuous , energy states of atoms aren't, that's bound to cause some problems.

That they have nothing in common is a connection?

 

No it's your fault that you were vague and purposely chose not to give any details.

Again: I CAN'T READ YOUR MIND. I don't know what details you need, and I am not going to write a book, or even a chapter, on any topic on the off chance that you might to need to know all of it. It's simply not going to happen. Maybe someone else is willing to do that, just for you. But since people already do it for a wider audience (they're called books), it's a huge duplication of effort.

 

Other peoples' laziness is not my fault.

[SamBridge]

 

That they have nothing in common is a connection?

 

Well until you could prove by being specific that they aren't related, I'll just assume what I'm saying, since I have no other concise basis to think otherwise.

 

 

 

 

 

 

Again: I CAN'T READ YOUR MIND. I don't know what details you need

So what? That doesn't mean you can't give an answer, and besides there's more than just me who's viewing this topic, there's probably plenty of other people who have similar questions, if somehow in some way you don't know what specifically I am asking, just assume I am a layman who's googled a few things who has passed high-school.

Edited May 24, 2013 by SamBridge

[katesisco]

Miles Mathis has a new paper on the net: Blackbody Radiation Is The Charge Field

R Feynman said that the reason you don't understand something is that the person explaining it to you doesn't understand it.

[EdEarl]

Clearly, a great learner will learn little from an ignorant teacher.

 

A great teacher can lecture in English to someone who only understands Latin, but little or no learning will occur.

 

The process works best with a great teacher and a great learner.

[swansont]

Miles Mathis has a new paper on the net: Blackbody Radiation Is The Charge Field

 

A link would be useful here.

 

R Feynman said that the reason you don't understand something is that the person explaining it to you doesn't understand it.

 

Also here.

 

 

Feynman has said a few things that are almost the opposite of this, which raises some doubt. Such as:

 

https://www.youtube.com/watch?v=wMFPe-DwULM

 

"I really can’t do a good job, any job, of explaining magnetic force in terms of something else that you’re more familiar with, because I don’t understand it in terms of anything else you’re more familiar with."

(at the very end)