I wonder if any of the more scientifically minded people on here could help me, please.

[Horsa]

I've just been reading a thread on a science forum I'm on about basic relativity. I understand most of it & found it interesting. I found some information about Cherenkov's radiation interesting & understood it but I've got 2 questions which I'd be very grateful if someone who is more scientifically minded than me could answer 2 questions for me, please. (I normally post my poems in the "your talent" section). The questions I want to ask are;-
1. What is the frame of reference for light where relativity is concerned?
2. What is the Lorentz boost?

I guess we could use this thread for other science questions we'd like answers to & anyone who knows the answers could help out. Just an idea.

 

[mrzz]

EA, quick answer (and quick answers are always deceptive in physics):

1) There is no special frame of reference for light in relativity. The point of the theory is that all reference frames are equivalent, one principle of the theory is that in all those reference frames the speed of light is the same. Furthermore, there is no reference frame which can (roughly speaking) move along with the light (as you can have a reference frame that moves along with a plane or a car, for example).

2) Maybe the word "boost" is misleading. This is not meant to be a "physical" thing. It is basically a name for a coordinate system change. For example, if I am standing by a road, I see cars passing by at given speeds. A passenger in one of those cars see the others with different speeds with respect to those I see. If he is at 80 Km/h (according to me), he sees the guys who are cruising at 100 KM/h at 20 KM/h relatively to him. This "change" from 20 KM/h to 100 Km/h, that is, the change from what one observer sees to what another, in a different reference frame, sees, is a "boost", and the one I described, which is the "classical" physics one, is the Galilean boost. It sounds like common sense, but it is a reflection of how Newtonian physics describe reality. In other words, all I wrote above is valid in the Newtonian physics paradigm.

In relativity things do not work like that. The change from one coordinate system (reference frame) to another is more complex (although in the example above it would give answers that numerically are 99,999999999% similar to the one given). This change not only gives numerical values which are different but also reflects on how time is measured by both observers. All this is described (or comprised) in the term "Lorentz boost" (because it was Lorentz who came up with this before Einstein).

Hope it helps!

 

[Horsa]

EA, quick answer (and quick answers are always deceptive in physics):

1) There is no special frame of reference for light in relativity. The point of the theory is that all reference frames are equivalent, one principle of the theory is that in all those reference frames the speed of light is the same. Furthermore, there is no reference frame which can (roughly speaking) move along with the light (as you can have a reference frame that moves along with a plane or a car, for example).

2) Maybe the word "boost" is misleading. This is not meant to be a "physical" thing. It is basically a name for a coordinate system change. For example, if I am standing by a road, I see cars passing by at given speeds. A passenger in one of those cars see the others with different speeds with respect to those I see. If he is at 80 Km/h (according to me), he sees the guys who are cruising at 100 KM/h at 20 KM/h relatively to him. This "change" from 20 KM/h to 100 Km/h, that is, the change from what one observer sees to what another, in a different reference frame, sees, is a "boost", and the one I described, which is the "classical" physics one, is the Galilean boost. It sounds like common sense, but it is a reflection of how Newtonian physics describe reality. In other words, all I wrote above is valid in the Newtonian physics paradigm.

In relativity things do not work like that. The change from one coordinate system (reference frame) to another is more complex (although in the example above it would give answers that numerically are 99,999999999% similar to the one given). This change not only gives numerical values which are different but also reflects on how time is measured by both observers. All this is described (or comprised) in the term "Lorentz boost" (because it was Lorentz who came up with this before Einstein).

Hope it helps!

Thank you very much for your explanation, Mrzz. You made everything so easy to understand. It's fascinating. Now I can put it all together. I've had a fascinating couple of days.

 

[Horsa]

I couldn't be bothered to write my take on it but in case someone else would find it interesting & they're not familiar with it I decided to share these links.

https://www.space.com/17661-theory-general-relativity.html
https://en.wikipedia.org/wiki/Cherenkov_radiation

I hope you find it as fascinating as I did.

 

[mrzz]

Thank you very much for your explanation, Mrzz. You made everything so easy to understand. It's fascinating. Now I can put it all together. I've had a fascinating couple of days.

You´re welcome. Physics is fascinating.

 

[Horsa]

You´re welcome. Physics is fascinating.

It is indeed.

 

[Horsa]

1 of these questions isn't quite a science question but the other is. I wonder if anyone can help me please.

1. Does the family name for the group of animals including horses, ponies, zebras, donkeys & mules equine or equidae come from the modern horses scientific name equus caballus or 1 of the horses ancestors equus sylvestris, please?
2. 1 of the horses ancestors equus sylvestris had 66 chromosomes. The modern horse equus caballus has 64 chromosomes. What happened to the other 2 chromosomes, please?

 

[mrzz]

@Horsa, I remembered you had opened this thread (by the way I do not know a good answer for the above questions), and they seem to be a good place to put the ones you asked on the "what is art" thread.

Your questions:

1) What is low energy applied nuclear physics?

2) What is the difference in scale between nuclear physics & low energy applied nuclear physics, please?

3) What is Thomas Khun's approach to scientific evolution?

4) Heisenberg Principle, what is that please?

5) Chris mentions the difference between quantum mechanics & classical mechanics. What is the difference in scale, please?


6) mrzz mentioned ad hoc energy quantization. What is that please?


Wow! There is stuff for a few books here, let's see how far I can go.


1) What is low energy applied nuclear physics?

Answer: There was a context behind this example -- I wanted to highlight a given sub-area of a more general branch of physics. Nuclear physics deals with the nuclei of atoms. Physics, in general, is divided in its theoretical, experimental and applied branches. Applied physics is roughly speaking a way to approach physics which is focused on technological and/or practical applications of physics, so you can have applied nuclear physics. The guys that invented the nuclear magnetic resonance machines (heavily used for medical diagnoses) where doing applied nuclear physics. Also, nuclear physics can be roughly divided in low energy and high energy nuclear physics. Roughly again, low energy NP is a bit easier to deal with, as you need to take less into account effects which are only fully explained using relativity theory. High energy phenomena are even more complicated, and ask for a more complicated theoretical treatment. I am not even sure if there is a definite low energy applied nuclear physics field. I wanted to give an example of a branch within a branch within a branch.


2) What is the difference in scale between nuclear physics & low energy applied nuclear physics, please?

Answer: the difference would be between low and high energy nuclear physics. It all goes down to the average energy involved in the reactions. It is of little help just to give you numbers, it is more important to say that in some cases in can easily have more than a thousand times more energy than others. It is a whole different ball game.

3) What is Thomas Khun's approach to scientific evolution?

Answer: Thomas Kuhn discusses history of science, and he basically states that science evolves in two different ways: "normal" science, when scientists work within a given paradigm, and basically fill the gaps and study the details and/or consequences of a given field. "Revolution", when someone comes and breaks the old paradigm, bringing new ideas that solve a whole set of questions that the old one could not deal with. Classical (Newtonian) mechanics, Theory of Evolution, Relativity, Quantum Mechanics, they are all examples of scientific revolutions in Kuhn's sense.

 

[mrzz]

I can go one more:

4) Heisenberg Principle, what is that please?

Answer: It is the cornerstone of a very important physical theory called Quantum Mechanics. This theory is built on very different concepts than, say, "ordinary" Newtonian mechanics. The theory evolved a lot in the last 100 years, so the original Heisenberg phrasing is a bit "old fashioned" today, but the principle basically says that one cannot, at the same time, determine, with total accuracy, the position and the linear momentum of a physical particle. Remember that "momentum" is something related to velocity, on high school you learn that momentum p = mv (mass times velocity), which is a particular case but good enough here. This principle is also known as uncertainty or indeterminacy principle.

There are a lot of different ways to interpret this. One is that "we cannot know" both position and momentum at the same time (the epistemological approach), other is that both quantities are not defined at the same time (the ontological approach). Physics has more and more leaned to the second option. There is a vast literature on the subject, also on the internet, but there is a lot of bad stuff out there, so take a lot of care and check the source of what you read.

 

[Horsa]

@Horsa, I remembered you had opened this thread (by the way I do not know a good answer for the above questions), and they seem to be a good place to put the ones you asked on the "what is art" thread.

Your questions:

1) What is low energy applied nuclear physics?

2) What is the difference in scale between nuclear physics & low energy applied nuclear physics, please?

3) What is Thomas Khun's approach to scientific evolution?

4) Heisenberg Principle, what is that please?

5) Chris mentions the difference between quantum mechanics & classical mechanics. What is the difference in scale, please?


6) mrzz mentioned ad hoc energy quantization. What is that please?


Wow! There is stuff for a few books here, let's see how far I can go.


1) What is low energy applied nuclear physics?

Answer: There was a context behind this example -- I wanted to highlight a given sub-area of a more general branch of physics. Nuclear physics deals with the nuclei of atoms. Physics, in general, is divided in its theoretical, experimental and applied branches. Applied physics is roughly speaking a way to approach physics which is focused on technological and/or practical applications of physics, so you can have applied nuclear physics. The guys that invented the nuclear magnetic resonance machines (heavily used for medical diagnoses) where doing applied nuclear physics. Also, nuclear physics can be roughly divided in low energy and high energy nuclear physics. Roughly again, low energy NP is a bit easier to deal with, as you need to take less into account effects which are only fully explained using relativity theory. High energy phenomena are even more complicated, and ask for a more complicated theoretical treatment. I am not even sure if there is a definite low energy applied nuclear physics field. I wanted to give an example of a branch within a branch within a branch.


2) What is the difference in scale between nuclear physics & low energy applied nuclear physics, please?

Answer: the difference would be between low and high energy nuclear physics. It all goes down to the average energy involved in the reactions. It is of little help just to give you numbers, it is more important to say that in some cases in can easily have more than a thousand times more energy than others. It is a whole different ball game.

3) What is Thomas Khun's approach to scientific evolution?

Answer: Thomas Kuhn discusses history of science, and he basically states that science evolves in two different ways: "normal" science, when scientists work within a given paradigm, and basically fill the gaps and study the details and/or consequences of a given field. "Revolution", when someone comes and breaks the old paradigm, bringing new ideas that solve a whole set of questions that the old one could not deal with. Classical (Newtonian) mechanics, Theory of Evolution, Relativity, Quantum Mechanics, they are all examples of scientific revolutions in Kuhn's sense.

I thought I was doing quite well only needing to ask you 6 questions. I think next time I'll be nice to you & keep my questions to myself. It took me a long time before I'd even think about asking questions. For years I didn't bother asking questions because where I come from asking questions was seen as a sign of stupidity unless you were setting a quiz or you taught for a living. I was forever answering other people's questions but never asking other people questions.

Thank you very much for your answers @mrzz.

Question 1. I understood the context behind what you said but not this particular example & knew there would be some difference in the difficulty level of scale. Although I understood most of what was said, I'm quite strict with myself & feel the need to try to understand everything. I was actually in 2 minds as to whether I should ask this question. I guess to use another example of a science within a science within a science I could have used equine anatomy is a science which is part of zoology which is part of biology. You have a way of making complex things sound easy though I knew some of what you said like what is involved in physics & we had to learn about atoms, molecules, protons, electrons & nuclei but didn't go on the proper sub-division names for physics. I guess I just thought "this is hard. I can't get it". I guess I'll have to re-read that basic relativity stuff which I found fascinating. I also realised that if I'd have thought about it I could probably have come up with an answer.

Question 2. You're saying that it is a difficult job to quantify the difference.

Question 3. I had an idea that scientific evolution would be about the history of science. It's just when you mentioned Kuhn's scientific evolution I wondered what his theory was. Thank you very much for the answer. It makes sense really.

 

[Horsa]

I can go one more:

4) Heisenberg Principle, what is that please?

Answer: It is the cornerstone of a very important physical theory called Quantum Mechanics. This theory is built on very different concepts than, say, "ordinary" Newtonian mechanics. The theory evolved a lot in the last 100 years, so the original Heisenberg phrasing is a bit "old fashioned" today, but the principle basically says that one cannot, at the same time, determine, with total accuracy, the position and the linear momentum of a physical particle. Remember that "momentum" is something related to velocity, on high school you learn that momentum p = mv (mass times velocity), which is a particular case but good enough here. This principle is also known as uncertainty or indeterminacy principle.

There are a lot of different ways to interpret this. One is that "we cannot know" both position and momentum at the same time (the epistemological approach), other is that both quantities are not defined at the same time (the ontological approach). Physics has more and more leaned to the second option. There is a vast literature on the subject, also on the internet, but there is a lot of bad stuff out there, so take a lot of care and check the source of what you read.

Thank you very much for your information. I understand. You have the ability to make difficult things seem easy.

Are you trying to tell me I've got skills & resources so should use them? O.K.

 

[Chris Koziarz]

inside the sun

@Horsa, I remembered you had opened this thread (by the way I do not know a good answer for the above questions), and they seem to be a good place to put the ones you asked on the "what is art" thread.

Your questions:

1) What is low energy applied nuclear physics?

2) What is the difference in scale between nuclear physics & low energy applied nuclear physics, please?

3) What is Thomas Khun's approach to scientific evolution?

4) Heisenberg Principle, what is that please?

5) Chris mentions the difference between quantum mechanics & classical mechanics. What is the difference in scale, please?


6) mrzz mentioned ad hoc energy quantization. What is that please?


Wow! There is stuff for a few books here, let's see how far I can go.


1) What is low energy applied nuclear physics?

Answer: There was a context behind this example -- I wanted to highlight a given sub-area of a more general branch of physics. Nuclear physics deals with the nuclei of atoms. Physics, in general, is divided in its theoretical, experimental and applied branches. Applied physics is roughly speaking a way to approach physics which is focused on technological and/or practical applications of physics, so you can have applied nuclear physics. The guys that invented the nuclear magnetic resonance machines (heavily used for medical diagnoses) where doing applied nuclear physics. Also, nuclear physics can be roughly divided in low energy and high energy nuclear physics. Roughly again, low energy NP is a bit easier to deal with, as you need to take less into account effects which are only fully explained using relativity theory. High energy phenomena are even more complicated, and ask for a more complicated theoretical treatment. I am not even sure if there is a definite low energy applied nuclear physics field. I wanted to give an example of a branch within a branch within a branch.


2) What is the difference in scale between nuclear physics & low energy applied nuclear physics, please?

Answer: the difference would be between low and high energy nuclear physics. It all goes down to the average energy involved in the reactions. It is of little help just to give you numbers, it is more important to say that in some cases in can easily have more than a thousand times more energy than others. It is a whole different ball game.

3) What is Thomas Khun's approach to scientific evolution?

Answer: Thomas Kuhn discusses history of science, and he basically states that science evolves in two different ways: "normal" science, when scientists work within a given paradigm, and basically fill the gaps and study the details and/or consequences of a given field. "Revolution", when someone comes and breaks the old paradigm, bringing new ideas that solve a whole set of questions that the old one could not deal with. Classical (Newtonian) mechanics, Theory of Evolution, Relativity, Quantum Mechanics, they are all examples of scientific revolutions in Kuhn's sense.

Great responses, mrzz.
It's my turn to contribute to the answers, as much as my knowledge goes.
1) What is low energy applied nuclear physics?
As you noted, it's abount practical nuke applications. MRI, as you recall is indeed "practical" and can be called "low energy" according to your definition, because to describe radioactive decay of an isotope used in medical imaging here, we don't need relativity theory. But the fact MRI process is "low energy" is rather obvious, a name "applied nuclear physics" would be sufficient. So this example does not illustrate, why a specialised field in question was created to start with.The answer to this latest question is: since we understood the reaction within the sun, we wanted to recreate it in controlled conditions, without a need for high energy input, thus benefiting from thermonuclear energy right here in our hands, and not 150 giga metres away. Without high energy input, it meant that the "artificial sun" would be cold (possibly even at room temperature) rather than as hot as a real sun (million degrees). The idea was called "cold fusion":
https://en.wikipedia.org/wiki/Cold_fusion
As you can read, various apparatuses have been created with various chemical compositions, where the researchers have claimed to obtain Helium from Deuterium fusion (the same reaction as inside the sun) but with only few eV (electronoVolt) per nuclei energy input (some pressurisation I guess). Deuterium is "heavy hydrogen" with an extra neutron in addition to the proton. Water composed of Deuterium is also called "heavy water". Typical "hot" nuke reaction such as Deuterium fusion inside the sun requires several MeV energy input per nuclei. As you can read in the above wiki, the very first claim to obtain Helium from heavy water came in 1989, so almost 30y ago. But the experiment failed to reproduce. Since then, "Cold Fusion" term feel into disgrace, their researchers found harder and harder to obtain grants. Eventually, they decided to rename their specialised field to low-energy nuclear reactions or condensed matter nuclear science and herein is the answer how the field in question came about. In general, it deals with nuke reactions where energy input is up to few keV per nuclei. It's quite an obscure area today (only few hundred researchers) and they may not recreate deuterrium fusion at room temperature but who knows, they may find out some other nuke reaction that will bring virtually unbound, and revolutionise the global energy production.

2) What is the difference in scale between nuclear physics & low energy applied nuclear physics, please?
I've already answered it above. Tpical nuke reaction involves order of MeV energy input (the same order as the energy output, output should be more if we want to source our energy from it!), while "cold Fusion" researchers are trying to excite nuke reactions with just few eV (unrealistic IMO), up to say few keV (more realistic)

3) I cannot add anything to your answer. Thank you!

 

[Chris Koziarz]

I can go one more:

4) Heisenberg Principle, what is that please?

Answer: It is the cornerstone of a very important physical theory called Quantum Mechanics. This theory is built on very different concepts than, say, "ordinary" Newtonian mechanics. The theory evolved a lot in the last 100 years, so the original Heisenberg phrasing is a bit "old fashioned" today, but the principle basically says that one cannot, at the same time, determine, with total accuracy, the position and the linear momentum of a physical particle. Remember that "momentum" is something related to velocity, on high school you learn that momentum p = mv (mass times velocity), which is a particular case but good enough here. This principle is also known as uncertainty or indeterminacy principle.

There are a lot of different ways to interpret this. One is that "we cannot know" both position and momentum at the same time (the epistemological approach), other is that both quantities are not defined at the same time (the ontological approach). Physics has more and more leaned to the second option. There is a vast literature on the subject, also on the internet, but there is a lot of bad stuff out there, so take a lot of care and check the source of what you read.

All I can say is I agree. You are great science communicator, mrzz.

 

[Horsa]

inside the sun
Great responses, mrzz.
It's my turn to contribute to the answers, as much as my knowledge goes.
1) What is low energy applied nuclear physics?
As you noted, it's abount practical nuke applications. MRI, as you recall is indeed "practical" and can be called "low energy" according to your definition, because to describe radioactive decay of an isotope used in medical imaging here, we don't need relativity theory. But the fact MRI process is "low energy" is rather obvious, a name "applied nuclear physics" would be sufficient. So this example does not illustrate, why a specialised field in question was created to start with.The answer to this latest question is: since we understood the reaction within the sun, we wanted to recreate it in controlled conditions, without a need for high energy input, thus benefiting from thermonuclear energy right here in our hands, and not 150 giga metres away. Without high energy input, it meant that the "artificial sun" would be cold (possibly even at room temperature) rather than as hot as a real sun (million degrees). The idea was called "cold fusion":
https://en.wikipedia.org/wiki/Cold_fusion
As you can read, various apparatuses have been created with various chemical compositions, where the researchers have claimed to obtain Helium from Deuterium fusion (the same reaction as inside the sun) but with only few eV (electronoVolt) per nuclei energy input (some pressurisation I guess). Deuterium is "heavy hydrogen" with an extra neutron in addition to the proton. Water composed of Deuterium is also called "heavy water". Typical "hot" nuke reaction such as Deuterium fusion inside the sun requires several MeV energy input per nuclei. As you can read in the above wiki, the very first claim to obtain Helium from heavy water came in 1989, so almost 30y ago. But the experiment failed to reproduce. Since then, "Cold Fusion" term feel into disgrace, their researchers found harder and harder to obtain grants. Eventually, they decided to rename their specialised field to low-energy nuclear reactions or condensed matter nuclear science and herein is the answer how the field in question came about. In general, it deals with nuke reactions where energy input is up to few keV per nuclei. It's quite an obscure area today (only few hundred researchers) and they may not recreate deuterrium fusion at room temperature but who knows, they may find out some other nuke reaction that will bring virtually unbound, and revolutionise the global energy production.

2) What is the difference in scale between nuclear physics & low energy applied nuclear physics, please?
I've already answered it above. Tpical nuke reaction involves order of MeV energy input (the same order as the energy output, output should be more if we want to source our energy from it!), while "cold Fusion" researchers are trying to excite nuke reactions with just few eV (unrealistic IMO), up to say few keV (more realistic)

3) I cannot add anything to your answer. Thank you!

Thank you very much for your answer. That was fascinating. I understand.

 

[Chris Koziarz]

Time to answer this as it's product of my talk:
5) Chris mentions the difference between quantum mechanics & classical mechanics. What is the difference in scale, please?
Classical mechanics deals with macroscopic matter that we can observe and measure in time and space. The most common mass measure is gram (g).
QM deals with microscopic particles that we cannot accurately measure in time and space so we use probabilistic distributions to describe said microscopic world. How small is this world? The best perspective is given by Avogadro Number, wich is a number of atoms within 1 g of Hydrogen, equal to A=6.02×10e23.
https://en.wikipedia.org/wiki/Avogadro_constant
That's a hell lot, considering million to be 10e6, and billion 10e9.
You can also say that the mass of one proton or one neutron is 1g/A (an electron complementing Hydrogen atom is so light that we can ignore electron's mass here). Substances more complex than Hydrogen are accordingly heavier. For example Helium has 2 protons & 2 neutrons in its nuclei, so A atoms of He weigh 4g. And so on for more complex, heavier elements, like Carbon (12g or 13g - two stable isotopes, 14g - semi-stabe isotope), Oxygen - (two isotopes 16g or 18g), etc.
But how many particles/atoms of a given substance you need to stop bothering with QM to describe the properties of said piece of substance? The answer: depends, and I really don;t know because I'm not an expert in this field. What I do understand is, with sufficient number of atoms, the probabilistic distributions describing the properties of each individual atom average, according to the Bernoulli law of large numbers, into mean points in space, where we can use measures such as g and metres to describe the matter that we perceive. Given A number is so large, you can divide it by several order of magnitude (example average milions, or bilions of QM described particles) and still have a piece of matter "infinitely small" (e.g. 6.02x10e-14g of Hdrogen) for most practical purposes.

 

[Horsa]

Time to answer this as it's product of my talk:
5) Chris mentions the difference between quantum mechanics & classical mechanics. What is the difference in scale, please?
Classical mechanics deals with macroscopic matter that we can observe and measure in time and space. The most common mass measure is gram (g).
QM deals with microscopic particles that we cannot accurately measure in time and space so we use probabilistic distributions to describe said microscopic world. How small is this world? The best perspective is given by Avogadro Number, wich is a number of atoms within 1 g of Hydrogen, equal to A=6.02×10e23.
https://en.wikipedia.org/wiki/Avogadro_constant
That's a hell lot, considering million to be 10e6, and billion 10e9.
You can also say that the mass of one proton or one neutron is 1g/A (an electron complementing Hydrogen atom is so light that we can ignore electron's mass here). Substances more complex than Hydrogen are accordingly heavier. For example Helium has 2 protons & 2 neutrons in its nuclei, so A atoms of He weigh 4g. And so on for more complex, heavier elements, like Carbon (12g or 13g - two stable isotopes, 14g - semi-stabe isotope), Oxygen - (two isotopes 16g or 18g), etc.
But how many particles/atoms of a given substance you need to stop bothering with QM to describe the properties of said piece of substance? The answer: depends, and I really don;t know because I'm not an expert in this field. What I do understand is, with sufficient number of atoms, the probabilistic distributions describing the properties of each individual atom average, according to the Bernoulli law of large numbers, into mean points in space, where we can use measures such as g and metres to describe the matter that we perceive. Given A number is so large, you can divide it by several order of magnitude (example average milions, or bilions of QM described particles) and still have a piece of matter "infinitely small" (e.g. 6.02x10e-14g of Hdrogen) for most practical purposes.

Now I get you. Thank you very much for your answer.

 

[Chris Koziarz]

6) mrzz mentioned ad hoc energy quantization. What is that please?
I'm only about 90% sure, but I think mrzz meant discovery of fundamental QM equasion by Max Plank:
https://en.wikipedia.org/wiki/Planck_postulate
You can read my link above but it maybe hard to understand equasions therein.
In essence, Plank discovered that the Energy emitted by black body atoms (atoms "oscillate" when excited or "hot" and the oscillation can change to a "lower energy oscillation" and a photon is emitted as "radiative heat" in earthly conditions) is quantised and proportional to the wavelength of the emitted photons. By way of illustrative only example (numbers made up by myself, not from real world), say the smallest portion of energy one atom of a given substance can emit is 2eV and it corresponds to a wavelength of 1GHz. Plank postulated that said atom can only emit multiples of said energy, i.e. 4eV into wave of 2GHz, 6eV into 3GHz, etc. How did Max come up with his genious idea? As a result of spectroscopic measures. He noted the quantum frequencies in emission spectrum of pure substances, and hence his postulate. That's how QM revolution started. Then Neils Bohr picked it up and came up with his model of atom with "quantised" electron orbits. Then people started looking at spectra of various gasses and discovered why some gasses (CO2, O3, H2O) absorb/emit within room temperatres (greenhouse gasses) while other gasses (O2, N2) in higher temperature.(gasses transparent to greenhouse effect), and so on and on. Everything from a simple experiment with spectrometer by Plank in 1900 exactly...

 

[Horsa]

6) mrzz mentioned ad hoc energy quantization. What is that please?
I'm only about 90% sure, but I think mrzz meant discovery of fundamental QM equasion by Max Plank:
https://en.wikipedia.org/wiki/Planck_postulate
You can read my link above but it maybe hard to understand equasions therein.
In essence, Plank discovered that the Energy emitted by black body atoms (atoms "oscillate" when excited or "hot" and the oscillation can change to a "lower energy oscillation" and a photon is emitted as "radiative heat" in earthly conditions) is quantised and proportional to the wavelength of the emitted photons. By way of illustrative only example (numbers made up by myself, not from real world), say the smallest portion of energy one atom of a given substance can emit is 2eV and it corresponds to a wavelength of 1GHz. Plank postulated that said atom can only emit multiples of said energy, i.e. 4eV into wave of 2GHz, 6eV into 3GHz, etc. How did Max come up with his genious idea? As a result of spectroscopic measures. He noted the quantum frequencies in emission spectrum of pure substances, and hence his postulate. That's how QM revolution started. Then Neils Bohr picked it up and came up with his model of atom with "quantised" electron orbits. Then people started looking at spectra of various gasses and discovered why some gasses (CO2, O3, H2O) absorb/emit within room temperatres (greenhouse gasses) while other gasses (O2, N2) in higher temperature.(gasses transparent to greenhouse effect), and so on and on. Everything from a simple experiment with spectrometer by Plank in 1900 exactly...

I understand now. Thank you very much for the information.

 

[Chris Koziarz]

I understand now. Thank you very much for the information.

Oops, I deserve not just thanks for my elaboration, because I mispelled Max Planck's name as "Plank" within it. It's too late to edit, so I'll leave it with the remorseful erratum here: sorry!

 

[Horsa]

Oops, I deserve not just thanks for my elaboration, because I mispelled Max Planck's name as "Plank" within it. It's too late to edit, so I'll leave it with the remorseful erratum here: sorry!

Of course you deserve thanks. I asked a question. You answered it for me. I understand now. You made a simple spelling mistake. We're all human. We make mistakes even careless ones sometimes. You're being a bit harsh on yourself here. Forgive yourself. You don't have to apologise. (I know this sounds a bit rich coming from me.)