What is the Origin of Light ?

[timothy42b]

Actually, I find that the really great scientists - Hawking, Feynmann, Gerzon etc. - can give at least some sense of what these things are about in words that the 'layman' to understand.

If you want to really understand it, you have to do the math.

If you're content with getting the sense of it, and maybe leaving a couple of contradictions, the layman language is good enough fo 99% of us.

For m1469's purpose, three oversimplifications:

Light is commonly emitted when an electron drops from a higher energy orbit to a lower one, and gives up the extra energy as light.  What frequency light is emitted depends on how far it dropped.

For us to see color the light has to hit the three primary color receptors we have in the eye, and these are blue, red, and green.  (NOT what you were taught in art class).  I have fewer than average red cones, so I am mildly color blind like a lot of males.  Then the brain puts together the signals from the three types of cones and you perceive a color.

When light hits something it is absorbed and re-emitted through the same process.  If it hits an opaque solid like a brick it is emitted backwards.  If it hits glass it is emitted forward from molecule to molecule till it comes out the other end.  If it hits a mirror it is emitted backward in phase. 

[gyzzzmo]

Actually, I find that the really great scientists - Hawking, Feynmann, Gerzon etc. - can give at least some sense of what these things are about in words that the 'layman' to understand.

Hawking already has written good-to-read and well illustrated books like 'the universe in a nutshell'. Though, physics IS complicated, you cant just write down nonsense so retards can understand it. For example light, you need a decent knowledge of how molecules are build, how electrones behave and even something of Einsteins E=mc2 how mass, energy and light interact. And lots of other biological stuff how the eye translates lightreflections of items to understandable pulses for your brains. I wont even start about wave/partical duality lol.
Light is hard, not something for your 'layman' to understand :p

[prometheus]

Actually, there is a lot of math in physics that is surprisingly simple.

[gyzzzmo]

The maths might be simple, but most people dont have the 'freedom of mind' to combine that math with reality. They want stuff visualised before they can understand it, but how can you visualise stuff like duality or the concept of 'time'?

[timothy42b]

The maths might be simple, but most people dont have the 'freedom of mind' to combine that math with reality. They want stuff visualised before they can understand it, but how can you visualise stuff like duality or the concept of 'time'?

That is a subtly profound comment.

For physicists, and we engineers, and a number of other technical types, somewhere in the education process math BECOMES reality.  There is one-to-one correspondence with reality.  Math is "necessary and sufficient."

We forget that for most of the world math is parallel to reality, and not really required at all.  Math is neither necessary nor sufficient.  And if you're part of that population, you just aren't going to believe me. 

[leahcim]

Actually, I find that the really great scientists - Hawking, Feynmann, Gerzon etc. - can give at least some sense of what these things are about in words that the 'layman' to understand.

Indeed. Hence the popularity some of their books have. But not enough to actually make someone really understand and actually do something useful with the science or make a valid argument about which experiment / theorist or paper is correct.

For that you need to either use the model to make predictions, make observations, do experiments to test predictions or come up with modifications to current theory to explain discrepancies.

So you are making precisely my point. Any buffoon can read Black holes and baby universes or Brief history and (mis)understand it. I did that, I'm sure from the sales figures a lot more did, although I suspect more copies went unread. Give the ones that fancy they understand it, a copy of Hawking / Ellis the Large scale structure of space-time and ask them if it's correct.

For Feynman it's not even worth bothering with someone who claims to understand it, unless they're well on their way towards their own Nobel Prize.

If some layman claims to understand Feynman, they are claiming to be better than Feynman did himself. In truth, they probably can't spell his name properly.

But of course, those videos on the web https://vega.org.uk/video/subseries/8 are worth watching because physics and science in general is a fascinating subject for scientists and laymen alike.

Once something is known - or is the currently accepted pov, as you note, it's easy to explain, in layman terms, what was done and what it means, in prose. This is as profound as saying, once a proof is known in maths you can google for it or even, the more perverse, that maths is easy. Of course maths is relatively easy when someone else has figured it all out for us.

This is the equiv to that IQ test where you keep resending your answers until you get top marks, or have someone else point out the pattern - then it's easy - of course it is. The tricky part is getting top marks yourself, and then coming up with something new, where you can't check your answers against the teachers sheet, or on a website, at the end.

It's like Feynman's story of Fritz Houtermans telling his girlfriend he knew why stars shine - at the time that was something - he was the only one that did. The other day at the OU someone explained it, in precisely the layman terms you make with your point, to my 8 year old. Yes it's kid's stuff.

The QI effect works too. This is that pretty much everything everyone knows is, in fact, not actually the case. For example, Hawking talks in his popular books / lectures about an expanding universe [mentioning Einstein and his cosmological constant / steady state mistake along the way], but not one where the expansion is accelerating [because at the time that wasn't known]

Now, whatever conclusions / experiments and theories will advance from this observation about the expansion is science. That's what makes the subject fascinating and interesting from a layman pov - the work of scientists. Some will soon know all about it, and how easy the maths is, because they they know about google and wikipedia. You see scientists aren't as computer literate as them

[bob3.1415926]

Not all science is easily explainable. There is still a large cash prize for anyone who can write a summary of general relativity that is accessible to the layman. I studied General Relativity in the third year of a maths degree, and the mathematical concepts involved are really difficult.

Of course maths is relatively easy when someone else has figured it all out for us.

I thoroughly disagree with this. Lots of maths is never easy. Reading mathematical research papers is massively time consuming. A 20 page paper is liable to take a fortnight to read and much longer to understand fully. Even just the statement of a result (ignoring the proof) can take days to figure out what it actually means, even for someone highly educated in the subject. Trust me on this, I'm a recovering mathematician 

[prometheus]

leahcim is just attempting to make fun of someone.


E=mc^2 is a first degree polynomial.

The relation between energy and matter could be so much more complex. Yet it isn't. Why should it be simple and elegant like it is? Of course this kind of relation makes sense. But why would it have to make sense?

E of m could be a crazy function with discontinuity and infinities all over the place. It could take 60 different variables rather than 1.
The only way it would be simpler is with E=m. It's extremely puzzling and interesting to wonder about why this math is so simple. And pointless, of course. At least, so it seems.


That is the point I was trying to make.

[bob3.1415926]

leahcim is just attempting to make fun of someone.

Oops! I should've noticed 

E=mc^2 is a remarkably simple formula, although understanding that formula is more central to Einstein's Special Relativity, which is considerably easier than General Relativity.

You do realise of course that it couldn't possibly just be E=m, the units don't match up on both sides of that equation. (Good ol' dimensional analysis  )

I agree that it is puzzling and interesting, but it is far from pointless. That equation led to the atom bomb, amongst other things....

[timothy42b]

E=mc^2 is the most famous equation in the world, yet it has zero application for 99.9999% of us, and it doesn't matter that most of us don't really understand it.

On the other hand, the lesser known F=ma affects every single one of our lives all day long, and deserves to become famous. 

[richard black]

E=mc^2 is the most famous equation in the world, yet it has zero application for 99.9999% of us

Well, you might think that, but if you get any of your electricity from nuclear power you're wrong!

[leahcim]

Oops! I should've noticed 

No I wasn't. That wasn't sarcasm. It is, in general, /relatively/ easier to understand a proof than to come up with it in the first place.

Markedly so. But that wasn't saying maths is easy.

If you're a mathematician then I can't see how you disagree. Otherwise why did you bother reading other papers? You'd be better writing your own new proofs, getting the medals and the cash prizes and leaving the difficult task of reading what you'd written to others

[bob3.1415926]

I see your point now. I thought you were saying that once someone has proved a result, then it is easy for all to understand. Which is not the case, some proofs are horrendous. But yes, it is (usually - but not always) much easier to try to understand someone else's proof than to write your own.

I'm a (former) mathematician. Have just finished a PhD, but am now in the process of trying to sell my soul and move out of academia into the real world. Do you have a maths background then?

[leahcim]

Do you have a maths background then?

No, comprehensive education in Nottingham. I didn't even learn to shoot though.

[bob3.1415926]

Hehe. I did my PhD in Nottingham! Ghetto represent 

[teresa_b]

m1469, your question is interesting, although not really answerable by anyone.  There have been some nice explanations of wave/particle duality and photons, and how light is reflected/ absorbed. 

The origin of all light is unknown, maybe the Big Bang!  (Or Genesis, if you lean that way.) 

Whether light does indeed exist without an observer is not so obvious.  (Photons are emitted by atoms when electrons jump energy levels, but just what are photons without something to sense them??) Certainly color only exists to an observer, and is an outcome of receptors interpreting particular wavelengths (Like pitch in music--just wavelengths of energy until somebody hears them). 

Interestingly, if you shine a flashlight into a completely black room, you will see NO light!

A Buddhist view of light equates it with universal "consciousness" --light infuses the universe and makes it coherent, just as consciousness infuses everything (to some degree), resulting in levels of awareness.  These levels are of course very, very different whether you have a human brain and nervous system, or you are a mushroom. 

Teresa

[pies]

a

[timothy42b]

A Buddhist view of light equates it with universal "consciousness" --light infuses the universe and makes it coherent, just as consciousness infuses everything (to some degree), resulting in levels of awareness.  These levels are of course very, very different whether you have a human brain and nervous system, or you are a mushroom. 

Teresa

Some of the Buddhist view may be metaphorical, but not all, as this story about the Dalai Lama illustrates.

He believed, based on religious doctrine, that the moon emits its own light.  When it was explained to him that science says the moon actually just reflects light, he asked for evidence.  An astronomer showed him shadows in the craters.  He accepted the evidence and changed his mind. 

I would suspect adherents of many religions would have the opposite response. 

[teresa_b]

This thread is like physics 101, where every poster gets an F

Excuse me, evrything I said in my post is true.

Teresa

[timothy42b]

Photons are emitted by atoms when electrons jump energy levels, but just what are photons without something to sense them?

They would still be photons. 

Doh. 

This is not a difficult concept.

What happens when there are only two people left in the universe, and one of them closes her eyes?  Does the sun go to half power?

I think an F was generous.  Perhaps you can defend your assertions or the authority with which you pronounce them. 

[bob3.1415926]

They would still be photons. 

Doh. 

This is not a difficult concept.

What happens when there are only two people left in the universe, and one of them closes her eyes?  Does the sun go to half power?

I think an F was generous.  Perhaps you can defend your assertions or the authority with which you pronounce them. 

I think you've missed the point here. Science assumes this, but obviously it cannot prove it. There is not a single piece of data about the behaviour of unobserved photons. Not one. Anything science tells you about them is an assumption based in the assumed truthood of their theories, and not based on experimental data, as science is supposed to be.
It depends how much you are willing to trust science beyond the empirical results. Besides, if you have an understanding of quantum mechanics, you'll know that when we're not observing very small particles really really crazy things start to happen to them. Would they still be photons? Who can say. I know several (actively researching) quantum gravitists, and I think they would probably sit on the fence. A good scientist rarely accepts any assumption without first questioning it.
I'm assuming Teresa's question deliberately  nods at the ol' 'tree falls in the forest' question. I think philosophy of science is wonderful, but I'm going to stop typing before I turn this into an essay.

[teresa_b]

I think you've missed the point here. Science assumes this, but obviously it cannot prove it. There is not a single piece of data about the behaviour of unobserved photons. Not one. Anything science tells you about them is an assumption based in the assumed truthood of their theories, and not based on experimental data, as science is supposed to be.
It depends how much you are willing to trust science beyond the empirical results. Besides, if you have an understanding of quantum mechanics, you'll know that when we're not observing very small particles really really crazy things start to happen to them. Would they still be photons? Who can say. I know several (actively researching) quantum gravitists, and I think they would probably sit on the fence. A good scientist rarely accepts any assumption without first questioning it.
I'm assuming Teresa's question deliberately  nods at the ol' 'tree falls in the forest' question. I think philosophy of science is wonderful, but I'm going to stop typing before I turn this into an essay.

Exactly.  These particles have attributes when they are measured, but quantum physicists agree that they are in some sort of limbo when they are not.  They have a lot of possible explanations for this strange behavior--Bohr's Copenhagen (the particles don't exist until measured), Wheeler's many-worlds (they follow all paths in multiple universes), Feynman's sum-over-histories, Einstein's feeling that quantum theory was an incomplete description--and now we have string theory and other newer hypotheses that attempt to explain it--but as Feynman said, nobody really understands it. 

As for the Buddhist idea I mentioned, the idea of light/consciousness infusing the universe is quite compatible with many of quantum physic's quandaries, such as Bell's theorem of action-at-a-distance. 

Teresa

[timothy42b]

Exactly.  These particles have attributes when they are measured, but quantum physicists agree that they are in some sort of limbo when they are not. 

I think you are generalizing from concepts you don't really understand, and conflating physics and philosophy.

In the universe there are roughly one billion galaxies, each containing a billion stars, some with planets. 

None of them care whether Teresa observes or not.  While some religions teach that all of this was created just for man, man's influence seems to be less than predicted. 

[bob3.1415926]

Timothy, you shouldn't berate Teresa when it is you who is out of your depth in terms of understanding of physics. The observer is massively important in physics, not just philosophy. The introduction of an mid-way observer to a quantum-level experiment drastically changes the result. If this is your first introduction to quantum mechanics (QM) you will think I'm wrong, but I suggest you read up 'the two slit experiment'.

https://en.wikipedia.org/wiki/Two_slit_experiment#Quantum_version_of_experiment

The results are so counter-intuitive that it is really difficult to believe, but there has been thousands of experiments to back them up. This is accepted mainstream scientific theory.

Also as currently there is no accepted 'theory of everything' (string theory is refuted by many as pseudo-religious) you should not jump from from particles on a quantum level (photons) to massive phenomena such as stars, galaxies and planets, as the same rules do not apply. One is covered by QM, the other by General Relativity. These theories are vastly different.

Interesting point arises here. If you happened to read last week's New Scientist, there was a fascinating article about how we could have massively shortened the lifespan of the universe when we measured its rate of expansion. This is hardly accepted theory, but is definitely not without some merit. So maybe these stars do care about Teresa observing them after all......

[timothy42b]

So maybe these stars do care about Teresa observing them after all......

You could be right if she is talking QM.  I think she is not, this feels much more like postmodernism to me, but I will leave it to you. 

If you read her wording carefully I think you'd have to agree I'm technically correct but I don't want to get hung up on a semantic detail. 

[bob3.1415926]

I see your point. Her comment was overly strong. I would go so far to say '....may exist in some sort of limbo....'
Anyway, I feel I've hijacked this thread for long enough now, so I'll retire to my geeky little corner. 

[teresa_b]

You could be right if she is talking QM.  I think she is not, this feels much more like postmodernism to me, but I will leave it to you. 

If you read her wording carefully I think you'd have to agree I'm technically correct but I don't want to get hung up on a semantic detail. 

I was talking about QM.  I don't know how my comment, which referred to Bohr, Einstein, Feynman, Wheeler and Bell could possibly be construed as "postmodernist".  Those were physicists' interpretations of quantum theory observations.  (bob pi's line about The stars "caring" about me observing them is obviously just a teleological /metaphorical comment on the indeterminacy of quatum phenomena until they are observed. And thanks, bob, for coming to my defense.) 

Subatomic particles apparently have no attributes until observed.  Einstein did not believe this, (He subscribed to your viewpoint that there is an objective reality that is there whether it is measured or not) and thus called quantum theory "incomplete".  Other physicists have disagreed. 

But none of what I was discussing is New Age woo-woo, it is basic QT.  I mentioned Buddhism, which of course is not postmodernist, but 2500 years old.  It is a philosophy, I grant you that.  Their idea of a universal connectedness or onenness is compatible with Bell's Theorem which involves faster-than-light influence of one particle on another.  If everything that exists is a manifestation of the same universal field, it could be compatible with QM.

When you talk about some people believing the universe was created for man, that is either (a) religion, or (b) the "strong version" of the Anthropic Principle.  I didn't say that, nor do I believe it.  And it really has nothing to do with quantum indeterminacy.

Teresa

[thierry13]

I think you've missed the point here. Science assumes this, but obviously it cannot prove it. There is not a single piece of data about the behaviour of unobserved photons. Not one. Anything science tells you about them is an assumption based in the assumed truthood of their theories, and not based on experimental data, as science is supposed to be.
It depends how much you are willing to trust science beyond the empirical results. Besides, if you have an understanding of quantum mechanics, you'll know that when we're not observing very small particles really really crazy things start to happen to them. Would they still be photons? Who can say. I know several (actively researching) quantum gravitists, and I think they would probably sit on the fence. A good scientist rarely accepts any assumption without first questioning it.
I'm assuming Teresa's question deliberately  nods at the ol' 'tree falls in the forest' question. I think philosophy of science is wonderful, but I'm going to stop typing before I turn this into an essay.

One of the most enlighted post I heard from a scientific! Congrats on this !

[bob3.1415926]

One of the most enlighted post I heard from a scientific! Congrats on this !

Why thank you  <insert really bad pun about origin of light/being enlightened here>