Nature of astrophysics (4) - physics and reality

[Nereid]

In my last thread in the Nature of Astrophysics series (Nature of astrophysics (3) - astronomy and reality), 'electromagnetic radiation' is central.

But what is the relationship of 'electromagnetic radiation' to reality?

We can say that 'light is a form of electromagnetic radiation', but that then raises the question 'what is light?' and 'what are some other forms?' and 'how do the other forms differ from light?' and ... and 'what does giving labels to things have to do with reality?' ... and so on.

Among those questions might be 'is light a wave? or a particle?', or, somewhat re-phrased, 'is light REALLY a wave? or, in reality, a particle?'

You might have heard that light consists of, or is composed of, or ... photons.

Imagine the following as a multiple-choice question in an exam:

Is the photon
a) a wave?
b) a particle?
c) both a wave and a particle?
d) neither a wave nor a particle?
e) none of the above?
f) all of the above?
For extra credit, explain your anwer.

(Note: the question does not include 'in reality', as in 'Is the photon, in reality,' but lots of people would assume that's what the questions means)

How would you answer?

Here's one way to think of this topic, an approach that I suspect is quite common among physicists: the only 'reality' which counts, in physics, is the objective, independently verifiable results of experiments/observations. Treating theories (of physics) as distilling some essence of reality, and models (based on one or more theories of physics) as some approximation of reality, is no more than a convenience (of course, by definition, theories which are internally inconsistent, and/or inconsistent with relevant experimental/observational results, cannot be accurate distillations of reality). The 'true' nature of reality is something for philosophers to worry about; it is not a question that physics can address, in any meaningful way.

[mharratsc]

It never did seem proper to me the notion of the 'duality' of a photon- that it behaves as both a particle (which should be a conductor) and a waveform (which should be considered as force)- is there a rational explanation how it could be both?

By contrast- if you have an 'aether', then EM radiation can go back to being a pure waveform, and the whole 'slit experiment' and 'spooky action at a distance' goes out the window, because you could simply be splitting a waveform rather than trying to explain how a particle can be in two places at once, and you no longer have the whole 'duality' thing to contend with.

Of course, this falls back on the Michaelson-Morley experiment, and whether you believe it was incontrivertible proof as some do, or believe that it wasnt as do some others. :\

[Nereid]

It never did seem proper to me the notion of the 'duality' of a photon- that it behaves as both a particle (which should be a conductor) and a waveform (which should be considered as force)- is there a rational explanation how it could be both?

Yes, many.

One goes something like this: 'wave' and 'particle' are concepts invented by humans, the universe (photons in this case) is under no obligation to conform to human intuitions; the photon is what it is (webolife should enjoy this answer, I think).

Another: QED provides a description of 'photons'; if you solve the various equations to predict observable behaviour (i.e. what you should expect from certain experiments or observations), then go do/make the experiments/observations, what you see will match what you predict (to within the uncertainties), every time.

By contrast- if you have an 'aether', then EM radiation can go back to being a pure waveform, and the whole 'slit experiment' and 'spooky action at a distance' goes out the window, because you could simply be splitting a waveform rather than trying to explain how a particle can be in two places at once, and you no longer have the whole 'duality' thing to contend with.

Are you sure about this Mike? I mean, aether plus EM radiation (per Maxwell's equations) would be wholly quantitative, wouldn't it? and so this could be easily (well, if you can handle the math) checked, objectively, couldn't it?

Do you have a reference where such an objective, quantitative, account is given?

Of course, this falls back on the Michaelson-Morley experiment, and whether you believe it was incontrivertible proof as some do, or believe that it wasnt as do some others. :\

Again, do you have any references? For the latter I mean, and ones which address the many, many repeats and versions of the Michaelson-Morley experiment (MMX) that have been published over the years (not just the original MMX).

[mharratsc]

No, sorry. :\

I am not usually such a combatant that I keep oodles of links handy for stuff like this. The best that I could tell you off the top of my head is that I've read (if I remember right) two separate accounts of each- confirmation, and contradiction.
Regarding my posting questions under your new threads here- it's only due to the courteous demeanor that both you and Physicist display that has really drawn me out to ask particular questions regarding more 'traditional' viewpoints of some of this material as I have been recently... for which I thank you both kindly! I really do appreciate your patience with my (sometimes laborious) attempts to understand both sides of some of these discussions.

[Nereid]

No, sorry. :\

I am not usually such a combatant that I keep oodles of links handy for stuff like this. The best that I could tell you off the top of my head is that I've read (if I remember right) two separate accounts of each- confirmation, and contradiction.

Well, I do hope it's got little (or nothing) to do with being combatitive, and a lot (or all) to do with being objective, and making sure there's independent verification.

Having been very active in BAUT's ATM section for a long time, I've read quite a lot of material that seems to resemble what you posted earlier (about MMX); one thing I learned from the discussions that ensued is that what you find on the internet, in 'soft' form (i.e. little to no quantitative content) is, er, 'selective', shall I say.

As I said in my earlier post, a great many MMX have been done and their results published; however, there seems to be a quite widespread perception (at least among those who 'think alternative', may I write), that there was only one or two (Dayton Miller's experiment seems to be often mentioned).

Regarding my posting questions under your new threads here- it's only due to the courteous demeanor that both you and Physicist display that has really drawn me out to ask particular questions regarding more 'traditional' viewpoints of some of this material as I have been recently... for which I thank you both kindly! I really do appreciate your patience with my (sometimes laborious) attempts to understand both sides of some of these discussions.

You're more than welcome Mike!

As I think I may have said in a post elsewhere in this Forum, there are no stupid questions! By all means, ask away!!

[Aardwolf]

Shouldn't the MM experiment be done in a true vacuum to be certain of its accuracy? The light has already been slowed by the atmosphere so it isn't possible to measure the velocity through the ether. Has one been done in a true vacuum?

[jjohnson]

Finding a 'true vacuum' is a challenge. The very best vacuum we can construct here on Earth is not as good as the interplanetary medium, which in turn is more densely populated with matter and energy than the interstellar medium. There are great voids estimated to lie between galaxy clusters and in "places" beyond what is called The Great Wall, where matter is thought to be extremely sparse. Space is never completely empty, of fields, photons, neutrinos or other species. How good a vacuum should the MM experiments be done in? How does one pick a cut-off point?

You can check Wikipedia for current estimates of particle densities in these various "media" for an idea of how sparse is it can be. If a number is given in "per cubic centimeter (cm^-1), multiply by 1 million to get the number of particles per cubic meter, which is easier (for me) to imagine.

Jim

[Aardwolf]

I guess my point is that you can't measure the effect of the ether on light while light is propogating in a medium. That medium will force light to propagate at a fixed slower speed. A null result should be expected from the experiment whether there's an ether or not.

[webolife]

Thanks again for the nod, Nereid. I do appreciate that a "photon" is a figment of human imagination.
In answers to altonhare, Plasmatic, and others about this, I've tried to describe the conical vector fields I believe are responsible for "light action", in order to define "photon", or to prove that "my" light is an "object" by their definition, but I'm afraid that one person's imagination is another person's rubbish... That being said, confessed or denied, whichever you prefer, I believe that light is a centropic pressure of same fundamental geometry as gravitation, directed toward the "source" as a sink, and that as we observe the effect in our retina, the cause is virtually simultaneously happening across the universe. This does not seem at all "spooky" to me, as the same observation is made of gravitation... no "stuff" has to flow from the earth to the moon and back in order for the moon to be held in its orbit, nor any other satellite, planet, star, galaxy, or... yet we feel/observe the effect of the gravitational field instantly. I find the same observation for light. It is impossible to observe light "flowing" from point A to B; any time an observation is made, the light is "already" there. While this may be justified by the theoretical limitations of "c", it is simply an inescapable attribute of light, and all light actions. So I believe it is as you said, just what light IS. It's not hard to speak of it as part of the fabric of space, as also the alleged "aether" is regarded, but it is also not difficult for me to describe it as a natural consequence of the geometry of the universe, understood as soon as one is able to acknowledge the "finiteness" of the universe. What we see anywhere/everywhere is at all times measurable, quantifiable, finite, and to imagine it otherwise is entirely beyond the realm of physics. Most around these boards philosophically hold to a view of matter and energy as "eternal", and altonhare and Plasmatic, et.al, feel compelled to this by their particular view of causation, or of objectivism [see other older threads for more of that debate]. I mention those names because of the considerable amount of dialogue they contributed to this view elsewhere, and in recognition to the contrast of my own view. Even using the word "quantifiable" one presumes upon the finiteness of physics from the outset. Is reality then finite? or eternal?
Or is it just physics that is bound by this limitation? Must physics measure a "c-rate" for light, even if in reality, it is an instantaneous cause/effect action?

[Nereid]

Aardwolf, jjohnson,

What is "a true vaccuum"? What is "light"? What is "velocity"? What is "the ether"? What is "a medium"? What is "propogating"?

And so on.

Do any of these things exist "in reality"?

More to the point, in terms of doing physics, does it matter what "reality" is, other than that which can be "seen" using experiments and observations?

[Nereid]

Or is it just physics that is bound by this limitation? Must physics measure a "c-rate" for light, even if in reality, it is an instantaneous cause/effect action?

It seems - to me at least - that you have just agreed with me, big time!

"Reality" is something for philosophers to worry about; when you do physics all you are concerned with is what results you get when you make observations/do experiments.

Well, you are also very much concerned with how consistent those results are with your models and theories ... but you freely acknowledge that the relationship between any theories in physics and reality is not your cup of tea (beyond questions of consistency).

[Lloyd]

when you do physics all you are concerned with is what results you get when you make observations/do experiments.

* What most scientists seem to be concerned about is how much salary they get for their work, just like most other folks. What real scientists are concerned about is what they learn about reality from their observations and experiments [and how this knowledge may help to benefit humanity].

[JaJa]

"Reality" is something for philosophers to worry about; when you do physics all you are concerned with is what results you get when you make observations/do experiments"

With respect this is why there is such a massive divide between the two disciplines. What the modern scientist is lacking from his/her earlier counterparts (in my very humble opinion) is the ability or the desire to apply metaphysics, epistemological thinking, philosophical logic (not just math logic), aesthetics and meta-ethics without fear that it might somehow de-value observations/experiments.

"Reality" is something for philosophers to worry about;

Fair enough if we have a physicist/philospher or astronomer/philosopher working within the same team but that's just not the case.

JJ

[Nereid]

"Reality" is something for philosophers to worry about; when you do physics all you are concerned with is what results you get when you make observations/do experiments"

With respect this is why there is such a massive divide between the two disciplines.

First off, I made a mistake.

Despite what I had intended to do - and, I hope, actually succeeded to some extent - in this series was to separate the people (scientists, physicists, philosophers, etc) from the subject (astronomy, physics, and philosophy, in this case).

I should have written "Reality" is a philosophical topic, part of philosophy, not physics.

Sorry.

What the modern scientist is lacking from his/her earlier counterparts (in my very humble opinion) is the ability or the desire to apply metaphysics, epistemological thinking, philosophical logic (not just math logic), aesthetics and meta-ethics without fear that it might somehow de-value observations/experiments.

I'm not sure how any of this would, or could, help (and I do not know what "philosophical logic (not just math logic)" is! I must remember to add it to my 'foundations' piece); in any case, perhaps this is more relevant in the science and scientists thread?

[JaJa]

I really don’t mind what thread this gets sectioned under to be honest.

I should have written "Reality" is a philosophical topic, part of philosophy, not physics.

Reality is a topic for any enquiring mind. Sir Roger Penrose is a physicist who likes to indulge in philosophical thought, although it tends to go by the name of theoretical physics. Stephen Hawking, Michio Kaku and Brian Greene all speculate away in the realm of theoretical (Math based) PHYSICS.

I'm not sure how any of this would, or could, help...

Are you sure about this? My first post was tongue-in-cheek...

Cosmology which is the study of the universe and our place in it is a traditional meta-physics discipline. Physical cosmology deals with the physical origins and evolution of the universe – however, the likes of Penrose, Hawking, Kaku and Greene (all physicists) regularly cross over to meta-physics because they seek to explain the origin of the Universe (Big Bang) and they try to understand its cause (beginning with an apparent singularity). In addition to this, trying to understand the ultimate material components of the universe (i.e. strings, CERN and the GOD particle) is meta-physical. Trying to understand the ultimate reason for the existence of the universe, as in does the cosmos have a purpose (i.e. gravity is the LAW and spontaneous creation is a consequence of such a LAW) is meta-physics.

Perhaps we could rename theoretical physics or cosmology - philosophy?

Epistemology is generally concerned with the nature and capacity of knowledge which in this case would be DATA collected from observation and experimentation. Epistemology would then look at the relationships between truth and the beliefs and the justifications we then apply to the data, i.e. my idea about how this data is interpreted is right and yours is wrong in which case I will defend my beliefs by banning your theory from publication in certain journals so no one else can get to read it.

Philosophical logic I am sure you have already googled...

JJ