Hi Hans

It depends what parameters of 'influence' or 'particles' you care to define.

By our best measure, photons pass through space uninfluenced by matter, other photons or intense electromagnetic fields unless they directly impact on the same.

However there is strong evidence that all photons are influenced by gravity - although there is no clear causation between gravity and photonic energy (there is plenty of correlation).

In the Einsteinian view it is assumed that red-shift is a function of the expansion of space time, rather than an interaction with gravity or other forces. But when there is a good case for gravity reducing the energy content of light then the space-time theory "does not compute".

So to answer your basic exam question, the answer is "No, a particle must be influenced, either by gravity or by space-time expansion - or by whatever other theory you defer to."

Dear Hans,

If you accept the idea that photons are electromagnetic in nature, and that electrons are also electromagnetic in nature, protons and neutrons and their known inner charged subcomponents also are electromagnetic in nature, and that macroscopic masses are made exclusively of atoms made from these particles then there is no way that any of them could even exist without interacting at least electrically, since they are then by definition minimally subject to Maxwell's first equation, which is Gauss's equation for the electric field, which is a generalization of the Coulomb equation.

Best Regards

André

There is a practical answer. How can you observe what happens to a photon on its journey through space? Any attempt at observation entails a disruption of the photon's travel and thus is an "influence" on the photon. Another problem is that as the photon passes by you in this moment, right now today, tomorrow it will be long gone down the road and there is no way that you can ever know what becomes of it.

One probably should not think of individual photons but rather of "swarms" of photons traveling throuh space, say, from a distant star to our telescope here on Earth. In the the swarm the photons are not identifiable individually but only as a swarm of radiant energy. Clearly if the photon swarm passes through a cloud of interstellar dust it will be reddened by Rayleigh scattering but if the swarm is passing through nominally empty space it continue its journey uninfluenced by anything.

By the conservation of energy and Newton's first law of motion, photons travel with constant velocity c along straight lines (geodesics) with fixed energy and spin state unless acted on by a force (e.g., gravitation) or by interaction with matter.

Photons from the CMB have not been travelling "for eternity", only for 13.8 billion years. In that time, either a photon interacts with something (through Thomson or Compton scattering) or it doesn't. The probability (and hence the fraction affected) is low if the mean free path is greater than 13.8 billion light years. Those were equal after around 380 thousand years which is when the universe essentially became "transparent", and the free path has continued to increase rapidly ever since.

If a photon does interact, it gets scattered and that would slightly dim our view and create a background glow of scattered photons if it happened to any great degree, but we see clear point sources such as quasars from almost as long ago so observation confirms the theory. Tired Light, which is what you are describing, has been eliminated by observation for decades.

I LIKED MOST OF THESE REPLIES TO THE QUESTION. HOW TO BRING THEM TOGETHER UNDER A RATIONAL SYSTEM THAT FACILITATES FURTHER PARADOX-RESOLUTIONS? THIS IS WHAT I HAVE BEEN TRYING FOR DECADES. The results i have reached are now available in 3 books:

(1) Causal Ubiquity in Quantum Physics: A Superluminal and Local-Causal Physical Ontology, 361 pages, Frankfurt: Peter Lang, 2014;

(2) Physics without Metaphysics? Categories of Second Generation Scientific Ontology, 385 pages, Frankfurt: Peter Lang, 2015; and

(3) GRAVITATIONAL COALESCENCE PARADOX AND COSMOGENETIC CAUSALITY IN QUANTUM ASTROPHYSICAL COSMOLOGY, 647 pages, Berlin: Peter Lang, 2018.

The third of them includes a summary of the first two. If you have critiques, feel free to contact via

https://uni-leipzig1.academia.edu/RaphaelNeelamkavil

To add something to the other replies using photons as an example: Even if a photon would not interact with other particles at all, it would still be subject to redshift due to the expansion of the universe. Figuratively speaking, the expansion of space will stretch the photons wavelength, and it will loose energy. In this sense the answer is always no in any case, as long as we accept that we live in an expanding universe.

Dear Gernot,

You wrote: "Even if a photon would not interact with other particles at all, it would still be subject to redshift due to the expansion of the universe. Figuratively speaking, the expansion of space will stretch the photons wavelength, and it will loose energy. In this sense the answer is always no in any case, as long as we accept that we live in an expanding universe."

Yes, this is the traditional conclusion grounded on the electromagnetic wave theory, combined with the idea of the universe in expansion.

The stretching of the photons "wavelength", in particular, was the only possible option before de Broglie defined the possible electromagnetic characteristics that a localized photon should have to remain completely Maxwell equations compliant.

His conclusions imply that the electric and magnetic aspects of the quantum would mutually induce each other while oscillating in standing mode transversely with respect to the direction of motion, while part of the quantum's energy would act as momentum energy propelling the transversely oscillating part.

This establishes a novel perspective for electromagnetic energy travel as self-propelling without the need for an underlying medium, which is required for a traditional transverse wave to propagate.

From this new perspective, the wavelength of the "longitudinally punctual` transversely oscillating quantum simply becomes the distance that the quantum must travel in space for one of its transverse cycles to be completed. And red shifting of such a localized photon can come about only if some of its energy is spent by its trajectory being deflected along the way to us as its passes by massive bodies.

If interested, this de Broglie photon is described in this paper published in 2016:

https://www.omicsonline.org/open-access/on-de-broglies-doubleparticle-photon-hypothesis-2090-0902-1000153.pdf

Best Regards

André

SEG: The wave length (lambda). Planck’s constant (h) and the speed of light (c) can’t change at all (proofed by experiments and observations).

The wavelength at an observer differs from that at the source if there is relative motion between them, proven by the Doppler Shift. That change of frame is provided by the expansion. As Gernot said, the usual "stretching the photon" is figurative language.

Dear Sydney,

SEG :"What is the amplitude of an electromagnetic wave? The wave length (lambda"

GS: Amplitude of electromagnetic wave is electric and magnetic vectors....It not wavelength.... As photon travel in media, it interact with media with electric and magnetic field... Mostly, electric field... Electric-field set free electron in oscillation Free electron oscillates in dissipative media and thus energy get lost... After that amplitude of electric field get reduced... And thus energy of photon get reduced as well .....

The first law in physics: Nothing can happen what is not allowed to happen by theory. I' sorry!

@Dwight: You can clearly observe the results of the interactios between photons and any form of matter in the universe after it's very long journey. We have also some more possibilities to examinate interactions of photons or better electromagnetic radiation with material matter and electromagnetic radiation by oneself. Our knowledge about the properties of photons is limited espacially by earthboun experiments and theories.

@GD: The assumption of 13,8*10E9 years results from the questionable theory of the big bang. It is under no circumstances a fact. We can observe only 13,8*10E9 ly of real space! If you lock at the pictures of very old galaxies you can see that they have the same shape as galaxies close by us. This is a counterevidence of the 'big bang' and the interpretation of the red shift in physics.

Dear Sydney,

You wrote: " electromagnetic waves show electric and magnetic vectors. However, if I have to explain the amplitude of the electromagnetic wave in relation to the wave length with the help of these vectors I also have to explain the origin of these vectors. That is impossible without the carrier of these vectors,"

No doubt you mean "without a longitudinal wave carrier for these vectors"

Yes it is possible, because the electric and magnetic vectors are oriented transversely with respect to the direction of motion, and if electromagnetic quanta can be shown to be self-propelling, by providing their own momentum energy, then the electromagnetic "wavelength" of such a longitudinally point-like behaving, transversely oscillating electromagnetic quantum, resolves as simply the distance that the quantum has to travel in vacuum at the speed of light for one of its transverse cycle to be completed:

https://www.omicsonline.org/open-access/on-de-broglies-doubleparticle-photon-hypothesis-2090-0902-1000153.pdf

Close analysis shows that the electromagnetic amplitude of an electromagnetic quantum is related to its wavelength via the fine structure constant:

http://www.gsjournal.net/Science-Journals/Research%20Papers-Relativity%20Theory/Download/2257

Best Regards

André

Dear Hans,

You wrote " The first law in physics: Nothing can happen what is not allowed to happen by theory."

Doesn't this presume that all has already been theoretically accounted for in physical reality?

Best Regards

André

Dear Hans,

HGH: The assumption of 13,8*10E9 years results from the questionable theory of the big bang. It is under no circumstances a fact.

There are many open questions about the details of the model but the overall outline has been beyond question for decades, certainly since the CMB was observed by COBE. The exact age is open to some adjustment, for example I note the effect that recalibration of Cepheids had some years ago, but those changes are at the few percent level at most.

HGH: We can observe only 13,8*10E9 ly of real space!

No, we ca observe 13.8 billion years back into the past. Expansion means the oldest images are of objects much farther away.

HGH: If you lock at the pictures of very old galaxies you can see that they have the same shape as galaxies close by us.

The same shape but thousands of times smaller.

HGH: This is a counterevidence of the 'big bang' ...

No, it is evidence in favour of dark matter because the CMB was emitted from matter that was far more uniform. Something unseen at that time must already have been forming halos into which the normal matter could fall once released by re-ionisation.

HGH: and the interpretation of the red shift in physics.

That understanding was proven beyond doubt by Goldhaber in 2001 although the paper made little news because the professionals had known it for decades.

Article Timescale Stretch Parameterization of Type Ia Supernova B ‐B...

Regarding the discussion on EM, Gokaran said:

GS: Electric-field set free electron in oscillation Free electron oscillates ..

A free electron doesn't oscillate, it has no associated positive charge to create a restoring force.

GS: in dissipative media

Free electrons in space are not like those in matter, there is no surrounding medium so their motion is not dissipative.

GS: amplitude of electric field get reduced..

Reducing the field dims the light by absorbing some of the flux of photons but those that remain have the same frequency, there are just fewer of them if the light passes through an absorbing region.

It is disappointing that nobody else corrected these errors.

Dear Sydney,

Strange that the first link didn't work, because the paper is freely available from the Journal of Physical Mathematics site.

Here it is again, directly copied from my browser's access field:

https://www.omicsonline.org/open-access/on-de-broglies-doubleparticle-photon-hypothesis-2090-0902-1000153.pdf

This one may help understanding what you found in the second paper.

One tip that greatly helps coming to terms with these equations is using a simple scientific calculator that provides standard physics constants. All equations are purposefully first level (no derivatives nor integrals - unless needed to explain the first level equations) in which the standard constants and the few variables can be directly substituted.

Best Regards

André

Possible yes, but not probable.

Dear Hans,

You said "The first law in physics: Nothing can happen what is not allowed to happen by theory". If you were to replace "theory" by "Nature", I would agree with you. However, it is Nature that is in charge of and responsible for all that happens in the Universe. She knows nothing of "theory". She acts as she does without giving heed to our "theories" or to what we think it is that she is doing (or should be doing).We and our "theories" are only attempts to second-guess Nature who goes about her business as she sees fit.

Dear Jerry,

You wrote "Possible yes, but not probable."

It was not clear to what you were alluding to with this remark.

If it was to my contributing "Yes it is possible, because the electric and magnetic vectors ..."

Then I would say why would it be less probable than the ether solution, which involves that to be able to carry a longitudinal wave transversely oscillating needs to be rigid, with its substance oscillating transversely without being able to move longitudinally, as per the only currently existing definition of "transverse waves", such as s-waves in solid materials; an ether "substance" that while being totally undetectable, is deemed to be solid enough to longitudinally carry a pulse?

Also, contrary to the wave solution, the localized self-propelling de Broglie photon solution allows reconciling classical/relativistic mechanics (not SR nor GR) with electromagnetic mechanics to the point that the equations of either mechanics can be directly converted to the equations of the other mechanics.

Best Regard

André

Distance traveled, by itself, can't cause a particle to lose energy. Energy loss of the photon would have to come from interacting with forces along the way, such as gravitational fields from heavenly bodies.

But infinity is a very long time. Individual photons going through space will experience gravitational forces, which will shift their course, rob them of energy, or potentially add energy. And sooner or later, the photon will collide with some atom, knock some electron to a higher energy level, possibly dislodge an electron entirely, but whatever the case may be, that photon could become absorbed. It's a matter of probabilities, I would say.

So in short, I don't find a problem with the idea that energy from these traveling photons could be added, or subtracted, from the massive objects they go by, on their journey. Like a roller coaster has energy added and subtracted. Massless a they might be (some people insist photons do have rest mass), if we go by "traditional" relativity, a massless particle constrained to v = c can understandably be affected by gravitational forces of massive objects. And furthermore, the photon can impart energy on the massive object, or it can take energy from that massive object. Mass of the photon might be zero, but Gamma tends to infinity.

Dear Albert,

I completely agree with you.

Indeed, this energy variation process of point-like behaving electromagnetic photons without any variation in their equilibrium velocity of light can now be mechanically explained thanks to a discovery made by Paul Marmet, published in 2003, that clearly relates the magnetic field to the concept of classical "mass", when correlated with de Broglie's hypothesis about photon's transverse vs longitudinal inertia.

This allowed completely harmonizing classical/relativistic mechanics with fundamental electromagnetism, and further clearly relating electromagnetism with Schrödinger's wave function, in this recent paper, titled "The Hydrogen Atom Fundamental Resonance States":

https://file.scirp.org/pdf/JMP_2018042716061246.pdf

All aspects summarized in this paper are analyzed and explained in detail with confirming equations in a series of other referenced papers.

Best Regards

André

The notion of eternity raises the question of infinity and the cosmological principle that governs our Universe. On this we must distinguish what we know and believe. But we can only believe in this or that hypothesis. Whatever the model, it is not for the photon since the Hubble effect shows an influence by the space itself in the model of expansion or by any braking in a model of infinite universe and "eternal" . For a known particle; it is not for expansion if we look far enough in time since it seems that we must assume a come and go if gravitation or space is what we believe, if not???; it is also not for the infinite Universe if we look far enough in space, because at 1019 megaparsec for a constant density we meet a star with more than 99% probability, and through an infinite sum of layers of this thickness, even a neutrino will not cross without interaction.

Cordially.

TDM: ... light .. is interacting with cosmic hydrogen ..

There is no "cosmic hydrogen" in general, look up "Lyman Alpha Forest" and "Gunn Peterson Trough" to learn about the evidence.

Dear Maurice,

I understand what you are saying but I need to interject a bit of criticism. First of all "belief" in the sense of "unsubstantiated faith" has no place in science. Science is based on evidence obtained by observation and experiment.

We probe the Universe on, within and from our Earth-based vantage point to acquire “data to which we apply our mental faculties to arrive at meanings and interpretations that constitute our knowledge of the Universe. From analyses of these data we deduce the content of the Universe and develop hypotheses and theories to describe the operation of the Universe. These descriptions, hypotheses, and theories are of our own creation and, at best, they only approximate (with varying degrees of accuracy) what might be called “the absolute truth of being” of the Universe.

We must be very careful not to accept as “truth”, in any absolute sense, the inferences we draw regarding our Universe from the data we collect. We have made great strides in assembling a coherent construction of the Universe from our point of view but many issues (What is life?) elude us. We must be ever receptive to no new ideas in science and accept nothing dogmatically.

It is from the above that I take (perhaps nit-picking) issue with your statement “the cosmological principle that governs our Universe”. The “cosmological principle” is of our own creation” and in itself governs nothing.

TDM: If you read Chepick's paper, it's not about absorption.

I didn't suggest it was.

TDM: If you say that there is no hydrogen in the cosmos, I think you are wrong.

I didn't say there was none.

If you are going to answer at all, at least read what I write first.

What I said was "look up 'Lyman Alpha Forest' and 'Gunn Peterson Trough' to learn about the evidence.". These and "Damped Lyman" features allow us to map where the hydrogen lies along our line of sight. The Lyman Alpha Forest in particular only starts at high redshift showing there is very little atomic hydrogen at less than z=5 and below z=6 it is in small patches.

Before trying to comment on cosmology, you need to learn basic astronomy.

Thierry, please try to get past you own outdated religious convictions and learn some basic astronomy before promoting crackpots, the Lyman Alpha Forest is direct observation with no assumptions whatsoever.

A photon traveling through nominally empty space interacts with nothing because there is nothing with which to interact. Thus, in principle, the photon should continue moving on without constraint through all space and for all time unless there is some process as yet unknown that would act on the photon in the absence of intervening substance. Insofar as material interaction is concerned (for example, with a hydrogen atom) one confronts a scattering process or an absorption and reemission process, both of which "influence" the photon in the context of this discussion. Given our present state of knowledge it would seem that photons can travel for however long that there is time and for however far that there is (empty) space.

TDM: As usual, you try to interpret issues ...

There is no issue other than you trying to bluff your way through a conversation when you have no clue about the observational astronomy on which it is based.

Dear Dwight,

I agree with you. It seems that I lacked rigor in the choice of my words. Cosmological was a word of too much in "cosmological principle". I should have used the word "principle" alone, and in literary sense.

Best regards

In short:

@Dwight: Electromagnetic radiation (photons) can par example split into an electron-positron-pair if the energy is high enough.

We have to consider also interactions between electromagnetic radiation. The Laser technology offers experimental possibilities to verification.

The cosmological space is never a pure empty space. Uninfluenced spreading of radiation is impossible. Hubbles opinion to declare the decrease of energy of electromagnetic radiation by movement is on of the many fundamental failures in modern physics. It leads to the invention of the "big bang" by the cleric LeMaitre. The creation of the world by God becomes on this way socially acceptable.

@Hans

"Electromagnetic radiation (photons) can par example split into an electron-positron-pair if the energy is high enough."

Have I misunderstood you here?

Are you saying photons can be split into an electron-positron pair?

My understanding is the opposite. That electrons are significantly larger than and can absorb and emit photons and are probably (but not proven) made up from groups of photons

HG: "Electromagnetic radiation (photons) can par example split into an electron-positron-pair if the energy is high enough."

An electron has a mass of 511keV as does a positron so to create a pair needs a photon with an energy in excess of 1MeV, optical photons are around 2eV so cannot convert into particle pairs.