A hypothesis for gamma ray bursts: photon cohesion

[wogoga]

The conclusion of incredibly high energies involved in gamma ray bursts depends on the following premises:

1. The sources are far away.
2. The released energy becomes continuously distributed on an increasing surface (proportional to the distance square from the source).

Based on the second premise one concludes that one "gamma ray burst" could be detected in a huge region of the universe. Nevertheless, one should not forget that this certainly reasonable assumption is not necessarily valid without exception in all possible situations.

Properties of a detected electromagnetic signal can originate from

• the source
• the transmission of the signal (transmission effect)
• the detecting system (instrumentation effect)

Typical instrumentation effects can result e.g. from "improving" faint signals by means of additional electronics and software. A good example of a transmission effect is a mirage (Fata Morgana, an image produced by very hot air).

The existence of coherent sun light consisting of more than one photon (in the same way as induced emission in general) is strong evidence that also photons are "social" particles, interacting with each other.

Because of cohesion forces between molecules, water molecules are not homogeneously distributed in the atmosphere, but can often be found in groups (droplets). Reasoning from analogy could suggest the hypothesis of small cohesive forces between photons.

Such cohesive forces could explain why gamma rays are not always diluted more and more with increasing distance from the source, but break apart into fragments (which are currently interpreted as being a direct result of bursts somewhere in the universe).

Normally the distance between two objects, emitted at the same time with the same speed in slightly different directions from a point-like source, increases continuously. If the two objects are tied with a string of a given length, then instead of drifting apart further they exchange momentum when their distance has reached the length of the string.

The separating force between two photons side by side depends on the angle between the propagation direction of each photon. If they travel in exactly the same direction, then no force at all is necessary to prevent them from drifting apart. If the angle is small, then the separating force is proportional to the angle.

Take the case of fullerenes. Nobody would have been able to predict their existence from our physical theories. Under certain conditions however, hollow balls consisting of each 60 carbon atoms emerge with ease.

In the same way, certain conditions (e.g. photon densities) may lead to cohesive forces between neighbouring photons. So instead of a continuous increase of the mean distances between photons, continuously increasing strain leads to fissures in the gamma ray field.

Photons of the same fragments have therefore adjusted their directions to each other (by exchanging lateral momentum) so that they continue to constitute a detectable unity, even long after the cohesive forces (having led to fragmentation) have disappeared. Nevertheless, in the end the fragments are lost more and more in the normal gamma background noise.

The hypothesis entails that the occurrence of gamma ray bursts must have a strong statistical component, because it depends on chance whether such gamma-ray fragments originating from far-away sources hit detectors on the earth or not.

Cheers, Wolfgang

(This article is a composition of paragraphs from three posts of mine to sci.astro: post_1, post_2 and post_3)

 

[Ziggurat]

The existence of coherent sun light consisting of more than one photon (in the same way as induced emission in general) is strong evidence that also photons are "social" particles, interacting with each other.

But sunlight is not coherent. And in order for light to interact directly with itself, that would require electromagnetic fields to be nonlinear. There is no evidence that either occurs.

Because of cohesion forces between molecules, water molecules are not homogeneously distributed in the atmosphere, but can often be found in groups (droplets). Reasoning from analogy could suggest the hypothesis of small cohesive forces between photons.

Except that Maxwell's equations for electromagnetism are explicitly linear. They would need to be wrong in order for photons to interact directly. There's no evidence they are. I don't think you really understand what you're proposing.

Take the case of fullerenes. Nobody would have been able to predict their existence from our physical theories.

Not so. They are easy to predict: they have the same local bonding structure as graphite. The difficulty was manufacturing and detecting them.

 

[ben m]

The existence of coherent sun light consisting of more than one photon (in the same way as induced emission in general) is strong evidence that also photons are "social" particles, interacting with each other.

Because of cohesion forces between molecules, water molecules are not homogeneously distributed in the atmosphere, but can often be found in groups (droplets). Reasoning from analogy could suggest the hypothesis of small cohesive forces between photons.

You don't need to reason from analogy. If there is a force between photons, we would be able to measure it. Many, many experiments have searched for this "force" at optical wavelengths, and all have shown that photon-photon interactions are incredibly small. The force was finally observed in a special case (inelastic gamma ray interactions) and it agreed with all theoretical predictions.

Thanks for the hypothesis, Wogoga! Unfortunately it has been falsified by these experiments.

 

[zosima]

Isn't photon-photon interaction(perhaps with other intermediary particles) what Feynman diagrams are all about? But because of renormalization, you generally find that a straight line is the best model for a photon?

 

[ben m]

Isn't photon-photon interaction(perhaps with other intermediary particles) what Feynman diagrams are all about? But because of renormalization, you generally find that a straight line is the best model for a photon?

That's not quite right, but there is a class of photon-photon interaction diagrams; the dominant has a virtual electron going around a loop and touching all four (two incoming, two outgoing) real photons. This has indeed been measured, for extremely high-energy photons: see http://prola.aps.org/abstract/PRL/v79/i9/p1626_1, which isn't quite the process you are looking for but is related.

 

[zosima]

I wouldn't say I'm looking for anything.
I was thinking that some of the more complex feynman diagrams were essentially computationally intractable due to their combinatoric complexity. Thus as skeptical as I am of these claims, can we necessarily exclude low energy photon-photon interaction?

Or is it correct to say that if we've worked out all the interactions with a small number of particles we can exclude these sorts of interactions with larger numbers of particles?
Is it something like interactions involving large numbers of particles become vanishingly improbable?

I'm not looking to attract any flame here, I'm just interested in understanding this a little better.

 

[ben m]

I wouldn't say I'm looking for anything.
I was thinking that some of the more complex feynman diagrams were essentially computationally intractable due to their combinatoric complexity. Thus as skeptical as I am of these claims, can we necessarily exclude low energy photon-photon interaction?

This is incorrect; more complex Feynman diagrams represent an infinite series. To evaluate a certain cross section to a certain accuracy, you evaluate the first N "orders" in the series, and you can show that the N+1th and N+2th orders are smaller and can be neglected. (Asking whether the *entire series* converges, if you evaluate all orders, is a messy question, but the answer appears to be "effectively yes for physics purposes") So, to say that "the photon-photon elastic cross section is X" isn't all that different than saying "for small x, sin(x) is x - x^3/3! + x^5/5! plus a very small correction."

In practice, it turns out that the simple electron loop should be hugely more important than the next order, so you'll get photon-photon scattering right within (my guess) about 0.01% by evaluating exactly two diagrams: the simple loop and a "crossed" version of it. You can totally ignore the diagrams with two separate electron loops bridged by a virtual photon, or a muon loop bridged by a photon coupling to a virtual W loop, etc.

The more complex diagrams usually become important at high energies; the approximation of ignoring them becomes more and more accurate, not less accurate, at lower energies.

Of course, it's always good to do the experiment. People have looked for optical photon-photon scattering for hundreds of years, always with null results; there are proposals to mount new searches (which may actually be sensitive to the QED prediction) using giant NIF-class lasers.

 

[zosima]

Thanks, ben, that was a very clear and illuminating explanation.

 

[wogoga]

The existence of coherent sun light consisting of more than one photon (in the same way as induced emission in general) is strong evidence that also photons are "social" particles, interacting with each other.

But sunlight is not coherent.

Sunlight should indeed be incoherent, because sunlight emerges from thermal radiation, and thermal radiation is considered spontaneous emission. So the phase of one photon should be independent from all other photons.

However photons, as social particles, tend to emerge and travel in coherent groups. And the longer they travel next to one another, the more they become coherent, by exchanging momentum and energy.

So even if sunlight (in a given direction) should not be coherent on Earth, it certainly will become coherent after having travelled some years, as starlight from our nearest stellar neighbors is highly coherent.

"Light from distant stars, though far from monochromatic, has extremely high spatial coherence." (Source)

"Finally it all makes perfect sense: starlight is ULTIMATELY coherent, that's why Stellar Interferometry works: starlight has coherence length in thousands of km, starlight is far more coherent than any human-made laser light." (Source)

So, in the case of starlight we get:

Huge areas of mutually coherent photons separated by "fissures", i.e. boundaries between photons of different phase shift (and maybe of slightly different frequencies).​

If we add the hypothesis of cohesion (i.e. attractive forces), we get as a very reasonable consequence:

The gamma rays break apart along the fissures into fragments, and thereafter distances between such fragments will increase more and more.​

Cheers, Wolfgang

 

[Ziggurat]

Sunlight should indeed be incoherent, because sunlight emerges from thermal radiation, and thermal radiation is considered spontaneous emission. So the phase of one photon should be independent from all other photons.

Not "should be". Is.

However photons, as social particles, tend to emerge and travel in coherent groups. And the longer they travel next to one another, the more they become coherent, by exchanging momentum and energy.

First off, your source is basically religious, not scientific. Second, you seem to be confusing the coherence effects that lead to lasers with thermal emissions. This is wrong, very wrong. Stimulated emission does lead to coherence, but it can never dominate emissions unless you've got population inversion, and thermal emissions from a star are very much NOT inverted thermal populations. Third, photons interact with each other very little. As ben explains above, the photon-photon interaction is basically non-existent within the optical range.

So even if sunlight (in a given direction) should not be coherent on Earth, it certainly will become coherent after having travelled some years, as starlight from our nearest stellar neighbors is highly coherent.

It is spatially coherent at long distances simply because the waves have traveled so far that they're basically all traveling parallel to each other. You can only get spatial decoherence when light arrives at your detector from different directions. This is a purely geometric effect, it involves zero interactions between photons. A distant star subtends so little solid angle from our view that it's about as good a point source as you could hope for.

Huge areas of mutually coherent photons separated by "fissures", i.e. boundaries between photons of different phase shift (and maybe of slightly different frequencies).​

This makes no sense whatsoever.

 

[Monketi Ghost]

Have you guys looked at the OP date on this zombie or am I missing something?

 

[ehcks]

Have you guys looked at the OP date on this zombie or am I missing something?

The OP brought back his own thread and is on-topic. Though still horribly wrong.

 

[Monketi Ghost]

I get it now, and yes he is.

 

[fuelair]

The OP brought back his own thread and is on-topic. Though still horribly wrong.

So, now there are four, none of whom is a specialist, published in peer reviewed journals, doing actual experiments applicable to their idea(s), or taking real suggestions seriously.

Color me unimpressed.

And, just to remind all, if you have an idea about why something accepted in the science of your choice is obviously wrong, do not send it here - none of us is going to be able to help you in any functional way except to suggest what I just did in my first sentence.

 

[Monketi Ghost]

Yes... I have a layman's fascination with GRB's and stellar physics in general, and this kind of thread title attracts my interest... but usually devolves into nonsense a few sentences into the opening post.

 

[wogoga]

However photons, as social particles, tend to emerge and travel in coherent groups...

... Second, you seem to be confusing the coherence effects that lead to lasers with thermal emissions. This is wrong, very wrong. Stimulated emission does lead to coherence, but it can never dominate emissions unless you've got population inversion, and thermal emissions from a star are very much NOT inverted thermal populations.

Population inversion essentially means that the majority of atoms/ molecules are in an excited state. This concept is not necessarily useful in the case of thermal radiation, where instead of discrete energy states a continuous velocity distribution of the atoms/ molecules is the driving force of photon emission. So you cannot conclude from the inadequacy of population inversion in thermal radiation to non-involvement of stimulated emission. Quote:

In 1917 Albert Einstein published an extraordinary piece of analysis which is generally accepted as the foundation of laser physics. This article [On the Quantum Theory of Radiation] is also notable for first introducing the concept (but not the name) of the photon. In this article Einstein argues that in the interaction of matter and radiation there must be, in addition to the processes of absorption and spontaneous emission, a third process of stimulated emission. If stimulated emission exists then he can derive the Planck distribution for blackbody radiation and without it the same argument implies the empirically invalid Wien distribution.

But, in addition to establishing the existence of the process of stimulated emission, Einstein also asserts that the radiation produced in stimulated emission is identical in all relevant aspects to the incident radiation. This is a truly remarkable result.​

That "the radiation produced in stimulated emission is identical in all relevant aspects to the incident Radiation" leads directly to the conclusion that photons tend to emerge and travel in coherent groups.

Cheers, Wolfgang

 

[Ziggurat]

Population inversion essentially means that the majority of atoms/ molecules are in an excited state. This concept is not necessarily useful in the case of thermal radiation, where instead of discrete energy states a continuous velocity distribution of the atoms/ molecules is the driving force of photon emission. So you cannot conclude from the inadequacy of population inversion in thermal radiation to non-involvement of stimulated emission.

Still wrong. Thermal emission applies even to systems with discrete energy levels. It does not produce a blackbody spectrum in such a case, but that's irrelevant.

But no matter. The point, which eludes you, is that stimulated emission (which produces coherence in lasers) is essentially irrelevant for thermal emissions. Thermal emission is always, always, dominated by spontaneous emission, which is why it's always incoherent.

 

[Reality Check]

Population inversion essentially means that the majority of atoms/ molecules are in an excited state....

That is not exactly what the Wikipedia article states, wogoga:

In physics, specifically statistical mechanics, a population inversion occurs when a system (such as a group of atoms or molecules) exists in a state with more members in an excited state than in lower energy states.

That is expanded on later - the major point is that it is the same excited state that the members are in.
For thermal emission from stars it is different excited states. We do not see one spectrum line from a star as in a laser, we see many lines superimposed on a continuum.

Also: Linking to a crank web site as in

photons, as social particles

does not look good, wogoga.

Photons are in fact "social" but that is because they are bosons and obey Bose–Einstein statistics and have Bose–Einstein correlations, not because some crank thinks they have souls!

 

[wogoga]

The point, which eludes you, is that stimulated emission (which produces coherence in lasers) is essentially irrelevant for thermal emissions. Thermal emission is always, always, dominated by spontaneous emission, which is why it's always incoherent.

Without stimulated emission, thermal radiation would result in the Wien distribution law. By adding the hypothesis of stimulated emission, we get the Planck law of black body radiation. We conclude that the effect of stimulated emission is the difference between the Wien and the Planck distribution laws, and this difference becomes substantial in the low frequency range.

Population inversion essentially means that the majority of atoms/ molecules are in an excited state.

... the major point is that it is the same excited state that the members are in. For thermal emission from stars it is different excited states.

This is not the decisive point. The relevant condition for stimulated emission is the existence of "excited" states being able to provide the energy (and recoil), necessary for the emission of photons being coherent with the stimulating photons. In the case of blackbody radiation, the probability of this condition is the higher, the lower the frequency of the emitted photons. The reason is simple: The energy for emitted photons comes from kinetic energy of atoms/ molecules. The lower the needed photon energy, the more atoms/ molecules can provide it.

At the far end of the far-infrared (1 mm wavelength) of blackbody radiation of 5777 °K, the proportion between stimulated emission and spontaneous emission is 400*. This means: One photon emerging spontaneously leads on average to around 400 coherent photons.

In the case of green light of 540 nm, only around 1 percent of the photons are due to stimulated emission. But this does not prevent such green photons from later becoming coherent with other photons of (almost) the same wavelength flying in (almost) the same direction.

Cheers, Wolfgang

* I hope my calculation (Planck's distribution formula at wavelength of 1 mm divided by corresponding value of Wien's distribution formula) is correct.

 

[Ziggurat]

Without stimulated emission, thermal radiation would result in the Wien distribution law. By adding the hypothesis of stimulated emission, we get the Planck law of black body radiation. We conclude that the effect of stimulated emission is the difference between the Wien and the Planck distribution laws, and this difference becomes substantial in the low frequency range.

And which part of the spectrum do you suppose gamma ray bursts come from? The low frequency tail of the spectrum?

You have not proven your original hypothesis. You have helped to refute it.