Explaining The Nature Of Cosmic Rays

[rynner2]

It seems that relativity and quantum mechanics have collided again to present us with a very confusing situation connected with cosmic rays.

This page sets out the problem quite neatly, if you have a little familiarity with the Uncertaintly principle and time dilation.

I wouldn't be surprised if some big changes in cosmology develop from this. It also reminds me that I was complaining on another thread somewhere that relativity gives us no explanation for exactly what is 'waving' in light waves. This new idea might have some bearing on this, since it develops from the fact that the energy of a photon is assumed to be proportional to its frequency, but several basic assumptions are now in doubt.

(Unless, of course, this is all an April Fool stunt - look at the date of the magazine mentioned!)

 

[Anonymous]

It looks to me that this may be an "April Fool" - Cosmic Rays are just high energy photons, which means that, as photons are massless, they shouldn't interact at all. Obviously, photons do, or we couldn't see, but I'm afraid I left QM behind with my third year Pure Math options :-(
What makes it smell fishy to me is the use of Planck Time in measurements. If my current reading serves me right, the most accurate timing devices are stuck at the femto (or possibly atto) second level. This makes me think that this article is baseless, as the interactions that occur could not be measured to such a degree of accuracy.

Of course, I may be wrong, but just try me on Cauchy series

 

[intaglio]

It might be an April Fool but ...

There is a problem with high energy cosmic rays (New Scientist 2? 3? years ago)

If it is a genuine piece of research then it knocks out a lot of the foundation of Relativity which is that physics on a non-accelerating moving object will be the same as on a stationary object in the same frame of reference.

 

[rynner2]

It looks to me that this may be an "April Fool" - Cosmic Rays are just high energy photons, which means that, as photons are massless, they shouldn't interact at all.

From the article:

"Cosmic rays are presumed to be the nuclei of atoms, stripped of their electrons and accelerated to speeds near the speed of light. "

Thus they ARE particles, not photons.

From the point of view of such a high speed particle, the low energy (from our point of view) photons of the cosmic background radiation would in fact be very energetic indeed, and cause all sorts of particle physics mayhem. Hence the conclusion that cosmic rays should not be able to cross intergalactic distances.

 

[Anonymous]

As I remember (back in the day!) the Cosmic Rays that we detect are just high energy photons. If they are nucleii, then they are hard targets, and can increase their lifespan (as the Muon and Tauon do) but not string it out indefinitely. If they are indeed nucleii, then their detection would also be accompanied by the detection of decay particles that the Standard Model suggests, namely Kaons, a few assorted Leptons (Electrons, although at the energies suggested, maybe a few Muons or Tauons) and perhaps the odd Omega Minus. As I am aware, the Cosmic Ray detectors that we have here on Earth have only detected extremely weak interactions, which suggests to me either High Energy Photons, or the Neutrinos associated with the Leptons above.

 

[intaglio]

Sorry, Anton, but CRs really are stripped nucleii see this site (one of many). Their detection is often accompanied, indeed is characterised, by the detection of kaons, pions, mesons of all descriptions, leptons, bosons old uncle Tom Cobbleigh and all.

 

[DerekH16]

In my last Physics class (University of Edinburgh, Physics 1B, 1975-76) none of these particles even existed!

Ah, bugger.......

 

[rynner2]

In my last physics class they hadn't even split the atom!

(Well, laugh, dammit, that was a joke. Although the class was of the order of a decade before Derek's...)

 

[rynner2]

An update. (So I guess it wasn't an April Fool after all.)

Doubts about relativity have been caused partly by a mystery regarding cosmic rays, the high-energy particles that rain down on Earth from outer space.

According to relativity, there should be a limit — known as the G.Z.K. limit — after Kenneth Greisen, Georgi Zatsepin and Vadim Kuzmin, three theorists who independently came up with it in 1968 — to the energies of cosmic rays that can hit Earth from distant realms in the cosmos.

Cosmic rays carrying about 1020 electron volts of energy would bang into the haze of microwaves left behind by the Big Bang fireball and break up before traveling more than a few hundred million light-years.

But in the last decade cosmic ray detectors have recorded a sprinkling of cosmic rays with energies greater than the G.Z.K. limit, which is a hundred million times the energy produced in the Fermi National Accelerator Laboratory's giant Tevatron particle accelerator. The result has been a flood of papers proposing explanations as diverse as unknown particles and the breakdown of relativity.

In the late 1990's Dr. Luis Gonzalez-Mestres of the National Center for Scientific Research in France, and, independently, the Harvard theorists Dr. Sheldon Glashow and Dr. Sidney Coleman proposed that a small violation of relativity would allow high-energy cosmic rays to evade the G.Z.K. energy limit on travel.

"Is the sky sending us a signal?" Dr. João Magueijo, a theorist at Imperial College London, asked rhetorically last spring.

No one can say for sure. A new experiment in Utah, the High Resolution Fly's Eye, hasn't seen as many high-energy events as it should have based on the earlier data. This fall Dr. John Bahcall, a theorist at the Institute for Advanced Study in Princeton, and Dr. Eli Waxman, from the Weizmann Institute in Israel, combined the data from Fly's Eye and two other detectors, in Yakutsk, Russia, and Halverah Park in Britain and said they found nothing inconsistent with the G.Z.K. cutoff after all.

That would mean that relativity would be off the hook. But the analysis of Dr. Bahcall and Dr. Waxman has been criticized because they left out the Akeno Giant Air Shower Array in Japan, which has continued to record the high-energy rays.

The answer, all agree, will come from the Pierre Auger Observatory, a giant array, named after a pioneer cosmic ray scientist, operated by a multinational collaboration in Argentina. A tiny fraction of the array began operating this year.

Even a negative result from Auger would not relieve physics of a deep mystery, however, said Dr. James Cronin, a University of Chicago physicist and Nobelist who is the American spokesman for the project. Tinkering with relativity, he pointed out, would explain only how such high-energy cosmic rays get here, but not how they are produced in the first place. "How does a source produce cosmic rays of 1020 electron volts?" wondered Dr. Cronin. "It's such a fascinating problem," he said, "one for the twilight of my career."

 

[Anonymous]

Rynner, the 1.02 keV is the energy threshold for lepton pair production, i.e. an electron has a rest mass equivalent to 511 eV. (IIRC) (Note that this only applies in the centre of mass rest frame.) It is, however, a very low energy in cosmological terms. I'm guessing that there is something screwy with the numbers in the article as 1.02 keV is a hell of a lot smaller that the ~1 TeV that you would expect a Tevatron to produce. I think that the article has been garbled by a journo who doesn't really understand what he is writing.

 

[Anonymous]

O.K. There's a nice article at

http://physicsweb.org/article/world/15/9/3

Based on a quick scour I believe that the article in the NY Times should have referred to energies of 10^20 eV rather than 1020 eV. (Hence my comment about the pair production threshold, whilst true, was just coincidence. )

 

[rynner2]

Based on a quick scour I believe that the article in the NY Times should have referred to energies of 10^20 eV rather than 1020 eV.

Yes, we've had that sort of problem mentioned elsewhere on this board!

Any how, good link.

 

[Anonymous]

So let's see...
for an observer on a fast moving ray/particle the planck time would stretch--ch--chh
and would appear to be much longer to a stationary observer...

conversely the ray observer would see the planck time of stationary particles get shorter and shorter and events would occur impossibly fast...
no wonder the behaviour of these rays is unpredictable when they hit other particles

ooh! cryptons!
another type of postulated dark matter!

 

[Anonymous]

Before we can discuss the relationship between time space and photons I need someone to clear up a point for me. I read in previous posts that photons were relative to the energy of the radiation. I thought the photon was a constant. Planks constant a packet of energy. A unit that would not change. The energy required to move an elecrton into a higher orbital shell. Am I wrong I am afraid I have not heard of photons being relitive.