Origin of Cosmic Rays Confirmed 155
cats-paw writes in with news of research that seems to confirm and support current theories of how cosmic rays are created. The prevailing thinking has been that cosmic rays are generated in the regions where supernovas' shock waves interact with the interstellar medium. The new research used the variability in X-ray emissions from a supernova remnant to estimate the strength of the magnetic fields present in that environment. The results lend support to the possibility of protons and nucleii being accelerated in supernova remnants to energies of 1 PeV (10^15 eV) and beyond. Here is the abstract from Nature.
Re:When I punch 10^15 eV into Google... (Score:5, Informative)
Re:When I punch 10^15 eV into Google... (Score:5, Informative)
~Ben
nuclei, NOT nucleii (Score:5, Informative)
"nucleus" -> "nuclei"
"radius" -> "radii" (because there's already an "i" before the "us")
Re:[OT] Nitpicking summary (Score:2, Informative)
Re:When I punch 10^15 eV into Google... (Score:5, Informative)
So, imagine the energy level to be 8-9 ORDERS OF MAGNITUDE (or around a billion times) more energetic than a nuclear fission chain reaction.
Re:When I punch 10^15 eV into Google... (Score:3, Informative)
Re:When I punch 10^15 eV into Google... (Score:5, Informative)
So, it takes 4.1868 joules to heat one cubic centimeter of water (one gram of water) one degree centigrade. So 0.00160217 joules is enough to heat one gram of water 383 microdegrees.
So, yes, in one sense that's not very much energy.
But, if you're going to scale the mass up, you should scale the energy up. So, it's one proton that has that much energy. The gram of water has approximately 6.02*10^23 proton masses. If every proton mass in the gram of water had that much energy, it would be equivalent to that gram of water being heated by 2.3*10^20 degrees. This is 230 trillion trillion degrees (yes, that's two trillions).
I hope this gives you a sense of the scale involved here.
When you have a single proton with enough energy to make a measurable difference in the temperature of a gram of water, you are talking an amazingly huge amount of energy.
Re:When I punch 10^15 eV into Google... (Score:5, Informative)
Some of them apparently violate a theoretical limit on the energy of a particle that has traveled a long way across the universe... leading to the question of where exactly they come from.
Re:When I punch 10^15 eV into Google... (Score:4, Informative)
The only way we currently have of energizing protons to even a measurable fraction of energy like this is in particle accelerators. They're spun around in magnetic fields to faster and faster speeds, gaining mass and energy or energy as they go. That energy ultimately comes from some kind of generator and the fuel it uses.
Eventually, they're slammed into a stationary target or a particle going the other way in the same accelerator. The more mass and energy the particles have accumulated, the more exotic the reactions that occur when that happens. The point of the experiment is to funnel a massive amount of fuel energy into one spot and see what happens when it goes 'boom'.
The super-energetic cosmic rays use the magnetic shockwave created by a Supernova to achieve about the same effect. Rather than being spun around a particle accelerator, they're being spun around the coiled loops of magnetic flux created when a super-massive star decides to disembowel itself.
So, to get anywhere near the ability to create one of these, let alone some kind of ray weapon utilizing them, we'd need a particle accelerator larger than the Sun (or able to churn out more energy than the Sun does). By the time we were able to build one, we'd be dismantling planets by other means anyway.
Re:Oh My God Particle (Score:3, Informative)
Maybe at 1AU, but out beyond the magnetosphere that isn't true.
For what it's worth, the many flavors of galactic cosmic rays you mention is pretty much the periodic table. While true there are a variety of ways to accelerate a charged particle, there are not that many known ways to get them to those energies that don't stick out like sore thumbs (which is why supernovae were always the best candidates). For the galactic cosmic rays, at least one of the methods must be able to accelerate very large nuclei such as silicon or iron, without blowing apart the nuclei while accelerating them.
The problem with the really really high energy cosmic rays is that when they travel at those speeds everything is blue-shifted up. The cosmic background radiation shifts up to x-rays and gamma rays and so these particles would interact like crazy with the background and thus should not be able to travel very far (like across the universe). So where the hell do they come from? If I knew, I'd have a nice tenured position somewhere.
Re:Very, very hot (Score:2, Informative)
While we're at it, a million millions is one trillion.
No offense, but geez, call it what it is.
Re:Roasting Times (Score:3, Informative)
Re:Olbers Anti-Paradox? (Score:3, Informative)
But Olber's paradox says that if the universe were infinitely large and infinitely old, then no matter where you looked you'd eventually see the surface of a star, so the sky wouldn't just be bright: it would be be sun-bright, rather than just faintly hazy.
Re:Roasting Times (Score:2, Informative)
So, if I need to cook a turkey, how long should I leave it in at 6,446,700,000,000,000,000 degrees?
0.0000000003186 seconds