- 2858 - COSMIC RAYS - where do they come from? Earth is being constantly bombarded from space by “cosmic rays” of an unknown origin! Mysterious cosmic rays traveling at speeds approaching that of light constantly pelt Earth’s upper atmosphere from the depths of space, creating high-energy collisions that dwarf those produced in even the most powerful particle colliders.
---------------------- 2858 - COSMIC RAYS - where do they come from?
- Cosmic Rays create these atmospheric crashes that rain down gigantic showers of secondary particles to the surface of our planet. Despite being discovered more than a century ago, physicists still don’t know where cosmic rays come from.
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- The short answer to why we can’t trace cosmic rays back to their source is magnetic fields. Charged cosmic-ray particles are redirected by the magnetic fields they pass through on their long journey through space. As magnetic fields in space have local, small, randomly oriented structures, a prediction of the exact path of a cosmic-ray particle is impossible.
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- We do know that cosmic rays are comprised of extremely energetic charged particles , like protons, alpha particles, and atomic nuclei like helium and iron, with miniscule proportions of antiparticles thrown into the mix.
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- It’s hard to imagine just how shocking the discovery of cosmic rays must have been to physicists in the early 1900s. The energies of these particles were monumental in comparison to those of every other particle they had observed until that point.
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- The average energy of a solar “photon” is approximately 1.4 electron volts (eV). For reference, a flying mosquito has an energy of about 1 trillion eV, or 10^12 eV, but a mosquito is also much, much larger than a single particle. Meanwhile, an alpha particle emitted during the decay of Uranium-238 possess 4.27x10^6 eV of energy (or, 4,270,000 electron-volts)
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- Compare that to a cosmic ray “proton“, which has an energy of some 10^20 eV.
Imagine a proton that is accelerated so that it has an energy of 100 Joule. This energy corresponds to that of a tennis ball smashed with a velocity of around 124 miles per hour. Only, the tennis ball 10^29 times heavier than the proton.
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- That means a proton can only reach that extreme, macroscopic energy by traveling at almost the speed of light. The universe must be able to accelerate particles to these energies, but we still do not know how it does it. The processes that accelerate cosmic rays to such astounding energies must result from powerful and violent events, which considerably narrows down possible sources.
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- One of the best ways of accelerating particles is a shock front that occurs when a medium with a large velocity runs into a slower one, producing a shock, a sudden change in the properties of the medium. In the case of the universe, the changed properties are velocity and density, and even magnetic fields. The field becomes highly turbulent in that process. And the combination of a shock front with turbulence is a great particle accelerator.
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- What could produce such a shock front? One likely suspect is supernovae. As a shell of shocked material blasted away from an exploding star, it hits the cool interstellar medium that lies between stars, almost like a cosmic tsunami. The phenomena of a traveling shock front can also be found in active galaxies, where huge plasma jet exist.
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- A better understanding cosmic rays, as well as their origins, is expected to open an important window into tremendously powerful and awe-inspiring cosmic events, such as supernovae and collisions between black holes and neutron stars.
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- It was August 1912 when Austrian-American physicist Victor Hess began a series of flights to the upper atmosphere in a hydrogen-filled balloon equipped with an electroscope. His aim was to take measurements of ionizing radiation.
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- At the time, it was widely believed that radiation from the Earth itself was responsible for this phenomenon of knocking electrons off atoms. Should this be the case, however ionization should be strongest near the planet’s surface.
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- That’s not what Hess found. Hess discovered something startling. At a nosebleed-inducing altitude of 3.3 miles, ionization rates of the air were three times that measured at sea level. He concluded that the source of this ionization was not coming from below our feet, but instead from above.
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- Further measurements made during a solar eclipse also showed the Sun wasn’t the source of this ionization radiation.
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- During the course of seven balloon trips, Hess discovered cosmic rays , later confirmed and named by Robert Millikan in 1925 , coming from beyond our solar system. While the detection of cosmic rays has been associated with balloon flights ever since, the upper atmosphere isn’t the most convenient laboratory to investigate the high-energy particle collisions they produce.
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- To study the collisions caused by cosmic rays, particle physicists retreated below ground, employing increasingly monstrous particle accelerators to slam together particles in an attempt to replicate the collisions that cosmic rays spark in the upper atmosphere.
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- CERN’s Large Hadron Collider (LHC) is 16-mile circumference deep tunnel beneath the French/Swiss border. despite its impressive size, power and utility, the LHC still can’t reach the energies produced by cosmic ray collisions.
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- At roughly the same time as a balloon ride changed our perspective of the universe forever, a physicist named Einstein was working on a wild theory that would radically change our understanding of the fabric of space-time. And this theory, many decades later, could provide the next step to decoding cosmic rays.
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- The discovery of gravitational waves , ripples in space-time predicted by Einstein’s theory of general relativity, has made a new form of astronomy possible, allowing us to investigate events and objects that we could never hope to observe in the electromagnetic spectrum alone.
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- This combination of electromagnetic or “traditional” astronomy and gravitational-wave detections, along with detecting neutrinos, which are ghost-like particles with virtually no mass or electric charge, is known as multi-messenger astronomy. And it has a significant role to play in future investigations of cosmic rays, and, the high-energy universe.
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- There is no other way than multi-messenger astronomy to understand the origin and impact of cosmic rays. Cosmic rays alone cannot give an answer, neither can gamma-rays or neutrinos for themselves.
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- The hope is that we can answer the question of the origin of cosmic rays within the next decade. This sounds like a long time, but given the fact that cosmic rays were discovered in 1912, 10 years is short. Let’s keep working.
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---------------------------------- Other Reviews about cosmic Rays:
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- 2834 - COSMIC RAYS - The Risks of Space Travel. The scariest menace for space travelers are Cosmic Rays. They are not “rays” at all. They are charged particles that are everywhere in space hurtling at near light speed. Most are positive ions of hydrogen nuclei ( a proton, H+1 ) but some are the nuclei of the heavier elements, even iron ( Fe +26 ).
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- 2739 - COSMIC RAYS - new discoveries? - A lot of what we know about the Standard Model of Nature’s fundamental particles came from studying Cosmic Rays. All ordinary matter that we know is made of Leptons and Quarks. Cosmic Rays are mostly protons that are made up of 3 Quarks
- 2729 - COSMIC RAYS - to explain an expanding Universe? Could the Universe have expanded faster than the speed of light? The Universe appears to be “homogeneous” and “isotropic“ , the same in all directions. If light really was faster in the beginning then that could explain it. One way to test this theory is to study cosmic rays.
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- 2305 - Cosmic Rays are not rays at all, they are particles, sub-atomic particles, traveling through space at nearly the speed of light. Look at your thumbnail. Now imagine that 200 cosmic ray particles traveled through your thumb nail every second. Thousands of these ‘rays” zipping through your body and through the entire Earth.
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- 1927 - Cosmic Rays, are they a curse or are they a blessing? See Review 1926 about Cosmic Rays and Planetesimals. This review continues the discussion about Cosmic Rays.
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- 1926 - To learn how Cosmic Rays may be responsible for the evolution of life on Earth.
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- 1747 - Compares Cosmic Rays and Gamma Rays. Adding up the power of Cosmic Rays leads to 10^29 megawatts, or billion times the power of the Sun’s output. This review footnotes 11 other Reviews about Cosmic Rays.
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- 1659 - Cosmic Rays can take tens of million so years traveling at near light speeds in their magnetically twisted spiral paths to reach Earth.
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- 1624 - Most Cosmic Rays pass through Earth without touching anything. How powerful are Cosmic Rays? How often do they reach Earth? What new discoveries have discovered the source of the high energy Cosmic Rays?
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- 1568 - Cosmic Rays hit air molecules and create a shower of billions of electrons, muons, positrons, pions, etc.
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- 1496 - 90% of Cosmic Rays reaching Earth’s surface are protons. About 10 of them pass through your thumb every minute.
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- 1377 - Astronauts experience much higher bombardment of Cosmic Rays 5,000 hit their body every second.
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- 810 - an average body absorbs enough Cosmic Ray energy to equate to 2 chest X-rays per year.
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- 709 - the risks of space travel.
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- 386 - Gamma Rays and Cosmic Rays
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- October 10, 2020 2858
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