Related papers: The Height of a Giraffe
The rapid rise in the cosmic ray positron fraction above 10 GeV, as measured by PAMELA and AMS, suggests the existence of nearby primary sources of high energy positrons, such as pulsars or annihilating/decaying dark matter. In contrast,…
The arrival times of gravitational waves and optical light from orbiting binaries provide a mechanism to understand the propagation speed of gravity when compared to that of light or electromagnetic radiation. This is achieved with a…
The rest mass of the neutron is exactly equal to the rest mass of a proton plus that of an electron plus the mass equivalent of the kinetic energy of those two particles after they have electrostatically accelerated from very far apart…
The number of baryons in the observable universe is of the order of $10^{80}$, as is the number of electrons. The number of photons is about nine orders of magnitude greater, $10^{89}$, as is the estimated number of neutrinos. However, the…
Cosmic ray (CR) particles arrive at the top of the Earth's atmosphere at a rate of around 1000 per square meter per second. They are mostly ionized nuclei - about 90% protons, 9% alpha particles traces of heavier nuclei and approximately 1%…
We investigate theoretically the ballistic motion of small legged insects and legless larvae after a jump. Notwithstanding their completely different morphologies and jumping strategies, these legged and legless animals have convergently…
It is proposed that the highest energy $\sim 10^{20}$eV cosmic ray primaries are protons, decay products of a long-lived progenitor which has propagated from typically $\sim 100$Mpc. Such a scenario can occur in e.g. SU(15) grand…
Given the recent tragedy involving a 350 pound Siberian Tiger and the death of teenager Carlos Souza Jr., one must ask a fundamental question: Can a tiger overcome an obstacle that is thirty-three feet away and twelve and a half feet tall?…
Define a body A to be able to hide behind a body B if the orthogonal projection of B contains a translation of the corresponding orthogonal projection of A in every direction. In two dimensions, it is easy to observe that there exist two…
Cosmic rays have been observed up to energies $10^8$ times larger than those of the best particle accelerators. Studies of astrophysical particles (hadrons, neutrinos and photons) at their highest observed energies have implications for…
The acceleration of the expansion of the universe has been argued for by several research groups. If the universe is accelerating and if the universe or some part of the universe has a charge, then there may be electromagnetic radiation…
The process e(+) e(-) -> n gamma (n>=2) are studied to estimate the total and differential cross sections of these reactions using the L3 data collected during 1991-1998 at centre of mass energies in the range 91-193 GeV. The lower limits…
Candidate astrophysical acceleration sites capable of producing the highest energy cosmic rays (E > 10^{19.5} eV) appear to be at far greater distances than is compatible with their being known particles. The properties of a new particle…
In this letter, the size (height and weight) of fictional characters in animations, superhero series, movies, and other media is studied. We find that the distributions of character height and weight approximately follow lognormal…
We estimate the cosmological variation of the proton-to-electron mass ratio \mu=m_p/m_e by measuring the wavelengths of molecular hydrogen transitions in the early universe. The analysis is performed using high spectral resolution…
We give a summary of the theoretical attempts to make sense of the observational data concerning the highest energy cosmic rays, (E > 3x10^{19} eV).
Recently, under the assumption that the Doppler effect of the relativistically expanding fireball surface is important, Qin et al. showed that in most cases the power law relationship between the pulse width and energy of gamma-ray bursts…
Gamma ray bursts (GRBs) are the most luminous physical phenomena in the universe. The relativistic effect on the blast wave associated with the GRB introduces the gamma factor. Here we put an upper limit on the gamma factor via constraints…
Some recent experiments detecting very high energy (VHE) gamma-rays above 10-20 TeV independently reported VHE bursts for some of bright gamma-ray bursts (GRBs). If these signals are truly from GRBs, these GRBs must emit a much larger…
Collisions of cosmic rays in the atmosphere may produce heavy hadrons of very high energy. The decay length of a $B$ meson of energy above $10^7$ GeV is larger than 1 km, implying that such a particle tends to interact in the air before it…