Introduction

Author(s):  
Richard A. Posner

You wouldn’t see the asteroid, even though it was several miles in diameter, because it would be hurtling toward you at 15 to 25 miles a second. At that speed, the column of air between the asteroid and the earth’s surface would be compressed with such force that the column’s temperature would soar to several times that of the sun, incinerating everything in its path. When the asteroid struck, it would penetrate deep into the ground and explode, creating an enormous crater and ejecting burning rocks and dense clouds of soot into the atmosphere, wrapping the globe in a mantle of fiery debris that would raise surface temperatures by as much as 100 degrees Fahrenheit and shut down photosynthesis for years. The shock waves from the collision would have precipitated earthquakes and volcanic eruptions, gargantuan tidal waves, and huge forest fires. A quarter of the earth’s human population might be dead within 24 hours of the strike, and the rest soon after. But there might no longer be an earth for an asteroid to strike. In a high-energy particle accelerator, physicists bent on re-creating conditions at the birth of the universe collide the nuclei of heavy atoms, containing large numbers of protons and neutrons, at speeds near that of light, shattering these particles into their constituent quarks. Because some of these quarks, called strange quarks, are hyperdense, here is what might happen: A shower of strange quarks clumps, forming a tiny bit of strange matter that has a negative electric charge. Because of its charge, the strange matter attracts the nuclei in the vicinity (nuclei have a positive charge), fusing with them to form a larger mass of strange matter that expands exponentially. Within a fraction of a second the earth is compressed to a hyperdense sphere 100 meters in diameter, explodes in the manner of a supernova, and vanishes. By then, however, the earth might have been made uninhabitable for human beings and most other creatures by abrupt climate changes.

2016 ◽  
Vol 69 (6) ◽  
pp. 1057-1064 ◽  
Author(s):  
Joo-Hee Oh ◽  
Nam-Suk Jung ◽  
Hee-Seock Lee ◽  
Seung-Kook Ko

1999 ◽  
Author(s):  
Stephen V. Musolino ◽  
Steven F. Kane ◽  
Joseph W. Levesque

Abstract The Relativistic Heavy Ion Collider (RHIC) is a high energy particle accelerator built to study basic nuclear physics. It consists of two counter-rotating beams of fully stripped gold ions that are accelerated in two rings to an energy of 100 GeV/nucleon. The rings consist of a circular lattice of superconducting magnets, 3.8 km in circumference. The beams can be stored for a period of five to ten hours and brought into collision for experiments during that time. The first major physics objective when the facility goes into operation is to recreate a state of matter, the quark-gluon plasma, that has been predicted to have existed at a short time after the creation of the universe. There are only a few other high energy particle accelerators like RHIC in the world. Each one is unique in design and contains systems and hazards that are not commonly found in general industry. Therefore, the designers of the machine do not always have consensus design standards and regulatory guidance available to establish the engineering parameters for safety. Some of the areas where standards are not available relate to the cryogenic system, containment of large volumes of flammable gas in fragile vessels in the experimental apparatus and mitigation of a Design Basis Accident with a stored particle beam. The ASME Code requires Charpy testing of welds at cryogenic temperature, but testing at 4 K is nearly impossible to conduct. Engineered welds were used to provide an equivalent level of safety. A cryogenic system is a process system. The RHIC system was designed first by selecting a safe operating mode, then analyzing to ensure this mode was preserved. Cryogenic systems have unique processes, and the safe mode will surprise most process engineers. The experimentalists require detectors to be designed to meet the need of the physics objectives, but the application of standard construction techniques would make research mission impossible. Unique but equivalent safety engineering must be determined. The rules promulgated in the Code of Federal Regulations under the Atomic Energy Act do not cover prompt radiation from accelerators, nor are there any State regulations that govern the design and operation of a large superconducting collider. Special design criteria for prompt radiation were developed to provide guidance for the design of radiation shielding.


2016 ◽  
Vol 25 (14) ◽  
pp. 1650103 ◽  
Author(s):  
M. S. Pshirkov

Quark matter which contains [Formula: see text]-quarks in addition to [Formula: see text]- and [Formula: see text]- could be stable or metastable. In this case, lumps made of this strange matter, called strangelets, could occasionally hit the Earth. When travelling through the atmosphere they would behave not dissimilar to usual high-velocity meteors with only exception that, eventually, strangelets reach the surface. As these encounters are expected to be extremely rare events, very large exposure is needed for their observation. Fluorescence detectors utilized in large ultra-high energy cosmic ray observatories, such as the Pierre Auger observatory and the Telescope Array are well suited for a task of the detection of these events. The flux limits that can be obtained with the Telescope Array fluorescence detectors could be as low as 2.5 × 10−22 cm−2s−1sr−1 which would improve by two orders of magnitude of the strongest present limits obtained from ancient mica crystals.


Author(s):  
Richard A. Posner

Catastrophic risks are much greater than is commonly appreciated. Collision with an asteroid, runaway global warming, voraciously replicating nanomachines, a pandemic of gene-spliced smallpox launched by bioterrorists, and a world-ending accident in a high-energy particle accelerator, are among the possible extinction events that are sufficiently likely to warrant careful study. How should we respond to events that, for a variety of psychological and cultural reasons, we find it hard to wrap our minds around? Posner argues that realism about science and scientists, innovative applications of cost-benefit analysis, a scientifically literate legal profession, unprecedented international cooperation, and a pragmatic attitude toward civil liberties are among the keys to coping effectively with the catastrophic risks.


2012 ◽  
Vol 05 ◽  
pp. 25-50 ◽  
Author(s):  
Luca Bottura ◽  
Arno Godeke

Superconductivity is the technology that enabled the construction of the most recent generation of high-energy particle accelerators, the largest scientific instruments ever built. In this review we trace the evolution of superconducting materials for particle accelerator magnets, from the first steps in the late 1960s, through the rise and glory of Nb–Ti in the 1970s, till the 2010s, and the promises of Nb3Sn for the 2020s. We conclude with a perspective on the opportunities for high-temperature superconductors (HTSs). Many such reviews have been written in the past, as witnessed by the long list of references provided. In this review we put particular emphasis on the practical aspects of wire and tape manufacturing, cabling, engineering performance, and potential for use in accelerator magnets, while leaving in the background matters such as the physics of superconductivity and fundamental material issues.


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