Edward A. Spiegel (1931 — January 2, 2020) was an American professor of

astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

Columbia University Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...

. He worked on

convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...

theory and on the application of

fluid dynamics In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids— liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) an ...

astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the h ...

Career

In the 1960s his research focused on

turbulence In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...

and on

chaos theory Chaos theory is an interdisciplinary area of scientific study and branch of mathematics focused on underlying patterns and deterministic laws of dynamical systems that are highly sensitive to initial conditions, and were once thought to have co ...

, returning to mathematical aspects of that subject from 1975 to 1985. In the late 1980s he concentrated on mathematical pattern theory in fluids and other systems. Afterwards, Spiegel's work focused on models of the

solar cycle The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surfa ...

and radiative processes in hot stars. He authored or co-authored more than 100 papers involving collaborations with over 60 individuals; these papers have been cited well in excess of 3000 times. "A thermally excited non-linear oscillator" . by E.A. Spiegel and D.W. Moore contains a discussion of chaotic dynamics in terms of the wandering from one

unstable In numerous fields of study, the component of instability within a system is generally characterized by some of the outputs or internal states growing without bounds. Not all systems that are not stable are unstable; systems can also be mar ...

periodic orbit In mathematics, in the study of iterated functions and dynamical systems, a periodic point of a function is a point which the system returns to after a certain number of function iterations or a certain amount of time. Iterated functions Given a ...

to another. Their prescient vision anticipated much of our present day understanding of

strange attractor In the mathematical field of dynamical systems, an attractor is a set of states toward which a system tends to evolve, for a wide variety of starting conditions of the system. System values that get close enough to the attractor values remain ...

s. Like

Edward Lorenz Edward Norton Lorenz (May 23, 1917 – April 16, 2008) was an American mathematician and meteorologist who established the theoretical basis of weather and climate predictability, as well as the basis for computer-aided atmospheric physics and me ...

's famous paper, which appeared just a few years earlier, this paper provided one of the first models that showed how simple fluid systems can display complex dynamics. "Cosmic Arrhythmias" in "Chaos in Astrophysics" (Reidel 1985) is a compendium of Edward Spiegel's ideas for rationalizing cosmic phenomena. The article talks about the philosophy of why low-dimensional systems are relevant, useful and important in astrophysics. Between the lines, is the understanding that these ideas extend well beyond the subject of

. The work also cites some specific cosmic examples where low-dimensional dynamics and

may provide a key to understanding the

astrophysical Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the h ...

phenomena. His insights and ideas have had a long-term effect on

. For example, Spiegel's work on

vortices In fluid dynamics, a vortex ( : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in th ...

in disks led to many papers in the 1990s, with vortices now recognized as key ingredients to the mechanisms by which disks maintain an accretion flux and how planets are able to form. His work on photo-hydrodynamics is now recognized as potentially important in

pulsars A pulsar (from ''pulsating radio source'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Ea ...

, and the Moore-Spiegel

oscillator Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

and chaos have become influential from 1980s onward. He also coined the terms "

blazar A blazar is an active galactic nucleus (AGN) with a relativistic jet (a jet composed of ionized matter traveling at nearly the speed of light) directed very nearly towards an observer. Relativistic beaming of electromagnetic radiation from the ...

" and " photon bubble".

Awards

Awarded a

Guggenheim Fellowship Guggenheim Fellowships are grants that have been awarded annually since by the John Simon Guggenheim Memorial Foundation to those "who have demonstrated exceptional capacity for productive scholarship or exceptional creative ability in the ar ...

in 1974

References

External links

Research page at Columbia
{{DEFAULTSORT:Spiegel, Edward 1931 births 2020 deaths 21st-century American physicists American astronomers Place of birth missing Place of death missing University of Michigan alumni