Wheeler–Feynman absorber theory

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The Wheeler–Feynman absorber theory (also called the Wheeler–Feynman time-symmetric theory), named after its originators, the physicists Richard Feynman and John Archibald Wheeler, is an interpretation of electrodynamics derived from the assumption that the solutions of the electromagnetic field equations must be invariant under time-reversal transformation, as are the field equations themselves. Indeed, there is no apparent reason for the time-reversal symmetry breaking, which singles out a preferential time direction and thus makes a distinction between past and future. A time-reversal invariant theory is more logical and elegant. Another key principle, resulting from this interpretation and reminiscent of Mach's principle due to Tetrode, is that elementary particles are not self-interacting. This immediately removes the problem of self-energies.

T-symmetry and causality

The requirement of time-reversal symmetry, in general, is difficult to conjugate with the principle of causality. Maxwell's equations and the equations for electromagnetic waves have, in general, two possible solutions: a retarded (delayed) solution and an advanced one. Accordingly, any charged particle generates waves, say at time ${\displaystyle t_{0}=0}$ and point ${\displaystyle x_{0}=0}$, which will arrive at point ${\displaystyle x_{1}}$ at the instant ${\displaystyle t_{1}=x_{1}/c}$ (here ${\displaystyle c}$ is the speed of light), after the emission (retarded solution), and other waves, which will arrive at the same place at the instant ${\displaystyle t_{2}=-x_{1}/c}$, before the emission (advanced solution). The latter, however, violates the causality principle: advanced waves could be detected before their emission. Thus the advanced solutions are usually discarded in the interpretation of electromagnetic waves. In the absorber theory, instead charged particles are considered as both emitters and absorbers, and the emission process is connected with the absorption process as follows: Both the retarded waves from emitter to absorber and the advanced waves from absorber to emitter are considered. The sum of the two, however, results in causal waves, although the anti-causal (advanced) solutions are not discarded a priori.

Feynman and Wheeler obtained this result in a very simple and elegant way. They considered all the charged particles (emitters) present in our universe and assumed all of them to generate time-reversal symmetric waves. The resulting field is

${\displaystyle E_{\text{tot}}(\mathbf {x} ,t)=\sum _{n}{\frac {E_{n}^{\text{ret}}(\mathbf {x} ,t)+E_{n}^{\text{adv}}(\mathbf {x} ,t)}{2}}.}$

Then they observed that if the relation

${\displaystyle E_{\text{free}}(\mathbf {x} ,t)=\sum _{n}{\frac {E_{n}^{\text{ret}}(\mathbf {x} ,t)-E_{n}^{\text{adv}}(\mathbf {x} ,t)}{2}}=0}$

holds, then ${\displaystyle E_{\text{free}}}$, being a solution of the homogeneous Maxwell equation, can be used to obtain the total field

${\displaystyle E_{\text{tot}}(\mathbf {x} ,t)=\sum _{n}{\frac {E_{n}^{\text{ret}}(\mathbf {x} ,t)+E_{n}^{\text{adv}}(\mathbf {x} ,t)}{2}}+\sum _{n}{\frac {E_{n}^{\text{ret}}(\mathbf {x} ,t)-E_{n}^{\text{adv}}(\mathbf {x} ,t)}{2}}=\sum _{n}E_{n}^{\text{ret}}(\mathbf {x} ,t).}$

The total field is retarded, and causality is not violated.

The assumption that the free field is identically zero is the core of the absorber idea. It means that the radiation emitted by each particle is completely absorbed by all other particles present in the universe. To better understand this point, it may be useful to consider how the absorption mechanism works in common materials. At the microscopic scale, it results from the sum of the incoming electromagnetic wave and the waves generated from the electrons of the material, which react to the external perturbation. If the incoming wave is absorbed, the result is a zero outgoing field. In the absorber theory the same concept is used, however, in presence of both retarded and advanced waves.

The resulting wave appears to have a preferred time direction, because it respects causality. However, this is only an illusion. Indeed, it is always possible to reverse the time direction by simply exchanging the labels emitter and absorber. Thus, the apparently preferred time direction results from the arbitrary labelling.

Alternatively, the way that Wheeler/Feyman came up with the primary equation is: They assumed that their Lagrangian only interacted when and where the fields for the individual particles were separated by a proper time of zero. So since only massless particles propagate from emission to detection with zero proper time separation, this Lagrangian automatically demands an electromagnetic like interaction.

T-symmetry and self-interaction

One of the major results of the absorber theory is the elegant and clear interpretation of the electromagnetic radiation process. A charged particle that experiences acceleration is known to emit electromagnetic waves, i.e., to lose energy. Thus, the Newtonian equation for the particle (${\displaystyle F=ma}$) must contain a dissipative force (damping term), which takes into account this energy loss. In the causal interpretation of electromagnetism, Lorentz and Abraham proposed that such a force, later called Abraham–Lorentz force, is due to the retarded self-interaction of the particle with its own field. This first interpretation, however, is not completely satisfactory, as it leads to divergences in the theory and needs some assumptions on the structure of charge distribution of the particle. Dirac generalized the formula to make it relativistically invariant. While doing so, he also suggested a different interpretation. He showed that the damping term can be expressed in terms of a free field acting on the particle at its own position:

${\displaystyle E^{\text{damping}}(\mathbf {x} _{j},t)={\frac {E_{j}^{\text{ret}}(\mathbf {x} _{j},t)-E_{j}^{\text{adv}}(\mathbf {x} _{j},t)}{2}}.}$

However, Dirac did not propose any physical explanation of this interpretation.

A clear and simple explanation can instead be obtained in the framework of absorber theory, starting from the simple idea that each particle does not interact with itself. This is actually the opposite of the first Abraham–Lorentz proposal. The field acting on the particle ${\displaystyle j}$ at its own position (the point ${\displaystyle x_{j}}$) is then

${\displaystyle E^{\text{tot}}(\mathbf {x} _{j},t)=\sum _{n\neq j}{\frac {E_{n}^{\text{ret}}(\mathbf {x} _{j},t)+E_{n}^{\text{adv}}(\mathbf {x} _{j},t)}{2}}.}$

If we sum the free-field term of this expression, we obtain

${\displaystyle E^{\text{tot}}(\mathbf {x} _{j},t)=\sum _{n\neq j}{\frac {E_{n}^{\text{ret}}(\mathbf {x} _{j},t)+E_{n}^{\text{adv}}(\mathbf {x} _{j},t)}{2}}+\sum _{n}{\frac {E_{n}^{\text{ret}}(\mathbf {x} _{j},t)-E_{n}^{\text{adv}}(\mathbf {x} _{j},t)}{2}}}$

and, thanks to Dirac's result,

${\displaystyle E^{\text{tot}}(\mathbf {x} _{j},t)=\sum _{n\neq j}E_{n}^{\text{ret}}(\mathbf {x} _{j},t)+E^{\text{damping}}(\mathbf {x} _{j},t).}$

Thus, the damping force is obtained without the need for self-interaction, which is known to lead to divergences, and also giving a physical justification to the expression derived by Dirac.

Criticism

The Abraham–Lorentz force is, however, not free of problems. Written in the non-relativistic limit, it gives

${\displaystyle E^{\text{damping}}(\mathbf {x} _{j},t)={\frac {e}{6\pi c^{3}}}{\frac {\mathrm {d} ^{3}}{\mathrm {d} t^{3}}}x.}$

Since the third derivative with respect to the time (also called the "jerk" or "jolt") enters in the equation of motion, to derive a solution one needs not only the initial position and velocity of the particle, but also its initial acceleration. This apparent problem, however, can be solved in the absorber theory by observing that the equation of motion for the particle has to be solved together with the Maxwell equations for the field. In this case, instead of the initial acceleration, one only needs to specify the initial field and the boundary condition. This interpretation restores the coherence of the physical interpretation of the theory.

Other difficulties may arise trying to solve the equation of motion for a charged particle in the presence of this damping force. It is commonly stated that the Maxwell equations are classical and cannot correctly account for microscopic phenomena, such as the behavior of a point-like particle, where quantum-mechanical effects should appear. Nevertheless, with absorber theory, Wheeler and Feynman were able to create a coherent classical approach to the problem (see also the "paradoxes" section in the Abraham–Lorentz force).

Also, the time-symmetric interpretation of the electromagnetic waves appears to be in contrast with the experimental evidence that time flows in a given direction and, thus, that the T-symmetry is broken in our world. It is commonly believed, however, that this symmetry breaking appears only in the thermodynamical limit (see, for example, the arrow of time). Wheeler himself accepted that the expansion of the universe is not time-symmetric in the thermodynamic limit. This, however, does not imply that the T-symmetry must be broken also at the microscopic level.

Finally, the main drawback of the theory turned out to be the result that particles are not self-interacting. Indeed, as demonstrated by Hans Bethe, the Lamb shift necessitated a self-energy term to be explained. Feynman and Bethe had an intense discussion over that issue, and eventually Feynman himself stated that self-interaction is needed to correctly account for this effect.

Developments since original formulation

Gravity theory

Main article: Hoyle–Narlikar theory of gravity

Inspired by the Machian nature of the Wheeler–Feynman absorber theory for electrodynamics, Fred Hoyle and Jayant Narlikar proposed their own theory of gravity in the context of general relativity. This model still exists in spite of recent astronomical observations that have challenged the theory. Stephen Hawking had criticized the original Hoyle-Narlikar theory believing that the advanced waves going off to infinity would lead to a divergence, as indeed they would, if the universe were only expanding.

Transactional interpretation of quantum mechanics

Main article: Transactional interpretation

Again inspired by the Wheeler–Feynman absorber theory, the transactional interpretation of quantum mechanics (TIQM) first proposed in 1986 by John G. Cramer, describes quantum interactions in terms of a standing wave formed by retarded (forward-in-time) and advanced (backward-in-time) waves. Cramer claims it avoids the philosophical problems with the Copenhagen interpretation and the role of the observer, and resolves various quantum paradoxes, such as quantum nonlocality, quantum entanglement and retrocausality.

Attempted resolution of causality

T. C. Scott and R. A. Moore demonstrated that the apparent acausality suggested by the presence of advanced Liénard–Wiechert potentials could be removed by recasting the theory in terms of retarded potentials only, without the complications of the absorber idea. The Lagrangian describing a particle (${\displaystyle p_{1}}$) under the influence of the time-symmetric potential generated by another particle (${\displaystyle p_{2}}$) is

${\displaystyle L_{1}=T_{1}-{\frac {1}{2}}\left((V_{R})_{1}^{2}+(V_{A})_{1}^{2}\right),}$

where ${\displaystyle T_{i}}$ is the relativistic kinetic energy functional of particle ${\displaystyle p_{i}}$, and ${\displaystyle (V_{R})_{i}^{j}}$ and ${\displaystyle (V_{A})_{i}^{j}}$ are respectively the retarded and advanced Liénard–Wiechert potentials acting on particle ${\displaystyle p_{i}}$ and generated by particle ${\displaystyle p_{j}}$. The corresponding Lagrangian for particle ${\displaystyle p_{2}}$ is

${\displaystyle L_{2}=T_{2}-{\frac {1}{2}}\left((V_{R})_{2}^{1}+(V_{A})_{2}^{1}\right).}$

It was originally demonstrated with computer algebra and then proven analytically that

${\displaystyle (V_{R})_{j}^{i}-(V_{A})_{i}^{j}}$

is a total time derivative, i.e. a divergence in the calculus of variations, and thus it gives no contribution to the Euler–Lagrange equations. Thanks to this result the advanced potentials can be eliminated; here the total derivative plays the same role as the free field. The Lagrangian for the N-body system is therefore

${\displaystyle L=\sum _{i=1}^{N}T_{i}-{\frac {1}{2}}\sum _{i\neq j}^{N}(V_{R})_{j}^{i}.}$

The resulting Lagrangian is symmetric under the exchange of ${\displaystyle p_{i}}$ with ${\displaystyle p_{j}}$. For ${\displaystyle N=2}$ this Lagrangian will generate exactly the same equations of motion of ${\displaystyle L_{1}}$ and ${\displaystyle L_{2}}$. Therefore, from the point of view of an outside observer, everything is causal. This formulation reflects particle-particle symmetry with the variational principle applied to the N-particle system as a whole, and thus Tetrode's Machian principle.^[13] Only if we isolate the forces acting on a particular body do the advanced potentials make their appearance. This recasting of the problem comes at a price: the N-body Lagrangian depends on all the time derivatives of the curves traced by all particles, i.e. the Lagrangian is infinite-order. However, much progress was made in examining the unresolved issue of quantizing the theory. Also, this formulation recovers the Darwin Lagrangian, from which the Breit equation was originally derived, but without the dissipative terms. This ensures agreement with theory and experiment, up to but not including the Lamb shift. Numerical solutions for the classical problem were also found. Furthermore, Moore showed that a model by Feynman and Hibbs is amenable to the methods of higher than first-order Lagrangians and revealed chaoticlike solutions. Moore and Scott showed that the radiation reaction can be alternatively derived using the notion that, on average, the net dipole moment is zero for a collection of charged particles, thereby avoiding the complications of the absorber theory.

This apparent acausality may be viewed as merely apparent, and this entire problem goes away. An opposing view was held by Einstein.

Alternative Lamb shift calculation

As mentioned previously, a serious criticism against the absorber theory is that its Machian assumption that point particles do not act on themselves does not allow (infinite) self-energies and consequently an explanation for the Lamb shift according to quantum electrodynamics (QED). Ed Jaynes proposed an alternate model where the Lamb-like shift is due instead to the interaction with other particles very much along the same notions of the Wheeler–Feynman absorber theory itself. One simple model is to calculate the motion of an oscillator coupled directly with many other oscillators. Jaynes has shown that it is easy to get both spontaneous emission and Lamb shift behavior in classical mechanics. Furthermore, Jaynes' alternative provides a solution to the process of "addition and subtraction of infinities" associated with renormalization.

This model leads to the same type of Bethe logarithm (an essential part of the Lamb shift calculation), vindicating Jaynes' claim that two different physical models can be mathematically isomorphic to each other and therefore yield the same results, a point also apparently made by Scott and Moore on the issue of causality.

Conclusions

This universal absorber theory is mentioned in the chapter titled "Monster Minds" in Feynman's autobiographical work Surely You're Joking, Mr. Feynman! and in Vol. II of the Feynman Lectures on Physics. It led to the formulation of a framework of quantum mechanics using a Lagrangian and action as starting points, rather than a Hamiltonian, namely the formulation using Feynman path integrals, which proved useful in Feynman's earliest calculations in quantum electrodynamics and quantum field theory in general. Both retarded and advanced fields appear respectively as retarded and advanced propagators and also in the Feynman propagator and the Dyson propagator. In hindsight, the relationship between retarded and advanced potentials shown here is not so surprising in view of the fact that, in field theory, the advanced propagator can be obtained from the retarded propagator by exchanging the roles of field source and test particle (usually within the kernel of a Green's function formalism). In field theory, advanced and retarded fields are simply viewed as mathematical solutions of Maxwell's equations whose combinations are decided by the boundary conditions.

Hugh Everett III

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Hugh_Everett_III 

 

Hugh Everett III
Hugh Everett in 1964
Born	November 11, 1930 Washington, D.C., U.S.
Died	July 19, 1982 (aged 51) McLean, Virginia, U.S.
Citizenship	United States
Alma mater	Catholic University of America Princeton University (Ph.D.)
Known for	Many-worlds interpretation Everett's theorem
Children	Elizabeth Everett, Mark Oliver Everett
Scientific career
Fields	Physics Operations research Optimization Game theory
Institutions	Institute for Defense Analyses American Management Systems Monowave Corporation
Doctoral advisor	John Archibald Wheeler

Hugh Everett III (/ˈɛvərɪt/; November 11, 1930 – July 19, 1982) was an American physicist who first proposed the many-worlds interpretation (MWI) of quantum physics, which he termed his "relative state" formulation. In contrast to the then-dominant Copenhagen interpretation, the MWI posits that the wave function never collapses and that all possibilities of a quantum superposition are objectively real.

Discouraged by the scorn of other physicists for MWI, Everett ended his physics career after completing his PhD. Afterwards, he developed the use of generalized Lagrange multipliers for operations research and applied this commercially as a defense analyst and a consultant. In poor health later in life, he died at the age of 51 in 1982. He is the father of musician Mark Oliver Everett.

Although largely disregarded until near the end of Everett's lifetime, the MWI received more credibility with the discovery of quantum decoherence in the 1970s and has received increased attention in recent decades, becoming one of the mainstream interpretations of quantum mechanics alongside Copenhagen, pilot wave theories, and consistent histories.

Early life and education

Hugh Everett III was born in 1930 and raised in the Washington, D.C. area. Everett's parents separated when he was young. Initially raised by his mother (Katherine Lucille Everett née Kennedy), he was raised by his father (Hugh Everett Jr) and stepmother (Sarah Everett née Thrift) from the age of seven.

At the age of twelve he wrote a letter to Albert Einstein asking him whether that which maintained the universe was something random or unifying. Einstein responded as follows:

Dear Hugh: There is no such thing like an irresistible force and immovable body. But there seems to be a very stubborn boy who has forced his way victoriously through strange difficulties created by himself for this purpose. Sincerely yours, A. Einstein

Everett won a half scholarship to St. John's College High School in Washington, D.C. From there, he moved to the nearby Catholic University of America to study chemical engineering as an undergraduate. While there, he read about Dianetics in Astounding Science Fiction. Although he never exhibited any interest in Scientology (as Dianetics became), he did retain a distrust of conventional medicine throughout his life.

During World War II his father was away fighting in Europe as a lieutenant colonel on the general staff. After World War II, Everett's father was stationed in West Germany, and Hugh joined him, during 1949, taking a year out from his undergraduate studies. Father and son were both keen photographers and took hundreds of pictures of West Germany being rebuilt. Reflecting their technical interests, the pictures were "almost devoid of people".

Princeton

Everett graduated from the Catholic University of America in 1953 with a degree in chemical engineering, although he had completed sufficient courses for a mathematics degree as well. He received a National Science Foundation fellowship that allowed him to attend Princeton University for graduate studies. He started his studies at Princeton in the mathematics department, where he worked on the then-new field of game theory under Albert W. Tucker, but slowly drifted into physics. In 1953 he started taking his first physics courses, notably Introductory Quantum Mechanics with Robert Dicke.

During 1954, he attended Methods of Mathematical Physics with Eugene Wigner, although he remained active with mathematics and presented a paper on military game theory in December. He passed his general examinations in the spring of 1955, thereby gaining his master's degree, and then started work on his dissertation that would (much) later make him famous. He switched thesis advisor to John Archibald Wheeler some time in 1955, wrote a couple of short papers on quantum theory and completed his long paper, Wave Mechanics Without Probability in April 1956.

In his third year at Princeton, Everett moved into an apartment which he shared with three friends he had made during his first year, Hale Trotter, Harvey Arnold and Charles Misner. Arnold later described Everett as follows:

He was smart in a very broad way. I mean, to go from chemical engineering to mathematics to physics and spending most of the time buried in a science fiction book, I mean, this is talent.

It was during this time that he met Nancy Gore, who typed up his Wave Mechanics Without Probability paper. Everett married Nancy Gore the next year. The long paper was later retitled as The Theory of the Universal Wave Function.

Wheeler himself had traveled to Copenhagen in May 1956 with the goal of getting a favorable reception for at least part of Everett's work, but in vain. In June 1956 Everett started defense work in the Pentagon's Weapons Systems Evaluation Group, returning briefly to Princeton to defend his thesis after some delay in the spring of 1957. A short article, which was a compromise between Everett and Wheeler about how to present the concept and almost identical to the final version of his thesis, was published in Reviews of Modern Physics Vol 29 #3 454-462, (July 1957), accompanied by an approving review by Wheeler. Everett was not happy with the final form of the article. Everett received his Ph.D. in physics from Princeton in 1957 after completing his doctoral dissertation titled "On the foundations of quantum mechanics."

After Princeton

Everett's attendance marked the transition from academia to commercial work.

Upon graduation in September 1956, Everett was invited to join the Pentagon's newly-forming Weapons Systems Evaluation Group (WSEG), managed by the Institute for Defense Analyses. Between 23–26 October 1956 he attended a weapons orientation course managed by Sandia National Laboratories at Albuquerque, New Mexico to learn about nuclear weapons and became a fan of computer modeling while there. In 1957, he became director of the WSEG's Department of Physical and Mathematical Sciences. After a brief intermission to defend his thesis on quantum theory at Princeton, Everett returned to WSEG and recommenced his research, much of which, but by no means all, remains classified. He worked on various studies of the Minuteman missile project, which was then starting, as well as the influential study The Distribution and Effects of Fallout in Large Nuclear Weapon Campaigns.

During March and April 1959, at Wheeler's request, Everett visited Copenhagen, on vacation with his wife and baby daughter, in order to meet with Niels Bohr, the "father of the Copenhagen interpretation of quantum mechanics". The visit was a complete disaster; Everett was unable to communicate the main idea that the universe is describable, in theory, by an objectively existing universal wave function (which does not "collapse"); this was simply heresy to Bohr and the others at Copenhagen. The conceptual gulf between their positions was too wide to allow any meeting of minds; Léon Rosenfeld, one of Bohr's devotees, talking about Everett's visit, described Everett as being "undescribably [sic] stupid and could not understand the simplest things in quantum mechanics". Everett later described this experience as "hell...doomed from the beginning".

However, while in Copenhagen, in his hotel, he started work on a new idea to use generalized Lagrange multipliers for mathematical optimization. Everett's theorem, published in 1963, relates the Lagrangian bidual to the primal problem.

In 1962 Everett accepted an invitation to present the relative-state formulation (as it was still called) at a conference on the foundations of quantum mechanics held at Xavier University in Cincinnati. In his exposition Everett presented his derivation of probability and also stated explicitly that observers in all branches of the wavefunction were equally "real." He also agreed with an observation from the floor that the number of branches of the universal wavefunction was an uncountable infinity.

In August 1964, Everett and several WSEG colleagues started Lambda Corp. to apply military modeling solutions to various civilian problems. During the early 1970s, defense budgets were curtailed and most money went to operational duties in the Vietnam War, resulting in Lambda eventually being absorbed by the General Research Corp.

In 1973, Everett and Donald Reisler (a Lambda colleague and fellow physicist) left the firm to establish DBS Corporation in Arlington, Virginia. Although the firm conducted defense research (including work on United States Navy ship maintenance optimization and weapons applications), it primarily specialized in "analyzing the socioeconomic effects of government affirmative action programs" as a contractor under the auspices of the Department of Justice and the Department of Health, Education and Welfare. For a period of time, the company was partially supported by American Management Systems, a business consulting firm that drew upon algorithms developed by Everett. He concurrently held a non-administrative vice presidency at AMS and was frequently consulted by the firm's founders.

Everett cultivated an early aptitude for computer programming at IDA and favored the TRS-80 at DBS, where he primarily worked for the rest of his life.

Later recognition

In 1970 Bryce DeWitt wrote an article for Physics Today on Everett's relative-state theory, which evoked a number of letters from physicists. These letters, and DeWitt's responses to the technical objections raised, were also published. Meanwhile DeWitt, who had corresponded with Everett on the many-worlds / relative state interpretation when originally published in 1957, started editing an anthology on the many-worlds interpretation of quantum mechanics. In addition to the original articles by Everett and Wheeler, the anthology was dominated by the inclusion of Everett's 1956 paper The Theory of the Universal Wavefunction, which had never been published before. The book was published late in 1973, sold out completely, and it was not long before an article on Everett's work appeared in the science fiction magazine, Analog.

In 1977, Everett was invited to give a talk at a conference Wheeler had organised at Wheeler's new location at the University of Texas at Austin. As with the Copenhagen visit, Everett vacationed from his defense work and traveled with his family. Everett met DeWitt there for the first and only time. Everett's talk was quite well received and influenced a number of physicists in the audience, including Wheeler’s graduate student, David Deutsch, who later promoted the many-worlds interpretation to a wider audience. Everett, who "never wavered in his belief in his many-worlds theory", enjoyed the presentation; it was the first time for years he had talked about his quantum work in public. Wheeler started the process of returning Everett to a physics career by establishing a new research institute in California, but nothing came of this proposal. Wheeler, although happy to introduce Everett's ideas to a wider audience, was not happy to have his own name associated with Everett's ideas. Eventually, after Everett's death, he formally renounced the theory.

Death and legacy

At the age of 51, Everett, who believed in quantum immortality, died suddenly of a heart attack at home in his bed on the night of July 18–19, 1982. Everett's obesity, frequent chain-smoking and alcohol drinking almost certainly contributed to this, although he seemed healthy at the time. A committed atheist, he had asked that his remains be disposed of in the trash after his death. His wife kept his ashes in an urn for a few years, before complying with his wishes. About Hugh's death his son, Mark Oliver Everett, later said:

I think about how angry I was that my dad didn't take better care of himself. How he never went to a doctor, let himself become grossly overweight, smoked three packs a day, drank like a fish and never exercised. But then I think about how his colleague mentioned that, days before dying, my dad had said he lived a good life and that he was satisfied. I realize that there is a certain value in my father's way of life. He ate, smoked and drank as he pleased, and one day he just suddenly and quickly died. Given some of the other choices I'd witnessed, it turns out that enjoying yourself and then dying quickly is not such a hard way to go.

Of the companies Everett initiated, only Monowave Corporation still exists (in Seattle as of March 2015). It is managed by co-founder Elaine Tsiang, who received a Ph.D. in physics under Bryce DeWitt at the University of North Carolina at Chapel Hill before working for DBS as a programmer.

Everett's daughter, Elizabeth, died by suicide in 1996 (saying in her suicide note that she wished her ashes to be thrown out with the garbage so that she might "end up in the correct parallel universe to meet up w[ith] Daddy"), and in 1998, his wife, Nancy, died of cancer. Everett's son, Mark Oliver Everett, who found Everett dead, is also known as "E" and is the main singer and songwriter for the band Eels. The Eels album Electro-Shock Blues, which was written during this time period, is representative of these deaths.

Mark Everett explored his father's work in the hour-long BBC television documentary Parallel Worlds, Parallel Lives. The program was edited and shown on the Public Broadcasting Service's Nova series in the USA during October 2008. In the program, Mark mentions how he wasn't aware of his father's status as a brilliant and influential physicist until his death in 1982.