Life, The Universe, and Nothing: Life and Death in an Ever-Expanding Universe

Current evidence suggests that the cosmological constant is not zero, or that we live in an open universe. We examine the implications for the future under these assumptions, and find that they are striking. If the Universe is cosmological constant-dominated, our ability to probe the evolution of large scale structure will decrease with time ---presently observable distant sources will disappear on a time-scale comparable to the period of stellar burning. Moreover, while the Universe might expand forever, the integrated conscious lifetime of any civilization will be finite, although it can be astronomically long. We find that this latter result is far more general. In the absence of possible exotic and uncertain strong gravitational effects, the total information recoverable by any civilization over the entire history of our universe is finite, and assuming that consciousness has a physical computational basis, life cannot be eternal.Comment: 23 pages, latex, submitted to Ap.

Universal Limits on Computation

The physical limits to computation have been under active scrutiny over the past decade or two, as theoretical investigations of the possible impact of quantum mechanical processes on computing have begun to make contact with realizable experimental configurations. We demonstrate here that the observed acceleration of the Universe can produce a universal limit on the total amount of information that can be stored and processed in the future, putting an ultimate limit on future technology for any civilization, including a time-limit on Moore's Law. The limits we derive are stringent, and include the possibilities that the computing performed is either distributed or local. A careful consideration of the effect of horizons on information processing is necessary for this analysis, which suggests that the total amount of information that can be processed by any observer is significantly less than the Hawking-Bekenstein entropy associated with the existence of an event horizon in an accelerating universe.Comment: 3 pages including eps figure, submitted to Phys. Rev. Lett; several typos corrected, several references added, and a short discussion of w <-1 adde

Simulations of Electron Acceleration at Collisionless Shocks: The Effects of Surface Fluctuations

Energetic electrons are a common feature of interplanetary shocks and planetary bow shocks, and they are invoked as a key component of models of nonthermal radio emission, such as solar radio bursts. A simulation study is carried out of electron acceleration for high Mach number, quasi-perpendicular shocks, typical of the shocks in the solar wind. Two dimensional self-consistent hybrid shock simulations provide the electric and magnetic fields in which test particle electrons are followed. A range of different shock types, shock normal angles, and injection energies are studied. When the Mach number is low, or the simulation configuration suppresses fluctuations along the magnetic field direction, the results agree with theory assuming magnetic moment conserving reflection (or Fast Fermi acceleration), with electron energy gains of a factor only 2 - 3. For high Mach number, with a realistic simulation configuration, the shock front has a dynamic rippled character. The corresponding electron energization is radically different: Energy spectra display: (1) considerably higher maximum energies than Fast Fermi acceleration; (2) a plateau, or shallow sloped region, at intermediate energies 2 - 5 times the injection energy; (3) power law fall off with increasing energy, for both upstream and downstream particles, with a slope decreasing as the shock normal angle approaches perpendicular; (4) sustained flux levels over a broader region of shock normal angle than for adiabatic reflection. All these features are in good qualitative agreement with observations, and show that dynamic structure in the shock surface at ion scales produces effective scattering and can be responsible for making high Mach number shocks effective sites for electron acceleration.Comment: 26 pages, 12 figure

Old Galaxies at High Redshift and the Cosmological Constant

In a recent striking discovery, Dunlop {\bf \it et al} observed a galaxy at redshift z=1.55 with an estimated age of 3.5 Gyr. This is incompatible with age estimates for a flat matter dominated universe unless the Hubble constant is less than $45 kms^{-1}Mpc^{-1}$. While both an open universe, and a universe with a cosmological constant alleviate this problem, I argue here that this result favors a non-zero cosmological constant, especially when considered in light of other cosmological constraints. In the first place, for the favored range of matter densities, this constraint is more stringent than the globular cluster age constraint, which already favors a non-zero cosmological constant. Moreover, the age-redshift relation for redshifts of order unity implies that the ratio between the age associated with redshift 1.55 and the present age is also generally larger for a cosmological constant dominated universe than for an open universe. In addition, structure formation is generally suppressed in low density cosmologies, arguing against early galaxy formation. The additional constraints imposed by the new observation on the parameter space of $h$ vs $\Omega_{matter}$ (where $H= 100 h kms^{-1}Mpc^{-1}$) are derived for both cosmologies. For a cosmological constant dominated universe this constraint is consistent with the range allowed by other cosmological constraints, which also favor a non-zero value.Comment: latex, 10 pages, including two embedded postscript figure

The Original Understanding of the Seventh Amendment Right to Jury Trial

I ought to be very angry with my friend Akhil Amar. His new book, The Bill of Rights: Creation and Reconstruction, strengthens, develops, and popularizes his strikingly original claim that the meaning of our Bill of Rights must be sought in the understanding of the people who enacted the Fourteenth Amendment, rather than that of James Madison and his contemporaries. If Akhil carries the day on this question-and I find his arguments quite powerful, my ongoing research into the original meaning of the Bill will be of interest only to antiquarians

Adjusting to Life in Mexico – One Couple’s Adaptation Process and Suggestions for Coping

In this paper I present challenges which confronted Sharon Beckett, my partner, and me as we underwent the process of adapting to life in Mexico during a three month stay. Some of the issues are unique to a couple with our respective back­ grounds, but, many are applicable to any couple or individual traveling to Mexico or other foreign countries. I discuss some guidelines and principles of interacting which proved helpful to us in Mexico and also offer some suggestions for coping to couples or individuals going abroad. The primary source of data for the paper is a daily journal which I kept in Mexico throughout our stay

Peters v. Kiff and the Debate About the Standing of White Defendants to Object to the Exclusion of Black Jurors After Batson: The Nonuse and Abuse of Precedent

In Batson v. Kentucky, the Supreme Court held that the racially based use of the prosecution\u27s peremptory challenges to exclude blacks from a black defendant\u27s jury violates the defendant\u27s rights under the Equal Protection Clause of the fourteenth amendment. In addition, the Court noted that denying a person participation in jury service on account of his race” in this manner violates the excluded juror\u27s rights under that Clause. As might be expected, this decision has fueled the debate about whether white defendants may complain when the State uses peremptory challenges to exclude blacks from their juries. One remarkable aspect of this post-Batson controversy has been the way courts and commentators have treated Peters v. Kiff the only Supreme Court decision actually to determine the standing of a white defendant to protest discrimination against blacks in the selection of juries. More often than not, Peters has simply been ignored by courts considering this issue since Batson. Those exceptional opinions that do not overlook it entirely display a truly breathtaking inability accurately to report what the Justices said in that case. Nor has Peters fared much better at the hands of the commentators. There are two reasons why it is important to bring this situation to light. One is doctrinal: Peters must somehow be rescued from this morass, and its bearing upon the standing of white defendants to contest the use of peremptory challenges to exclude black jurors clarified. As a practical matter, this problem is pressing, because the Supreme Court will address the standing question this Term in Holland v. Illinois. The other reason to examine Peters’ fate, although not doctrinal in nature, is no less important: it is only by studying this spectacle that we can hope to learn what lessons it holds for our legal system and our profession. With these twin goals of exposure and explication in mind, I begin by introducing the reader to Batson and Peters. Once this has been accomplished, Part II of the Article surveys the treatment of Peters in the judicial opinions and commentary discussing the standing question. In Part III, I speculate about the reasons for the abuse that Peters has endured in this context