Health Problems and Job Layoffs Crack Retirement Nest Eggs

As people prepare for retirement, even the best-laid plans can go awry. Health fails. Spouses or other family members become ill. Marriages end in widowhood or divorce. Investments sour. People lose their jobs. Health, employment, and marital shocks can have serious financial consequences -- out-of-pocket health bills, reduced earnings, disrupted retirement saving -- forcing people as young as 50 or 60 to dip into their nest eggs

How Secure Are Retirement Nest Eggs?

Life's uncertainties can upend the best-laid retirement plans. Health can fail as people grow older, or their spouses can become ill. Older people can lose their jobs, and often have trouble finding new ones. Marriages can end in widowhood or divorce. Health, employment, and marital shocks near retirement can have serious financial repercussions, raising out-of-pocket medical spending, reducing earnings, disrupting retirement saving, and forcing people to dip prematurely into their nest eggs. This brief examines different types of negative events that can strike near retirement. It reports the incidence of widowhood, divorce, job layoffs, disability, and various medical conditions over a 10-year period, and estimates their impact on household wealth. Data come from the Health and Retirement Study (HRS), a nationally representative survey of older Americans conducted by the University of Michigan for the National Institute on Aging. The survey interviewed a large sample of non-institutionalized adults ages 51 to 61 in 1992 and re-interviewed them every other year. The analysis uses data through 2002, the most recent year available. The results show that many people in their 50s and 60s experience negative shocks that threaten retirement security. Job layoffs, divorce, and the onset of work disabilities near retirement substantially erode retirement savings. The findings highlight the limitations of the safety net when things go wrong in late midlife. This Brief was written for the Center for Retirement Research based at Boston College

Covariance, correlation and entanglement

Some new identities for quantum variance and covariance involving commutators are presented, in which the density matrix and the operators are treated symmetrically. A measure of entanglement is proposed for bipartite systems, based on covariance. This works for two- and three-component systems but produces ambiguities for multicomponent systems of composite dimension. Its relationship to angular momentum dispersion for symmetric symmetric spin states is described.Comment: 30 pages, Latex, to appear in J Phys

Fourier-Space Crystallography as Group Cohomology

We reformulate Fourier-space crystallography in the language of cohomology of groups. Once the problem is understood as a classification of linear functions on the lattice, restricted by a particular group relation, and identified by gauge transformation, the cohomological description becomes natural. We review Fourier-space crystallography and group cohomology, quote the fact that cohomology is dual to homology, and exhibit several results, previously established for special cases or by intricate calculation, that fall immediately out of the formalism. In particular, we prove that {\it two phase functions are gauge equivalent if and only if they agree on all their gauge-invariant integral linear combinations} and show how to find all these linear combinations systematically.Comment: plain tex, 14 pages (replaced 5/8/01 to include archive preprint number for reference 22

Randomness, Nonlocality and information in entagled correlations

It is shown that the Einstein, Podolsky and Rosen (EPR) correlations for arbitrary spin-s and the Greenberger, Horne and Zeilinger (GHZ) correlations for three particles can be described by nonlocal joint and conditional quantum probabilities. The nonlocality of these probabilities makes the Bell's inequalities void. A description that exhibits the relation between the randomness and the nonlocality of entangled correlations is introduced. Entangled EPR and GHZ correlations are studied using the Gibbs-Shannon entropy. The nonlocal character of the EPR correlations is tested using the information Bell's inequalities. Relations between the randomness, the nonlocality and the entropic information for the EPR and the GHZ correlations are established and discussed.Comment: 19 pages, REVTEX, 8 figures included in the uuencoded postscript fil

An Operational Interpretation of Negative Probabilities and No-Signalling Models

Negative probabilities have long been discussed in connection with the foundations of quantum mechanics. We have recently shown that, if signed measures are allowed on the hidden variables, the class of probability models which can be captured by local hidden-variable models are exactly the no-signalling models. However, the question remains of how negative probabilities are to be interpreted. In this paper, we present an operational interpretation of negative probabilities as arising from standard probabilities on signed events. This leads, by virtue of our previous result, to a systematic scheme for simulating arbitrary no-signalling models.Comment: 13 pages, 2 figure

Bell's theorem without inequalities and without unspeakable information

A proof of Bell's theorem without inequalities is presented in which distant local setups do not need to be aligned, since the required perfect correlations are achieved for any local rotation of the local setups.Comment: REVTeX4, 4 pages, 1 figure; for Asher Peres' Festschrift, to be published in Found. Phy

Bell's theorem without inequalities and without probabilities for two observers

A proof of Bell's theorem using two maximally entangled states of two qubits is presented. It exhibits a similar logical structure to Hardy's argument of ``nonlocality without inequalities''. However, it works for 100% of the runs of a certain experiment. Therefore, it can also be viewed as a Greenberger-Horne-Zeilinger-like proof involving only two spacelike separated regions.Comment: REVTeX, 4 page

Quantum correlations are not local elements of reality

I show a situation of multiparticle entanglement which cannot be explained in the framework of an interpretation of quantum mechanics recently proposed by Mermin. This interpretation is based on the assumption that correlations between subsystems of an individual isolated composed quantum system are real objective local properties of that system.Comment: REVTeX, 3 page

Real Time Relativity: exploration learning of special relativity

Real Time Relativity is a computer program that lets students fly at relativistic speeds though a simulated world populated with planets, clocks, and buildings. The counterintuitive and spectacular optical effects of relativity are prominent, while systematic exploration of the simulation allows the user to discover relativistic effects such as length contraction and the relativity of simultaneity. We report on the physics and technology underpinning the simulation, and our experience using it for teaching special relativity to first year university students