I excavated Peter Brannen’s article “Can a Time Capsule Outlast Geology?” from a long-term storage site—my nightstand—where it had been protected by the superstratum of his book The Story of CO2 Is the Story of Everything.
We have the capability to place a time capsule on or just below the surface of the moon. Calculations predict that our nearest celestial neighbor will not escape Earth’s orbit prior to when it is engulfed by the expected red giant phase of our sun some five billion years hence. I would therefore suggest we deposit the long-term records we wish a future civilization and/or species to use to evaluate our rather mixed legacy near a lunar pole. Alternatively, I might consider offering my nightstand.
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DANIEL SPITZER PIERMONT, N.Y.
The dangers of creating a bacterium with mirror molecules are clearly expounded by Vaughn S. Cooper in “Deadly Mirror.” But the article doesn’t mention the danger of encountering mirror DNA while exploring outside our planet. I would think the chances of encountering such DNA as part of an extraterrestrial life-form would be higher beyond the moon and Mars—and would be much greater as we explored more of our solar system, including bodies that come from other solar systems.
ED YALOW VIA E-MAIL
I found Cooper’s article oddly comforting. I’ve been feeling bad about the fact that, within several thousands of years, inevitable periods of societal instability will cause improper nuclear waste storage somewhere on the planet, and we will be responsible for the suffering of innocent future humans and animals when they are unsuspectingly exposed to dangerous levels of radiation that will make them sick.
I don’t think I have to worry about that anymore: a mirror bacterium will be created by somebody in a dark lab using some kind of AI-powered chemical printer before that happens. We will be wiped out pretty quickly, and multicellular life will evolve again to become compatible with the existence of both threats—and, let’s hope, a little less “intelligent” this time.
FRANCES SIMONSON REGINA, SASKATCHEWAN
In “The First Stars,” by José María Diego Rodríguez, the ability to see very distant stars via the use of gravitational lensing by large galaxy clusters is nicely described and mentioned as a means of possibly further understanding dark matter. Is what allows for the estimate of dark matter within a cluster the geometric arrangement of the situation, the focal lengths and, especially, the amount of light bending associated with the very small regions called caustics? Or are there other factors involved?
G. RICHARD THOMPSON VIA E-MAIL
DIEGO RODRÍGUEZ REPLIES: The driving factor is the amount of curvature that can be produced by certain dark matter models that can result in small lenses (microlenses). The microlenses can be seen best near cluster caustics. Some models are able to produce additional microlenses, whereas other models don’t. The distant stars can be used to create a census of microlenses that favor some dark matter models and discard others.
“The Neuroscience of the ‘Parenting Paradox,’ ” by Anthony Vaccaro [Mind Matters], describes the author’s research around a seeming contradiction: “parents report lower mood and more stress and depression in their daily lives than adults without children”; at the same time “parents also tend to report greater life satisfaction in general.” The article presents the idea as if parents are less happy day to day but more fulfilled overall. But I don’t think this is really a paradox—it’s about how happiness is measured. Quick daily mood check-ins mostly capture stress and exhaustion while missing the small joys, pride and love woven throughout parenting. Raising kids can be tiring and meaningful at the same time. Much of the stress parents feel also comes from lack of sleep, financial pressure or limited support—not simply from having children.
JAMAL I. BITTAR TOLEDO, OHIO
When I began life as a neuroscientist 40 years ago, the nature of consciousness was understood about as well as it is now. In “The Hardest Problem,” Allison Parshall uses the terms “consciousness,” “awareness” and “conscious awareness” interchangeably. It might be to our advantage to look at consciousness and awareness as different things.
Admittedly, without the benefit of functional magnetic resonance imaging (fMRI) and other modern techniques, thinkers such as Dōgen, Hongzhi Zhengjue, and many others of the long Buddhist tradition reasoned that consciousness is impermanent, mutable, divisible and easily misidentifiable as the “self” but is emergent from and dependent on awareness, a fundamental and unchanging thing. This may point to a distinction that could be usable by scientists.
KENNETH B. THOMAS VIA E-MAIL
In “Inside Asteroid Family Trees” [The Universe; January], Phil Plait writes that when two space rocks collide in the main asteroid belt, “their high orbital speeds mean they can have collision velocities far higher than that of a rifle bullet.” I’m puzzled by this comment. I assume that because the two asteroids are in the same orbit, they have the same speed, so their relative speeds would be very low. Where would the collision’s high velocity come from?
ROBERT I. MASTA ANN ARBOR, MICH.
PLAIT REPLIES: While it’s true that most asteroids orbit in the same direction around the sun—counterclockwise if you’re looking “down” on the solar system from the north—the orbits are all different shapes. An asteroid that’s on a more elliptical orbit, for example, may be moving significantly faster when it’s closest to the sun than another asteroid that’s on a nearly circular orbit at that same distance. Also, some asteroids have their orbits changed by Jupiter’s gravity, which can alter their velocities. Collisions in the asteroid belt may be less energetic on average than when an asteroid hits Earth, but they can still disrupt a largish rock to create families with many members.
“War’s New Fuel,” by Sarah Scoles [The Science of War; April], incorrectly identified the image of a water-filled structure as a cooling pool. It is the open core of a nuclear reactor.
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