Long, hot summer
Extraterrestrial life and what it could mean for a hot universe.
Our planet Earth formed 4.5 billion years ago, and after a billion years passed, life appeared on our planet. It took another 3.48 billion years for us humans to evolve into the thinking, technology-making, clever creatures we are.
Our Milky Way galaxy, home to a few hundred billion stars and at least as many planets, has existed for more than 10 billion years, more than twice as long as Earth has been around. If our planet is at all typical, there should be many intelligent species throughout the galaxy and many of them should be much older than we are. With a few billion years head start on us, they should possess the technology to colonize all the habitable planets and moons in our galaxy. Enrico Fermi, the physicist who built the first controlled nuclear reactor, was puzzled by this. If civilizations million or billions of years older than we are exist, then they — or at least their self-replicating machine explorers — should be everywhere in our galaxy. “Where are they?” he asked a group of lunch colleagues in 1950. It’s a question now known as the Fermi Paradox.
Since then, many scientists have offered suggestions in an attempt to explain Fermi’s Paradox. Perhaps space travel is just too dangerous, space being so full of deadly radiation and all. Perhaps technological societies destroy themselves before leaving their own stellar systems, by wars or the evolution or accidental (or deliberate) creation and release of deadly viruses or bacteria. It’s entirely possible, some scientist believe, that life or at least intelligent, technology-producing life is extremely rare and we humans represent the very first such evolution. Maybe we eventually will be the aliens that take over the galaxy.
Scientists with the Future of Humanity Institute offer a quite different solution to the paradox: alien aestivation. Aestivation refers to the hibernation-like state seen more commonly in bacteria. Essentially they go into a deep sleep until conditions emerge that better support life. They reason that the more advanced and more numerous alien civilizations become, the more computations they’ll need. The problem has to do with the thermodynamics of computation. Every single one releases some miniscule amount of heat. Think of your computer needing a fan to keep it functional. And with millions of trillions of aliens all over the galaxy needing who knows how many computations on whatever they use for computers, entropy becomes a problem: too much heat generated in a universe not cold enough to sink it all away.
A member of the group, Anders Sandberg, a research associate to the Oxford Uehiro Center for Practical Ethics, explained it this way. “There is an entropy cost to irreversible logical operations, including error correction,” Sanders said. “So unless there is some magical energy source or entropy sink, if you want to do as much computation as possible you should wait until the cosmic background radiation levels off,” or cools off so that the heat generated by computation isn’t limited by a “hot” universe.
The answer to Fermi’s Paradox may just be that the aliens are all on a trillionyear-long siesta.
Do hotter temperatures signal nearness to the sun?
Generally speaking, things astronomical orbit some other astronomical thing. The moon orbits Earth, Earth orbits the sun and our solar system orbits the giant black hole in the center of the Milky Way galaxy. And also, generally speaking, those orbits are not circular but rather elliptical in shape. That means the distance between the orbiter and the orbitee varies over the course of each revolution. All that is true for our Earth as we orbit the sun.
At Earth’s closest point to the sun, known as perihelion, we are 3,102,000 miles closer than at aphelion, our most distant point. Earth reached aphelion yesterday at 3 pm. Perihelion occurs on Jan. 4 each year.
And you thought summer heat occurred because we’re closer to the sun.
July highlights: The Delta Aquarid meteor shower occurs on the July 27. A thin crescent moon sets before midnight and the best activity, about 20 to 25 meteors per hour, happens after midnight.
Planet Visibility Report: Mercury spends the entire month in the evening twilight, one of its best apparitions in quite a while. It is joined in the evening sky by both Jupiter, in the south at sunset, and Saturn, in the east at sunset. Venus spends the entire month outshining everything in the morning predawn sky while Mars spends the entire month hiding behind the sun. Full moon occurs on the July 8 with new moon following on the July 23.