SALT LAKE CITY — Predicting the future is a difficult task because the effects of one event impact and change events that lie beyond it. But some things in our universe follow such precise laws of behavior that scientists, knowing how they behave, can make certain predictions of the future, at least on a broad scale.

Not only do scientists have the ability to predict the extreme future of the universe, they have actually sat down and done it, charting the universe’s course for the next 3x10⁴³ years.

A couple of examples: Astrophysicists know how long it takes a star to burn up its supply of hydrogen fuel. Armed with that knowledge, they can then predict when the last stars will burn out. And physicists know that matter itself will decay over time, for the simple reason that matter is made of elements, and all elements will come under the influence of radioactive decay and break apart into subatomic particles. Knowing the half-life of an element, they can then extrapolate forward and determine how long it will take for the elements to completely decay into subatomic particles.

The tentpole upon which the future of the universe hangs is the second law of thermodynamics, which states that the energy available to do work will decrease over time.

All right then, let’s take this time machine for a ride.

In 25,000 years, the Arecibo Message, which is a packet of data transmitted by radio signal in November 1974, reaches its destination, the globular cluster Messier 13.

In 50,000 years, assuming that the Arecibo Message is received by intelligent beings in the Messier 13 cluster, and they send a message back, their message will then be received on Earth.

In 500,000 years, astrophysicists predict that it’s likely that Earth will have been hit by a meteorite of a kilometer in diameter or larger. According to Stephen Nelson, a professor of geology at Tulane University, the Earth gets struck by meteorites of that size once every 100 million years. Nelson says getting hit by a meteorite that large would likely cause the extinction of humanity due to effects of the impact, in the form of magnitude 13 earthquakes, tsunamis large enough to flood the interior of continents, and an atmospheric dust cloud that would block incoming solar radiation long enough that most plants would die from lack of photosynthesis, and that affects everything up the food chain.

The Earth has suffered at least five mass extinctions already, and at least some of these were caused by meteoric impacts, Nelson says. The most recent mass extinction was caused by an interstellar impact, the asteroid that hit the Yucatan Peninsula 65 million years ago and killed off the dinosaurs.

But astrophysicists say it’s also likely that we will detect such a large asteroid or comet approaching Earth and may be able to deflect its course away from Earth with a well-placed nuclear detonation.

1 million years from now is the outside edge of the window in which Michio Kaku, a professor of theoretical physics at the City College of New York City University, theorizes humanity will have become a Type III civilization, capable of harnessing any energy available in the universe.

By 8.4 million years from now, the orbits of the LAGEOS (Laser Geodynamic Satellites) will decay and re-enter Earth’s atmosphere. The two LAGEOS satellites are aluminum-covered brass balls covered with retro-reflectors, which geologists use to track tectonic plate movement and continental drift. LAGEOS 1 also contains a plaque that shows the arrangements of the Earth’s continents past, present and how they’re expected to look in 8.4 million years, meant as a greeting to Earth’s future inhabitants.In anywhere from 5 million to 50 million years from now, even traveling at sublight speeds, humanity could colonize the entire galaxy, writes Ian Crawford in the July 2000 Scientific American. “Even in these early days of the space age, engineers have envisaged propulsion strategies that could reach 10 to 20 percent of the speed of light, thereby permitting travel to nearby stars in a matter of decades. Consider a civilization that sends colonists to a few of the planetary systems closest to it. After those colonies have established themselves, they send out secondary colonies of their own, and so on.”

Some 250 million years ago, all of Earth’s continents were clustered into a single supercontinent, called Pangea. Due to plate tectonics, the continents have drifted away from each other to their present positions. But geologists say that those plates are reversing course, and over the next 250 million years, the continents will slowly move back together and form another supercontinent. Based on observations of plate tectonic movements, geologists from the University of Texas at Arlington have made educated guesses how the continents will move over the next 250 million years.

About 10 million years from now, they predict the East African Rift valley will widen and open up to the Red Sea, which will flood into it, creating a new ocean that will divide the African continent. But that new ocean will be short-lived, geologically speaking, because Africa will continue its tectonic collision with Eurasia — something it has been doing for the last 40 million years — and in the process this collision will create a new mountain range similar to today’s Himalayas where the Mediterranean Sea is now. And the Atlantic Ocean will shrink to about the size of today’s Mediterranean Sea as the continents again come together.

By 100 million years from now, Earth likely will have been hit by a meteorite in size comparable to the one that killed the dinosaurs 65 million years ago. It’s worth pointing out that scientists are not predicting that Earth will be struck by a K-Pg size meteorite in 100 million years, they’re saying that that is the far edge of the window, and the K-Pg size meteorite will strike sometime inside that window.In 240 million years, our solar system will have completed one full orbit around the Galactic Center.

As catastrophic as the events listed above will be to inhabitants of Earth, it is all stuff that Earth has gone through before. But around 600 million years from now, things will start happening that will affect Earth and its inhabitants in entirely new ways.

Our sun will increase in luminosity — the amount of energy emitted by a star — to the point that it will disrupt the carbonate-silicate cycle. In today’s conditions, Earth’s rocks slowly leak carbon dioxide, but according to Jack O’Malley-James, a physicist and astronomer at the University of St. Andrews at Fife, England, the sun’s increased luminosity will weather the surface rocks to the point that they will trap the carbon dioxide inside the rocks as carbonate, the same way that a seared steak retains its juices.

Furthermore, writes O’Malley James, the increased heat will evaporate more water from Earth’s surface, and this process will make rocks even harder. This will cause plate tectonics to slow down and eventually stop. With the tectonic plates “frozen,” there will be no more volcanoes, and volcanoes are the primary engine in the Earth’s carbonate-silicate cycle, because volcanoes recycle carbon from inside the Earth back into the atmosphere. Without carbon being extruded into the atmosphere, carbon dioxide levels will dwindle to the point that C3 photosynthesis becomes impossible. Ninety nine percent of the Earth’s plants will die, as well as any animals or insects dependent on those plants.

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Two hundred million years after that, carbon dioxide levels will fall to the point in which C4 photosynthesis becomes impossible. Whatever multi-cellular life remains on Earth will die out.One billion years from now, the sun’s luminosity will continue to increase until it will be cranking out about 10 percent more energy than it is today, writes Donald E. Brownlee, professor of astronomy at the University of Washington, and principal investigator for NASA’s Stardust Mission. The surface temperature of the Earth will reach an average 116 degrees Fahrenheit. This will result in the unstoppable evaporation of the oceans. However, it’s possible that some pockets of water may remain at the poles, which may be suitable to sustain life.

The sun’s increasing luminosity will be bad news for Earth but could be good news for Mars. As the sun’s circumstellar habitable zone expands farther into the solar system, Mars may reach temperatures that make it habitable, Brownlee writes. Increasing Martian temperatures will pull CO2 into the atmosphere from where it’s stored in rocks, and maybe a little water. According to Jeffrey Kargell, professor at the University of Arizona’s Department of Hydrology and Water Resources, and author of "Mars: a Warmer, Wetter Planet," Mars could reach a climate similar to the Earth's Ice Age. And in about 6.5 billion years from now, it’s possible that Mars could reach a temperature and climate similar to what the Earth experiences today.

In 2.3 billion years, Earth’s outer core freezes. The Earth’s magnetic shield is produced by the friction created by the movements of the Earth’s outer core. When the Earth’s outer core freezes, the magnetic shield will shut down. The Earth’s magnetic shield protects it from charged particles from the sun that would erode away its atmosphere, but lack of a magnetic shield will have little consequence 2.3 billion years from now when the only life left on Earth are small pockets of unicellular life.

2.8 billion years from now, the last remnants of life on Earth will die. At that time, the only life remaining on Earth will be unicellular life, if at all, in isolated pockets at the poles. It will die out when the Earth’s temperature reaches 296 degrees Fahrenheit, even at the poles, as the sun’s luminosity continues expanding.

Four billion years from now marks the median point by when the Milky Way Galaxy will have collided with the Andromeda Galaxy. After this median point of “collision,” the two galaxies will thereafter be considered a single galaxy, which astrophysicists have dubbed the Milkomeda Galaxy. The Andromeda Galaxy contains about one trillion stars, and the Milky Way Galaxy contains about three hundred billion stars, but according to Abraham Loeb, a theoretical physicist at Harvard University, co-author of “The Collision Between the Milky Way and Andromeda,” the distances between the stars in merging galaxies are so vast that no planets, or suns, are expected to collide with each other.

In 5.4 billion yearsw, our sun will have exhausted all the hydrogen at its core. When the nuclear reactions in the core stop, the core will contract under constraints of its own gravity. This will heat a shell just outside the core, where some hydrogen still remains, and this will initiate fusion of hydrogen into helium. This will start the process where it will evolve from a yellow sun into a red giant. It will expand in size and luminosity.

A couple of significant things will occur during the sun’s expansion, writes K.R. Rybicki, professor of geophysics at the Polish Academy of Sciences. The first: about 7.5 billion years from now, the Earth and Mars will likely become tidally locked with the sun, due to the sun’s increasing gravity, meaning the Earth and Mars will no longer spin on their axies; just one side of the planets will face the sun.

The second is that the sun will go through a second expansion, about 7.9 billion years from now, and reach the Asymptotic Giant Branch of its evolution. In the process of this gross expansion, it will destroy Mercury, Venus and the Earth, says Rybicki. But on the bright side, during this period it’s possible that Saturn’s moon, Titan, could reach surface temperatures necessary to support life.

In 8 billion years, the sun will become a white dwarf. A white dwarf no longer possesses the material to perform fusion reactions. It will shrink to about half of its present size. From there it will morph into a black dwarf over the next six billion years, falling below three trillionths of its current level of energy, making it invisible to the naked eye.

Anywhere from 1 trillion to 100 trillion years from now, the formation of new stars ends as galaxies deplete the gas clouds that are necessary to form new stars, according to Fred C. Adams, professor of physics at the University of Michigan. This marks what astrophysicists call the Degenerate Era. With no remaining free hydrogen to form new stars, all remaining stars will slowly exhaust their fuel and die.

In 2x10³⁶ to 3x10⁴³ years from now, all the nucleons in the universe will have decayed. And since the elements are made of nucleons, as the nucleons decay the elements will disappear with them. Most radioactive elements do not decay directly to a stable state but undergo a series of decays until they finally reach a stable isotope. Eventually every element will have decayed into its most stable form.

“You have to divide the element world into two,” says Sam Kean, author of "The Disappearing Spoon," a book about the discovery and assembly of the periodic table. “(1) All those elements up to and including lead, and (2) all the elements heavier than lead. All the elements heavier than lead will eventually decay someday."

“With elements smaller than lead, it’s a different story,” says Kean. “There are radioactive forms of potassium and nearly every other element, and all those radioactive atoms will decay over the very long run as well. But there are also non-radioactive forms of most elements, and as far as scientists know now, those elements will always be with us.”

Scientists still don’t know if protons decay, but depending on if they do or don’t, a couple different scenarios will play out. If protons do decay, in 10¹⁰²⁶ years black holes will be the only remaining celestial objects.

If protons do not decay all baryonic matter will have either fused together to form iron-56, or decayed from a higher mass element to form iron-56.

If you ask me, that seems like a pretty boring place to put the Restaurant at the End of the Universe.

If you have a science subject you'd like Steven Law to explore in a future article, send him your idea at curious_things@hotmail.com.

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