Too Short for a Blog Post, Too Long for a Tweet 214

Here are a few excerpts from a book I recently read, "The Future of Humanity: Terraforming Mars, Interstellar Travel, Immortality, and Our Destiny Beyond Earth," by Michio Kaku.

If our ancestors in the last century would think of us today as magicians and sorcerers, then how might we view our descendants a century from now? 

More than likely, we would consider our descendants to be like Greek gods. Like Mercury, they would be able to soar into space to visit nearby planets. Like Venus, they would have perfect immortal bodies. Like Apollo, they would have unlimited access to the sun’s energy. Like Zeus, they would be able to issue mental commands and have their wishes come true. And they would be able to conjure up mythical animals like Pegasus using genetic engineering. 

In other words, our destiny is to become the gods that we once feared and worshipped. Science will give us the means by which we can shape the universe in our image. The question is whether we will have the wisdom of Solomon to accompany this vast celestial power.

A quick calculation shows that the moon separated from the Earth billions of years ago. And modern evidence indicates that 4.5 billion years ago, not long after the Earth was formed, there was a cosmic impact between the Earth and a large asteroid of some sort. This asteroid, which we call Theia, was about the size of Mars. Computer simulations have given us dramatic insight into this explosion, which gouged out a huge chunk of the Earth and propelled it into space. But because the impact was more of a glancing blow than a direct strike, it didn’t take much of the interior iron core of the Earth. As a result, the moon, while it does contain some iron, has no significant magnetic field because it lacks a molten iron core. 

After the collision, the Earth resembled a Pac-Man, with a huge pie-shaped piece carved out. But because of the attractive nature of gravity, eventually both the moon and Earth condensed into spheres again. 

Evidence of the impact theory was provided by the astronauts who brought 842 pounds of rock back from their historic trips to the moon. Astronomers discovered that the moon and the Earth are made of almost the same chemicals, including silicon, oxygen, and iron. By contrast, random analysis of rocks from the asteroid belt shows that their composition is quite different from that of the Earth’s.

Rough calculations suggest that it may be prohibitively expensive at present to terraform Mars and that it would take centuries to complete the process. However, what is intriguing and promising about the planet is the geographic evidence that liquid water was once abundant on the surface, etching riverbeds, riverbanks, and even the outline of an ancient ocean the size of the United States. Billions of years ago, Mars cooled down before the Earth did and had a tropical climate when the Earth was still molten. This combination of mild weather and large bodies of water has led some scientists to speculate that DNA originated on Mars. In this scenario a giant meteor impact blasted tremendous amounts of debris into outer space—some of it later landing on Earth and seeding it with Martian DNA. If this theory is correct, then all you have to do to see a Martian is look in the mirror.

The early solar system was full of cosmic debris that constantly rained down on the Earth. Fortunately, the gravitational field of Jupiter acted as a vacuum cleaner, either absorbing it or flinging it away. Computer simulations show that, without Jupiter, the Earth even today would be bombarded with giant meteors, which would make life impossible. In the future, when considering solar systems to colonize, it would be better to look for those that have their own Jupiter, big enough to tidy up the debris.