Interstellar travel in search of extraterrestrial life

When Professor Brand first met Cooper, he told him that the Lazarus Missions had sent humans on a journey to find a new home.

Cooper replied: "There are no planets in the solar system capable of supporting life, and the nearest stars are thousands of years away. It's not even worth a try. Where did you send them, Professor?" ? ”

When you realize how far away the nearest star is, you can immediately understand how “not worth a try” this challenge is without a wormhole (see Figure 12- 1).

How far is the nearest star from us?

We generally think that the nearest star (not counting the sun) with habitable planets is Tau Ceti (Tau Ceti), which is 11.9 light-years away from the earth, so even if you travel at the speed of light It will take 11.9 years to get there. Even if there are other planets suitable for human habitation that are closer, they will not be much closer than it.

In order to appreciate how far away Tau Ceti is from the earth, let's compare it with something familiar. Let's compress the distance dramatically in proportion. Imagine this distance is equivalent to traveling from New York to Perth, Australia – almost halfway around the world.

Apart from the sun, the nearest star to the earth is Proxima Centauri, which is 4.24 light-years away, and there is no evidence that there are habitable planets around it. If the distance to Tau Ceti is equivalent to traveling from New York to Perth, then the distance to Proxima Centauri is equivalent to traveling from New York to Berlin, not much closer than Tau Ceti! For comparison, Voyager 1, the farthest unmanned spacecraft ever launched by humans into interstellar space, is now about 18 light-hours away from Earth and has spent 37 years traveling there. If the distance to Tau Ceti is equivalent to New York to Perth, then the distance from Earth to Voyager 1 is only about 3,000 meters: the distance from the Empire State Building to Greenwich Village The distance to the south end of (Greenwich Village) is much farther than the distance from New York to The Pas.

Correspondingly, the distance from Earth to Saturn is even shorter: only 200 meters, the width of two east-west city blocks in New York City, equivalent to the distance from the Empire State Building to Park Avenue. The distance from the Earth to Mars is only equivalent to 20 meters; and the distance from the Earth to the Moon (the farthest distance humans have ever reached) corresponds to only 7 centimeters in length.

Compare the difference between the moon we have reached - 7 centimeters away and halfway around the world. This is the technological leap required when humans want to colonize habitable planets outside the solar system.

Travel time under 21st century technology

"Voyager 1" is flying out of the solar system at a speed of 17 kilometers per second. It has used the gravitational slingshot of Jupiter and Saturn The effect speeds things up. In the movie "Interstellar", it took the "Eternal" two years to fly from Earth to Saturn, with an average speed of about 20 kilometers per second. I believe that using rocket technology and the gravitational slingshot effect in the solar system, the maximum navigation speed in the 21st century may reach about 300 kilometers per second.