Wednesday, February 23, 2022

Will traveling to the stars be possible?

Will interstellar travel be possible? At the current level of our technology, the answer is clearly no. Will it be possible in the future? It is always dangerous to make predictions: reality often strays from what was supposed to happen. But it doesn't look like interstellar travel is going to become feasible anytime soon. Of course, in the scientific literature, both serious and imaginative, various methods have been proposed, some of which we’ll review in this and future posts, by analyzing the relative probabilities of each one.

Many writers consider interstellar travel the next frontier of human spread, and the only guarantee to avoid our extinction, either accidental, if a cosmic catastrophe occurs, or caused by ourselves with a nuclear war. The problem is, a trip to the stars would be much more difficult than planet exploration in the solar system. Apart from the sun, the closest star to us is 4.27 light-years away, just over 40 trillion kilometers. With our current technique, speeds of the order of one million kilometers per day can be reached, so a trip to that star would last more than one hundred thousand years. Taking advantage of the gravitational pull of giant planets, like Jupiter, it would be possible to triple the speed, but even so we are talking about tens of thousand years.

Let's look at some of the proposed methods to solve the problem and reach the nearest stars, in order of their difficulty to be carried out:

1.                  Generational journeys: we would travel to the stars in huge, ecologically closed ships, propelled and maintained by the energy of nuclear fusion, where several thousand people would leave towards a destination that would be reached by their distant descendants.

2.                  Travel in suspended animation: the same as the previous one, but the travelers would be in a state of hibernation, so the necessary energy expenditure would be much lower, and the same people who undertook the trip would reach their destination, which would eliminate many problems of the previous method.

3.                  Relativistic speeds: Although the speed of light is unattainable for a moving object, according to the special theory of Relativity, perhaps sufficient speeds could be reached to reduce the time of interstellar travel. For instance: half the speed of light. In this case there would be no need to put travelers in a state of latent life, and the trip could be roundtrip, although this would cause new problems, such as time shortening.

Many science fiction novels make it clear that even relativistic speeds do not satisfy our impulses to explore. We would like to travel to the stars as easily as we cross the Atlantic today. We would like the time of a trip to the center of the galaxy to be measured in days, if not hours. Is there any chance that this will happen? Perhaps in the future some property of the universe, unknown today, will be discovered that will help us break the limit of the speed of light, which seems firmly established and would make us spend thousands of years on interstellar travel to most of the stars, except the nearest ones.

4.                  Methods based on undiscovered scientific findings: Just now, most are pure science fiction, although there are a few serious scientific proposals, more or less imaginative. This group of solutions can, in turn, be classified as follows:

    1. Travel at speeds greater than that of light. Either using tachyons (hypothetical particles not known to exist), or special effects, such as the Alcubierre drive, also called warp drive, a name inspired by the science fiction series Star Trek.
    2. Travel through wormholes. The simplest would be a black hole connected to a white hole, an object not known to exist.
    3. Travel through unknown dimensions of space. This is one of the favorite procedures of science fiction writers, who call these dimensions with names such as hyperspace or subspace.

In future posts we’ll talk in turn about these procedures. 

The same post in Spanish

Thematic Thread on Space Exploration: Previous Next

Manuel Alfonseca

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