How will humans colonize the stars beyond our own solar system? Research in space travel has only recently begun to tackle this problem. But almost 100 years ago, Albert Einstein made some revolutionary
claims about the types of challenges that await those who travel at high
speeds across the cosmos. Particularly with regards to the way they experienced time. While most people view time as a constant, Einstein's special theory of relativity proved that the passage of time is affected by how fast an object moves relative to its
The faster one travels through space, the more one's perception of time changes. This phenomenon is called: time dilation. If an astronaut can travel at close to the speed of light, time will pass much more slowly for her. When she returns to Earth, her friends will have aged more than she has.
For example, if near lightspeed travel were possible, an astronaut could travel to Alpha
Centauri, our closest neighboring star system, 4.37 Light years away. Moving at 99.1 Percent of the speed of
light, it would take 8.82 Years to get there and backas measured by an Earth observer. However, due to time dilation, the astronaut would experience a round-trip journey of just over one year. Einstein also theorized that the speed of light represented a fundamental speed limit in the physical world.
Einstein's theory, objects with mass cannot exceed the speed of light because
they would require an infinite amount of energy to do so. This is true for
everything from spaceships to neutrinos. In spite of this limit, scientists
continue to ponder the possibilities of faster than light travel. The first example of faster than light speeds in popular culture, occurred in the television series Star
On the show, spaceships generated a fictional subspace bubble, by surrounding themselves in a warp field, in order to exceed the speed of light without experiencing relativistic effects like time dilation. Using this technology, the Starship Enterprise was able to travel billions of kilometers in a matter of seconds. For those of us hoping to seek out new life and new civilizations, Scientists have hypothesized that interstellar travelers could be detected. In Space, photons can cause drag and because a fast-moving spaceship would encounter so many more photons than a ship moving slowly, the ship would generate an energy signature that would be both visible in
the infrared spectrum, and detectable by us.
This means that alien civilizationsif
they existwould also be able to detect us traveling at this nearly light speed. Outside of science fiction, the fastest we've ever flown in space was during the Apollo 10 mission, which reached speeds of about 39 897 km/h. At that speed, it would take 165 000 years to reach the nearest star system. This suggests that with conventional propulsion technology, humanity will never reach even nearby stars.
The problem with current
spacecraft technology is that the propellant they carry with them, and use
for thrust, has mass. Interstellar space craft require a lot
of propellant, which makes them heavy, which requires more propellant, making them heavier and so on. However, some of physics' brightest minds, including Stephen Hawking, believe that new technologies are making interstellar
travel a real possibility. In the latest initiative launched by the Breakthrough Prize Foundation, Hawking and his team pledged $100 million dollars to
send tiny ships to our closest neighboring star system, Alpha Centauri.
that lasers are now advanced enough to help launch interstellar space probes. Researchers can currently build phased laser arrays. These arrays are made up of many relatively modest laser amplifiers that can synch up to act like a single
powerful laser, kind of like the Death Star Laser… …But not all death-like.
Eventually, the scientists want to build a 50-70 gigawatt laser array that is ten
kilometers by 10 kilometres in size. Launched into orbit around Earth, the array could shoot light at a very small spacecraft, about the size of a saltine
crackers and the weight of a paper clip that's equipped with the one metre wide
sail. The scientists calculate that this would
accelerate the tiny probe to more than 25% of the speed of light after about 10
minutes of illumination. At that rate, it could reach Mars in 30 minutes and Alpha Centauri in about 20 years.
The laser array could launch roughly 40,000 relativistic wafer-sized probes per year, carrying sensors, cameras, communications devices, power, and other systems. Some challenges remain. It would take the same array about 2,200 years to propel a fully loaded space shuttle to Alpha
Centauri. A much larger array would be needed for a human interstellar trip in
the distant future.
But with the emergence of these new propulsion technologies, galactic travel might be closer than we previously anticipated. Thanks for watching! Want more Thought Caf and Popular Science? Click to watch our last collaboration. And make sure to subscribe so you never miss a new video!.