Space Travel
For years, science-fiction filmmakers and novelists have been creating alternative, habitable planets in parallel universes. Many of their fans ask: Do these planets really exist? If they do, can humans reach these planets?
The reality of planets beyond our solar system is not a piece of fiction. Outer space is filled with millions of galaxies and, in each galaxy, there are thousands of stars and planets. Whether or not humans can reach these distant planets is debatable. In order to understand why this has created a debate, one should understand the design of our universe's many galaxies.
To begin with, the universe is immeasurably vast and expanding. In order to cover vast distances, one needs speed. On the other hand, the distance in space is measured by light years. The fastest traveling entity known to humans is light. It travels at the speed of 186,000 miles per second! The distance traveled by light in a year is called one light year. In other words, in order to travel a distance of one light year, one should travel at 186,000 miles per second—if that's ever possible—for a year! For this reason, visiting a neighboring galaxy planet may be impossible. The nearest galaxy is approximately 70 years away from Earth!
Light travels fast because of its composition. Light is made up of small photo packets called photons. These are very tiny particles of energy, which make light quick enough to travel. This opens up another promising science-fiction field: teleporting! Moving from one place to another without the use of physical space or a vehicle is called teleporting. The fact that this transportation mode is still in its developmental phase rules out teleporting facilitating current space travel.
Space theorists and researchers believe in another concept known as a wormhole. A wormhole, theoretically, is a tunnel that might connect two vast spaces, such as two far off galaxies. Astrophysicists believe that when two black holes meet each other, they may form a wormhole. Wormholes are only probabilities and no observable evidence has been found so far.
These theories might seem obscure and outlandish. When Nicolaus Copernicus first said that the Earth revolved around the Sun, people made fun of him. They did not understand how Earth could not be the center of the universe. But many challenging questions have been answered by theories that initially seemed to make no sense. Space travel to distant planets may not be viable now, but we have no reason to believe that it will remain so for long. In the past few decades, people have come to understand much more about space, which has in turn helped them to better understand planet Earth. As the famous astrophysicist Stephen Hawking put it, "Not to leave planet Earth would be like castaways on a desert island not trying to escape." Unless we keep exploring, we will never understand the mysteries of space!
12
What does the word "debatable" in paragraph 2 suggest about space travel?
A.
It is doubtful that people can travel outside our solar system.
B.
People are indifferent to the idea of space travel.
C.
The ability to travel beyond our galaxy is open to question.
D.
The possibility of intergalactic space travel is uncertain.