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Can We Travel Through Time?

   

The mystery of time travel as it is portrayed in science fiction is not as simple as building a time machine. In fact, these fictional ideas require overturning Albert Einstein's special theory of relativity and somehow traveling close to the speed of light.


     Physicists continue to ponder the possibilities of faster-than-light travel (FLT) and what it means for space exploration and our universe. The first example of faster-than-light speeds in popular culture occurred in the television series Star Trek, when "warp drive" sent spaceships traveling billions of light-years away in a matter of seconds. If this were possible, those space travelers might return to their original location and find that time had progressed at its usual speed, meaning 50 years may have passed during the short time the ship was absent, simulating time travel.

    While most people view time as a constant, Einstein proved that time is relative to how fast an object moves according to its surroundings. Einstein pointed out that time is not a consistent flowing entity, but linked with space, and so the faster one travels through space, the more the perception of time changes, a phenomenon called time dilation. If an astronaut can somehow travel close to the speed of light, he will experience time differently than his friends left behind on Earth traveling at the usual speed. Time will pass much slower for the astronaut, and when he returns to Earth, his friends will have aged faster. However, the laws of physics state that the speed of light is constant, represented by c in Einstein's famous equation.  E = mc. The speed of light in a vacuum is 186,000 miles per second (299,337 km/h), and while some physicists have identified processes like quantum entanglement that travel faster than light, they do not carry mass or information. For a particle with mass, reaching the speed of light would require infinite acceleration and therefore infinite energy-an unrealistic accomplishment.

      In 2011, physicists at the CERN institute in Switzerland thought they were close to a FLT discover. A new subatomic particle called the neutrino, which carried a very small mass, appeared to travel faster than the speed of light. Their experiment launched particles from Switzerland to Italy, and the neutrinos arrived in Italy in record time, intriguing the world with thoughts of time travel and visits to distant galaxies. Unfortunately for CERN, the experiment was flawed. One cable was not properly connected, resulting in incorrect measurements.
  
    According to Einstein's theory, objects with mass cannot exceed the speed of light because they would require an infinite amount of energy-be they spaceships or neutrinos. Even in all theoretical scenarios in which we travel faster than light, we can never travel backward in time, only forward. However, many scientists believe that traveling into the future is still a possibility that just needs more study.
Wormholes, a theoretical passage through space-time that connects distant points in the universe, are attractive starting point for these theories. But however enticing the possibilities, it seems that success is still light-years away.


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