time travel

nTime traveling is an idea about moving from one point of time to another point of time.

nWe are all living in a natural law of time: second by second. So time travelling can also mean breaking this natural law: travel from now to somewhere in the past or future.

nEinstein: an German American scientist. In his concept, we meet the idea about real time travelling.

nBefore the principle of relativity the time travelling only exists in novels.

nIn principle of relativity, Einstein gave us an example: if there have two people A and B. A went to south America from NYC by Airplane, and then came back. The time on A’s watch will be different from B’s watch.

The reason why it will happen is, based on principle of relativity, the physical speed can change the speed of time. if we can reach half of the speed of light, the time will go 13% slower than now.

nHere has another example:

nAssume there has a pair of twinborn brothers: Sam and Bob. One day, Sam went to somewhere was 10 light-years away from Earth by a spaceship at speed of 99% of light’s speed. Sam returned as soon as he got to that place. The whole trip would took him about 3 years, but on earth, it would be already 20 years later when he came back.

In another word, after the trip, Bob became 17 years older than Sam. They could never twins anymore. Or, actually we can say, Sam time travelled to the future.