I had hoped to become an astronomer when I was about 10 years old, I read up on many fascinating theories of time travel then. Recently, I finally felt the effects of time travelling; in a very unique way.
The most simple and direct theory of time travel would be this: Light, the fastest particle in the universe, takes time to travel. For example, the light emitted from the Sun takes about 8 minutes to travel to the earth and reach our eyes. If the sun explodes this very moment at 3.00pm, it would be 3.08pm for us on Earth to know. For a man standing on Mars, it would take another 5 more minutes for him to realise the sun has exploded; at about 3.15pm. For a person standing in another galaxy 100 lightyears away, he will only know that the sun exploded at about 100 years later.
As the light continues to travel along, you can imagine it as a man running very fast. But if we could travel faster than speed of light; if we can run faster than this man, then we can catch up with him and see the past. For example, as the sun explodes, the light from that event starts to travel outwards from the source, like a man wearing a 'the sun exploded' tag on his shirt, running a 10000 meter race. At 20 meters, 8 minutes later, the man runs past checkpoint 'Earth' which the people on Earth then sees the event 'the sun exploded'. At 50 meters, 13 minutes later, he runs pasts Mars; the Martians would then realise 'the sun exploded'. The man continues to runs forward at a constant speed.
Lets assume 5 minutes after seeing the 'sun-man', someone from Earth at the 20 meters line, decides he wants to catch up with the man wearing the 'the sun exploded' tag and see it again. It would be possible for this person to do that if he runs faster than the man. Depending on how fast he is, as long as he is faster than the sun-man, he would catch up with him and see the tag again.
By this theory, we know that it is theoretically possible to travel back in time. We just have to find a way to be faster than the speed of light. We can 'chase' back time and see events of the past.
I recently discovered time travelling, albeit in a more philosophical way. There had been a renaissance of my primary school days. A group of us met up for a mini reunion, the momentum of this mini reunion generated a mass search for all our primary 6 classmates. Everyone stayed in contact with someone who stayed in contact with another. Now there are just 7 of the 43 originals unfound.
It is quite amazing considering 15 years have elapsed since all 43 of us were under one roof.
Of the 43 classmates that we were, I stayed in touch with around 4 guys. For the rest of them, time froze at the last day of school, 15 years ago on 1992, in that old classroom with that old wooden blackboard, filled with sweet adolescent words of goodbyes like 'Primary 6D Forever', 'All the best 6D'. Mention their names and the images that float up in my mind are still the skinny, geeky 12 year olds.
15 years later, I have spoke, for the first time in 15 years, with my primary school best pal on msn messenger; Had tea with two primary school friends and spoke to them more words in one afternoon than the whole of my primary school years; Visited a fashion boutique opened by a beautiful lady whom my last memory of her was a skinny tomboy.
The sensation one gets is exactly like time travelling. Because with respect to primary 6 and her people, time stood still and then fast forwarded 15 years to the present. When I look at the people standing in front of me, they do not appear to grow little by little over 15 years. It was as though 15 years of growth hit them within a second. Instant transformation of geeky, bespectaled nerds to gorgeous men and women. The way they talk, their maturity and the things that they are doing in their lives.
A number of them are already married or getting married; another shock. 'Nooo, she can't be married! She is still a that annoying little girl!' I would exclaim in my mind. The last recollection of them were from the young innocent years, where one would blush even thinking about his or her 'crush'. Within an instant, the next thing you know about them is they are already building their own families.
Some of them are teachers themselves now. Hard to believe too. Like in an instant they switched alliance and now they are on the other side of the 'teachers vs students' war.
One travels back to the past too in this little philosophical time machine. Things that you have forgot over the course the years, start to come back again. Like the forgotten fact that I was a grubby untidy kid, who wore unwashed, wrinkled uniforms to school, or that special crush on this special girl my friend used to have, or the other bitchy girl that all boys made fun of, or the guy who liked to put his hands underneath his desk and 'rubbed' himself during chinese class; the scandals and gossips of the 12 year olds, now just seems like one big joke because they do not matter anymore.
15 years on, everyone has their own lives, we could afford to laugh at ourselves 15 years ago. How about 15 years from now if we look back to the present? Maybe things that we think are important now could be put into better perspective?
So while we have to wait a few more years for science to let us travel through time. Everyone can always take a trip down memory lane, and do a little time travelling with their very own philosphical time machine. 
