I personally don't believe that it is possible to time travel to the past. However if it ever does become possible to do so then surely any effects cause by such time travel have lead us to this moment, me typing this and you reading it. Is my statement correct? Our past cannot be changed from what it is, therefore any conceivable time travel to the past in the coming years has been done and dusted before this moment in time, yes?
One of the most compelling arguments against time travel is: where are all the time travellers from the future? Supposing time travel was perfected in the year 2215 - why has no-one from that time travelled back in time to tell us about it...?
If you could travel back in time, you would now be called bodabolf.
Since your name does not say that, I deduce that you have NOT travelled back in time.
Time travel to the past, no problem ... Head up the M4, onto the A48, turn right at Carmarthen and you've magically travelled back in time about 50 years.
Time travel, if it were possible then a 'time machine' that has not been invented yet would have to exist in the 'now' for someone to travel back to it (using it).
as for a paradox... hmm
we wouldn't know would we...?