A lot of scientists say that through quantum physics based theorys - it is possible to travel back in time. If this is true - does it mean we live forever?
It doesn't mean that you will live forever but it means for you this world will die earlier (velocity and gravitational time dilation) but if you have passed through a wormhole or sth. like a time machine there will be created two of you, one living in the present world and other in different time.
No, you can't travel back in time. If you were to go faster than the speed of light I guess you might be able to see yourself coming, if that makes sense, so that you are technically seeing things that already happened, but you wouldn't fall into some weird time warp and end up in 1000 BC or something.
If you go the speed of light (300,000 km/s or 186,000 miles/s), time would stop, including your biological clock. Thus you would not age. Ever.
No, we still age no matter what happens, theoretically if you travel back in time, there will be 2 of you, one young version, and then you, the older you.