If we could see people/aliens/things that have traveled back in time would we not be seeing them now? This kind of suggests that we will never harness the ability to travel back in time.
It is possible to travel into the future though. If you went on a train at near the speed of light and stepped off at the end of your journey you would find that time appears to have jumped forwards for everyone else compared to what you experienced. This is due to time dilation from special relativity.
Originally Posted by Belimawr
quantum theory basically says our physics is bollocks and pretty much anything is possible,
Classical physics may not be technically correct but on the scales that human beings live in it allows us to predict stuff very well. Science is about making observations creating models from these observations. If said models can predict what well happen in the future then the model is kept. It doesn't mean that the model is describing exactly what is happening but it is the best we have. Thermodynamics treats atoms to be tiny little classical balls which we know not to be true but the laws of thermodynamics are still used and were vital in allowing the industrial revolution to happen.
All of our models are probably not strictly true but are we ever going to be able to find the absolute truth? How would we know?
“There has seldom if ever been a shortage of eager young males prepared to kill and die to preserve the security, comfort and prejudices of their elders, and what you call heroism is just an expression of this simple fact; there is never a scarcity of idiots.” - Ian Banks