Researchers at the Hong Kong University of Science and Technology claim to have established that time travel is impossible. More specifically, they claim to have established that an individual photon (the smallest unit of light) may not travel faster than the speed of light (introducing the obvious question of how could it if it is light) and that this precludes anything from going backward in time.
Per the article:
"The study, which showed that single photons also obey the speed limit c, confirms Einstein's causality; that is, an effect cannot occur before its cause," the university said.
The findings have been published in the U.S. peer reviewed journal, Physical Review Letters.
Think of it like a flowing river. To place that river back in time you have to have some way to place every drop of water exactly where it was. I know we can't do it with a river. How can you imagine that we can doit with the entire universe
Some may argue that science cannot prove a negative. Just like it can't prove the non-existence of god(s). How can it prove the non-existence of time travel?
The universe has many surprises left for us to discover. Time travel may be one of them. Possibly through some means other than travelling faster than the speed of light.
Impossible, based on what we understand at this time. I don't think science deals in absolutes... correct? Just to be nuanced here isn't it better to write there doesn't seem to be any possibility of time travel based on what we know?