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Asked by khian to Sian, Dawn, David, Dan, Christie on 21 Jun 2016.
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Christie Waddington answered on 21 Jun 2016:
Stephen Hawking talked about the possibility of time travel and said that the only way to do so would be to go forwards because of the time paradox (i.e. you cannot go back and kill yourself).
The Arrow of Time is a concept that was developed in the 1920s by Eddington and stated that there is an obvious direction of time, forwards, since this is the direction in which the universe is expanding.
As far as Physics is concerned though, there is no reason why time should have a direction. Although having time running forward means things can be observed. Time may be running in multiple directions but as the observer (human or otherwise), we can only perceive time going forwards.
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David Robertson answered on 21 Jun 2016:
This is a really good question, so good that I’m not sure anyone can answer it properly!
When we look at lots of detailed physical interactions such as particle collisions, then they look fine whether you run time backwards or forwards, so in that sense what is really odd is that we think there is a direction to time when these interactions don’t seem to need one!
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Dawn Lau answered on 21 Jun 2016:
This is way out of my expertise so I just have another question to answer you with…what if time has no direction, but we can only experience time going forwards? We physically can’t experience time going backwards, at least not in the way our memories are encoded – even if it was, you wouldn’t know.
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Sian Thomas answered on 21 Jun 2016:
Oh, I am learning such a lot from this challenge. Who would have thought that I would encounter a time conundrum!
Seems that we can only observe forwards. Which is interesting in itself as we would never know if someone went back and changed things!
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