So i had an interesting thought about being able to send information back in time. Primarily my interest was sparked by a series on NETFLIX called "Travellers", where people from the future have their consciousness sent back in time into a person that was about to historically die. It's an interesting series and I would recommend it.
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Anyway.... let's talk about this "time machine". So some readers may be familiar that two particles can be ENTANGLED, such that any measurement on one particle immediately effects the other particle.
So we can create a system where we have 2 entangled particles, one that is "red" and one that is "blue", but we don't know which is which until we measure one of them. If we place one particle on Earth and another on close to the sun ( 7 light minutes distance), the very moment we measure one particle on earth and discover it is "Blue" then faster than the speed of light the particle close to the Sun would collapse into a state that is "red", so this information travelled faster than light. This is infact true, information between two entangled particles travels faster than the speed of light. So two particles are entangled in Space ( 3 dimensions).
Albert Einstein, who I am sure you know, famously proved that space and time where one of the same thing and are fundamentally connected. Does this mean that two particles can be entangled in a time dimension???
Let's consider now we make a system just like before, two particles (1 & 2) entangled, "red" and "blue", we can leave the particles entangled and wait some period of time.
So let's wait a week and say that if DOGE goes up in price, then we can say that we will observe particle 1 as blue!
Which means particle 2 will be red.
What happens if we go back in time and try to observe if particle 2 is red??? Think about for it a moment.....
Well you have then collapsed the system a week before you intended too, which means that you can not perform in a weeks time the observation to tell the PAST You if DOGE is up or down.
It breaks the fundamental rule of causality.
But what do you think?
Do you think that physicists in the future could overcome such a problem? Do you believe that time travel is possible? I my self am a physicist and i believe that one day we will understand space-time a lot more than we do now and we will discover ways to overcome such problems as described.
I hope you found this interesting and it made you think a little bit about such a paradox.
Have fun!!