No-cloning theorem and time travel

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The discussion centers on the relationship between the no-cloning theorem and the concept of time travel. A participant suggests that sending a photon back in time could create two identical photons, implying a potential violation of the no-cloning theorem. However, another contributor points out that this scenario contradicts the principle of unitary evolution, which underlies the no-cloning theorem. The conversation highlights the need for clarity on how time travel operations could disrupt unitary evolution. Ultimately, the consensus is that the no-cloning theorem remains intact when considering the implications of time travel.
stevenytc
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Does no-cloning theorem contradict with the possibility of time travelling?

If i send a photon back in time from t1 to t0, then between t0 an t1, I could have two identical photons, in other words, i can use the time machine to clone my photons.

Have I missed out something?
 
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stevenytc said:
Does no-cloning theorem contradict with the possibility of time travelling?

If i send a photon back in time from t1 to t0, then between t0 an t1, I could have two identical photons, in other words, i can use the time machine to clone my photons.

Have I missed out something?

Time machine? Really?
 
stevenytc said:
Does no-cloning theorem contradict with the possibility of time travelling?

If i send a photon back in time from t1 to t0, then between t0 an t1, I could have two identical photons, in other words, i can use the time machine to clone my photons.

Have I missed out something?
Your procedure violates unitary evolution. The no-cloning theorem assumes that evolution is unitary.
 
Demystifier,

Thanks for your response.

But could you elaborate on exactly how this operation violates the unitary assumption?

Thanks.
 
Unitary evolution involves an evolution from t0 to t1, but not an independent evolution from t1 to t0.
 

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