No-cloning theorem and time travel

Click For Summary

Discussion Overview

The discussion centers around the relationship between the no-cloning theorem in quantum mechanics and the theoretical implications of time travel. Participants explore whether sending a photon back in time could lead to the creation of identical photons, thereby suggesting a potential contradiction with the no-cloning theorem.

Discussion Character

  • Debate/contested

Main Points Raised

  • Some participants propose that sending a photon back in time could result in two identical photons existing simultaneously, which they suggest could imply a form of cloning.
  • Others question the feasibility of time travel itself, indicating skepticism about the premise of the discussion.
  • A participant argues that the proposed procedure violates unitary evolution, which is a foundational assumption of the no-cloning theorem.
  • Another participant requests clarification on how the operation in question violates the unitary assumption.
  • It is noted that unitary evolution pertains to the evolution from an earlier time to a later time, rather than an independent evolution occurring in reverse.

Areas of Agreement / Disagreement

Participants express differing views on the implications of time travel for the no-cloning theorem, with some asserting a contradiction and others challenging the assumptions underlying the argument. The discussion remains unresolved.

Contextual Notes

The discussion relies on assumptions about the nature of time travel and the implications of quantum mechanics, particularly the no-cloning theorem and unitary evolution, which are not fully explored or defined by participants.

stevenytc
Messages
12
Reaction score
0
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?
 
Physics news on Phys.org
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.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 8 ·
Replies
8
Views
994
Replies
15
Views
4K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 81 ·
3
Replies
81
Views
7K
  • · Replies 32 ·
2
Replies
32
Views
5K
  • · Replies 5 ·
Replies
5
Views
2K