A Possible Challenge To Chronology Protection Conjecture?

In summary, the conversation discusses the Chronology Protection Conjecture (CPC) and its potential for creating a paradox in which radiation builds up in a wormhole used as a time machine, leading to its destruction. However, the participant raises an objection to this theory, questioning why virtual particles would necessarily re-enter the wormhole after traveling back in time, and suggesting that this could prevent the buildup of radiation. The conversation then delves into the specifics of how this paradox would occur and the role of the censorship hypothesis in preventing it. Overall, the participants acknowledge the speculative nature of this topic and the need for further investigation.
  • #1
Troodon Roar
7
1
Correct me if I am wrong, but my basic understanding of how the Chronology Protection Conjecture (CPC) would work is that, as virtual particles created from the quantum fields of the vacuum would traverse a wormhole and arrive in the past, they would then travel back into the wormhole alongside their past self, doubling the amount of energy entering the wormhole, and this process would continue, ad infinitum, until there is so much radiation traversing the time machine that it is destroyed.

However, this scenario does not make sense to me. I have thought of an objection to it. This is that, once the photon (for example) enters the wormhole and arrives in the past, what would compel it to join its past self in, once again, traversing the wormhole? To furnish an analogy, let's say a human builds a restaurant, and then, once finished, travels back in time through a wormhole to see their past self building the restaurant. However, there is nothing to compel them to assist their past self in building the restaurant, as their past self is already doing it.

I feel that the same would apply to the radiation that is supposed to build up in this process and destroy the wormhole before it can be utilized as a time machine. In other words, I am saying that there is no reason to suppose that the virtual particle would necessarily join its past self in traversing the wormhole, and, thus, no reason to necessarily suppose that radiation would build up in the wormhole until it destroys it.

Does anyone notice any glaring flaws or errors in my argument? If so, please point them out, so I can either account for them or, if my original hypothesis turns out to be unsalvageable, to admit I am wrong on this point and discard it, in the spirit of empirical scientific investigation. Thanks.
 
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  • #2
I had to read up on it first, but the way I understand it now is that, if there *were* to be a chronological violation (I.e. a paradox), the two mouths of the wormhole would need to be close enough to each other so that a particle that exited mouth B in the past, can, within the bounds of relativity, make it to mouth A before the particle had entered it there. So, the scenario is:

1. Particle enters mouth A of wormhole
2. Particle travels through wormhole
3. Particle exits at mouth B, but now in the past
4. Particle travels to mouth A, arriving *before* 1. happened

That would be the requisite for the violation, because if the particle couldn't get back to A in time, it couldn't cause a violation if it tried.

Now, the way I understand it, the censorship hypothesis essentially say this constitutes a feedback loop. After the first time travel, you now have *two* particles, which would then enter mouth A. This would obviously escalate to infinity.
The bone of contention in research seemed to have been that for normal particles, they would "defocus", thus not making it back into mouth A. But, for those virtual particles, they somehow refocus, and that's where the censorship mechanisms would kick in. That is, even barring any nefarious attempts, the normally occurring virtual particles would create this feedback loop, thus immediately destroying the wormhole.

This is all crazy hypothetical though. It all rest on using theories in areas where we know they might not apply. I find these discussions interesting, but more in the sense of probing where our current theories fall apart.
 
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1. What is the Chronology Protection Conjecture?

The Chronology Protection Conjecture is a hypothesis put forth by theoretical physicist Stephen Hawking that states that the laws of physics prevent the occurrence of time travel and the creation of closed timelike curves.

2. What is the possible challenge to the Chronology Protection Conjecture?

The possible challenge to the Chronology Protection Conjecture is the discovery of a hypothetical particle called the tachyon. Tachyons are hypothetical particles that travel faster than the speed of light and could potentially violate the causality principle, leading to the creation of closed timelike curves and the possibility of time travel.

3. How does the existence of tachyons challenge the Chronology Protection Conjecture?

The existence of tachyons challenges the Chronology Protection Conjecture because if they were proven to exist and could be controlled, they could potentially be used to create closed timelike curves and violate the causality principle, thus challenging the idea that the laws of physics prevent time travel.

4. What are the implications of a successful challenge to the Chronology Protection Conjecture?

If the Chronology Protection Conjecture is successfully challenged, it would have significant implications for our understanding of the laws of physics and the concept of time. It could potentially open up the possibility of time travel and raise questions about the stability of causality and the consequences of altering the past.

5. What research is currently being done to investigate the possible challenge to the Chronology Protection Conjecture?

Scientists are currently conducting experiments and theoretical studies to investigate the existence and properties of tachyons, as well as exploring other potential challenges to the Chronology Protection Conjecture. This research is ongoing and will continue to expand our understanding of the laws of physics and the nature of time.

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