Comments on: Time Travel Simulated by Australian Physicists

By: Hurr

Hurr — Fri, 10 Oct 2014 19:28:56 +0000

Hollywood has been doing this kind of simulation for many years. Whats new?

By: James Paton

James Paton — Sat, 16 Aug 2014 01:37:33 +0000

I wasn’t able to read their actual research paper (you have to pay to read that) so maybe they already thought of this- what if the ‘fuzziness’ of quantum particles is due to their actually going back in time through closed loops? since they couldnt occupy the same space we would see them exist as a cloud of potentials(?)…which we do. One thing I’ve never understood is do they return to a state like that after observing them ends, if not then perhaps the act of observation would have to somehow cut off the particles being able to ‘jump back’.

By: zero

zero — Sat, 28 Jun 2014 18:05:17 +0000

Snake Oil anyone?

By: Carlos Tr

Carlos Tr — Thu, 26 Jun 2014 04:43:54 +0000

Excellent explanation, very simple and to the point. Thanks for illustrating in a simple language the core of your fascinating experiment. This is the best result in time travel theories in a century. I am eager to buy the paper and read it. Thanks Tim.

By: Charles Dicken

Charles Dicken — Mon, 23 Jun 2014 18:07:31 +0000

I would believe such an assertion if wormholes were actually real. Wormholes have never been discovered and observed, nor has anyone ever been able to create one. They only exist in the minds of those who enjoy fantasy over reality.

By: Cody Jungers

Cody Jungers — Sun, 22 Jun 2014 19:01:32 +0000

How would a photon exit said time loop?

By: The Speaker

The Speaker — Sun, 22 Jun 2014 03:49:51 +0000

This email from Professor Timothy Ralph, which was unfortunately received just after publication, further explains the research. Thanks again, Tim.

Dear Day,

We simulated a photon that traveled to the past and was allowed to interact with its past self. We used single photons to do this, but the time-travel was simulated by using a second photon to play the part of the past incarnation of the time travelling photon. No worm-holes are required!

The reason this is interesting is because, although general relativity appears to allow for passages to the past (i.e. closed time-like curves created for example by wormholes), the passing of macroscopic objects, like us, through them seems to lead to paradoxes. For example, I go into the past and kill myself, but then I am not alive to go into the past to kill myself…etc. However, it was first shown by David Deutsch a bit over 20 years ago that microscopic particles described by quantum mechanics (like photons) can avoid these paradoxes and you can always find a consistent description of events. Roughly speaking, this occurs because of the uncertainty principle – we can never be exactly sure of all the properties of quantum particles and this uncertainty leaves enough “wiggle room” to always find a consistent evolution.

In our paper we experimentally show that if we prepare the state of the past incarnation of the time travelling photon in just the right way then indeed we get consistent evolutions in situations where we would expect paradoxes for classically described macroscopic objects. Although the evolutions are consistent, they are unusual – breaking rules that quantum mechanics would normally obey. This is another reason it is interesting. However, I emphasize it is a simulation – we “cheat” when we prepare the 2nd photon that represents the time traveler in the past.

All the best

Tim