There are few ideas in science as compelling as time travel. While fiction is littered with time machines ranging from the TARDIS to the DeLorean, it is perhaps a surprise that time travel also regularly appears in genuine research. In this regard, time machines have been proposed in the form of wormholes and giant rotating cylinders. However, the most recent proposal for a machine to study time travel is a little more realistic; in fact, it already exists. A paper posted online by researchers at Vanderbilt University suggests that in may be possible to detect time travelling particles at the Large Hadron Collider [Ho and Weiler (2011) arXiv:1103.1373v1 (hep-ph)].

Ho and Weiler’s paper is based on M-theory; the theory that encompasses all of the separate string theories, and considers the universe as having up to eleven dimensions, rather than the four we are used to. In one such framework, our familiar four-dimensional universe is viewed as a 4D brane, and all of the standard particles we are familiar with are (to some degree) anchored to this brane. In this model there also exist exotic particles, such as the graviton, sterile neutrino, and Higgs singlet, that are not bound in this manner, and are free to move through the extra dimensions. This results in particles that, from our perspective, can jump backward in time.
The theoretical study focuses on Higgs singlets, which could be produced at the LHC through the decay of a Higgs boson, or through a mixing of individual Higgs particles. If the singlets are produced, and they take the correct path between points on the brane, the secondary decay of these particles could be observed before the original particles are created.
Prof Tom Weiler explained to Materials Today that predicting when and where these particles will appear is problematic, due to the “inherent randomness” of the situation. However, we can place limits on our capability to detect them, “Since all relativistic particles travel about a foot per nanosecond, and since the containment size of the LHC detectors is of the order of 10 meters, the LHC can in principle see pre-appearances in the range of to 0.001 to 100 nanosec. There is nothing to forbid the pre-appearance time from being quite different from this mean value, in which case the pre-appearance would not be noticed at the LHC.”
As to why these particles have not been detected before, Ho and Weiler speculate that it could be because it is only now, with the development of the LHC, and its sensitive detectors, that we are finally in a position to be able to detect them.
In their paper, Ho and Weiler point out that although their ideas may seem bizarre to some, and downright “unsettling” to others, such an accusation may be also made toward quantum mechanics, which is now universally accepted.
Weiler is now looking to streamline the arguments leading to time-traveling particles, and “expand the detection possibilities to include neutrino and cosmic-ray experiments”.


Stewart Bland