This Week’s Hype

Space.com has a new story entitled Space Bursts Provide Insight to Theory of Everything, which has been picked up elsewhere as “evidence for string theory”. For instance Physicists Find New Evidence Of A ‘Theory Of Everything’ In The Wreckage Of Dead Stars tells us:

Physicists studying the rotation of minuscule particles fired by exploding stars light years from Earth have found new evidence for a so-called ‘Theory of Everything’.

Researchers have been frantically studying ways to reconcile two apparently contradictory pillars of modern physics for decades.

Put simply, those are Einstein’s theory of relativity – which covers the interaction of space and time on a large scale – and quantum theory, which covers the strange ways that sub-atomic particles behave.

One of the ideas mooted as a possible explanation is string theory, a framework which proposes that all of matter is made up of loops of vibrating strings…

What is relevant for this story is the proposal in superstring theory that every particle of matter has an equal and opposite ‘anti-matter’ particle, which if time were reversed would behave in exactly the same way as normal matter.

And it is this that new observations by the Japanese Aerospace Exploration Agency’s Ikaros spacecraft could help reinforce…

Using their Gamma-Ray Burst Polarimeter, the scientists are studying how those particles rotate. If the rotation of their polarity had changed even slightly, it would indicate a lack of symmetry if time were reversed – thus evidence against superstring thory.

And, luckily, the reported conclusion is that no change was detected. The team said that they are confident to one part in 10 million that the symmetry is consistent – a new record.

So the idea seems to be that CPT symmetry is evidence for string theory. Kind of like how it has become popular to claim observations being consistent with quantum mechanics as “predictions of string theory”.

The Space.com story seems very confused: string theory predicts no CPT violation, but finding evidence for it would support string theory:

The findings could have implications for superstring theory — the idea that all fundamental particles are actually loops of vibrating string — which is one attempt to unify nature’s forces and create a theory of everything. If the idea is right, it would help reconcile two contradictory theories: Einstein’s general relativity, which describes things that are very big, like gravity, and quantum mechanics, which describes the realm of the very small…

Superstring theory scientists predict that if particles and anti-particles (antimatter is an opposite form of normal matter) traded places and time was reversed, the world would still look the same. If any evidence is uncovered that matter and antimatter actually act differently, or violate their apparent symmetry, it could offer support for superstring theory.

They also link to a new story about 5 reasons we may live in a Multiverse.

What’s generating these stories is this press release from the University of Tokyo, based on PRL acceptance of this paper. It’s about an interesting test of CPT invariance, but bringing string theory into it is bizarre, and even the authors aren’t clear about whether string theory says CPT or no CPT. From the paper:

Lorentz invariance is the fundamental symmetry of Einstein’s theory of relativity. However, in quantum gravity such as superstring theory [1], loop quantum gravity [2] and Horava-Lifshitz gravity [3], Lorentz invariance may be broken either spontaneously or explicitly. Dark energy, if it is a rolling scalar field, may also break Lorentz invariance spontaneously. In the absence of Lorentz invariance, the CPT theorem in quantum field theory does not hold, and thus CPT invariance, if needed, should be imposed as an additional assumption. Hence, tests of Lorentz invariance and those of CPT invariance can independently deepen our understanding of the nature of spacetime.

and the press release:

Some quantum gravity theories, trying to unify Einstein’s theory of relativity with quantum mechanics, (e.g., superstring theory) predict that structures of space-time at extremely short distances may be totally different from what we think we know. On the scales treated by terrestrial experiments, the world looks exactly the same as its mirror image if the roles of particles and anti-particles are exchanged and the direction of time is reversed (i.e., CPT symmetry is conserved). If this symmetry is broken at extremely short distances, as predicted in some quantum gravity theories, polarization of photons from distant celestial objects would rotate during its long journey to us.

I was starting to get more optimistic that the days of nonsensical “tests of string theory” might be over, but it looks like this phenomenon is here to stay.

Update: Scientific American has the same story, headed with:

Gamma rays emitted during the formation of neutron stars and black holes allow scientists to study fundamental principles like superstring theory