Mathematicians have found a hidden 'reset button' for undoing rotation

Understanding the new “reset” result

• Commenters clarify that the core result is not that rotations are reversible (which is already known), but that:
  • Given almost any path (sequence of rotations / time-dependent field) in SO(3) or SU(2),
  • You can find a scaling factor λ and an integer m>1 such that repeating the λ‑scaled path m times returns you exactly to the starting orientation.
• In the physics framing: a complicated pulse B(t) acting on spins can be “neutralized” by rescaling its strength or duration and applying it twice (or m times), without constructing a bespoke inverse pulse.

Relation to known rotation phenomena

• Several people connect this to:
  • The belt/plate/Dirac string trick and the topology of SO(3)/SU(2), including the “two full turns” phenomenon for spinors.
  • The anti‑twister mechanism (used to avoid twisting cables in rotating systems), which relies on the same rotational topology but is ultimately a different construction.
• Some emphasize that in software or robotics, inverting a rotation is already trivial with quaternions (conjugate/inverse), so the result doesn’t simplify numerical “undo” operations; it’s about what you can do physically by just rescaling a given control signal.

Applications and practicality

• Suggested applications:
  • NMR/MRI pulse sequence design to undo unwanted spin rotations more simply.
  • Rolling or morphing robots that follow repeatable “roll–reset–roll” cycles.
  • Rotating systems (antennas, domes, carousels) where twist-free cabling is desirable, though anti‑twister implementations have practical constraints (need slack/looping, moving contact points).
• The theorem is largely existential: it proves such λ exist but doesn’t give an easy general method to compute them. Several commenters note this limits immediate engineering utility, though it may be a basis for further work.

Reception of the popular article and side topics

• Some see the New Scientist piece as over-sensationalized, especially lines suggesting it’s surprising that rotations can be undone at all; others think the “hidden reset” framing is fair given the shortcut nature.
• There is extended discussion on:
  • Accessing the work via arXiv and archives vs. bypassing paywalls, and the ethics of that.
  • Broader math/physics topics: simply connectedness of SO(3), spinors, knots that can’t be untangled, and philosophical digressions about simulations and identity.