Much about our universe remains unknown and scientists admit that their current theory of physics is incomplete. Today we move once step closer (or depending on your perspective, one step further away) as the popular idea for extending physics called Supersymmetry (SUSY) is tittering on the edge of being tossed out the window after scientists discover overwhelming evidence that the fundamental property that carries electrical charge, the electron, is… wait for it… round. More specifically, the electron is unbelievably, mind-blowing round.
Some theories, including Supersymmetry (a theory that suggests each known particle in the universe has a supersymmetric twin particle that has yet to be discovered), maintain that the electron is slightly squashed or oblong shaped, in other words – not round. With these theories, a deformed electron shape would help explain the basic principles of these theories. According to Scientific American:
“Although the electron has traditionally been considered to be an infinitesimally small point of charge, it actually drags a cloud of virtual particles around. These fleeting particles pop in and out of existence, and contribute to the electron’s mass and volume… Hypothetical virtual particles predicted by extensions to the standard model would make the cloud bulge slightly along the electron’s axis of spin. This bulge would make one side of the electron slightly more negatively charged than the other, creating an electric dipole similar to the north and south poles of a bar magnet.”
To prove (or disprove) Supersymmetry, researchers search for the so-called electric dipole moment in the electron (remember, the Standard Model of particle physics predicts a practically zero electric dipole moment for the electron). A familiar example of a dipole is a bar magnet with a north and a south pole. Electrons are traditionally thought of as spherical, but if they had dipole moments, they would be slightly squashed and periodically oblong-shaped. “It’s a question of: Does the electron look the same no matter which way you look at it?” explains physicist Jony Hudson of Imperial College London. “The dipole moment is physicists’ technical way to describe if it’s symmetric or not.”
The latest study, published today in Nature, looked for the effect of this asymmetry on the spins of electrons exposed to strong electric and magnetic fields. And what did they find? Nothing. Indeed, the researchers say that any deviations from perfect roundness within electrons must measure less than a billionth of a billionth of a billionth of a centimeter across.
“If you imagine blowing up the electron so that it is the size of the Solar System, then it is spherical to within the width of a human hair.”
The previous study, conducted in 2011 by Edward Hinds, used molecules (prior studies used hard-to-measure atoms), which are more sensitive to the magnetic and electric fields. Using ytterbium fluoride, Hinds was able to more than double the sensitivity of the earlier measurements to prove that the electron is likely round. Today, a group called the ACME collaboration, led by David DeMille of Yale University and John Doyle and Gerald Gabrielse of Harvard University, performed a test using a different molecule, terbium fluoride, that is 10 times more sensitive than the 2011 experiments – and still found no signs of an electric dipole moment in the electron. The ACME scientists relied on careful measurements with microwave spectroscopy to notice any wobbling, and labored to keep their experiment free of magnetic fields or other contaminants that could cause systematic errors. This new 2013 ACME study suggests that the electron appears to be spherical to within 0.00000000000000000000000000001 centimeter which deals a significant blow to many new physics theories, most notably Supersymmetry. The new findings have scientists once again scratching their heads.