It’s that time of the week when we review the news of physics, and, as it is often the case, a lot of strange stuff is going in the world of physics. If you would like to receive these news weekly, follow our RSS feed newsletter.
1. Big Bang Under a… Microscope (January 3)
Scientists have replaced the telescope with the microscope to investigate the similarities between the structure of a crystals and the state of the cosmos in the early universe. In doing so they have explored a yet unconfirmed phenomenon, the formation of cosmic strings. These so-called “topological defects” are believed to have formed as the universe expanded shortly after the Big Bang. Nicola Spaldin, Professor for Materials Theory and Manfred Fiebig, Professor for Multifunctional Ferroic Materials at the ETHZ tackled a fundamental question of cosmology using a small crystal of a material called yttrium manganite. The crystal first attracted the researchers’ attention because of its so-called multiferroic behavior, in which the electric charges and magnetic dipoles arrange themselves spontaneously. Interestingly the spontaneous arrangement of the electric charges follows the same rules that describe the universe during its early expansion. Read the full report here.
2. Gas With a Temperature Below Zero? (January 4)
Just a few days ago a group of physicists in Germany have succeeded in cooling down a sample of gas below the temperature of absolute 0 K. Now I know what you’re thinking — there has to be some kind of a catch. And there is… sort of.
Absolute zero was first defined by Lord Kelvin back in the mid 1880s, as the lowest possible temperature state, where atoms stop moving. So how can a temperature of a gas be lower than that of an absolute 0 K? This is possible, as the scientists of the group say, because the temperature of a system is generally considered to be the average energies of the particles in it. Most hover around a certain point, with a few moving to higher levels. But, when the system is turned upside down, with most of the particles exhibiting higher energy levels, and just a few have lower energy, the system is reversed as are the temperature signs, indicating temperatures below absolute zero.
To turn such a system upside down in the real world, the physicists started by chilling a quantum gas made up of potassium atoms to near absolute zero. They used lasers and magnetic fields to force the atoms into a lattice pattern. At temperatures above absolute zero, the atoms naturally want to repel one another, keeping the system stable. But by adjusting the lasers and magnetic field, the researchers were able to force the atoms to attract one another, essentially, turning the system on its head. Full article here.
Lord Kelvin doesn’t look impressed with the new discovery
3. Testing Einstein’s Most Famous Equation (January 4)
Perhaps the most iconic equation is the famous mass and energy relation formulated by Albert Einstein: E=mc2 . And even though this famous relation has been tested hundreds of times before, a University of Arizona physicist Andrei Lebed offered yet another interesting way to test it in outer space.
The idea is as follows – the equation E=mc2 may not hold up in certain circumstances. This is based on a belief by the scientist that the inertial and the gravitational masses, which are believed to be equal, might be different in some parts of space due to some quantum effects. So according to Lebed, the iconic Einstein’s equation might only be right for inertial mass but not for gravitational mass. His idea is that this hypothesis could be tested by measuring a weight of a Hydrogen atom in a gravitational field and in no gravitational field. In a gravitational field, there’s a probability that an electron orbiting the nucleus could make a jump to a different energy level, which would change the mass of the atom for a short time. In an uncurved space this probability is different and that’s what the scientist is trying to investigate. A simple experiment, according to Lebed, could test the equivalence of gravitational and inertial masses — a container with a sample of Hydrogen could be sent to outer space and then “weighted”. This rather simple yet elegant experiment could also give insights on the relations between Quantum Mechanics and General Relativity. Full article here.