The key insight came to Einstein in one of his famous thought experiments. He imagined a man falling off a building.
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The man would be floating as happily as an astronaut in space, until the ground got in his way. When Einstein realized that a person falling freely would feel weightless, he described the discovery as the happiest thought of his life. It took a while for him to pin down the mathematical details of general relativity, but the enigma of gravity was solved once he showed that gravity is the curvature of space-time itself, created by massive objects like the Earth.
Symmetry in quantum mechanics
When general relativity was first published, 10 years after the special version, a problem arose: It appeared that energy might not be conserved in strongly curved space-time. It was well-known that certain quantities in nature are always conserved: the amount of energy including energy in the form of mass , the amount of electric charge, the amount of momentum.
Noether showed that the symmetries of general relativity — its invariance under transformations between different reference frames — ensure that energy is always conserved. Noether and symmetry have both occupied center stage in physics ever since. Post Einstein, the pull of symmetry only became more powerful.
It does. Soon after, Wolfgang Pauli, in an attempt to account for the energy that seemed to go missing during the disintegration of radioactive particles, speculated that perhaps the missing energy was carried away by some unknown, elusive particle. It was, and that particle is the neutrino. Gauge symmetries describe the internal structure of the system of particles that populates our world.
They indicate all the ways physicists can shift, rotate, distort and generally mess with their equations without varying anything important. The result is a peek at the hidden scaffolding that supports the basic ingredients of nature. Video : David Kaplan explains how the search for hidden symmetries leads to discoveries like the Higgs boson. Filming for this video by Petr Stepanek.
Editing and motion graphics by Ryan Griffin. Music by Kevin MacLeod. The abstractness of gauge symmetries causes a certain unease in some quarters. To compound the problem, gauge symmetries produce a multitude of ways to describe a single physical system — a redundancy, as the physicist Mark Trodden of the University of Pennsylvania put it.
Where does all that complexity in the middle come from? And one possible answer to that is this redundancy of description that gauge symmetries give you. In laboratory experiments with ultracold lithium atoms, researchers from the Center for Quantum Dynamics at Heidelberg University have proven for the first time the theoretically predicted deviation from classical symmetry.
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Their results were published in the journal " Science ". This is a direct consequence of scale symmetry, and the same relation is true in every scale invariant system. In the world of quantum mechanics, however, the interactions between the quantum particles can become so strong that this classical scale symmetry no longer applies", explains Associate Professor Dr Tilman Enss from the Institute for Theoretical Physics.
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In laboratory experiments with ultracold lithium atoms, researchers from the Center for Quantum Dynamics at Heidelberg University have shown for the first time the theoretically predicted deviation from classical symmetry. Their results were published in the journal " Science.
This is a direct consequence of scale symmetry, and the same relation is true in every scale invariant system. In the world of quantum mechanics, however, the interactions between the quantum particles can become so strong that this classical scale symmetry no longer applies," explains Associate Professor Dr Tilman Enss from the Institute for Theoretical Physics.
http://medical-network-hessen.org/includes/2019-07-19/gazon-watch-tv.php In their experiments, the researchers studied the behaviour of an ultracold, superfluid gas of lithium atoms. When the gas is moved out of its equilibrium state, it starts to repeatedly expand and contract in a "breathing" motion. Unlike classical particles, these quantum particles can bind into pairs and, as a result, the superfluid becomes stiffer the more it is compressed.
Jochim and Dr Enss -- observed this deviation from classical scale symmetry and thereby directly verified the quantum nature of this system.
The researchers report that this effect gives a better insight into the behaviour of systems with similar properties such as graphene or superconductors, which have no electrical resistance when they are cooled below a certain critical temperature. Materials provided by University of Heidelberg.