Quantum experiment reveals time really CAN flow backwards (but don't expect a time machine any time soon) - RiseEarth

Quantum experiment reveals time really CAN flow backwards (but don't expect a time machine any time soon)


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by Mark Prigg; Dailymail.com

Experiment found heat can spontaneously flow from a cold quantum particle to a hotter one under certain conditions

Shows the quantum world operates under very different rules


Time travel may be possible - for sub atomic particles, at least, a new experiment has found.

Physicists have discovered that heat can spontaneously flow from a cold quantum particle to a hotter one under certain conditions - effectively reversing the 'arrow of time'.


While the discovery doesn't advance the possibility of building a time machine, it does show the quantum world operates under very different rules, researchers say.
THE ARROW OF TIME

The Arrow of Time, or Time's Arrow, is a concept developed in 1927 by the British astronomer Arthur Eddington involving the 'one-way direction' or 'asymmetry' of time.

This states that entropy, or disorder, tends to increase over time.

It explains why, for instance, its easy to shatter a glass or break an egg, but hard to put them back together, and why heat spontaneously flows from hot to cold but not the opposite direction.
The new experiment 'shows that the arrow of time is not an absolute concept, but a relative concept,' study coauthor Eric Lutz, a theoretical physicist at the University of Erlangen-Nürnberg in Germany, told Science News.

The team published their study in the journal arXiv.org.

It examined heat passing from hot and cold objects.

'We here experimentally demonstrate the reversal of the arrow of time for two initially quantum correlated spins-1/2, prepared in local thermal states at different temperatures, employing a Nuclear Magnetic Resonance setup,' they wrote.

Effectively the experiment looked at how heat should never pass from a cold object to a warmer one.

'We observe a spontaneous heat flow from the cold to the hot system,' the team wrote.

The existence of a 'time arrow' follows from the second law of thermodynamics.

This states that entropy, or disorder, tends to increase over time.

It explains why, for instance, its easy to shatter a glass or break an egg, but hard to put them back together, and why heat spontaneously flows from hot to cold but not the opposite direction.

Different systems can have arrows of time that point in different directions, Lutz said.

While the arrow was apparently reversed for the two quantum particles, known as qubits, the researchers studied, for example, the arrow pointed in its typical direction in the rest of the laboratory.

The Arrow of Time, or Time's Arrow, is a concept developed in 1927 by the British astronomer Arthur Eddington involving the 'one-way direction' or 'asymmetry' of time. Pictured, Doctor Who's time travelling Tardis

Scientists hope to use the unique thermodynamics of quantum particles to create quantum engines that could perform tasks beyond the reach of typical machines, such as controlling the direction of heat flow on small scales, the researchers say.

'By revealing the fundamental influence of initial quantum correlations on time’s arrow, our experiment highlights the subtle interplay of quantum mechanics, thermodynamics and information theory,' the team wrote.

'It further emphasizes the limitations of the standard local formulation of the second law for initially correlated systems and offers at the same time a novel mechanism to control heat on the microscale. '

However, they do hint the research could have larger implications, concluding 'Our results on the thermodynamic arrow of time might also have stimulating consequences on the cosmological arrow of time.'


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