Science in the News

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gaining_age
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Re: Science in the News

Post by gaining_age » Thu Nov 30, 2017 9:14 pm

Rusty wrote:
Thu Nov 30, 2017 8:22 pm
infidel wrote:
Thu Nov 30, 2017 3:10 pm
...That doesn’t mean that time was running backwards. But what the scientists saw happen between the two particles over time was the opposite of what you or I can expect in our ordinary lives...
Clickbait.
Nope, doesn't appear to be clickbait. Probably ends up in quantum computing. These are Qubits violating the 2nd law at will apparently and they're not entangled but their spin is correlated, I think. The second law presumes uncorrelated components in the system so what do you call this? It's real even if the exotic interpretation seems a little strained. But how do you define the arrow of time (think of it as evolution in time LOL!)? They think they can do this with larger systems as well.

Their paper is quite real - https://arxiv.org/abs/1711.03323

Ugh-- the PBS (first link) was mind numbingly confusing with imprecise declarations. It was mixing and matching concepts.

The journal article has a better intro paragraph to sort out what is of interest:
Irreversibility is a longstanding puzzle in physics.
While microscopic laws of motion are invariant under
time reversal, all macroscopic phenomena have a preferred
direction in time [1, 2]. Heat, for instance, spontaneously
flows from hot to cold. Eddington has called this
asymmetry the arrow of time [3]. At the phenomenological
level, the second law of thermodynamics allows one
to predict which processes are possible in nature: only
those with non-negative mean entropy production do occur
[4]. A microscopic resolution of the apparent paradox
of irreversibility was put forward by Boltzmann, when he
noted that initial conditions break the time-reversal symmetry
of the otherwise reversible dynamics [5]
"Microscopic laws of motion are invariant under time reversal"--- the fundamental physics relations don't have an arrow to them. Backwards and forwards doesn't matter-- what is source and what is detector with optics? The wave equations and boundary conditions don't care which way time flows (as an example). We choose time moving forwards since that is what we observe in our macroscopic world.

Aha! Now we come to the paper point of interest-- the conundrum-- the puzzle stated at the beginning: Where does irreversability (at macroscopic level) come from? In the experiment they keep to the microscopic level to check out a macroscopic phenomena (entropy/heat flow) and observe that it doesn't follow macroscopic tendencies. Why? Because we're still at the microscopic level.

It's an interesting puzzle and information but this is not truly about time direction change (at a macroscopic level). It's microscopic where solutions exist for both positive and negative time--- but what they have is aligned correlation of the quantum properties with statistical (thermodynamic) properties to observe heat flow (macroscopic phenomena) go differently than what we observe with true/normal macroscopic observations.

G.
Out of control odd rare old man (or possibly an hobbyist). -- Label by The Big R.
The 6s of 1st John:
2:6 Whoever claims to live in him must walk as Jesus walked
3:6 No one who lives in him keeps on sinning


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