Skip to comments.Researchers look beyond space and time to cope with quantum theory
Posted on 10/28/2012 8:50:13 PM PDT by JerseyanExile
Physicists have proposed an experiment that could force us to make a choice between extremes to describe the behaviour of the Universe.
The proposal comes from an international team of researchers from Switzerland, Belgium, Spain and Singapore, and is published today in Nature Physics. It is based on what the researchers call a 'hidden influence inequality'. This exposes how quantum predictions challenge our best understanding about the nature of space and time, Einstein's theory of relativity. "We are interested in whether we can explain the funky phenomena we observe without sacrificing our sense of things happening smoothly in space and time," says Jean-Daniel Bancal, one of the researchers behind the new result, who carried out the research at the University of Geneva in Switzerland. He is now at the Centre for Quantum Technologies at the National University of Singapore.
Excitingly, there is a real prospect of performing this test. The implications of quantum theory have been troubling physicists since the theory was invented in the early 20th Century. The problem is that quantum theory predicts bizarre behaviour for particles such as two 'entangled' particles behaving as one even when far apart. This seems to violate our sense of cause and effect in space and time. Physicists call such behaviour 'nonlocal'. It was Einstein who first drew attention to the worrying implications of what he termed the "spooky action at a distance" predicted by quantum mechanics. Measure one in a pair of entangled atoms to have its magnetic 'spin' pointing up, for example, and quantum physics says the other can immediately be found pointing in the opposite direction, wherever it is and even when one could not predict beforehand which particle would do what. Common sense tells us that any such coordinated behaviour must result from one of two arrangements. First, it could be arranged in advance. The second option is that it could be synchronised by some signal sent between the particles.
In the 1960s, John Bell came up with the first test to see whether entangled particles followed common sense. Specifically, a test of a 'Bell inequality' checks whether two particles' behaviour could have been based on prior arrangements. If measurements violate the inequality, pairs of particles are doing what quantum theory says: acting without any 'local hidden variables' directing their fate. Starting in the 1980s, experiments have found violations of Bell inequalities time and time again. Quantum theory was the winner, it seemed. However, conventional tests of Bell inequalities can never completely kill hope of a common sense story involving signals that don't flout the principles of relativity. That's why the researchers set out to devise a new inequality that would probe the role of signals directly. Experiments have already shown that if you want to invoke signals to explain things, the signals would have to be travelling faster than light more than 10,000 times the speed of light, in fact. To those who know that Einstein's relativity sets the speed of light as a universal speed limit, the idea of signals travelling 10,000 times as fast as light already sets alarm bells ringing.
However, physicists have a getout: such signals might stay as 'hidden influences' useable for nothing, and thus not violating relativity. Only if the signals can be harnessed for faster-than-light communication do they openly contradict relativity. The new hidden influence inequality shows that the getout won't work when it comes to quantum predictions. To derive their inequality, which sets up a measurement of entanglement between four particles, the researchers considered what behaviours are possible for four particles that are connected by influences that stay hidden and that travel at some arbitrary finite speed.
Mathematically (and mind-bogglingly), these constraints define an 80-dimensional object. The testable hidden influence inequality is the boundary of the shadow this 80-dimensional shape casts in 44 dimensions. The researchers showed that quantum predictions can lie outside this boundary, which means they are going against one of the assumptions. Outside the boundary, either the influences can't stay hidden, or they must have infinite speed. Experimental groups can already entangle four particles, so a test is feasible in the near future (though the precision of experiments will need to improve to make the difference measurable). Such a test will boil down to measuring a single number. In a Universe following the standard relativistic laws we are used to, 7 is the limit. If nature behaves as quantum physics predicts, the result can go up to 7.3. So if the result is greater than 7 in other words, if the quantum nature of the world is confirmed what will it mean? Here, there are two choices. On the one hand, there is the option to defy relativity and 'unhide' the influences, which means accepting faster-than-light communication. Relativity is a successful theory that researchers would not call into question lightly, so for many physicists this is seen as the most extreme possibility.
The remaining option is to accept that influences must be infinitely fast or that there exists some process that has an equivalent effect when viewed in our spacetime. The current test couldn't distinguish. Either way, it would mean that the Universe is fundamentally nonlocal, in the sense that every bit of the Universe can be connected to any other bit anywhere, instantly. That such connections are possible defies our everyday intuition and represents another extreme solution, but arguably preferable to faster-than-light communication. "Our result gives weight to the idea that quantum correlations somehow arise from outside spacetime, in the sense that no story in space and time can describe them," says Nicolas Gisin, Professor at the University of Geneva, Switzerland, and member of the team.
I sense a disturbance in The Force........
Whenever I read about this stuff my brain starts to hurt. I still like to do it though.
I say this is fundamentally idiotic. It presumes a classical foundation to reality which must perforce have these strange properties to present the appearance of quantum reality. It reminds me of the old Peanuts strip where Lucy points out the queen ant to Linus, observing that all the other ants attend to her while she just sits there. Linus says, "That's not an ant Lucy, that's a jelly bean." Lucy replies, "I wonder how a jelly bean ever got to be queen?"
When they get to the top of Quantum Mountain, St Thomas will be waiting for them with a cup of ale and some venison.
This should be interesting.
To me, it’s simple: What is before time began and after time ends? Easy. God.
What is one inch beyond the end of space? Easy. God.
But are they really YOUR hands?
It has to be admitted that Aquinas’ contemplations of the properties and powers of angels puts one in mind twentieth century quantum philosophy. Whether this puts him at the top of the Quantum Mountain, I don’t know. Perhaps one ought to be generous in these matters.
He set up rules that we get to learn, and gave us at least one universe to play in, using those rules, if we can figure them out. Maybe more, but we see through a glass, darkly, right now.
We do stuff everyday, today that would have had you burned at the stake 200 years ago.
Organized religion is going to have to learn to accept God's universe(s) as they are. His wisdom, not ours, controls it. All we can do is learn it, to whatever extent we can.
“Organized religion is going to have to learn to accept God’s universe(s) as they are. His wisdom, not ours, controls it. All we can do is learn it, to whatever extent we can.”
I don’t think “organized religion” has that problem...it is generally the secular world and even at times science fields themselves that seem to have the problems...
All you have to do is get rid of distance and time in our 3 spacial dimensions, one temporal dimension reference frame for entangled particles and you have spooky actions at a distance between them.
The weird stuff happens at lower dimensions (Just 2 or less), not higher, in my very, very humble opinion.
Really? Reminds me of a movie quote.
[Anson and Garrad have explained they must go and calculate the height.]
Thomas Twp Too: And how d’you know later?
Reginald Anson: Well, w-we’ve made, um, we’ve made measurements with those two hills, and w-we already know the height of Newton Beacon and Whitchurch Hill...
Thomas Twp: But how were they measured?
Reginald Anson: The same way, by comparing them with other hills.
Thomas Twp Too: But who measured the first hill?
Rev. Robert Jones: [whispering] God, my boy. God.
I’m tell ya our universe and we are our Creator’s video game.. probably in the Creator’s world the equivalent of 14-year-olds are playing Good vs. Evil.
Organized religion is getting better at accepting God's universe(s) recently (last 100 years or so).
Terra really does orbit Sol in an ellipse. As do the other planets and stuff in this solar system. It took a while for that to be accepted by organized religion, even with the evidence that God provided.
That’s Nietz-sche ... Nietzsche. Give him his due.
Y’know, Nietzsche says, “Out of chaos, comes order.”
Ah, but therein lies a problem: If God is outside Time, then God can neither begin, nor sustain, any action. In other words, a change in the prevailing circumstances necessitates Time. Without Time, all of God’s actions fall onto a singularity, a single moment, simply because outside Time, Time does not exist to separate the events. So, God did not yet think about creating you, God began creating you, and God ended the process of creating you, all at the same moment. That is the consequence of not being under Time. You baked the cake, ate it, and yet are still gathering ingredients for it, all at once - an absurdity. No change is possible without Time elapsing.