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First Experimental Evidence That Time Is an Emergent Quantum Phenomenon
KentuckyFC writes "One of the great challenges in physics is to unite the theories of quantum mechanics and general relativity. But all attempts to do this all run into the famous 'problem of time' — the resulting equations describe a static universe in which nothing ever happens. In 1983, theoreticians showed how this could be solved if time is an emergent phenomenon based on entanglement, the phenomenon in which two quantum particles share the same existence. An external, god-like observer always sees no difference between these particles compared to an external objective clock. But an observer who measures one of the pair — and so becomes entangled with it--can immediately see how it evolves differently from its partner. So from the outside the universe appears static and unchanging, while objects that are entangled within it experience the maelstrom of change. Now quantum physicists have performed the first experimental test of this idea by measuring the evolution of a pair of entangled photons in two different ways. An external god-like observer sees no difference while an observer who measures one particle and becomes entangled with it does see the change. In other words, the experiment shows how time is an emergent phenomenon based on entanglement, in which case the contradiction between quantum mechanics and general relativity seems to melt away."
First time I've seen no comments show up a few minutes into a Slashdot story going up.
Are most other people, like me, scratching their heads and trying to wrap their minds around this? :)
But only from the point of view of an external god-like observer.
We need to start likening things to quantum physics. At this point rocket science is frikkin' easy compared to all this quantum stuff.
Until quantum entangled particles gets harnessed into the faster than light communications they've talked about over the years, no one will really care anyway.
Occasionally living proof of the Ballmer peak.
At least this time they're not pointing loaded guns at cats.
Science advances one funeral at a time- Max Planck
what exactly is the difference?
From the outside, the universe looks like a photograph.
I hope we're hanging on a nice wall.
I read this essentially as saying that without an observer, time does not exist. Essentially, a "god-like" observer does not observe any change unless he or she becomes entangled in the universe he or she is observing. That universe, therefore, is without change, and therefore timeless. However, observers that are entangled within the universe (as we are), observe change and thus the universe (to them) has time.
This sounds a fair bit like some of the effects of relativity (on the train the shots appear simultaneous...on the ground they do not).
What is most intriguing to me, though, is that if the universe is both timeless (from the outside) and has time (from the inside), is it possible for us to gain the outside perspective (or any information about that timeless perspective). This shouldn't necessarily be impossible - we would need to not become entangled in the thing we are trying to observe (which we can easily do). Perhaps observing the surrounding universe would give unentangled information about the experiment in question, and thus give us a glimpse of the future?
Great warrior...hrmph! Wars not make one great.
Time is an illusion. Lunch time doubly so.
Slashdot - News for Nerds, Stuff that Matters, in ISO-8859-1 Has just realised that beta makes this signature redundant
What? Of course time isn't man-made. Why would you say only man cares about time? I'm pretty sure plants and animals are also happily perceiving the passage of time.
Pretty good is actually pretty bad.
...how this is related to the fact that the speed of light is the only true (known) constant in the universe.
for example...you are on a train going 50 km/hr north...you throw a ball 30 km/hr north and the ball is now going 30 km/hr north relative to you and 80 km/hr to a stationary observer...standard stuff.
BUT...you are on a light beam going 0.5c (half the speed of light) with a flashlight in your hand...you turn on the light...how fast is that light coming out of your flashlight going relative to you and our stationary observer?
well...relative to you its going...the speed of light...to the observer?
this is where it all gets weird...to the observer its going..the speed of light!
how can this be, slashdotters?
never bring a twinkie to a food fight.
That's entropy, not time.
It's very possible that the development of language in humans sort of locked us into the concept of time. For further reading, some of which sounds insane, look into pigeons and their homing instincts to see how other animals aren't necessarily perceiving time in the way that we do.
Bill Clinton: Pimp we can believe in. - The Shirt!!!
Mdash is still just a theoretical particle, they haven't actually detected mdash yet.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
Worth reading what C. S. Lewis attributed to George McDonald in "The Great Divorce" for some speculation on this same issue.
He is all those three, plus one more: omnihumorous.
We just haven't got the punchline yet.
ACs never did have a sense of humour.
Slashdot - News for Nerds, Stuff that Matters, in ISO-8859-1 Has just realised that beta makes this signature redundant
After reading a lot on this is that sometimes an issue becomes a problem without reason.
Now, time is ONLY a man made measure - a measure between events. Nature/the universe doesn't know what time is nor cares about it. It is only us humans that need to try to explain time dilation and various other 'time issues' to make the maths work. Remove time, and I bet it will balance these equations.
Time cannot run backwards,as there is no such thing as time except in the human brain and the human concept of measuring changes.
Nature doesn't care about time? Tell that to the laws of thermodynamics. Entropy only goes one way.
If you watch a video of a ball rolling on a desk, you can't tell just by the video whether time has been reversed. The physics governing that motion don't care about time. If you watch a video of an egg being shattered, you'll know when the video is reversed. You know all the contents of the egg can't spontaneously get back together as time moves forward. That would be going to a much more well-ordered state.
Also, the GPS device you use to triangulate your position and navigate to your destination? Well, consider that relativity tells us that the satellites zooming up above us have slower ticking clocks. They're actually moving through time slower than you are, and our current GPS accuracy wouldn't be achievable if we didn't take that into account.
GPS is about the only consumer use system that has to deal with not only general relativity, but also special relativity.
I read the internet for the articles.
Just imagine a banana. Right, now forget that, because it's nothing like a banana.
systemd is Roko's Basilisk.
Most of this has been known and stated fairly clearly in the quantum theory of open systems for some time now. The Nakajima-Zwanzig (generalized master) Equation is derived based on the assumption of a "universal" quantum description that is partitioned into "system" and "everything else", with a projection of all dynamics from everything else onto the system variables. The universe is, of course, completely deterministic, but entropy (and hence "time" as an arrow) enters the system from the incomplete information available on the system "bath", everything else.
The proper treatment of this completely eliminates the common quantum "paradoxes" such as Schrodinger's Cat because one can clearly see where one makes an incorrect assumption about the possibility of quantum entanglement of the cat and the microscopic decay process independent of "everything else". The entire "system" consisting of cat and box is coupled to the rest of the Universe and the apparently "purely random" decay that creates the supposedly tangled state that is resolved by opening the box is continuously resolved because the box and all of its contents is already tangled, so to speak, with everything else. It also helps to properly view and include time-reversibility in the description and not treat the quantum process of measurement non-relativistically and semi-classically. The same thing is true of the EPR paradox -- if it is treated relativistically there can obviously be no such thing as wavefunction collapse per se with some sort of transluminal communication of phase information, because the time reversal of this process makes no sense at all. The GME resolves this entirely because it correctly describes the infusion of classical entropy in a measurement process from the bath in an e.g. thermodynamic state within e.g. the random phase approximation.
Personally, I think the Nakajima-Zwanzig treatment and master equations are one of the most neglected areas of quantum theory, often completely untaught in graduate-level quantum series. It is one of the better ways to rigorously derive things like spontaneous emission and in the process explain a lot of things about the process that are otherwise mysterious, such as how "exponential decay" arises from the coupling of a two-level quantum emitter to a multimode bath (and how it does NOT occur if one, for example, couples a two-level quantum emitter to a single field mode). Loudon has a nice discussion of this point, and Agarwal describes the application of the GME to spontaneous emission including radiative shift. The outcome of this approach in quantum mechanics is often to transform exponential processes that typically move one out of the basis one begins in almost instantly (entanglement) to projective dynamics within the basis and with e.g. discrete dynamical transitions replacing cats that are half dead or half alive in an entangled state, a Langevin approach where the actual system really does either kill the cat or doesn't, at a particular time, with the correct probability distribution for an ensemble of diabolical cat-killing engines, because the rest of the Universe always functions as a "measuring apparatus" -- one cannot "disentangle" the cat, the poison, the radioactive source from the Universe by merely putting it in a box, and at the instant of the cat's death the future time evolution of the entire Universe is unique to this and only this outcome.
You can see some small part of the malaise that infects the terminology of quantum theory in the phrase above: "An external god-like observer sees no difference" -- the hardest single thing one has to deal with when correctly considering the quantum description of the Universe is the notion that there is no outside, most especially no outside from which the inside can be "seen". Seeing is the exchange of information, mediated by a field interaction. The Universe cannot possibly be "seen from the outside" because if the "outside" in question can see it at all, it is a part of it. It cannot
Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
Jesus said: If they say to you: Whence have you come?, say to them: We have come from the light, the place where the light came into being of itself. It [established itself], and it revealed itself in their image. If they say to you: Who are you?, say: We are his sons, and we are the elect of the living Father. If they ask you: What is the sign of your Father in you?, say to them: It is movement and rest.
--Thomas
Sometimes, this is almost too easy.
~ Whence do you come, slayer of men, or where are you going, conqueror of space?
If a tree falls in the forest and no one observes it, how long did it take to fall?
The problem is that they keep formulating and performing these measurements where the scientists work.
Everybody knows time doesn't pass at work. If they'd re-run the experiment under a rainbow or with a beautiful woman they'd find that time passes far too quickly in fact.
"Time, we know, is relative. You can travel light years through the stars and back, and if you do it at the speed of light then, when you return, you may have aged mere seconds while your twin brother or sister will have aged twenty, thirty, forty or however many years it is, depending on how far you traveled. This will come to you as a profound shock, particularly if you didn't know you had a twin brother or sister."
The preceding comment is my own, and in no way construes an opinon of the Emperor of Mankind.
It's not a 'problem of time' &mdash, it's a 'problem of validation' &mdash.
No kidding!
Line 6, Column 30: & did not start a character reference.
my, your, his/her/its, our, your, their
I'm, you're, he's/she's/it's, we're, you're, they're
Okay, to explain more fully: The second law states that entropy always increases over time (in a closed system). So nature very much does care about time - the progression of the three-dimensional state of the universe depends on the progression of time.
The direction of time is not arbitrary or human-defined. The other three dimensions are arbitrary, so far as we know; it doesn't matter whether you define those three dimensions relative to earth or the sun or the galaxy or whatever, and it doesn't matter which way around you define them, the behaviour of the universe will be the same. Your frame of reference when observing the universe doesn't matter, so long as you allow for its motion and rotation relative to other things.
But time is not like that. Time progresses in one direction in our perception and the behaviour of the universe would be fundamentally different if it progressed the other way. Entropy would decrease with time instead of increasing with it. The progression of physical laws would be different.
Also the assignment of units to time is not arbitrary. That is, we are not free define time completely arbitrarily. Just as we are not free to define distance arbitrarily. We can't say that the distance from the earth to the moon is the same distance from the earth to the sun just because we say so; there is some fixed, underlying measure of distance and something that is one metre long in one place will still be one metre long when you move it to another place. In the same way were are not free to take any two non-overlapping segments of time and define them to be equal. The relationship between duration in time and distance in space is fixed by the speed of light, which is an absolute constant (in a given medium). So light will take the same time to travel along that one metre object wherever it is in space and whenever in time it happens, no matter how we attempt to redefine duration. Our concept of seconds is merely a scaling of the time light takes to go a given distance.
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Speed of light delays in gigahertz CPUs are special relativity. Speed of light delays in transoceanic online gaming are special relativity. Speed of light delays between the stock exchange and the high frequency trading equipment is special relativity, but that's not "consumer use" except that HFTs are using the consumer.
Animals do have some concept of time, as they have the concept of both position and velocity, and can extrapolate the relation between the two over time. For example, a dog can instinctively judge its jump so that it intercepts a thrown frisbee, likewise birds of prey hunting birds or fish.
They may not be able to cogitate over the concepts they use, unlike us humans, but they can certainly put them into use.
Also FatPhil on SoylentNews, id 863
Step 1. Become Godlike ....
Well, consider that relativity tells us that the satellites zooming up above us have slower ticking clocks.
Actually, the GPS satellite clocks run 38 microseconds faster than ground based clocks.
This is because they are not moving fast enough (special relativity: faster means slower clock) to counter the general relativistic effects (stronger gravitational field means slower ground clocks).
Both clocks seem to be slower for an observer in free space.
http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html
In this case, the observer cannot detect any difference between the photons without becoming entangled with one or the other. And if there is no difference, the system appears static. In other words, time does not emerge.
This is the kind of in your face bullshit I have come to expect from a certain crowd of attention whores who regularly abuse terms like phase velocity and negative absolute temperatures to attract undue attention to their Sci-Fi ish ramblings which in reality are quite mundane.
Why yes dude you can't make a measurement without effecting what is being measured... newsflash from a century ago.
Since you can't measure something without changing it... you make the following jaw dropping assumption "And if there is no difference" to get to your assumption..
"the system appears static. In other words, time does not emerge."
"In other words" if you ASSume there is no difference time does not emerge.
As someone else with mod points, I almost modded you +1 Funny , but my god-like powers of commenting kicked in.
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