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Quantum Experiment Confirms Causality Is Fuzzy (physicsworld.com)
"An experiment has confirmed that quantum mechanics allows events to occur with no definite causal order," reports an article shared by long-time Slashdot readers UpnAtom and jd. Researchers at the University of Queensland in Australia believe this could link Einstein's general theory of relativity to quantum mechanics, according to Physics World:
In classical physics -- and everyday life -- there is a strict causal relationship between consecutive events. If a second event (B) happens after a first event (A), for example, then B cannot affect the outcome of A. This relationship, however, breaks down in quantum mechanics because the temporal spread of a particles's wave function can be greater than the separation in time between A and B. This means that the causal order of A and B cannot be always be distinguished by a quantum particle such as a photon.
In their experiment, Romero, Costa and colleagues created a "quantum switch", in which photons can take two paths. One path involves being subjected to operation A before operation B, while in the other path B occurs before A. The order in which the operations are performed is determined by the initial polarization of the photon as it enters the switch.... The team did the experiment using several different types of operation for A and B and in all cases they found that the measured polarization of the output photons was consistent with their being no definite causal order between when A and B was applied. Indeed, the measurements backed indefinite causal order to a whopping statistical significance of 18 -- well beyond the 5 threshold that is considered a discovery in physics.
Science Magazine applauds the experiments for "obliterating our common sense notion of before and after and, potentially, muddying the concept of causality.
In their experiment, Romero, Costa and colleagues created a "quantum switch", in which photons can take two paths. One path involves being subjected to operation A before operation B, while in the other path B occurs before A. The order in which the operations are performed is determined by the initial polarization of the photon as it enters the switch.... The team did the experiment using several different types of operation for A and B and in all cases they found that the measured polarization of the output photons was consistent with their being no definite causal order between when A and B was applied. Indeed, the measurements backed indefinite causal order to a whopping statistical significance of 18 -- well beyond the 5 threshold that is considered a discovery in physics.
Science Magazine applauds the experiments for "obliterating our common sense notion of before and after and, potentially, muddying the concept of causality.
Science Magazine applauds the experiments for "obliterating our common sense notion of before and after and, potentially, muddying the concept of causality.
If anything I'd say a big "Duck you" was in order for guaranteeing that no non-physicist will ever understand quantum physics ever again. ... But on the other hand, it might get me out of the dog house for getting drunk and breaking the living room table...
Anybody who wasn't an idiot would instead conclude that there is therefore no causal relationship, only correlation.
Your hosts file shit doesn't protect against speculative execution vulnerabilities no matter how much you lie and claim it does. Shut the fuck up and stop spamming.
If you sit close enough to your screen, you can know what TFA says before you can read it.
Don't disappoint your bird dog. Go to the range.
https://arxiv.org/abs/1803.043...
As I understand it, particles are not uncertain in time. You can't know both position and velocity (time in this case I suppose) with certainty. This doesn't mean the particles are uncertain in time. It is similar to the frequency and time duality.
How this, a distinctly unclassical behavior, links a macro behavior seems like nonsense.
"Science Magazine applauds the experiments for "obliterating our common sense notion of before and after and, potentially, muddying the concept of causality."
science-mag should applaud more before sh1t happens!
I've been thinking about time lately. Why do we assume we only move forward in time? We move forward and backward in all the other dimensions, why assume we aren't oscillating back and forth in time? What difference would that make if we were? How would we know?
Consider the double slit experiment. Everyone reading this by now knows that if you send a single photon through a double slit it refracts as a wave until it hits the screen, then the "waveform" collapses and becomes a single point of light. Now imagine that quantum particle moving forward a ways, then moving backward a ways, vibrating back-and-forth in time. Each time it vibrates backward it interacts with itself as it's waveform briefly overlap it past self at the edges. This would cause it to refract against itself through the double slit. Then, once it's finally made it to the screen it appears to the observer as a single photon.
I was confused with the description of the results of this experiment before they even did it.
I had a sucky sig.
"But do not forget this one thing, dear friends: With the Lord a day is like a thousand years, and a thousand years are like a day." -2nd Peter 3:8, NIV.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
I don't see c6gunner anywhere around here. Are you done trying to stalk him?
If you glance at what this boring Trumptard writes, you can know how stupid the bitch is before you read it. Trump level stupid.
horse, the cart before, you put
Grow old, you do.
Some drink at the fountain of knowledge. Others just gargle.
Quantum mechanics
The order does not matter
until classical
Some drink at the fountain of knowledge. Others just gargle.
Newton shot first.
Some drink at the fountain of knowledge. Others just gargle.
"But do not forget this one thing, dear friends: With Time Lords a day is like a thousand years, and a thousand years are like a day." - BBC
#DeleteFacebook
You're both blind AND stupid: The 1st link in the post you reply to shows how c6gunner operates/loses + his blowhard piehole being slammed shut. He gets what he deserved. Exposure as a lame pussy.
Time for rehab son.
I'm not high! I swear! I've been sober since.... shit.
Aw! Poor little pussy c6gunner is reacting and replies anonymously despite his fake name account used to impersonate apk caught in the act like the scumbag c6gunner is.
The parent actually wasn't posted by APK.
APK has an ex-marine roommate as his live-in butt buddy. This ex-marine butt buddy received a dishonorable discharge from the Marine Corps.
This ex-marine butt buddy is responsible for the posts defending APK.
Days of butthurt from APK and his dishonorably discharged ex-marine butt buddy.. Wow, how pathetic!
Pass that doobie, bro! Heavy thoughts. Ooooh. Causality is fuzzy, totally mind blowing!
Well, if you're John Wheeler or Richard Feynman, you could suggest that there's only one electron/positron in the universe, and all observable electrons are just manifestations of the same electron moving in one direction through time, while all observable positrons are just the same particle moving backwards.
Thanks folks !
Try the buffet, I'll be here all week.
Quantum management. CEOs now have a sound physical justification to act randomly.
It's a fun thought experiment, but how could you make an experiment to test that?
The universe simulator is a mess of spaghetti code and ugly hacks.
Marvel at the complexity of the macro-scale physics available in this application, but do not look behind the curtain. Be aware that certain boundary conditions - for example, extremely large point-size masses, recursive division of the basic set of subatomic particles, or investigating causality conditions on said particles - can cause unpredictable effects in your universe simulation that may require a restart and loss of existing saved state.
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
Look up time reversibility and you'll see that it's not that this hasn't been considered (because math would tend to presume you can negative change in time). It notes that at the quantum level "the weak nuclear force is not invariant under T-symmetry alone; if weak interactions are present reversible dynamics are still possible, but only if the operator also reverses the signs of all the charges and the parity of the spatial co-ordinates (C-symmetry and P-symmetry)."
It's one reason some physicists have argued that perhaps anti-particles are merely their like particles going backwards through time and hence exhibiting reverse charge/spacial parity. Waves though are inherently time reversible. But particle-wave duality has everything as a wave, so that's something of an incongruence. There's also the small wiggle that a photon is its own anti-particle, so it if were to simple reverse in time randomly it'd self-annihilate.
My limited understanding of physics is that things like photons don't do that because anything travelling at the speed of light doesn't experience time/change, so the only way it could change directions is if the path it traveled on changed. Everything else that has mass is constantly changing and its those changes that derive its mass (warpage of space) and whatever charge it has. If it were to repeatedly move back/forward through time, then it would repeatedly engage in this conversions and we'd see gravity/charge ripples a lot more frequently than we do or there'd be more to it--the force of each ripple would be smaller (so the total observed would add up to the same) and movement speed would have an inverse effect on the charge (presuming that faster particles don't move more back/forward in time their charge smaller charge would be spread out over a wider area). That's not what observation/math currently shows.
Basically, any idea you come up with has to line up with the math/observations we already have while you introduce new math and/or observations with either the former leading to the latter or the latter requiring the former because the current math doesn't work. As much as we don't comprehend quantum mechanics, we do have math and observation that match and we're not seeing observations that inherently fail the math. This experiment, AFAIK, is really separate because causality is much more a presumption based on the math we have (ie, it's a convenient axiom to describe things). Now, if you could use this experiment to disprove the current math, that'd be interesting/useful (show that if you throw away the axiom and use some new axioms that match this experiment, the math fails).
This not as outlandish as it sounds with speculative quantum gravity theories. Notably, past the event horizon, time could actually run backwards. Meaning time doesn't stand asymptotically still, but past there progressively starts running backwards from our perspective. Note that this doesn't imply time travel as the effect would manifest strictly locally. It has however interesting implications regarding possible "radiation" from the black hole. All you need to overcome is the difficulty of being near event horizon and not getting stuck there, but rest of it is essentialy "free ride". From perspective of black hole inhabitant, our universe would be center of black hole in their universe.
The intuition is thus that arrow of time is related to matter and gravity. The field equations for gravity would then point arrow of time as a multi dimensional wave where each cycle into negative half cycle manifested as black holes.
But then there wouldnâ(TM)t be mass (real mass)
God as the singularity before time existed with the single quantum state, and God as a .. wait, what happens with the heat death of the universe? Somebody please remove the entropy from the answer to the question.
Isn't that just a Quantum Eraser experiment? What's new about it?
The implications to Determinism should be interesting; it could either put a huge hole in the concept, OR provide an explanation for the 'uncaused causer' aside from the traditional solution of 'God did it'.
Moreover, I'm REALLY wondering why this effect was never previously noticed in transistor logic; it should apply to electron signals, not just photon polarity. I wonder if it could be utilized for some kind of quantum-scale out-of-order execution.
Corruption is convincing someone that the selfless ideal is the same as their selfish ideal.
We just call our direction "forward" because on the large scale most stuff on our side of the big bang goes that direction.
When you include virtual particles, your hypothesis actually makes quite a bit of sense. It's all a mess down there, and the notion of time going forward, just like causality itself, quickly becomes silly.
Entropy is one reason to believe there is a preferred direction for time.
So maybe we really can have thiotimoline after all?
How is the Riemann zeta function like Trump rallies? Both have an endless number of trivial zeros.
Are you the existics guy?
Mathematically I would fully agree.
However try and get your head around our control. We would like to think we are masters of our own universe but if we're oscillating backwards and forwards through time and setup in a way that we can only remember the past but not the future wouldn't it stand to reason that there is no such thing as free will?
Am I untyping this right now and just can't remember it? Were you destined to get this reply from me but you didn't know because you can't remember the future?
Gold star for you.
Quantum physics doesn't give shit about which way time is going, for most of the stuff described by quantum physics requires "time travel" to be happening for it to work.
Time is far from a fixed constant, or static, or only goes one way, in-fact its the flexible variable that changes to make shit work. Speed of light and all that stuff is fixed and unchanging as far as we know.
That's been around for some time.
We know that there is no discrete space and time, only spacetime, which means uncertainty applies to spacetime.
So we've known things get interesting.
We know there are limits to just how interesting because information is conserved and time travel allows infinite information.
What we don't know is where between those limits things get. This will help.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Do not blink. By the way, just because time is NOT a linear progression from cause to effect, do not try to kill statues by staring at them. On the other hand, I could be wrong. In which case, blink and you're dead.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
starts running backwards from our perspective.
would manifest strictly locally
Aren't those mutually exclusive? Assuming you meant our perspective as being from outside the black hole.
systemd is Roko's Basilisk.
As far as I can tell: the apparent continuity of Space & Time requires Quantum Fuzziness, otherwise there would be no continuity -- as there would be no connection between Past & Future, nor between anything separated in Space.
Without this fuzziness, even elementary particles like quarks could not hold themselves together, how else could one part of a quark stay in connection with the other parts?
Remember that Einstein taught us that Space & Time are commingled -- events that appear simultaneous will not be so to an second observer that is moving wrt to the first.
Space & Time Fuzziness allows us to control our feet, as our heads are experiencing time at a faster rate than our feet (General Relativity shows that things deeper in a gravitational field will experience time running slower). Note that if you live to be a hundred, the cumulative difference will be less than one microsecond!
Also Relativity shows why things moving art different speeds experience Time at different rates.
So even parts of the same quark will experience Time differently. Again this fuzziness is required to hold it together - albeit, fuzzily!
This Quantum Fuzziness is consistent with Heisenberg's Uncertainty Principle.
"Nothing" exists at a point in Space & Time. A bullet does not exist at a single point in Space. If you fire a rifle and the bullet hits armour, the front of the bullet stops while the back of it keeps moving for a while -- partly because a bullet is not perfectly rigid (this the most noticeable effect), and partly because it takes time for the back of the bullet to notice the front part has stopped (Relativity again). Without Space & Time Fuzziness, how would the back of the bullet 'find out' that the the front part has stopped?
Politicians will use this to blame recessions on their successors instead of predecessors.
Table-ized A.I.
Make an apparatus to permanently capture it.
The most excellent - if intellectually extremely humbling - YouTube channel "PBS Spacetime" had a video about that. I can't find it right now, but you might take a look.
I always knew the world was mad, utterly mad!
Can someone please explain this experiment and its implications for a more general audience? I mean, I know this is slashdot and all, but really, this place isn't really at risk of becoming a mainstream site if you make quantum physics stories slightly more accessible...
Yes. This is all a simulation.
You are living in a digital approximation of an analog universe. We are able to run the simulation forward and backward. Time only runs forward for you because that is how we designed your universe. Because we are outside your universe, we can run time forward or backward, just as we can adjust any other variable in the simulation.
This digital approximation explains quantum mechanics - we do not have the processing power to simulate a fully analog universe like our own, so we do some approximation at very small scales in order to reduce the overhead of the experiment. Because of these optimizations, we can run your universe from beginning to end several times per week. You would be surprised how many simulations do not wind up with any life forms. You should consider yourselves lucky.
"I just believe in doing what's right." by c6gunner on Thursday January 28, 2010 (#30931014) DO YOU (impersonating me altering /.er words = right)? https://linux.slashdot.org/com... cuz
All that, destroying your "rep" (behind a FAKE NAME no less, lol - hollow, like you UNABLE to stick your ass out there as I do CREATING things that work) https://linux.slashdot.org/com...
* DIG IT -> https://www.youtube.com/watch?...
YOU sow the wind? REAP A HURRICANE!
APK
P.S.=> "You JUST can't CATCH A HURRICANE" & in your case? You can't catch a cold even, lol... apk
c6gunner your FAKEname's on a post impersonating me & worse is you altering /. user's words https://linux.slashdot.org/com... as I challenged you to show you do better work and you can't after you tried to mock me you hypocrite LYING loser https://linux.slashdot.org/com... .
* You're online FAKENAME trash c6gunner & a childish dishonest punk... & I truly KNOW you know it - behind that FAKEname & what-not no balls, lol!
APK
P.S.=> Impossible to deny FACT of your FAKEname (for your FAKE wasted lie of a so-called life) on that 1st post link above you unbelievable pussy loser... apk
I've been thinking about time lately. Why do we assume we only move forward in time? We move forward and backward in all the other dimensions, why assume we aren't oscillating back and forth in time?
With regards to quantum determination time is just as irrelevant as distance.
At least until about 2 years ago, he lived with his mother. I rang the number APK posted (along with his other identifying info some years ago) and she answered. Nice lady. Said she'd talk to Alex about spending so much time on that Internet thing.
Graduate assistant: "Sir, but if we do this, wouldn't it end the universe as we know it?"
Professor: "That's called science, girl. Now, do you want me to sign off on your thesis defense or not. Throw the switch!"
Nothing that can't be fixed with a cellphone, microwave and banana.
Start and end of the circle.
"I run the streets @ night - I terrorize @ every corner: 500 horses running under the hood (my machine & I are thunder)! My wheels of fire, I am the wind! YOU TRY TO CATCH ME, but you JUST CAN'T CATCH A HURRICANE!" - THE RODS https://www.youtube.com/watch?...
Clue: NOBODY TOUCHES MY HURRICANE - nobody DARES to even TRY...
Those who do, like YOU fakename? Scorch themselves https://slashdot.org/comments.... just as you did! ... & you certainly CANNOT stop me (ask whipslash who FAILED in it, lol)!
* No, this WILL continue c6gunner FAKENAME - to YOUR PUBLIC DISMAY by letting everyone SEE the online SWINE you are (no honor)!
APK
P.S.=> ... & no skills either, lol - you did THAT proof of your lack of them YOURSELF in my post you replied to CHUMP (don't mess w/ the bull CHUMP - you'll get the horns & don't MESS w/ your BETTERS in myself either)... apk
In a vacuum maybe itâ(TM)s speed is constant, but thereâ(TM)s precious little of that about. Space may not have as much stuff in it as Earth or its atmosphere, but itâ(TM)s not empty. All sorts of stuff, particles, photons, radiation are zooming around out there.
quote: "If a second event (B) happens after a first event (A), for example, then B cannot affect the outcome of A."
But is that really what classical physics says? Does the chain of cause-and-effect not work when you trace the timeline in reverse? Then B can be interpreted as the cause of A. I think I can remember something about physicists struggling to explain why there is an arrow of time: why there is even a distinction between past and future.
Consider the decay of an unstable isotope. What "causes" the decay to happen when-and-where it does? It's random, isn't it? It can only be described statistically, by way of half-life. But if you mentally play that film in reverse, following the chain of events from future-to-past, then suddenly it becomes obvious why the decay event had to happen when-and-where it did, because that point is where the spray of decay particles intersect. The decay is "caused" by things in the future of its own timeline, and it's impossible to fit that into our spacetime continuum at any other point.
Entropy is one reason to believe there is a preferred direction for time.
Shhh, common sense is not allowed - besides, there's a reason why it's called the second law, and not the first - or zeroeth.
So in other words the damned cat is a zombie.
Here is why I think your explanation is wrong. If you send photons towards the double slit, but bias the experiment so that one slit is closer to the photon source than the other slit and you only enable the detector at the screen long enough to detect the photons that could have reached the detector via the closer slit at the speed of light, you will not see any double slit interference pattern. In other words, the waves that cause the interference appear to exactly propagate at the speed of light.
Look up neutrino oscillation.
Article topic reminds me of the quantum eraser (and related) experiments.
Jesus said, "The man old in days will not hesitate to ask a small child seven days old about the place of life, and he will live. For many who are first will become last, and they will become one and the same."
--Thomas
~ Whence do you come, slayer of men, or where are you going, conqueror of space?
This means that the causal order of A and B cannot be always be distinguished by a quantum particle such as a photon.
Great, soon we can take spooky pictures from the past (or the future).
Why do we assume we only move forward in time? We move forward and backward in all the other dimensions, why assume we aren't oscillating back and forth in time? What difference would that make if we were? How would we know?
Physics is not invariant under time reversal and we can unambiguously determine if time were suddenly reversed. Note that this is not related to entropy e.g. a shattered plate would not leap off the floor and reassemble itself if time were reversed this is far more fundamental than that.
Oscillations of kaon and B mesons have been shown to violate time-reversal symmetry so, if the "direction" of time were suddenly reversed we would know this because these oscillations would have the opposite bias.
There is a relativistic quantum behaviour similar to what you describe - called zitterbewegung - but only in space. Essentially electrons can be shown to hypothetically be travelling back and forth at the speed of light but direction biased so that the net movement is in the classical electron's direction at the classical speed.
The implications to Determinism should be interesting
Not really because there is no determinism in quantum mechanics, only probabilities of outcomes.
You got drunk because you were going to break the table.
This and the summary fails to understand QM properly. In QM the time of an event is not well determined. The smaller the energy change associated with an event the less well determined the time of the event.
To think of a classically equivalent question it would be like asking exactly when does a wave hit a beach? The wave has a finite size and hits the beach over a range of time as it comes in at a slight angle to the shore so it is impossible to pick on exact instant and say that is exactly when the wave hit the beach.
Hence the summary is wrong to say that A then B were performed on the particle. The time of A and B is not well defined and so it is literally impossible to say whether A or B occurred first: the time of both events overlapped.
Excuse me, but polarization is not an either/or phenomenon. Thus in principle A and B can be applied in both orders.
In classical physics (beams of light), some of the light follows one path while the rest follows the other. In quantum physics (single photons) you have superpositions so that a single photon follows both paths - so in either theory the two events happen in both orders.
"No, because in a universe this big it's a stone-cold certainty that (a) intelligent life has already evolved a huge number of times, and (b) someone, somewhere has already done it. And we're still here. Throw the switch, if you would be so good."
In my book this sort of result is a good argument for the "time is an illusion" school of thought. If time isn't a fundamental property of the universe, then it's much easier to conceive that all that's actually required of two states with different values of time is that they be consistent, rather than that one be inherently derivable from the other.
At quantum level, you can't measure. Therefore, it makes no sense to talk about causality at quantum level. You do not talk about causality among unknowns.
... the measured polarization of the output photons was consistent with their being no definite causal order between when A and B was applied.
Their what? Their being? Strangely, the sentence would, sort of, make sense if there was a full stop after the word being, but otherwise I think the word you were looking for was 'there'.
Next time a journalist asks why it's so hard to write error-free code feel free to point this gem out.
(Excuse rant, cuppa required!)
Why do we assume we only move forward in time?
I would hazard that, despite all the quantum mechanical masturbation, no one has ever done it, or even been able to point to anyone or anything as having actually done it, ever, as being the primary reason.
Have the [elec|posi]tron move through Los Angles. It will get tagged up, and we could observe the tag (or reverse tag) on the next pass.
I wish that I were joking. SpaceX's crew access arm got tagged in LA on the way to Cape Canaveral, you can clearly see where it was cleaned off in this photo of the arm installed at LC-39A:
http://www.spaceflightinsider....
It is dangerous to be right when the government is wrong.
APK is just a fictional character created to make ACs look bad and justify real name authentication on /.
Jk but I doubt it is only one person posting this trash as most of it is copy paste. And everyone knows apk spam is better than the shock spam, full of obscenities and slurs.
Are we supposed to read it? Spam just gets filtered imo.
I'm pretty sure everyone reads the article and then comments. Thank goodness quantum mechanics doesn't happen on the macro scale. Imagine how crazy this board would be.
Oh God here come the quantum trolley car memes....
Your post reminds me of this Youtube video I came across recently: https://www.youtube.com/watch?...
This is some grade A science speech mumbo jumbo. Get this guy to write some Star Trek dialog!
Fuzzy and with uncertain causality.
Please do not read this sig. Thank you.
Ockam will razor your unsupported speculations back to ... go for'ard young man go for'ard ...
Quantum mechanics
The order does not matter
until classical
hmmm. Niels, is that you? Let's call this the Copenhagen Haiku -- clever, but not quite right. :)
How about...
Quantum mechanics
The order does not matter
nor does classical
One universe, one set of rules, eh?
The Church of the One True Photon is pretty popular with an untold number of members. They even have swag:
https://seebuylove.myshopify.com/collections/ceramic-mugs/church-of-the-one-true-photon
--XYZZY--
It takes a special sort of stupid to use a "security solution" provided by a spammer.
Got any dating tips from convicted rapists, marketing strategies from EA executives, or tips on buying drugs from the police? Maybe got a bridge for sale?
I have read that the concept of time as unidirectional is a "construction adopted by physicists and others for its unraveling properties." In other words time going forward is a useful way of observing a system whereas in some less scientific cultures time is seen as cyclical in nature. But even in physics the unidirectional time can be traded for the frequency domain where all phenomena are a composition of cycles, and one can be trained in thinking very skillfully in that domain.
Can't be, reversing the polarity makes them sound more like the voyager script writer.
As someone who barely has a clue about QM, I loved your reply.
Another question for you:
The experiment seems to prove the photon definitely goes through both paths. Doesn't that prove Copenhagen decoherence?
And if so, does it not turn multiverse theory from Occam's favourite to Occam-says-no?
Its just proof that the 1st three dimensions aren't as important as we thought they were.
The rule of thumb was that that you could have any two of FTL, Relativity, and strict causality. Relativity's been increasingly well-tested, and everybody has just assumed strict causality existed despite a lack of rigorous evidence, and so FTL had to go.
But now that we've torpedoed strict causality, that should make FTL genuinely plausible, should it not?
--- Most topics have many sides worth arguing, allow me to take one opposite you.