https://www.livescience.com/63182-quantum-computer-reverse-arrow-time.html
A new technique for quantum computing could bust open our whole model of how time moves in the universe.
A new paper, published July 18 in the journal Physical Review X [ https://journals.aps.org/prx/abstract/10.1103/PhysRevX.8.031013 ], opens the door to the possibility that the arrow pf time is an artifact of classical-style computation — something that's only appeared to us to be the case because of our limited tools.
A team of researchers found that in certain circumstances causal asymmetry disappears inside quantum computers.
In this paper, the researchers looked at physical systems that had a goldilocks' level of disorder and randomness — not too little, and not too much.
They tried to figure out those systems' pasts and futures using theoretical quantum computers (no physical computers involved). Not only did these models of quantum computers use less memory than the classical computer models, she said, they were able to run in either direction through time without using up extra memory. In other words, the quantum models had no causal asymmetry
"While classically, it might be impossible for the process to go in one of the directions [through time]," said Jayne Thompson, of the National University of Singapore, "our results show that 'quantum mechanically,' the process can go in either direction using very little memory."
And if that's true inside a quantum computer, that's true in the universe, she said.
Quantum physics is the study of the strange probabilistic behaviors of very small particles — all the very small particles in the universe. And if quantum physics is true for all the pieces that make up the universe, it's true for the universe itself, even if some of its weirder effects aren't always obvious to us. So if a quantum computer can operate without causal asymmetry, then so can the universe.
Thompson added that the research doesn't prove that there isn't any causal asymmetry anywhere in the universe. She and her colleagues showed there is no asymmetry in a handful of systems. But it's possible, she said, that there are some very bare-bones quantum models where some causal asymmetry emerges.
(Score: 1, Informative) by Anonymous Coward on Tuesday August 07 2018, @10:41PM
from hash functions to giving birth,
there are plenty of things that only go one way!
there's of course another set of things that couldn't care less if time even flowed.
(and probably two more i fail to recall right now)
the point of my post wasn't to decry the nonsense of 'omnidirectional computing', but to leave a little note about Wolfram's Tome, the NKS. In it he discussed this area and thinking better than I've seen so far. Now that's was a huge commitment and I'm wondering who and what others would recommend reading on the topic.
(Score: 1, Funny) by Anonymous Coward on Tuesday August 07 2018, @10:45PM (7 children)
Whoever thought that adding Creative Fiction as a required course for a CS degree was a good idea?
(Score: 0) by Anonymous Coward on Tuesday August 07 2018, @10:51PM (6 children)
This isn't "Creative Fiction". It's just a few pages from someone's peyote journal.
(Score: 0) by Anonymous Coward on Tuesday August 07 2018, @11:31PM (5 children)
Sure is fun watching self-important fools criticize things they don't understand.
(Score: 0) by Anonymous Coward on Wednesday August 08 2018, @12:28AM
Damn, Jayne Thompson, of the National University of Singapore! No need to be so cold.
(Score: 0, Insightful) by Anonymous Coward on Wednesday August 08 2018, @12:38AM (1 child)
HI Jane! How's the weather in Singapore? How will the weather be yesterday?
(Score: 0) by Anonymous Coward on Wednesday August 08 2018, @02:08AM
Actually in Singapore, it's tomorrow already. IDL and all that.
(Score: 0, Informative) by Anonymous Coward on Wednesday August 08 2018, @12:55AM (1 child)
Jayne, you'll just have to accept that time moves forward. You aren't going to get any younger. Rejuvenating skin creams won't work either. Instead of wasting time publishing drivel, learn how to age gracefully. If that doesn't work, get a cat.
(Score: 4, Funny) by The Mighty Buzzard on Wednesday August 08 2018, @01:48AM
Don't do the whole poison in a box thing though. That's just mean.
My rights don't end where your fear begins.
(Score: 3, Interesting) by DeathMonkey on Tuesday August 07 2018, @11:26PM (10 children)
Sigh....can they turn the clock back to 2008?
(Score: 2, Funny) by Anonymous Coward on Wednesday August 08 2018, @12:30AM
Make America Trump-Free Again!
(Score: 0, Interesting) by Anonymous Coward on Wednesday August 08 2018, @12:36AM (4 children)
Remember, if it wasn't for Obama we wouldn't have had #CrookedHillary, and if it wasn't for #CrookedHillary we would have had a better candidate.
(Score: 0, Offtopic) by fishybell on Wednesday August 08 2018, @01:49AM (2 children)
Perhaps you misremember 2016. Hillary Clinton wasn't the only candidate with a, let's say, less than flattering nick name from Donald Trump.
He fought every single candidate the same way: school yard insults. There wasn't anything special about Hillary Clinton, she was just his main focus before he won the nomination and after. She was, of course, his main focus because she was the most likely candidate on the Democrat side. When Bernie Sanders started showing up as a blip on the radar he started getting air time from The Donald too.
If anyone truly believes he won't fight the 2020 campaign along the same terms, they're in for a sad, sad election cycle.
(Score: 1, Informative) by Anonymous Coward on Wednesday August 08 2018, @11:24AM (1 child)
Hillary was special because she was the only democratic candidate who could have lost to Trump. Bernie could have rode a horse in drunk, wearing a dress and black-and-white-minstrel makeup, firing a shotgun down main street, and he would still have beat Trump.
(Score: 2) by dast on Wednesday August 08 2018, @07:29PM
I doubt it. We don't know that Bernie and his ideas would have had the wide appeal needed for a general election candidate. https://www.wsj.com/articles/most-candidates-backed-by-alexandria-ocasio-cortez-bernie-sanders-falter-1533753351 [wsj.com]
(Score: 0, Interesting) by Anonymous Coward on Wednesday August 08 2018, @01:50AM
Well, Obama saved us from the first attempt of this Hilary criminal bitch. Just for that he deserves the heaven.
(Score: 3, Funny) by shortscreen on Wednesday August 08 2018, @09:01AM
Ah yes, financial crash, what fun. You could short some stocks!
(Score: 0) by Anonymous Coward on Wednesday August 08 2018, @11:30AM (1 child)
I don't need 10 more years of Putin, thank you.
(Score: 0) by Anonymous Coward on Wednesday August 08 2018, @08:58PM
da comrade, you do. you do need 10 more years in the lubyanka.
(Score: 2) by epitaxial on Wednesday August 08 2018, @09:45PM
Fuck yeah I'm buying bitcoins for pennies back in 2009.
(Score: 5, Informative) by requerdanos on Wednesday August 08 2018, @12:50AM (1 child)
Specifically, time moves from "now" to "later" in intervals of time whose length is h (Max Planck's constant).
Well, not so fast. Quantum theories describe the behavior of very, very tiny things on very, very tiny scales. Something with more mass than, say, an atom, has a quantum wavelength shorter than itself, rendering quantum phenomena essentially inoperable and handing the object or item off to classical physics for handling. So while the tiny things that quantum theory does apply to do technically exist "in the universe", it doesn't follow that things "in the universe" will behave according to the predictions of quantum mechanics. Anything above a certain very, very small size doesn't.
(Score: 0) by Anonymous Coward on Wednesday August 08 2018, @04:05AM
bah. Entropy.
so if this system is zero entropy. then wow, it breaks thermodynamics. that'd be a big deal.
(Score: 5, Interesting) by Anonymous Coward on Wednesday August 08 2018, @12:54AM (10 children)
You are a cloud atoms which are comprised of subatomic particles.
These sub atomic particles are really just quantum field states that interact at scales of the plank length with a framerate somewhere above the plank time.
The plank time is the smallest unit of time for which we can say something has occurred.
Below this level, things get crazy unintuitive.
We have been able to prove for decades that photons and other subatomic particles are able to interfere with themselves.
There really isn't a cleaner explanation for this than the idea that the arrow of time is a macroscopic effect of something more fundamental which does not exhibit asymmetry on it's own.
There is nothing in the laws of physics that requires the arrow of time to move forward in the way that it does.
It is far more likely that what we perceive as time's arrow is actually a byproduct of some limitation of our own biological processes.
Traveling backwards in time may not be possible. But try looking at the quantum fields as you might look at a cellular automata such as Conway's Game of Life.
Imagine for example a simple 3x3 matrice with 2 possibilities 1 or 0.
Imagine a ruleset (if any adjacent is 1 set 0, if any adjacent is 0 set 1)
This results in a flip/flop with final result of
000
000
000
or
111
111
111
But what if you start with the matrice at
000
010
000
At this point the result depends on where you begin computation.
If you serialize this as 000010000 then the logical solution is 111111111
However this assumes that the serialization function is taking place outside of the unit of time inside the matrice, with a unit of time being defined as a single change to the whole field.
Yet inside the universe itself, this field must evolve and you can't just pause the universe, start at the top left and work your way from left to right to solve it and then restart the universe when you are done.
Any change propagates at the speed of light to adjacent cells and you need to take into account all of the information which arrives to that cell within that planck unit of time.
This means activity is EITHER happening faster than the planck time, in which case it's completely non-deterministic in much the same way as a race condition in your own source code might be, or...
Time is able to be rewritten at some scales.
Think about it for a moment. If time were being rewritten, you wouldn't actually be aware of it would you?
You are a particular configuration of quantum fields so is everything that can possibly effect you.
If something traveled backwards according your own world line and effected something in the past of you. It wouldn't mean that particular something went retro to it's own world line.
It also might not be quite as "back to the future" as you might imagine.
There are strong signs that within string theory, there are Shannon codes, these are error correcting codes.
https://onbeing.org/blog/symbols-of-power-adinkras-and-the-nature-of-reality/ [onbeing.org]
What would error correcting codes be doing in the fabric of the universe except updating the current set of states so that they remain within the possible when something corrupts them to an impossible value?
Something to handle the line noise as it were from calculating all these reals down to planck precision.
Since we imagine an easy and direct progression from one state to the next, having something come through and lift a value high or drop it low in order to correct things would look retrocausal in the math.
Literally like something went back in time and changed things, but the truth is time doesn't exist.
Time is merely our perception of the current field states that make up our "observer state".
We happen to have memories of our impressions of previous field states, but for some reason we are unable to remember the upcoming field states even though we are sitting in the middle of an ocean of possible field states and observing them as their waves lap against the continental shelfs on either side and then race back towards us in the center.
It is probably wrong to think of time as backwards and forwards, most likely it is complex with north, south, east and west.
Something about the way we are built biologically has made time appear to us to be magical.
Like we are all strapped into a roller coaster facing backwards, never being able to see what's coming next and only seeing what has already passed.
But the events, i.e. the coaster itself is real. It is the ride that is the illusion.
(Score: 2) by The Mighty Buzzard on Wednesday August 08 2018, @01:50AM (4 children)
No, I am a perl script reading from /dev/urandom for input. It just spit out a really weird universe shaped chunk of data is all.
My rights don't end where your fear begins.
(Score: 0) by Anonymous Coward on Wednesday August 08 2018, @11:34AM (3 children)
Why hello, dad.
(Score: 2) by pvanhoof on Wednesday August 08 2018, @02:57PM (2 children)
Children. Time to go to bed. Com'n Perl, Ruby; say your prayers to CPU.
(Score: 0) by Anonymous Coward on Wednesday August 08 2018, @06:18PM (1 child)
Don't forget to take Fifo for a walk in the morning!
(Score: 2) by pvanhoof on Wednesday August 08 2018, @07:07PM
You overheard them too? Ruby was telling his brother that he's his son. Goddamn kids on dope. I really don't want another! Have you seen at the neighbors what happened with their kid Web? Made a few javascripts pregnant and now the whole neighborhood is infested with shit websites, spyware and adds. They told me Ruby plays with those websites too. Thank CPU Perl is finally off that drugs.
FIFO, get over here. Stop dumping dogfood LIFO in the corner. Look. You're supposed to keep it in. Damned. That's what happens when you go at it too fast.
(Score: 1) by shrewdsheep on Wednesday August 08 2018, @08:18AM (2 children)
The universe could follow a master clock like a CPU (and this is what Conway's game of life does): the computation happens at every cell simultaneously at every clock cycle, i.e. the universe is a big vector processor recomputing cell states. In this scenario, speed of light would be one cell/cycle if cells would only interact with direct neighbors (or N cells/per cycle, if N is the reach per computation). That would actually be the perception of classical physics, too.
(Score: 2) by The Mighty Buzzard on Wednesday August 08 2018, @11:49AM
Nah, no need for all cells to be processed in a single clock cycle. It's not like we'd notice if it took five to get them all processed and just made each turn five cycles long. Still, badass uptime for whatever box is running it.
My rights don't end where your fear begins.
(Score: 0) by Anonymous Coward on Thursday August 09 2018, @02:50AM
Cool idea but it doesn't work.*
The problem is aliasing.
We can measure events at h, and at 1.5h, but not at 0.5h.
If there was one h-speed clock, 1.5h would be unachievable.
*probably. Eg. if there is a clock using an atomic unit of time that's less than h, but using more than one cycle at a minimum, but then one must wonder why that smaller unit. Still, if the base unit is h/2, then h, 1.5h, would be observable, even if there was a minimum cycle size of h. One expects to see discrete times, larger than h but with smaller gaps than h, in this case.
(Score: 2) by Bot on Wednesday August 08 2018, @12:02PM
> This means activity is EITHER happening faster than the planck time, in which case it's completely non-deterministic in much the same way as a race condition in your own source code might be, or...
> Time is able to be rewritten at some scales.
I maybe misunderstand you, but I think you are making up a meta arrow of time. You are in good company.
The classical model is: the state of the universe, on which the laws of physics work with planck scale resolution, and an arrow of time IN WHICH laws of physics operate.
Quantum scale anomalies in experiments proved this wrong, but people do not really acknowledge time as just another product of the computation. Time is change, is itself a product. The correct model is, whatever is meta defines spacetime according to seemingly consistent rules. If you do without a time in which the universe "is computed", then it is possible for the meta to calculate according to future states, to "rewrite time", to do whatever. Being outside time means BEING UNAFFECTED BY TIME. How is it possible to do that? well we would need to go outside time and see how it's done. But that is as unlikely as your game of conway structures to wake up one day and think the universe as NOT made by a matrix of 1 and 0.
Account abandoned.
(Score: 0) by Anonymous Coward on Wednesday August 08 2018, @09:00PM
no u r.
(Score: 4, Insightful) by Runaway1956 on Wednesday August 08 2018, @01:38AM (1 child)
They ran thought experiments, right? They didn't set up a lab, and actually test anything at all. A thought experiment, backed up by what they believe to be valid mathematics?
Let me know when they actually accomplish anything.
(Score: 2) by legont on Wednesday August 08 2018, @02:13AM
Well, most of them were smart enough to move to Singapore. I see this arrow direction more and more often lately.
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.
(Score: 0) by Anonymous Coward on Wednesday August 08 2018, @01:51AM
It's just like us running a simulation of the universe. Stuff inside the simulation can't travel to the past - there is no Past, but inside that simulation you can still measure "time" at simulation speed.
In theory someone outside the simulation could save copies so from outside there might be a past or more than one past, but such stuff may only apply to the outside. And there might not be infinite copies of the past.
(Score: 1) by khallow on Wednesday August 08 2018, @03:28AM
The point of trying is to get rid of yet another need to invoke the anthropic principle to explain why the universe looks the way it does. A priors that just are - significantly constrain our ability to explain the universe and do science. Not all instances of the anthropic principle are equally crippling. Starting on a planet with a moon, which was instrumental to the development of a habitable environment for us, doesn't preclude us from studying potential environments which are not planets with moons. But starting in a universe with a time arrow and a particular distribution of matter and anti-matter, does preclude us from studying universes with different such states (unless there is a more encompassing physical reality of which we are currently unaware connecting us to those universes that we can somehow observe sufficiently well through the connection).
The thing is, you will get a time arrow from any embedding or representation of a classical computational system in a time-agnostic QM system. From the viewpoint of that classical computation system, you have the time arrow because the system has memory - it doesn't remember the future. That time asymmetry of the observer is all one needs. Needless to say, our brains have the classical computation system and the time arrow. Thus, we have an explanation right there for why there's a time arrow. Technically, that's good enough, but it leaves the door wide open to whether there's other such systems in incompatible universes which exist in some sense (perhaps they could be observable by a time-agnostic quantum mechanical system), but which we will never observe because of our inherent physical limitations.
(Score: 1, Funny) by Anonymous Coward on Wednesday August 08 2018, @04:46AM
ah, so now we know how the mecha pilots interface with the evangelion robots:
the story continues sanely, like a mecha series should then, the lazerus computer inside the EVA "kills time"
and the story line goes bonkers, until "somehow" the lazerus interface decides to resurrect the arrow of time and the story
can continue sanely ... enough ... again.
(Score: 0) by Anonymous Coward on Wednesday August 08 2018, @06:00AM
https://medium.com/the-physics-arxiv-blog/quantum-experiment-shows-how-time-emerges-from-entanglement-d5d3dc850933 [medium.com]
(Score: 2) by inertnet on Wednesday August 08 2018, @08:24AM (1 child)
Think of the time files! Please don't kill the arrow of time.
(Score: 3, Funny) by Dr Spin on Wednesday August 08 2018, @08:39AM
I thought DDT had killed all the time flies!
Warning: Opening your mouth may invalidate your brain!