Quantum Experiment Shows Effect Before Cause 465
steveb3210 writes "Physicists have demonstrated that making a decision about whether or not to entangle two photons can be made after you've already measured the states of the photons."
Here's the article's description of the experiment: 'Two independent sources (labeled I and II) produce pairs of photons such that their polarization states are entangled. One photon from I goes to Alice, while one photon from II is sent to Bob. The second photon from each source goes to Victor. Alice and Bob independently perform polarization measurements; no communication passes between them during the experiment—they set the orientation of their polarization filters without knowing what the other is doing. At some time after Alice and Bob perform their measurements, Victor makes a choice (the "delayed choice" in the name). He either allows his two photons from I and II to travel on without doing anything, or he combines them so that their polarization states are entangled. A final measurement determines the polarization state of those two photons. ... Ma et al. found to a high degree of confidence that when Victor selected entanglement, Alice and Bob found correlated photon polarizations. This didn't happen when Victor left the photons alone.'
In other quantum news . . . (Score:5, Funny)
Nevermind -- why bother telling you if you already know :-(
Sigh... (Score:5, Funny)
*Looks at physics degree.*
*Tosses it in the trash.*
Paradoxical (Score:5, Funny)
There's a simplier solution (Score:5, Funny)
Re:causality (Score:4, Funny)
Given that now cause/effect are now uncertain...
are you sure about that? :)
The new get rich scheme! (Score:4, Funny)
2. ???
3. Collide some photons!
Re:OK... (Score:2, Funny)
don't worry, you've already decided......
Re:Now they've done it (Score:5, Funny)
The argument goes like this:
`I refuse to prove that I exist,' says God, `for proof denies faith, and without faith I am nothing.'
`But,' says Man, `The Babel fish is a dead giveaway, isn't it? It could not have evolved by chance. It proves you exist, and so therefore, by your own arguments, you don't. QED.'
`Oh dear,' says God, `I hadn't thought of that,' and promptly disappears in a puff of logic.
`Oh, that was easy,' says Man, and for an encore goes on to prove that black is white and gets himself killed on the next zebra crossing.
Re:Sigh... (Score:5, Funny)
Shouldn't that be updated to be:
*Tosses it in the trash*
*Looks at physics degree*
Cabling? (Score:5, Funny)
FTFA:
They probably hired the cable guy that got fired from CERN [wikipedia.org] a few months ago.
Re:The new get rich scheme! (Score:5, Funny)
Comment removed (Score:5, Funny)
Re:Time delay - info from the future? (Score:4, Funny)
They want sub-millisecond latency on high-frequency transactions? We'll give them negative latency! Let's see what they do then!
Re:Sigh... (Score:2, Funny)
Top-posting
No, what?
Do you know what is the worst practice on usenet?
Re:Cabling? (Score:5, Funny)
They actually decided to one-up the CERN-OPERA people.
They fired the cable guy before they even hired him!
Re:In other quantum news . . . (Score:5, Funny)
The bartender says "no faster than light travel allowed in here."
A tachyon walks into a bar.
Re:In other quantum news . . . (Score:5, Funny)
Know any good jokes?
Re:Time delay - info from the future? (Score:4, Funny)
That reminds me of the old joke.
One day, the teacher asked Johnny, "What's the difference between 14 billionths and 15 billionths?
Johnny answered, "That's what I say, What's the fuckin' difference?!"
Re:Time delay - info from the future? (Score:5, Funny)
Re:In other quantum news . . . (Score:5, Funny)
I just experienced the effect firsthand. I was confused before I even read the summary.
Re:Time delay - info from the future? (Score:4, Funny)
Re:In other quantum news . . . (Score:5, Funny)
Gypsy: No
Interviewer: Is it true that you can read minds?
Re:Time delay - info from the future? (Score:5, Funny)
So, are they working on something that makes light travel a long distance and/or go slower before making that "decision", thus achieving a substantial delay that could actually be used for "time travelling information"?
Under the simple interpretation, nothing "goes back in time." It's essentially two Schrodinger's cats (A & B) being in a superimposed state for several nano-seconds. Then V adds a constraint, and eventually the A, B, and V information bubbles interact and collapse into an observed state that the scientists record.
The meta-computer that runs our universe probably printed a log message like 'ATOMIC MERGE-OP unexpected long delay on eval: d=7m, t=23ns.' If scientists persist in this sort of research, the person running this universe will probably just ^C the app.
Re:Time delay - info from the future? (Score:4, Funny)
They say newborns have an intuitive understanding of some basic physics, but nobody is born understanding quantum mechanics.
Well, in all honesty, how do you know - I mean, it not like we can ask. Maybe newborn babies do have an innate understanding of quantum mechanics, and we spend the first few years of their life to make them unlearn it? ~
Monster Cables (Score:2, Funny)
Due to the 104-meter fiber-optic cable, Victor's measurements occurred at least 14 billionths of a second after those of Alice and Bob
Should have used Monster cables...