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Physicist Trying To Send a Signal Back In Time

samzenpus posted more than 7 years ago | from the don't-be-so-gullible-McFly dept.

685

phil reed writes "University of Washington physicist John Cramer is attempting to send a signal back through time." From the article: "We're going to shoot an ultraviolet laser into a (special type of) crystal, and out will come two. lower-energy photons that are entangled," Cramer said. For the first phase of the experiment, to be started early next year, they will look for evidence of signaling between the entangled photons. Finding that would, by itself, represent a stunning achievement. Ultimately, the UW scientists hope to test for retrocausality — evidence of a signal sent between photons backward in time. The test will involve sending one of the photons down 10 miles of fiber optic cable, delaying it by 50 microseconds, then testing a quantum-mechanical aspect of the delayed photon. Due to quantum entanglement, the non-delayed photon would need to reflect the measurement made 50 microseconds later on the delayed photon. In order for this to happen, some kind of signal would need to be sent 50 microseconds back in time from the delayed photon to the non-delayed photon. (Confusing? Quantum physics is like that.)

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I heard about this (5, Funny)

alnapp (321260) | more than 7 years ago | (#16866808)

Yesterday

Re:I heard about this (5, Funny)

Anonymous Coward | more than 7 years ago | (#16866818)

and it was already a dupe!

Re:I heard about this (4, Funny)

ookabooka (731013) | more than 7 years ago | (#16866822)

Yeah, I told you about it tomorrow.

Re:I heard about this (5, Funny)

igny (716218) | more than 7 years ago | (#16866996)

The major problem of time travel is grammar. See, you have already screwed been have it up .

Re:I heard about this and the Thai (1)

davidsyes (765062) | more than 7 years ago | (#16867040)

IT Minister will tell us tomorrow... about 5,000 photons before ago

(yeh, that's english...)

http://it.slashdot.org/it/06/11/16/0323202.shtml [slashdot.org]

But, he will be caught off-guard when the Thai IT Coup of 2007 occurred

Captcha: sender

Re:I heard about this (4, Funny)

owlman17 (871857) | more than 7 years ago | (#16867206)

Testing testing. frist post. Oh wait, it didn't work. Folks, it doesn't work.

Re:I heard about this (1)

the_duke_of_hazzard (603473) | more than 7 years ago | (#16867208)

Get it right: you will haven been telling him tomorrow.

If you are struggling, I can recommend Dr Dan Streetmentioner's book on time travel grammar.

Re:I heard about this (4, Funny)

eclectro (227083) | more than 7 years ago | (#16867228)

So when the dupe shows up tomorrow, we will know the experiment is a success today.

I await notification of my Nobel prize any moment now.

Re:I heard about this (5, Funny)

Anonymous Coward | more than 7 years ago | (#16866832)

2009 called and they want their joke back.

Re:I heard about this (1)

Kangburra (911213) | more than 7 years ago | (#16866846)

Yesterday


Knowing /. someone will get the joke tomorrow. :-)

It reached Thailand (0, Troll)

asifyoucare (302582) | more than 7 years ago | (#16866890)

It seems to have sent their I.T. industry back by a decade

Here is the proof [slashdot.org] .

Re:I heard about this (1)

Mr2cents (323101) | more than 7 years ago | (#16866982)

Yeah, that was the dupe of this article.

Re:I heard about this (1)

rvw (755107) | more than 7 years ago | (#16867222)

The ultimate dupe!

Re:I heard about this (5, Funny)

niktemadur (793971) | more than 7 years ago | (#16867254)

A young rocket scientist named Wright
once travelled much faster than light.
He set out one day, in a relative way
and arrived on the previous night.

A HA! (5, Funny)

lavid (1020121) | more than 7 years ago | (#16866828)

So this is how Bif gets rich. I knew there was no Sports Almanac.

Leave my grandfather alone (0)

Anonymous Coward | more than 7 years ago | (#16866838)

you bastards, he never did anything to you...

Slashdot posting time travel test (2, Funny)

Aim Here (765712) | more than 7 years ago | (#16866852)

Test has succeeded!

Re:Slashdot posting time travel test (2, Funny)

Aim Here (765712) | more than 7 years ago | (#16866866)

We at Aim Here Research laboratories are now about to begin a similar time travel experiment!

We are now going to attempt to post the reply to a slashdot thread BEFORE posting the first post in the thread!

Wish us luck, guys. This could revolutionise the internet!

Great time to procrastrinate ! (1)

alexhs (877055) | more than 7 years ago | (#16867166)

A deadline approaching ? Don't stress ! Just log in the quantum network and get the code you will write after the deadline !

I've heard that Microsoft is constantly trying to master that technology since 30 years. Sadly it doesn't work that well for them, hence the legendary late releases.

Can't they just promise to do it? (1)

iogan (943605) | more than 7 years ago | (#16866872)

Like how about if they just say that they solemnly swear to send it back to today a year from now, when they have it working.. then we'd already know if it works today!

The question is, would we then spend as much time on trying to figure out how to do it? How about if we then didn't make it, how would that affect... I mean how would that.. What would...

ANOTHER TIMEQUAKE!!! RUUUUNNNNN!!!

I am Positive, this cant work... (1)

tonywestonuk (261622) | more than 7 years ago | (#16866874)

....Cuz one could scale this technique to work on, say, the lotto results. The only way this can work, is if the measurement of the 1st photon, requires the 2nd photon....so the measurement can only be made after the 2nd photon has been 'modified'.

Re:I am Positive, this cant work... (5, Funny)

MicrosoftRepresentit (1002310) | more than 7 years ago | (#16866946)

Yes, forget any of the laws of physics that might be violated here, the primary concern is this breaks the fundamental rule of the universe, the core axiom at the heart of space and time; it would allow people to cheat at the lottery.

Re:I am Positive, this cant work... (1)

07734 (947149) | more than 7 years ago | (#16867068)

In case you were serious. Have a read about quantum entanglement [wikipedia.org] . It's a bit like the way a twin will instantly know when the other one is getting laid. ... or something.

Re:I am Positive, this cant work... (2, Insightful)

bigmouth_strikes (224629) | more than 7 years ago | (#16867316)

....Cuz one could scale this technique to work on, say, the lotto results.

No, one couldn't. There are inherent differences between our world and the quantum world. Specifically, quantum effects do not scale.

Then again, if you used individual photons instead of lotto balls, we'd be in business.

Re:I am Positive, this cant work... (0)

Anonymous Coward | more than 7 years ago | (#16867384)

Even if it does work, I don't think it can be used to send information back in time. A very basic, laymans explanation of this (and I am no expert - just a small-time hobbyist) would be as follows:

State can only be 'undefined' in quantum terms for very, very small masses. An interesting point here is that the human brain is greater than the mass needed to prevent indeterminacy. What this means, is that when a human realises the result of a measurement, the undefined state [of whatever particle] is forced into one state or the other, as the human brain cannot exist in a state of indeterminacy (as a whole, at least. There are various theories suggesting the human brain may actually use quantum indeterminacy to function at a low, isolated level). This is probably related to why we, as humans, find quantum physics so difficult to get our heads around, along with perceiving time in a rather warped manner.

So, this experiment would only prove a link for some information to travel back in time between the involved particles. It wouldn't be possible to actually read this information (as a human) in the past. Which begs the question, are you really sending information back in time, or are you actually, in fact, sending information forward in time to the particle you are measuring 'first', by measuring the particle in the 'past'?

Also, the ability to send information 'back in time' via quantum entanglement is not a new thing, or even unlikely. It is generally accepted that 'spooky action at a distance' can be used to avoid the universe's 'sphere of influence' limit defined by the theory of relativity, as upon measuring one particle, the other is instantly forced to the opposing state, regardless of distance between the particles, thereby effectively sending information back in time, relatively speaking, at least.

So... (1)

r3st2 (987153) | more than 7 years ago | (#16866878)

Where would you look to see if it worked? In the news or in history books.

Inserting first post! (1, Informative)

AEton (654737) | more than 7 years ago | (#16866882)

@BEGIN MESSAGE
@author 321260
@target_time 0519
@subject I heard about this
@content Yesterday
@EOM

1998 called (-1, Offtopic)

Anonymous Coward | more than 7 years ago | (#16866884)

Psyche! 1998 didn't call.

This makes no sense (0)

Anonymous Coward | more than 7 years ago | (#16866900)

You mean to tell me that it only just now occurred to someone to send an entangled photon through a spool of fiber and see how it affects its twin, which took a direct path?

Also, I thought entanglement couldn't be used to transmit information, as a consequence of Somebody or Another's Law.

Can anyone clarify just what this poorly-written and sensational article is actually saying?

Re:This makes no sense (5, Funny)

rifter (147452) | more than 7 years ago | (#16866952)


You mean to tell me that it only just now occurred to someone to send an entangled photon through a spool of fiber and see how it affects its twin, which took a direct path?

Also, I thought entanglement couldn't be used to transmit information, as a consequence of Somebody or Another's Law.

Can anyone clarify just what this poorly-written and sensational article is actually saying?



No, this is Slashdot. You want real physicists, and you're probably barking up the wrong tree.

However you may receive several answers. They are statistically likely not to include the right answer to your question, but rather to fall into one of the following categories (in fact you may just get all of these):

1) Someone will pretend they know what they are talking about and give you a very long and detailed answer. Unfortunately it will be horribly wrong, but only people with the proper background will realize it (ie no one here). :D

2) Someone will post a completely offtopic ad hominem attack on you for no particular reason (brain hurt! must strike thing that make brain hurt!) for bonus it will probably have something to do with your sexual proclivities and/or your mother.

3) Someone will post a completely unrelated troll hoping to get people to actually read it.

4) Someone will post a smart-aleck comment predicting the reasons you will not receive your answer (Hi there!)

5) In Soviet Russia, ??? profits you!

Re:This makes no sense (0)

Anonymous Coward | more than 7 years ago | (#16867060)

In soviet russia, your mother is a cock smoking faggot! (there's 2 and 5 done)

Re:This makes no sense (4, Funny)

i_should_be_working (720372) | more than 7 years ago | (#16867110)

You mean to tell me that it only just now occurred to someone to send an entangled photon through a spool of fiber and see how >it affects its twin, which took a direct path?

That's been done. I think the new thing here is that the photons are now outside of each other's light cone. Before with entanglement experiments the photons were still close enough to each other during the measurements that a naysayer could claim that when the first measurement was made a signal (traveling
Also, I thought entanglement couldn't be used to transmit information, as a consequence of Somebody or Another's Law.

Law of causality. If these systems could be used to transmit information, they could send information faster than the speed of light.

Can anyone clarify just what this poorly-written and sensational article is actually saying?

Take two entangled photons and send one really far away. Since it's known that measuring the state of the one far away will result in knowing what the state of the close one is one could claim
a) that the one far away sent an instantaneous signal to the close one, telling it what state to be in or
b) if you measure the close one first, that the one you sent away sent it's information from the 50 microsecond-in-the-future-measurement back in time to the moment you measured the close one.

I think the physicists working on this would say both of those interpretations are wrong.

any lawyers available? (3, Interesting)

Patrik_AKA_RedX (624423) | more than 7 years ago | (#16866906)

I have a question: Is it legal to use a timetravel device to chea^H^H^H^Haid in winning the lottery?

Re:any lawyers available? (1)

bartron (772079) | more than 7 years ago | (#16867028)

You may have been joking but at this stage, yes. There is no law anywhere that says you can't travel back in time to learn the numbers of a future lottery. However if the whole time travel thing manages to have data passed a significant ammount of time into the past then my guess is that one day it will be made illegal. That will be moot though as there will be illegal setups and the whole lottery system will fall apart.

Re:any lawyers available? (2, Interesting)

blacksway (464427) | more than 7 years ago | (#16867094)

Surely we need the law NOW, so that when people from the future travel back to now with future library numbers they can be arrested in the past as well as the future, otherwise the past would become a country with no extradition treaties!

Re:any lawyers available? (4, Insightful)

balsy2001 (941953) | more than 7 years ago | (#16867386)

You can't travel back in time to GET the winning numbers for a lottery in the future. You have to SEND the winning numbers back to yourself.

Re: The Future (5, Insightful)

creysoft (856713) | more than 7 years ago | (#16866908)

If only it worked that way. Just because we can prove something is true in quantum physics doesn't mean it can be "upscaled" to the macro-universe. In short, even if this works it's a far cry from *you* being able to go back in time.

Re: The Future (5, Insightful)

Lord Kano (13027) | more than 7 years ago | (#16866994)

In short, even if this works it's a far cry from *you* being able to go back in time.

I'd settle for being able to send myself a short message.

LK

Re: The Future (1)

aussie_a (778472) | more than 7 years ago | (#16867354)

Why is this modded funny?

Re: The Future (1)

Patrik_AKA_RedX (624423) | more than 7 years ago | (#16867000)

Yeah I remembered you wrote this. Boy, are you up for a big suprise. Your grandson and I had quite a laugh with the prank we pulled on you 2 years from now. Leaving a living T-rex in your garage, I guess you didn't expected that! Amazing how that nanoreplicator was able to fit a garage in your appartement in the first place.

Re: The Future (1)

zeux (129034) | more than 7 years ago | (#16867002)

If you could send information back through time (which is what the FA is all about) then there would be no need to physically travel back through time.

I don't think it's possible though, otherwise we would probably be getting messages from the future, wouldn't we?

[HEAD EXPLODES]

Re: The Future (0)

Anonymous Coward | more than 7 years ago | (#16867132)

If you sent a radio signal back to 1242, would they be able to read it?

Perhaps the reason why we haven't received a signal yet, is that the technology required to read the "transport method" hasn't been invented yet?

Re: The Future (4, Funny)

ag0ny (59629) | more than 7 years ago | (#16867146)

I don't think it's possible though, otherwise we would probably be getting messages from the future, wouldn't we?

Maybe we're already getting them.

http://en.wikipedia.org/wiki/John_Titor [wikipedia.org]

Re: The Future (3, Insightful)

aussie_a (778472) | more than 7 years ago | (#16867382)

Oh yeah, that John Titor was definitely from the future. By the way, how's that Civil War going? Y'know, the one that started in 2004

Re: The Future (1)

constantnormal (512494) | more than 7 years ago | (#16867322)

Sending physical objects back in time is not the only way that time travel can be useful.

If this works out, it could be the beginnings of instantaneous communication to distant places. This would neatly do away with the need for autonomous (or semi-autonomous) robots for exploring Mars, as you could in principle drive a Mars rover in real time from Earth.

The financial community is well ahead of this, because I can see plenty of instances of buy-sell activity in selected stocks before the news that eventually moves the stocks occurs.

Isn't this axiomatically impossible? (5, Interesting)

rubberpaw (202337) | more than 7 years ago | (#16866910)

IANAP, but when I studied some basic quantum theory, I thought that one of the issues that arose in the EPR/Bell research was that in order for entanglement to be valid, it could not be used to transmit information, except via quantum teleportation [ibm.com] , which has strong limitations due to being a classical information channel. Does anyone care to clarify for me?

Re:Isn't this axiomatically impossible? (4, Insightful)

Metteyya (790458) | more than 7 years ago | (#16867066)

Actually the experiment is designed properly. The thing is, they are already going to misinterpret the results. Quantum entaglement means that at the moment of setting wavefunction of one of the particles, the wavefunction of second particle is immediately changed to "second" possible state.

The key word here is "immediately". Special relativity redefined "the same moment" as "the same interval", i.e. line of constant t^2 - (x/c)^2 instead of plain ol' time t. Entangled states are able to react in classically understood "same moment", without regard to c and limitation of transmitting the signal at most at light speed. Which, by means of special relativity, means travelling back in time (as any transmission of signal or matter with speed greater than light).

If I did any spelling or grammar error, excuse me, I'n not a native English speaker.

Re:Isn't this axiomatically impossible? (1, Interesting)

Anonymous Coward | more than 7 years ago | (#16867102)

Well, it will work. Argue against that. "Axiomatically impossible" is for mathematicians, not physicists. It was once axiomatically impossible to sail in westward direction and arrive back at the departure point from the east.

Re:Isn't this axiomatically impossible? (5, Insightful)

UnHolier than ever (803328) | more than 7 years ago | (#16867176)

There will be no signalling. What the researchers are looking for is a relation between two entangled photons, but the relation can only be found by comparing the results after.

To make a crude analogy, imagine I am sending you a bunch of random numbers, and that by altering something in my lab I can change the values of these random numbers. Then, afterwards I can tell you "look at random numbers #31,57 and 68, they form a message". The manipulation I made is instantaneous, but in order for you to get information out of it, I have to tell you where to look for via a classical communication.

This might not be very clear, maybe Wikipedia [wikipedia.org] is clearer.

In short, what they are trying to do is a nice experiment, and it should work, but it does not mean you can signal backwards in time.

measuring, or setting? (1, Informative)

Anonymous Coward | more than 7 years ago | (#16866916)

Okay, we all know spooky action at a distance involves guaranteeing that one measurement can determine the outcome of another billions of miles away; but this cannot actually be used for communication because there is no way of fixing the state of one, just measuring it, forcing an eigenstate. But the article suggests that we are *setting* "wave or particle-ness" (what? What quantum state is that referring to?) on the photon travelling the extra distance and transmitting that information back in time to the photon that first hits the detector. eh?

Please type the word in this image: predict

Dear Mr Gates... (5, Funny)

pandrijeczko (588093) | more than 7 years ago | (#16866966)

640K won't be enough.

Re:Dear Mr Gates... (4, Funny)

xoyoyo (949672) | more than 7 years ago | (#16867174)

Dear Mr Bush Now would be a really good time to consider adoption. Thanks The future

Re: the DOC (0)

Anonymous Coward | more than 7 years ago | (#16867188)

i knoooo weee need more power sarrge.... sumone get sum plutoniummm! we need a 21 gijawatt charge to make this worrkk!!

Re:Dear Mr Gates... (1)

Joebert (946227) | more than 7 years ago | (#16867238)

P.S. - I've included the... Whoah, Gates was visited by time travelers !

That's not a signal. (4, Informative)

i_should_be_working (720372) | more than 7 years ago | (#16866968)

It carries no useful information, and it's not going 'backwards in time'. It's just two entangled particles outside of each other's light cone. Once one particle is found to be in a certain state, the state of the other particle will be instantly known, but no information is traveling back in time or faster than the speed of light.
 
It would be cool to see it actually happen, since previous entanglement experiments have never put the particles outside of each other's light cone, but the effect is something that physicists have understood (as much as anything in quantum physics is) for decades. In the article one of them say they don't really expect it to work, but I'd guess this is for technical reasons. No one expects that it won't work for theoretical reasons.

Now (1)

jlebrech (810586) | more than 7 years ago | (#16866990)

If this is successful, all is needed is to tie this to a working teleportation system.

That's if teleportation data can be sent with neutrons.

FTL communication (2, Interesting)

JohnPM (163131) | more than 7 years ago | (#16867004)

From what I can understand the backwards-in-time measurement requires communication from one entangled photon to the other. This would allow faster-than-light communication which is the first thing you think of when you hear about entanglement. I thought it was well established that this was impossible since measuring one photon destroys the entanglement and you can never tell if you sent the signal or received it.
Can anyone explain how this experiment is different, and would it also allow for ftl comms?

Re:FTL communication (1)

Kickasso (210195) | more than 7 years ago | (#16867284)

FTL communication is strictly equivalent to communication backwards in time. If you can do one, you can do the other. If special relativity is correct, that is.

Yes (0, Redundant)

alexj33 (968322) | more than 7 years ago | (#16867008)

I knew you were going to type that.

Not the only scientist trying this (4, Interesting)

tjl2015 (673427) | more than 7 years ago | (#16867010)

Aside from the undoubtedly numerous crackpots who are attempting to build a time machine, I know of at least one more legitimate scientist who is working on something similar. Professor Ronald Mallet, at the University of Connecticut, is working on sending particles back in time. He is basing his on General Relativity, not quantum mechanics, using a circular path of lasers:

http://en.wikipedia.org/wiki/Ronald_Malett [wikipedia.org]

The importance of both of these projects is that if you can send photons back in time, you can send signals back in time, and send messages. For years people have wondered about temporal paradoxes and how they may be resolved. With a system such as these, paradoxes can be tested. We'll finally have an answer to the Grandfather paradox.

Even with paradoxes such as this, a temporal communication device would have incredible application. The scientist in the article might only be working with a few microseconds, but it sounds like that if you have a long enough fiber optic cable, you can send a signal as far back as you want. You might not be able to, say use it to prevent someone from having a fatal accident, since if the accident never happened, you would have never sent the message. But there are many useful applications, especially in forewarning events beyond human control. What if we knew exactly when and where every earthquake and hurricane was going to hit in a particular year? What if we knew rainfall patterns in advanced and could plan for draught ahead of time?

You wouldn't be able to use it to prevent the next 9/11, but you could probably use a temporal communicator to prevent the next hurricane Katrina disaster. The hurricane or earthquake will still devastate the city, but that doesn't mean there has to be anyone in it at the time.

Re:Not the only scientist trying this (0, Troll)

LuxMaker (996734) | more than 7 years ago | (#16867116)

You might not be able to, say use it to prevent someone from having a fatal accident, since if the accident never happened, you would have never sent the message.

Yes you could, you would have to send the message that was received in the earlier time, backward in time again, regardless of the outcome.

Re:Not the only scientist trying this (1)

tjl2015 (673427) | more than 7 years ago | (#16867200)

That assumes you already received the message. It's fine if you find yourself already witin the causality loop, but how do you actually start the loop. Say you're best friend gets hit by a bus. You want to try and prevent it, but you can't, because if you send the message back in time, the acciddent will have never happened, and you won't have gotten the idea to send the message.

Re:Not the only scientist trying this (0)

Anonymous Coward | more than 7 years ago | (#16867364)

I believe John Titor explained that there are no paradoxes like that possible, as every possible decision has been made or event has happened in one universe or another. Where every variable outcome is present; if you'd kill your own grandfather, that's fine. You were born in a dimension were your grandfather wasn't killed by you. In the dimension you currently are you have, and the reality of your grandfather being unable to conceive your father and thus conceiving you isn't happening in the dimension you're originated from, so it wont affect you personally.

In that sense aren't any unhandled exceptions in the universe.

Lotteries will become obsolete (0)

Anonymous Coward | more than 7 years ago | (#16867012)

If this could be scaled up to macro-timescales, then it would certainly put lotteries out of business (or at least the ones where you choose numbers in advance).

Rich.

Logic error... (1)

DerekTomes (1024783) | more than 7 years ago | (#16867038)

It says "...The test will involve sending one of the photons down 10 miles of fiber optic cable, delaying it by 50 microseconds..." So the photon takes 50 microseconds to get to the end of the fiber optic cable. Who cares, when the "magic signal" is sent from one photon to the other they'll still exist in the same time. One will just be part way down a fiber optic cable.

Einstein says no. (1)

Ihlosi (895663) | more than 7 years ago | (#16867198)

Who cares, when the "magic signal" is sent from one photon to the other they'll still exist in the same time.

You're obviously not intimately familiar with the theory of relativity.



Re:Einstein says no. (1)

DerekTomes (1024783) | more than 7 years ago | (#16867396)

I was under the impression that Einstein thought this was bollocks as well. But regardless, lets try this another way:

There are two twins (Fred and Bruce) who always blink at the same time no matter how far apart they are. Fred walks the short side of a city block, while Bruce walks the other three sides. It takes Fred 1 minute to do the trip and Bruce 3 minutes. When Fred finishes his walk, I poke him in the eye causing him to blink. Bruce also blinks, because they're twins and twins do this. Two minutes after Fred turns up, Bruce turns up with a sore eye.

I fail to see how this proves something went back in time...

Last Post (0)

Anonymous Coward | more than 7 years ago | (#16867046)

This is the last post of this thread. I have sent it backwards in time for your pleasure at this moment.

Re:Last Post (0)

Anonymous Coward | more than 7 years ago | (#16867234)

YUO FAIL IT

One major application (1)

LuxMaker (996734) | more than 7 years ago | (#16867050)

Instantaneous communication between two points in space no matter the distance. Great if you want to include other planets in the internet with very little latency. Also computers of tomorrow will be hooked up to these so all you carry is a laptop with a simple cpu and buy extra cpu power as needed.

The future called. (5, Informative)

Anonymous Coward | more than 7 years ago | (#16867078)

It wants its news back.
Quoting from:
http://en.wikipedia.org/wiki/Quantum_entanglement [wikipedia.org]

Although two entangled systems appear to interact across large spatial separations, no useful information can be transmitted in this way, so causality cannot be violated through entanglement.

The slashdot editor's brains seem to be traveling back in time though.

Sounds like quite a Quantum Leap... (1)

Channard (693317) | more than 7 years ago | (#16867086)

.. shame Dean Stockwell is tied up with Battlestar Galactica.

Re:Sounds like quite a Quantum Leap... (1)

Plugoor (655762) | more than 7 years ago | (#16867232)

.. shame Dean Stockwell is tied up with Battlestar Galactica.
actually he's got time to spare: http://www.imdb.com/title/tt0383588/ [imdb.com]

Why send a signal back in time ? (3, Insightful)

heytal (173090) | more than 7 years ago | (#16867088)

If you send a signal back in time, one will have to go back in time to verify that it has been received. And since you cannot verify this, you can either claim that the signal has been sent successfully and celebrate, or start new experiments to send people back in time to verify that the signals that have just been sent have been received. Once people verify that, experiments will have to be done to bring people forward in time to testify that they have verified that the signal just sent has been received back in time. How would one prove that anyways ?

A better experiment is to try and catch signals to be sent in future. You can verify that this signal is sent, once you have received it.

Critics will say that scientists, once they catch a signal, will ensure that the signal is sent in the future. But then critics are always there...

(Confusing ? Time related writing is like that)

Re:Why send a signal back in time ? (0)

Anonymous Coward | more than 7 years ago | (#16867204)

1. Receive outcome of toss
2. Toss a coin
3. Send outcome back in time
4. Verify that 1 and 2 are consistent

and ...
5. ? (well, not really)
6. Profit!

Re:Why send a signal back in time ? (1)

bitbucketeer (892710) | more than 7 years ago | (#16867266)

This is special relativity stuff... two photons travel at a constant, non-accelerating speed, and since that speed is the speed of light (by definition) all their momentum is in the space dimensions so that time doesn't pass for the photons. A photon emitted soon after the Big Bang still hasn't experienced any passage of time despite it being 14 billion years later.

Re: What about cause and effect? (1, Funny)

Anonymous Coward | more than 7 years ago | (#16867090)

This would be like posting a response before the initial post

And who says that can't be done?

Re: What about cause and effect? (1, Funny)

Anonymous Coward | more than 7 years ago | (#16867100)

This would be like posting a response before the initial post

What about cause and effect? (1)

91degrees (207121) | more than 7 years ago | (#16867122)

Okay, for short times this clearly isn't an issue, but what if I respond to a message that hasn't been sent preventing a message from being sent in the first place.

This would be like posting a response before the initial post. It wouldn't make any sense at all! It's impossible.

To be completely correct ... (3, Informative)

OeLeWaPpErKe (412765) | more than 7 years ago | (#16867092)

They're sending a RANDOM signal back in time.

Re:To be completely correct ... (1)

Seahawk (70898) | more than 7 years ago | (#16867390)

So youre saying it will work for lottery numbers? ;)

Time Knows (1)

xstaytruex (954638) | more than 7 years ago | (#16867106)

the only reason we would go back in it is to gain some money...screw science when you can always go back to it.

Obscure reference! (1)

laejoh (648921) | more than 7 years ago | (#16867108)

Great, such progress! No more worries soon about having missed an important television programme.


"It's, er, really quite fun in its way," he concluded.
"Certainly better than television and a great deal easier to
use than a video recorder. If I miss a programme I just pop
back in time and watch it. I'm hopeless fiddling with all those
buttons."
Dirk reacted to this revelation with horror.
"You have a time machine and you use it for... watching
television?"
"Well, I wouldn't use it at all if I could ge1 the hang of
the video recorder.

stupid thing doesn't work! (0)

Anonymous Coward | more than 7 years ago | (#16867114)

"oh' i forgot to put in the crystals."

Dupe (1, Redundant)

mrjb (547783) | more than 7 years ago | (#16867138)

This was previously posted tomorrow.

Who will reply? (1)

Lost Penguin (636359) | more than 7 years ago | (#16867150)

/John Titor unavailable for comment

No news, really! and even wrong (5, Informative)

DMiax (915735) | more than 7 years ago | (#16867168)

I actually graduated in quantum information, this is no news and it is wrong.

I explain my opinion:

- Entanglement has been observed, pairs of fotons and spin of electrons can be correlated in a manner impossible to describe in classical physics.

- The experiment described does not even measure entanglement, as you could achieve the same result classically:
Say I have a black ball and a white ball, I put one at random in a closed box, the other one in another box. Say the boxes are put 1000 miles away from each other, from the content of one of the boxes I can predict which ball is in the other one, as I can check later.

The point is that they are not choosing in which state (of polarization) the light will be in the moment they measure the first time. So they aren't going to send any message ever this way. To do it they would require a classical channel wich works as we expect...

For the proof of entanglement one must implement physically the Bell's system [wikipedia.org] or the Greenberger-Horne-Zeilinger one (I have no link), and SURPRISE! it has already been done.

Re:No news, really! and even wrong (-1, Troll)

Anonymous Coward | more than 7 years ago | (#16867252)

You graduated in quantum information, but cannot actually spell 'Photons'. Incredible.

frist post? (0, Redundant)

owlman17 (871857) | more than 7 years ago | (#16867202)

Once perfected, this will ensure first posts in /.

Exciting Applications (1)

smackenzie (912024) | more than 7 years ago | (#16867218)

Quantum entangledness is fun.

We wouldn't be able to send messages back in time right now (for example, 2006 -> 2005 and warn everyone of Katrina). However, we would be able to launch a split photon signal into the "future", and then receive messages back. You only need to extrapolate the science to many, many, many miles of fiber optics and send out enough particles to generate simple morse code. (Not 1 particle and 50 ms, but 1000 particles and 10 days.) This seems like less of a stretch than many other macro applications in quantum land.

However, how does this effect course of events? Send a signal out as Katrina is forming, split, receive morse "levies break, many deaths, evacuate city" so we evacuate the city and butress the levies... but then there aren't many deaths and the levies don't break...

Re:Exciting Applications (1)

niktemadur (793971) | more than 7 years ago | (#16867346)

However, how does this effect course of events? Send a signal out as Katrina is forming, split, receive morse "levies break, many deaths, evacuate city" so we evacuate the city and butress the levies... but then there aren't many deaths and the levies don't break...

Ah yes, the ol' 'Kill Hitler's mother' paradox. However, with the morse code scenario you describe, we will effectively break off the standard timeline, so to speak, and create a new, parallel one, then another, and another, in geometrical fashion I suppose, ever accelerating in the creation of the 'new branches' of our choosing. All will still exist, separated and never to meet again.

Which brings up an interesting question: how many times can you altruistically 'plan ahead' before population growth in itself causes a catastrophe? The answer might be to keep communications going a week into the future, but also ten, a hundred and a thousand years in advance, to regard consequences of current actions, then choose an equilibrium path.

Holy cow, the ice is getting thinner as I go along here.

Seems familar (1, Informative)

Anonymous Coward | more than 7 years ago | (#16867226)

This is what happens in Timescape, by Gregory Benford! I wonder if this guy's read it? Certainly looks like he might suffer the same fate as the protagonists of the book - being labelled a crackpot!

He's sending a signal... but is it information? (1)

Ed Avis (5917) | more than 7 years ago | (#16867246)

If you decide when planning the experiment that you're going to put the second photon into state X, and then 50ms before you do so you observe the first photon going into state X, then arguably you've seen some communication going backwards in time, but no information. You knew that state X was going to be used anyway.

More interesting would be to measure the state of the first photon and use that to affect the second one. So if the first one goes to state X, set the second one 50ms later to state Y, and vice versa. Or fix up a random number generator to change the state of the second photon and then observe the first photon to predict 50ms ahead of time what the random number is going to be. I'd expect this kind of thing is impossible.

Stupid know-nothing-about-quantum-physics question (2, Interesting)

aendeuryu (844048) | more than 7 years ago | (#16867250)

Wouldn't we know if the test was successful before we actually conducted it?

Best case scenario (1)

Knutsi (959723) | more than 7 years ago | (#16867258)

Hm, this is very interesting news. If it's possible to send information something more than 50 ms back, it could be very neat. You don't need a very complicated type og carrier to trasnsmit digital information, so imagine a digital broadcast sent back 200 years. Now that would really rock things.

That may be the core tho'. If it proves possible to send a cure for cancer back 200 years, imagine the impact for the future! Also, this is one of those things I suspect would not happen in nature on it's own, so we are entering a place where humans are truly walking into the unknown, as no such thing can be observed naturally. Perhaps we are actually at a point where time will go from linear to chaos since we can changes past events.

However, if you think about it, it appears logical that if you send something back, you will stop exsiting the moment you start, since time chages, thus no information is transmitted in the first place (:

Hrmz... back to work...

How will they measure the non-delayed particle? (2, Informative)

Per Abrahamsen (1397) | more than 7 years ago | (#16867268)

If they measure the non-delayed particle *before* the 50 ms have passed, the quantum state of the delayed particle will already be fixed at the time they get around to measure it.

On the other hand, if they wait 50 ms before measuring the non-delayed particle, they aren't really sending much of a signal back in time.

It isn't much use to send message back in time, if you aren't allowed to read them before the present time.

Why bother doing the test? (1)

Rik Sweeney (471717) | more than 7 years ago | (#16867296)

If it succeeds, then they'll know about it before they do it. Then again, if they do know it about it before they do it then they'll have to do it otherwise it'll create a paradox. No wait, if it does succeed then they can't NOT do it because they did do it.

I need to lie down.

Horray the experiment worked!!! (1)

CrazyJim1 (809850) | more than 7 years ago | (#16867338)

Now that we know it will work, so why should we do the work?

John Titor called (1)

kan0r (805166) | more than 7 years ago | (#16867342)

He says he has nothing to do with this.

special type of crystal ? (5, Funny)

ei4anb (625481) | more than 7 years ago | (#16867368)

I wonder if they are going to use resublimated thyotimoline?

Of course, in the clasical version of this experiment the crystal is usualy spherical with a diameter of about 20cm.

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