Have they really acheived instantaneous transmission of information?

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Offline DoctorBeaver

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Researchers have accomplished teleportation, though not of the “Beam me up, Scotty” variety. Instead, they sent information between two individual atoms of the element ytterbium, which were suspended in separate containers three feet apart. Because the quantum information instantly hops from one atom to the other without ever crossing the space between the two, scientists call the transfer “teleportation”

Extract from http://blogs.discovermagazine.com/80beats/2009/01/23/quantum-teleportation-is-a-go/

Anyone got any thoughts on this?
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Offline Vern

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I have often speculated that atoms transfer photons among each other by first sensing a suitable receiver then when one is found, the actual transfer is instantaneous. The advertising for a suitable receiver is bound by the speed of light.

Such speculation comes while contemplating Schrodinger's Cat.

This could be tested if it could be determined whether a neutron would delay its demise if there were not suitable receptors for the energy it must release to do so.
« Last Edit: 24/01/2009 15:01:50 by Vern »

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Offline DoctorBeaver

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This could be tested if it could be determined whether a neutron would delay its demise if there were not suitable receptors for the energy it must release to do so.

Interesting
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Offline Vern

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This could be tested if it could be determined whether a neutron would delay its demise if there were not suitable receptors for the energy it must release to do so.
Interesting
An easier test to devise might be to see if a neutron would decay more rapidly with an excess of suitable recptors available. That might be easier than restricting them.

I've looked back through bubble chamber results with this mindset, but so far haven't found suitable evidence.

Edit: However we do know that the act of observing can change how a system reacts; the act of observing must provide suitable receptors for the observation.
« Last Edit: 24/01/2009 15:21:34 by Vern »

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Offline yor_on

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Notice this "The wavelengths, or colors, of these photons depended on which states the electrons were in. Crossing these photons in a beamsplitter sometimes entwined the states of those electrons, a bizarre quantum phenomenon called entanglement "

What they seem to do is not to 'communicate' with the atom directly but to first 'force' it into a indeterministic 'state' then they give it a 'energy boost' to free one photon each which when subsequently observed will 'lock' the atoms states.

So in this experiment? 'time' have no 'meaning' at all if they are correct.
It doesn't 'back up' it doesn't move forward.

'Times' 'now' belongs both to the the interaction with the photons as well as with the atoms later 'defined states' as seen from the observers frame of reference.
Don't forget that the macroscopic arrow of time are at work for the observers of this experiment.

Either this 'entangled' state is  there a soon those two photons are released, before observed, or it is created only in the observing.

But seen from the observers frame of reference time will have an arrow and if the experiment could be seen as creating entanglement before observation then we are 'isolated' from influencing the outcome.

But as they can't, as I've understood it, define what spin the ion would have before observing?
I can't see how they think to transfer information by it??
As the spin will be aleatory (depending on 'chance') every 'time'?
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Offline Vern

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Very interesting thoughts yor_on. I'll dwell upon them some.

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Offline yor_on

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Thanks Vern.
I had a weak hope that this might be such an experiment wherein one would be able to observe a macroscopic 'backlog' of time as compared to the 'now' of the enanglement.
As that would make my ideas about 'time' seem more plausible:)

And I don't see it as a teleportation, I think it's a symmetry 'defined' by those mysterious rascals, the timeless photons but without our macroscopic arrow of time.
Therefore there can't be any 'information' exchanged.

Information has a beginning and a end. It's like a flow of water, and if you want it to go both ways you will need to 'pipe' it two ways, and for that you will need to apply some 'work'.
And 'work' seems to be a definition of our macroscopic reality, or am I wrong there?
A lot of the things we take for 'granted' macroscopically seems to lose their 'direction' when observed at a QM level.

Don't take me to seriously now:)
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Offline Vern

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Researchers have accomplished teleportation, though not of the “Beam me up, Scotty” variety. Instead, they sent information between two individual atoms of the element ytterbium, which were suspended in separate containers three feet apart. Because the quantum information instantly hops from one atom to the other without ever crossing the space between the two, scientists call the transfer “teleportation”

Extract from http://blogs.discovermagazine.com/80beats/2009/01/23/quantum-teleportation-is-a-go/

Anyone got any thoughts on this?
After going through the data several times I still haven't determined how they discover that the two ions are entangled. I guess one would need to study the original paper to fully understand.

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Offline Vern

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Quote from: yor_on
And I don't see it as a teleportation, I think it's a symmetry 'defined' by those mysterious rascals, the timeless photons but without our macroscopic arrow of time.
Therefore there can't be any 'information' exchanged.
Yes; it seems that you can't know the state of both ions. They look at the state of one and assume that because they are entangled, the other is the same state. I was trying to understand how it was that they determined that the ions were entangled.

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Offline yor_on

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It is a good question.

They need to test both ions to be sure that they do have a entanglement.

---------
So?
Is there anyone here that could give us a definition of that:)
« Last Edit: 24/01/2009 17:47:19 by yor_on »
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Offline Vern

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Quote from: yor_on
So?
Is there anyone here that could give us a definition of that:)
I have studied entanglement in photons; I always speculated that it was simply a state of photons that share the same EM fields. I visualize photons as saturated points surrounded by fields that extend outward forever diminishing in amplitude with distance. The observation that when you change the state of one the other automatically assumes that changed state results from the way you change the state of the one. You must change its polarization. Polarization is a measure of the photon's fields, which in entangled photons is the same fields for each photon.

It is long winded and speculative; and I will change my mind easily if I see a better view.

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Offline LeeE

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Although the article says that the main problem is basically just to do with aiming the photons there are a couple of other issues that need to be remembered.  The first is that the state in to which the system resolves cannot be specified, so you couldn't use this technique to send a specific sequence of values; the sequence would be random.  The second is that the state can't be examined without resolving it; the receiver would need to know that the sender has resolved their state before they [the receiver] examined their state, otherwise instead of the sender sending their state to the receiver, the receiver is sending their state to the sender.
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Offline yor_on

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Yep LeeE.
:)
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Offline Vern

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Quote from: LeeE
The second is that the state can't be examined without resolving it; the receiver would need to know that the sender has resolved their state before they [the receiver] examined their state, otherwise instead of the sender sending their state to the receiver, the receiver is sending their state to the sender.
Interesting; it seems that maybe two way communication might happen if the sender and receiver could synchronize their observations just right.

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Offline LeeE

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Quote from: LeeE
The second is that the state can't be examined without resolving it; the receiver would need to know that the sender has resolved their state before they [the receiver] examined their state, otherwise instead of the sender sending their state to the receiver, the receiver is sending their state to the sender.
Interesting; it seems that maybe two way communication might happen if the sender and receiver could synchronize their observations just right.

I can't see how that could work because it would need to be resolved in to two simultaneous states, which is a sort of contradiction in terms.  Also, how would you achieve syncronisation between the two parties?  You're back to light-speed limits again.
...And its claws are as big as cups, and for some reason it's got a tremendous fear of stamps! And Mrs Doyle was telling me it's got magnets on its tail, so if you're made out of metal it can attach itself to you! And instead of a mouth it's got four arses!

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Offline Vern

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Quote from: LeeE
I can't see how that could work because it would need to be resolved in to two simultaneous states, which is a sort of contradiction in terms.  Also, how would you achieve syncronisation between the two parties?  You're back to light-speed limits again.
Yes it would be problematic. I was thinking that slight changes (delay) in the observation ticks might put you in the receiving or sending mode. But then I don't know how you could know which mode you were in.

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Offline yor_on

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I don't think you will be able to send any information if you can't decide/lock the 'spin' before 'observing' it?
But if you could find out the 'spin' in advance, without observing, you would still need to reach a 'consensus' on that with your friends at Betelgeuse:)

And that 'consensus' would still need to be transmitted at lightspeed:)
Both ways::))
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Offline LeeE

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How could you know it's state without observing it?
...And its claws are as big as cups, and for some reason it's got a tremendous fear of stamps! And Mrs Doyle was telling me it's got magnets on its tail, so if you're made out of metal it can attach itself to you! And instead of a mouth it's got four arses!

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Offline Vern

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How could you know it's state without observing it?
I haven't got that figured out [:)] Maybe why we still communicate at light speed.

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Offline LeeE

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Maybe why we still communicate at light speed

Yup, I reckon.

Having thought about this a bit more though, there is one aspect about this that I've realised that I'm not sure about.  Does resolving the sender system actually resolve the receiver system, or does it just restrict the possible state of the receiver system so that when it's eventually resolved it can only resolve in to one possible state, dictated by the outcome of resolving the sender system?

Does anyone actually know the answer to this for sure?
...And its claws are as big as cups, and for some reason it's got a tremendous fear of stamps! And Mrs Doyle was telling me it's got magnets on its tail, so if you're made out of metal it can attach itself to you! And instead of a mouth it's got four arses!

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Offline Vern

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I sure don't know the answer.

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Offline JP

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Does resolving the sender system actually resolve the receiver system, or does it just restrict the possible state of the receiver system so that when it's eventually resolved it can only resolve in to one possible state, dictated by the outcome of resolving the sender system?

Is there a measurable difference between these two outcomes?  Philosophy aside, QM is about predicting the values of measurements.  It seems to me that in both cases, you know with 100% certainty that the measurement has to give you the resolved state.

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Offline LeeE

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What I was wondering about is that it's the act of measuring the state that resolves the state, as I understand it.  So although the first system may have been measured, and as a consequence, had it's state resolved, the second system has not yet been resolved and it will not be resolved until measured, at which point it can only resolve in to one possible state because of the entanglement.  Thus it is only the possible state for the second system that is conveyed instantly.
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Offline yor_on

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What I was wondering about is that it's the act of measuring the state that resolves the state, as I understand it.  So although the first system may have been measured, and as a consequence, had it's state resolved, the second system has not yet been resolved and it will not be resolved until measured, at which point it can only resolve in to one possible state because of the entanglement.  Thus it is only the possible state for the second system that is conveyed instantly.

If you find the answer to that one I would love to hear it LeeE.
And I think it should be worth a Nobel price:)

I should know.
I'm a Swede::))
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Offline Chemistry4me

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I should know.
I'm a Swede::))
And what is that supposed to mean? Are you getting complacent yor_on?

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Offline yor_on

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What?
With you around:)

No chance of that::))
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Offline Chemistry4me

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Good good, that is good to hear!

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Offline swansont

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After going through the data several times I still haven't determined how they discover that the two ions are entangled. I guess one would need to study the original paper to fully understand.

The two ions are excited and can decay in two possible ways (two colors).  The emitted light for both is sent through beamsplitters, so you don't know which ion gave which photon (two paths).  There is one combination of photons and paths where you don't know which ion is in which state, and this uncertainty is the same as saying they are entangled in a superposition of the two.

http://www.sciencedaily.com/releases/2009/01/090122141137.htm [nofollow]

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Offline Vern

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Quote from: swansort
The two ions are excited and can decay in two possible ways (two colors).  The emitted light for both is sent through beamsplitters, so you don't know which ion gave which photon (two paths).  There is one combination of photons and paths where you don't know which ion is in which state, and this uncertainty is the same as saying they are entangled in a superposition of the two.
Okay; I spent another few minutes going over the article. I can understand that if you look at the state of one of the entangled ions, you then know the state of the other. But it looks like getting the ions into the entangled state requires processes that are limited to c.

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Offline yor_on

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Ok, reading "There is one combination of photons and paths where you don't know which ion is in which state, and this uncertainty is the same as saying they are entangled in a superposition of the two." gave me a slight dizziness.

For me a entanglement primarily is when you split one wave into two.
This experiment seems if it is correct allow us to 'blend' as many 'waves' we like inside that beamsplitter and call the result entangled?

Does this mean that the absence of knowledge will be entanglement, and 'information'?
I have definite problems understanding the explanation given in the article
It is rather 'sloppy' writing there it seems.

Or I am really thick:)

Let us take a look on this experiment again.
We have two Ions (= electrons missing, or, being to many for a given atom) 'A' and 'B'
'A'  gets exited so it it is in a 'super position', meaning that it has a possible 50/50 chance of being in a given state (a or b, sort of).
Then we excite both Ions 'A' and 'B' and both releases one photon.
Those wander through a fiber-optic cable and 'meets', coming from opposite sides, to a beamsplitter.

So what is a beamspitter then?
"A beam splitter is an optical device that splits a beam of light in two.
In its most common form, a cube, it is made from two triangular glass prisms which are glued together.
The thickness of the resin layer is adjusted such that (for a certain wavelength)
half of the light incident through one "port" is reflected and the other half is transmitted.
Polarizing beam splitters use birefringent materials, splitting light into beams of differing polarization.

Another design is the use of a half-silvered mirror.
This is a plate of glass with a thin coating of aluminum (usually deposited from aluminum vapor).
With the thickness of the aluminum coating such that, of light incident at a 45 degree angle,
one half is transmitted and one half is reflected.
Instead of a metallic coating, a dielectric optical coating may be used.
Such mirrors are commonly used as output couplers in laser construction."

In this case it is easier to understand it as two waves ('A' 'B') meeting each other at that beamsplitter.
each wave will be split into two parts with one part trying to get through it, the other part will be reflected.
Already this is an entanglement, as both 'sides' of any one wave now are split into two.
So either you can see it as two Ions releasing photons, both getting entangled on their own,then mixed, meeting the detectors simultaneously.

Or, as they are coming from both sides simultaneously, you might see their waves as getting 'mixed' at that beamsplitter.
And here I get confused, when different waves meet they can reinforce each other.
Or they can quench each other but I don't see how they become 'entangled'?
But we will get two different 'half'-waves mixing into one 'whole' wave on both sides of the mirror.

Maybe one can see it as a 'entanglement'?
So let us assume that by meeting/splitting inside/outside the beamsplitter those two original waves now are 'entangled', or if you like interweaved/mixed.

That mean that the photons spin will be related when observed.
If one photon has what is called a 'spin up' when observed, the other photon must have a 'spin down' as I remember it. Here they use 'colours' to describe those possibility's.
As we have two times two possibilities from those Ions 'splitting' we should have either two, if seen as one 'whole' wave, where those two different 'half' waves now are 'mixed' or if seen as two entangled photons at each detector (from 'A' respective 'B')

As for the states of the Ions you only know at the beginning that they have an even probability to be in one of two states.
It is only when observed that this so called 'information' of any photon will 'fall out'
And as there is no 'information' defined when starting this experiment there is no way to know what 'state' of spin there might be before finally observing.

So I'm getting quite confused here?
They are saying that they are placing the Ion in a given 'groundstate' whatever that mean.
Then they state that the photons will reflect that 'groundstate'?
Or?

Then they give four possible colour combinations representing spin, polarization, or both?
I see it as two photons released from two Ions at the same time, getting split (entangled) each one by itself, and then 'mixed' together as two 'whole' waves, half from each Ion, again.

As I said, it made most sense when seen as waves, but then I'm not sure that mixing two already entangled 'waves' produces one entanglement afterwards?

But if they see it as two entanglements meeting a detector simultaneously?
then there would be four possibility's, right.

I don't get it to make sense.
Do you?
« Last Edit: 01/02/2009 02:16:08 by yor_on »
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Offline Vern

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Hi yor_on; I think that the thing observed would be polarization in photons and maybe spin in the ions. I am with you in not understanding the whole concept of superposition. I know that it means an undetermined state, but don't see how it can mean all possible states at the same time. But that is QM theory; I don't see how it is proven.

Someone here recently pointed out that observations involve an event and an observer and that the two comprise a system. An observation for one such system does not guarantee that another such system with the same event but a different observer will agree on the outcome. It is difficult to fathom.
« Last Edit: 01/02/2009 03:37:11 by Vern »

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Offline swansont

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Superposition is being in two states at once using the description (basis) that you are using to describe your system.  It would be like using an XY coordinate system to describe the position of something that is normally only on either axis.  But you put the item on the line at 45º and now it's in both states at once.  (You could, however, use a different coordinate system to describe that particle: rotate your system by 45º and it's on an axis again).  In this case it looks to be a superposition of the "spin up" and "spin down" states for the electron.  And yes, it's confusing and made more so because it's a popular article summary of some pretty advanced QM.

The wording of the article linked to, saying that in most cases the photons cancel out and end up at the same detector, sounds like they are interfering, and that the interference is what entangles the photon states, and by extension, the ion states.



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Offline yor_on

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Swansont:)

Yeah interference is definitively there, but if considered as waves I would expect that to be due to waves 'normal' interactions, quenching and strengthening.

But that mixing waves is 'entanglement'?
Do they transfer some magical property to mixing two already entangled waves.
Or is there a 'real' reason to why they call that result 'entangled'

To prove that this would be a real 'entanglement' they most certainly need to observe both detectors and observe that the spins are correct, don't you agree?

The idea, if correct, will allow us to create a 'network' of entanglements it seems to me?
And could we transfer information through that network we would have a 'direct' system communicating via one node to all nodes.

I could easily write a SF wherein this planet Erh :) have sent out entangled particles in such a 'net', all of them created as to be the same from one 'original' beamsplitter, for eons just waiting for us to observe their state and then having an instant communication::))

Ahh;;)) Perhaps even sending it/them 'backwards' in time, hmm.
And if those concepts worked I would expect it to be already done too:)
As with monkeys and typewriters, there should be this possibility already 'materialized' in a expanding possibly 'infinite' universe.
Yes, I will need to get myself one of those new 'spin' readers:)


If the idea worked that is:)
I know that there is a definite difference between ftl and information flow.
And it make eminent sense to me.

It is 'spacetime' who define what works, not us.
To get to a state where FTL (including information transfer) would be possible we need either to get 'outside' of 'spacetime', but if so I'm not sure that we could get back in, as I have this feeling that there will be two problems to that. One to find our way out, and another to find our way in:)

Or we need to break what I see as 'spacetimes' symmetry.
But how to do that without creating enormous energy expenditure?

Maybe BEC:s are an answer, as we get a lot of strange effects out from that without expending to much energy though. As a BEC seems to be a way to break 'symmetry's', just as high energy particle research does.
« Last Edit: 01/02/2009 16:31:46 by yor_on »
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Offline Vern

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Quote from: swansont
Superposition is being in two states at once using the description (basis) that you are using to describe your system.  It would be like using an XY coordinate system to describe the position of something that is normally only on either axis.  But you put the item on the line at 45º and now it's in both states at once.  (You could, however, use a different coordinate system to describe that particle: rotate your system by 45º and it's on an axis again).
This is the most understandable description of superposition that I have ever seen. Thank you for your contribution.
« Last Edit: 01/02/2009 17:41:36 by Vern »