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Magnetic Monopoles Detected for the First Time

Discussion in 'Science & Technology' started by SS-18 ICBM, Sep 4, 2009.

  1. SS-18 ICBM

    SS-18 ICBM Final Threshold

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    Magnetic Monopoles Detected In A Real Magnet For The First Time

    Link to research abstract.

     
  2. Atrebates

    Atrebates Chieftain

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    Well this is huge news if confirmed.

    Ah wait...[reading the links] Looks like a clever construct that makes dipoles look like a monopole. How odd, interesting stuff.
     
  3. dutchfire

    dutchfire Moderator Moderator

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    A friend of mine is working there at the moment.

    Interesting news, though it doesn't really seem to be "the real big thing".

     
  4. Tabster

    Tabster Chieftain

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    Just wondering, is something physicist have been searching for, like Higgs boson?

    Does this news, if confirmed, change any current ideas about electromagnetism or particle physics ? or is it just evidence backing up what was already thought ?
     
  5. Gigaz

    Gigaz civoholic

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    If that is true it would indeed be one of the most important findings in experimental physics ever.
     
  6. Atrebates

    Atrebates Chieftain

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    Yes, monopoles were searched for extensively.

    True monopoles would mess up physics in a serious way, they invalidate one of Maxwell's equations that the divergengence of a mag field must be zero(for background: there are 4eqts called Maxwells equations that completely sum up all electromagnetic phenomena and Special relativity is a consequence of Maxwell's eqts).

    However, the articles do not point to "real" monopoles. They are a clever collection of dipoles that happen to look like a monopole at the right length scale.
     
  7. Gigaz

    Gigaz civoholic

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    It is actually simple to find out whether a black box contains several magnetic dipoles or a magnetic monopole. I agree that this is probably a clever collection of dipoles but they have obviously found some weird quantum thing that makes them look like a monopole. I wonder how far two monopoles can be departed from each other.
     
  8. Atrebates

    Atrebates Chieftain

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    Read the links in the OP.

    They don't 100% explain but it looks like a solid state trick whereby (in a given crystal) the dipoles are aligned into a stucture a bit like a carbon nanotube, and there is a blob of monopole at each end of the tube.

    Now that's clearly not quite what's going on because that will never satisfy the divB=/=0 (for any gaussian surface) that defines a monopole.
     
  9. Gigaz

    Gigaz civoholic

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    I read it. They wouldn't claim to have a monopole if the thing does not behave like a monopole.
     
  10. Earthling

    Earthling Chieftain

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    Understatement much? ;)

    But this is actually really interesting news, I followed Atrebates' advice and what he got out of the article seems to be what I've gotten - it's a very interesting effect but doesn't seem like a true monopole.
     
  11. frekk

    frekk Scourge of St. Lawrence

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    Are you kidding? They make statements that get taken out of context by journalists all the time. Remember "quantum teleportation"? Nice phrase, except that it only communicates information. If communication were teleportation, then whoever sent the first smoke signal did it. Nor is it instantaneous - it can only work in conjunction with some other communication medium, such as a telephone line or radio transmission (or even smoke signals!), and in terms of communication, is limited by the speed and bandwidth of that communication. What it really is, is quantum encryption.

    If you said to a journalist "well, I'm oversimplifying in order to explain it in lay terms, but in a sense, you could think of it as being vaguely like X, however ..." the headline will say "Scientists discover X!!"
     
  12. uppi

    uppi Chieftain

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    "Quantum teleportation" does not communicate information. It is however instantaneous and that's where the "teleportation" comes from. Science journalism is notoriously bad, but in this case I don't blame them. Entanglement is a difficult subject and it's easy to get it wrong.

    If you compare quantum entanglement to smoke signals, then you badly missed the point of it.
     
  13. frekk

    frekk Scourge of St. Lawrence

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    That's precisely what it does.

    In quantum teleportation, an unknown quantum state is faithfully transferred from a sender (Alice) to a receiver (Bob). To perform the teleportation, Alice and Bob must have a classical communication channel and must also share quantum entanglement -- in the protocol we employ*, each possesses one half of a two-particle entangled state. Alice makes an appropriate projective measurement (Bell measurement) of the unknown state together with her component of the shared entangled state. The result of this measurement is a random piece of classical information which Alice sends to Bob over their classical communication channel. Bob uses this information to choose a unitary transformation which he performs on his component of the shared entangled state, thus transforming it into an output state identical to the original (unknown) input.

    http://www.its.caltech.edu/~qoptics/teleport.html

    No, see the abstract above. It has to do with the relational state being changed in two distant locations via entanglement. In this sense it is action at a distance. However, the only use is the transfer of information - no thing is being removed from one place and relocated at another, there is only a relation between two things at a distance that is maintained.

    The idea of teleportation doesn't come from the speed of the thing. It comes from the fact that, with no intermediate action occuring, a change in state in one particle is reflected by a change in state in another particle. A relation or state is changing at a distance. This does not mean you can send apples or any physical thing from one place to another ... it only means you can have a particle's spin state in one location reflected in another location.

    You missed the point if you think I was comparing them. Quantum "teleportation" requires a conventional medium to make use of the information being transferred. Technically, one could use smoke signals or any other conventional medium. In the example above, Alice could send the classical information by smoke signal. Or farting in Morse code, or whatever.
     
  14. uppi

    uppi Chieftain

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    No, you're reading it wrong. The point of quantum teleportation is the instantaneous transfer of a quantum mechanical state. This is not equivalent to information. Actually all information is going over the classical channel in these protocolls. If any information traveled through the quantum channel, you could use this for instantaneous communication.

    Actually the state is relocated. At the original site it is destroyed and then created at the other site.

    Yes, you cannot send any physical thing by quantum teleportation. However you cannot send any information either. What you can do is transfer a qunatum mechanical state in such a way that it doesn't exist at it's original place any more. And this happens instantaneously. Hence "quantum teleportation".


    Again you missed the point: You don't need the conventional medium to make use of the information, you need the conventional medium to transfer any information at all.
    No matter how slow that conventional medium is, be it electric signals, smoke signals or snail mail, the actual transfer, the exciting thing, happens instantaneously (Well, assuming that you can keep the state alive until the snail arrives...).
     
  15. frekk

    frekk Scourge of St. Lawrence

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    Yes, but the only use of that is qubits.

    No. If a state is being transferred - actually if anything detectable at all is being transferred - it can be used to send information. Alice and Bob have entangled particles; Alice sends Bob classical bits from her measurement of the particle, which Bob can use to reproduce qubits on Alice's end.

    Information is being passed through the quantum channel, because a state is information. If anything measurable is being passed, information is being passed, because any measurement is an expression of value and expressions of value are information. However, instantaneous communication is not possible because it is necessary for Alice to send her measurements to Bob before he can decipher, with accurate fidelity, these states as qubits.

    True, but in practical terms, there's no violation of the no-communication theorem because of the need for a classical communications channel.
     
  16. uppi

    uppi Chieftain

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    You cannot equate a state or a qubit with classical information, because one state cannot be measured. Any classical information about that state is generated at Bob's place. Alice doesn't know anything about the state, until Bob tells her about his measurements. How can Alice transfer information, that doesn't even exist yet?

    You could define a qubit as "quantum information" and could say that quantum information was transferred. But this is not equal to classical information and these shouldn't be confused.
     

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