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The article's title is misleading: they actually mean a new kind of permanent magnet (that was theoretically predicted but hadn't been observed until now), not

by pdonis 3y ago

The article's title is misleading: they actually mean a new kind of permanent magnet (that was theoretically predicted but hadn't been observed until now), not a new kind of magnetism (as in, something not predicted or accounted for by our existing theory of electromagnetism).

dang 3y ago
Ok, we've downgraded magnetism to just a magnet in the title above. Thanks!
- nhatcher 3y ago
  If I am reading correctly it is a new kind of magnetism: https://en.m.wikipedia.org/wiki/Magnetism#Types https://en.m.wikipedia.org/wiki/Magnetism#Types And I am not sure it can be called a magnet. It's definitely a new kind of magnetic state
  - pdonis 3y ago
    > it is a new kind of magnetism It's a new kind of magnetic medium that had not been previously observed. It is not something that can't be explained by our existing theory of electromagnetism. > I am not sure it can be called a magnet. It's an object that has magnetic properties. That's a magnet. It's a different kind of magnet from those we had previously observed.
    - lupire 3y ago
      Each magnetic medium exhibits its own kind of magnetism. Sometimes words are slightly ambiguous. This is not a hill to die on.
      - pdonis 3y ago
        > Each magnetic medium exhibits its own kind of magnetism. I agree that it is sometimes described this way, although as one commenter upthread said, such use of language is more common when physicists are talking among themselves, not when they are talking to the public. The comments in this discussion indicate that I am by no means the only one who was confused by the original wording. So I think the change was helpful.
purpleflame1257 3y ago
Yeah, for a minute there I thought they had found the monopole
- db48x 3y ago
  Monopoles are already accounted for though, because they’re explicitly ruled out by the character and form of the laws of electromagnetism. ∇⋅B = 0, or “the divergence of the magnetic field is zero”.
  - eigenket 3y ago
    I mean I we found a magnetic monopole then we'd just change that one of Maxwell's equations so it looks like the corresponding electrical equation Div(E) = ρ/ε. It essentially just happens that the thing which correspond to ρ for the B field is 0.
    - db48x 3y ago
      Except that if the divergence of the magnetic field were anything other than zero, the laws as presently written wouldn’t successfully predict electromagnetic effects. Because the laws as currently written _do_ make predictions, and exquisitely precise predictions at that, the divergence must be zero with no monopoles at all or so close to zero that monopoles would be extraordinarily weak if they did exist. Their effects would be so slight that they would be useless for any practical purpose except possibly impressing the Nobel committee.
      - eigenket 3y ago
        I don't really understand your point here. If we do discover magnetic monopoles (which would not necessarily be very weak but instead very rare) then we would take the equation Div(B) = 0 And update it to say Div(B) = sigma Where sigma is a field describing the monopole density. Theres a ready "gap" in Gauss' law for magnetism where you can easily stick monopoles. Of course the divergence would be zero in the absence of monopoles, just as the divergence of the electric field is zero in the absence of electric monopoles, but decidedly non-zero when there's an electron around.
EvgeniyZh 3y ago
I'd say that, for example, paramagnetism is kind of magnetism, not kind of magnet.
- pdonis 3y ago
  I agree that one could say that, but it still only makes sense in a context where you have an object that has this kind of magnetism, i.e., a magnet. And the same is true of the "magnetism" whose discovery this article is describing: it's a kind of magnetic state of an object.
  - planede 3y ago
    Paramagnetism/diamagnetism doesn't apply to "magnets", which I assume you use to refer to materials that have external magnetic field without applying external excitation.
    - pdonis 3y ago
      > Paramagnetism/diamagnetism doesn't apply to "magnets" I also said "objects" in the GP to this post. There is no paramagnetism or diamagnetism in vacuum. You need an object made of an appropriate material. I would not insist on calling such an object a "magnet" if there is an objection to that. However, what is described in the article is a kind of permanent magnetism; the term "magnet" applies to that in any case.
ddingus 3y ago
I was looking for the same and hot the paywall.
z2h-a6n 3y ago
As a condensed matter physicist (working in the same field but not on altermagnetism specifically), I would say this is being much more picky about the language than most people in the field tend to be. Moreover, I'm not sure you're even right about the language. You are correct that this doesn't involve any changes to our understanding of electromagnetism in general; whether or not that means that altermagnetism is not a new type of magnetism is a matter of semantics. If I read in a paper or heard in a seminar that "altermagnetism is a new type of magnetism", I would not quibble with the language, though that phrase by itsself is almost tautologically pointless. If you want a more technically meaningful phrase, I would propose that altermagnetism is a newly-discoved "magnetically ordered phase". Of course that doesn't fit so well in a headline.
- duckman1 3y ago
  [dead]
- pdonis 3y ago
  > I would say this is being much more picky about the language than most people in the field tend to be. Perhaps, but I think that when communicating with the public (as opposed to communicating with other physicists), "a new kind of magnetism" suggests something that isn't explained by our current theories, not just something that our existing theories predict but hadn't been observed before.
- sesm 3y ago
  > altermagnetism is a newly-discoved "magnetically ordered phase" I would prefer this headline.
- lanza 3y ago
  Sounds like shorthand terminology in your subfield is okay with the usage of "magnetism." But that's local slang, as a (former) high energy theorist I interpret the phrase "a new form of magnetism" as a new gauge theory or something equally spectacular. So I just rolled my eyes at the headline.
- Suppafly 3y ago
  As someone who isn't a physicist, headlines like this make me think they discovered magnets that work with some non-ferrous material, which would be amazing. But then I was like "wouldn't that be crazy" and then came to the comments specifically to see what the actual explanation would be.

by pdonis 3y ago

dang 3y ago

Ok, we've downgraded magnetism to just a magnet in the title above. Thanks!

nhatcher 3y ago
If I am reading correctly it is a new kind of magnetism: https://en.m.wikipedia.org/wiki/Magnetism#Types https://en.m.wikipedia.org/wiki/Magnetism#Types And I am not sure it can be called a magnet. It's definitely a new kind of magnetic state
- pdonis 3y ago
  > it is a new kind of magnetism It's a new kind of magnetic medium that had not been previously observed. It is not something that can't be explained by our existing theory of electromagnetism. > I am not sure it can be called a magnet. It's an object that has magnetic properties. That's a magnet. It's a different kind of magnet from those we had previously observed.
  - lupire 3y ago
    Each magnetic medium exhibits its own kind of magnetism. Sometimes words are slightly ambiguous. This is not a hill to die on.
    - pdonis 3y ago
      > Each magnetic medium exhibits its own kind of magnetism. I agree that it is sometimes described this way, although as one commenter upthread said, such use of language is more common when physicists are talking among themselves, not when they are talking to the public. The comments in this discussion indicate that I am by no means the only one who was confused by the original wording. So I think the change was helpful.

purpleflame1257 3y ago

Yeah, for a minute there I thought they had found the monopole

db48x 3y ago
Monopoles are already accounted for though, because they’re explicitly ruled out by the character and form of the laws of electromagnetism. ∇⋅B = 0, or “the divergence of the magnetic field is zero”.
- eigenket 3y ago
  I mean I we found a magnetic monopole then we'd just change that one of Maxwell's equations so it looks like the corresponding electrical equation Div(E) = ρ/ε. It essentially just happens that the thing which correspond to ρ for the B field is 0.
  - db48x 3y ago
    Except that if the divergence of the magnetic field were anything other than zero, the laws as presently written wouldn’t successfully predict electromagnetic effects. Because the laws as currently written _do_ make predictions, and exquisitely precise predictions at that, the divergence must be zero with no monopoles at all or so close to zero that monopoles would be extraordinarily weak if they did exist. Their effects would be so slight that they would be useless for any practical purpose except possibly impressing the Nobel committee.
    - eigenket 3y ago
      I don't really understand your point here. If we do discover magnetic monopoles (which would not necessarily be very weak but instead very rare) then we would take the equation Div(B) = 0 And update it to say Div(B) = sigma Where sigma is a field describing the monopole density. Theres a ready "gap" in Gauss' law for magnetism where you can easily stick monopoles. Of course the divergence would be zero in the absence of monopoles, just as the divergence of the electric field is zero in the absence of electric monopoles, but decidedly non-zero when there's an electron around.

EvgeniyZh 3y ago

I'd say that, for example, paramagnetism is kind of magnetism, not kind of magnet.

pdonis 3y ago
I agree that one could say that, but it still only makes sense in a context where you have an object that has this kind of magnetism, i.e., a magnet. And the same is true of the "magnetism" whose discovery this article is describing: it's a kind of magnetic state of an object.
- planede 3y ago
  Paramagnetism/diamagnetism doesn't apply to "magnets", which I assume you use to refer to materials that have external magnetic field without applying external excitation.
  - pdonis 3y ago
    > Paramagnetism/diamagnetism doesn't apply to "magnets" I also said "objects" in the GP to this post. There is no paramagnetism or diamagnetism in vacuum. You need an object made of an appropriate material. I would not insist on calling such an object a "magnet" if there is an objection to that. However, what is described in the article is a kind of permanent magnetism; the term "magnet" applies to that in any case.

ddingus 3y ago

I was looking for the same and hot the paywall.

z2h-a6n 3y ago

As a condensed matter physicist (working in the same field but not on altermagnetism specifically), I would say this is being much more picky about the language than most people in the field tend to be. Moreover, I'm not sure you're even right about the language. You are correct that this doesn't involve any changes to our understanding of electromagnetism in general; whether or not that means that altermagnetism is not a new type of magnetism is a matter of semantics. If I read in a paper or heard in a seminar that "altermagnetism is a new type of magnetism", I would not quibble with the language, though that phrase by itsself is almost tautologically pointless. If you want a more technically meaningful phrase, I would propose that altermagnetism is a newly-discoved "magnetically ordered phase". Of course that doesn't fit so well in a headline.

duckman1 3y ago
[dead]
pdonis 3y ago
> I would say this is being much more picky about the language than most people in the field tend to be. Perhaps, but I think that when communicating with the public (as opposed to communicating with other physicists), "a new kind of magnetism" suggests something that isn't explained by our current theories, not just something that our existing theories predict but hadn't been observed before.
sesm 3y ago
> altermagnetism is a newly-discoved "magnetically ordered phase" I would prefer this headline.
lanza 3y ago
Sounds like shorthand terminology in your subfield is okay with the usage of "magnetism." But that's local slang, as a (former) high energy theorist I interpret the phrase "a new form of magnetism" as a new gauge theory or something equally spectacular. So I just rolled my eyes at the headline.
Suppafly 3y ago
As someone who isn't a physicist, headlines like this make me think they discovered magnets that work with some non-ferrous material, which would be amazing. But then I was like "wouldn't that be crazy" and then came to the comments specifically to see what the actual explanation would be.