Groups Isomorphisms?


by ChrisVer
Tags: groups, isomorphisms
ChrisVer
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#1
Nov23-13, 11:52 AM
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I am not really sure whether this topic belongs here or not, but since my example will be a certain one I will proceed here....

Someone please explain me what "isomorphism" means physically? For example what is the deal in saying that the proper orthochronous Lorentz group is isomorphic to SU(2)xSU(2)?
I can understand as far that this example breaks everything in left-right handed movers, but I just can't generalize it in everything when we are talking about isomorphisms....
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dauto
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#2
Nov23-13, 01:30 PM
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It means that the generators of the group follow identical algebras
George Jones
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Nov25-13, 05:24 PM
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Quote Quote by ChrisVer View Post
For example what is the deal in saying that the proper orthochronous Lorentz group is isomorphic to SU(2)xSU(2)?
The proper orthochronous Lorentz group is not isomorphic to SU(2)xSU(2).

Bill_K
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#4
Nov25-13, 06:08 PM
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Groups Isomorphisms?


Quote Quote by George Jones View Post
The proper orthochronous Lorentz group is not isomorphic to SU(2)xSU(2).
Don't you think it would be even more useful, George, if you told us what it IS isomrphic to.
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Nov25-13, 09:50 PM
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Maybe I should have stayed quiet. There is a fair bit going on, and I am not sure that I can explain all of it well.

The statement in the OP is not true at the group level, but it is almost true at the level of Lie algebras (generators), i.e., it is true after the relevant real Lie algebras have been complexified.

I might try a longer explanation later.


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